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Coronary Artery Bypass Surgery With or Without Mitral Valve Annuloplasty in Moderate Functional Ischemic Mitral Regurgitation Final Results of the Randomized Ischemic Mitral Evaluation (RIME) Trial
Abstract
Background:
The role of mitral valve repair (MVR) during coronary artery bypass grafting (CABG) in patients with moderate ischemic mitral regurgitation (MR) is uncertain. We conducted a randomized, controlled trial to determine whether repairing the mitral valve during CABG may improve functional capacity and left ventricular reverse remodeling compared with CABG alone.
Methods and results:
Seventy-three patients referred for CABG with moderate ischemic MR and an ejection fraction >30% were randomized to receive CABG plus MVR (34 patients) or CABG only (39 patients). The study was stopped early after review of interim data. At 1 year, there was a greater improvement in the primary end point of peak oxygen consumption in the CABG plus MVR group compared with the CABG group (3.3 mL/kg/min versus 0.8 mL/kg/min; P<0.001). There was also a greater improvement in the secondary end points in the CABG plus MVR group compared with the CABG group: left ventricular end-systolic volume index, MR volume, and plasma B-type natriuretic peptide reduction of 22.2 mL/m(2), 28.2 mL/beat, and 557.4 pg/mL, respectively versus 4.4 mL/m(2) (P=0.002), 9.2 mL/beat (P=0.001), and 394.7 pg/mL (P=0.003), respectively. Operation duration, blood transfusion, intubation duration, and hospital stay duration were greater in the CABG plus MVR group. Deaths at 30 days and 1 year were similar in both groups: 3% and 9%, respectively in the CABG plus MVR group, versus 3% (P=1.00) and 5% (P=0.66), respectively in the CABG group.
Conclusions:
Adding mitral annuloplasty to CABG in patients with moderate ischemic MR may improve functional capacity, left ventricular reverse remodeling, MR severity, and B-type natriuretic peptide levels, compared with CABG alone. The impact of these benefits on longer term clinical outcomes remains to be defined.
... Screening of titles and abstracts led to the exclusion of 1614 pub-lications. After a full-text review, an additional 16 publications were excluded, leaving 20 studies [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] for inclusion. The process of literature selection is illustrated in Fig. 1. ...
... Further details regarding the fundamental characteristics of these studies are provided in Table 1 (Ref. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]). ...
... The analysis incorporated data from 20 RCTs [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] focusing on the 30-day all-cause mortality rate. The findings revealed that MVr significantly reduced the 30 Table 5. ...
Background
This study aims to systematically review the efficacy of various surgical approaches in the treatment of ischemic mitral regurgitation (IMR).
Methods
A comprehensive literature search was conducted using computerized databases, including PubMed, Cochrane Library, Embase, and Web of Science, up to February 2024. In our network meta-analysis, we utilized the Cochrane Handbook tool for quality evaluation, while a consistency model and the odds ratio (OR) were used to compile and analyze the data from the studies included, employing Stata 17.0 software for this purpose.
Results
The systematic review included a total of 20 randomized controlled trials (RCTs), which collectively involved 3111 patients and evaluated six different surgical techniques. The network meta-analysis demonstrated that mitral valve repair (MVr) exhibited a significant reduction in 30-day all-cause mortality rates when compared to coronary artery bypass grafting (CABG), mitral valve replacement (MVR), CABG combined with MVR, and transcatheter mitral valve edge-to-edge repair (TEER) using MitraClip. Furthermore, probability ranking analysis suggested that MVr may be the most effective approach in reducing 30-day all-cause mortality, while CABG combined with MVr had significantly fewer renal complications compared to CABG combined with MVR. Probability rankings also indicated that CABG+MVr may be the most effective technique in minimizing renal complications. However, there were no statistically significant differences observed in other outcome measures among the different surgical techniques.
Conclusions
Current limited evidence indicates that CABG combined with MVr may be the best surgical approach for patients with IMR. However, these conclusions are tentative and require further confirmation from more additional high-quality studies.
INPLASY Registration Number
INPLASY202420049. This study can be accessed at the following detailed address: https://inplasy.com/inplasy-2024-2-0049/, last accessed on February 11, 2024.
... Chan -RIME 13 ...
... Several techniques, including isolated restrictive mitral annuloplasty [11][12][13][14][15][19][20][21][22][23][24] RMA combined with leaflet procedure 37 , and subvalvular papillary muscle surgical repair like papillary muscles sling [1][2][3]7,9,18 , Papillary muscles approximation 1-3,5,6 , Papillary muscles relocation 4,8 , and Ring plus String 10 , have gained popularity as alternatives to the former routine of mitral valve replacement [19][20][21][22][23][24] for the surgery of secondary ischemic mitral regurgitation. In the last decade the introduction of subvalvular procedures appeared to enhance the outcomes of valve repair. ...
... There is an ongoing debate over the effectiveness of the combined MV repair procedure with CABG. Although various RCTs and observational studies indicate the advantages of including MV repair to CABG [3][4][5][6][7][8][9][10][11][12][13]25,26 , as it can prevent further negative changes and decrease the possibility of heart failure 13,15,26 , some contradict these findings 12,27,28,45 and others have neutral results 29,46 . For patients with severe ischemic mitral regurgitation, surgical revascularization's benefits are well-established, provided that they have coronary targets that are susceptible to high-grade proximal lesions affecting ischemic yet viable myocardium. ...
The objective of this study is to ascertain whether subvalvular papillary muscle repair in conjunction with restrictive mitral valve annuloplasty represents the most efficacious treatment for patients presenting with secondary ischemic mitral regurgitation, as compared to restrictive mitral valve annuloplasty alone and to mitral valve replacement. A network meta-analysis was conducted to investigate outcomes of randomized controlled trials, propensity-matched studies, and observational studies, comparing various treatments for secondary ischemic mitral regurgitation. The average follow-up duration for late mortality was 4.4 years. Coronary artery bypass grafting (CABG) without mitral valve surgery had a late mortality incidence of 3.7%. Restrictive mitral annuloplasty demonstrated a rate of 6.5%, while restrictive mitral annuloplasty + CABG resulted in a rate of 4.1%. Subvalvular papillary muscle repair plus restrictive mitral annuloplasty ± CABG and mitral valve replacement + CABG had rates of 4.4% and 5.1%. SUCRA analysis showed that CABG was the most effective treatment for reducing late mortality (70.0%). This was followed by subvalvular papillary muscle repair plus restrictive mitral annuloplasty with or without CABG (62.4%). The top strategy for decreasing early death, reoperation, and readmission to the hospital for heart failure is subvalvular papillary muscle repair plus restrictive mitral annuloplasty with or without CABG, based on SUCRA probabilities (84.6%, 85.54%, and 86.3%, respectively). Subvalvular papillary muscle repair plus restrictive mitral annuloplasty ± CABG has potential to reduce the risks associated with early mortality, reoperation, and re-hospitalization for heart failure. However, further research is required to substantiate these findings.
Supplementary Information
The online version contains supplementary material available at 10.1038/s41598-024-75173-y.
... After carefully reviewing the full text of the remaining studies, eight studies [13][14][15][16][17][18][19][20] were excluded for the following reasons [1] : patients had mixed MR etiologies [2] , the grade of MR was severe, and [3] the comparison was MVR + CABG versus CABG + LV reshaping. Ultimately, six RCTs [9,[21][22][23][24][25] were included in the quantitative meta-analysis. The search, screening, and study selection processes are illustrated in Fig. 1. ...
... Operative mortality was reported in all RCTs [9,[21][22][23][24][25] . The pooled analysis using a random-effects model revealed no statistically significant difference in operative mortality between patients who underwent MVR + CABG and those who underwent CABG alone (11/309 vs. 8/317; RR, 1.244; 95% CI, 0.514-3.014; ...
... The analysis revealed no significant heterogeneity (I 2 = 0%). The forest plot is shown in Fig. 3. Long-term mortality was reported in five RCTs [9,[21][22][23]26] . The pooled analysis using a random-effects model revealed no statistically significant difference in long-term mortality between patients who underwent MVR + CABG and those who underwent CABG alone (30/285 vs. 45/298; RR, 0.676; 95% CI, 0.417-1.097; ...
Background
The efficacy of mitral valve repair (MVR) in combination with coronary artery bypass grafting (CABG) for moderate ischaemic mitral regurgitation (IMR) remains unclear. To evaluate whether MVR + CABG is superior to CABG alone, the authors conducted a systematic review and meta-analysis of existing randomized controlled trials (RCTs).
Methods
The authors searched PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials for eligible RCTs from the date of their inception to October 2023. The primary outcomes were operative (in-hospital or within 30 days) and long-term (≥ 1 year) mortality. The secondary outcomes were postoperative stroke, worsening renal function (WRF), and reoperation for bleeding or tamponade. The authors performed random-effects meta-analyses and reported the results as risk ratios (RRs) with 95% CIs.
Results
Six RCTs were eligible for inclusion. Compared with CABG alone, MVR + CABG did not increase the risk of operative mortality (RR, 1.244; 95% CI, 0.514–3.014); however, it was also not associated with a lower risk of long-term mortality (RR, 0.676; 95% CI, 0.417–1.097). Meanwhile, there was no difference between the two groups in terms of postoperative stroke (RR, 2.425; 95% CI, 0.743–7.915), WRF (RR, 1.257; 95% CI, 0.533–2.964), and reoperation for bleeding or tamponade (RR, 1.667; 95% CI, 0.527–5.270).
Conclusions
The findings of this meta-analysis suggest that MVR + CABG fails to improve the clinical outcomes of patients with moderate IMR compared to CABG alone.
... Follow-up visits were completed with 243 patients in total. The median follow-up time was 42 months (IQR, [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50], with the shortest follow-up time being 30 months. At the 30-month follow-up, the incidence of moderate or more MR and the proportion of NYHA class III and IV did not differ either before or after matching ( Table 3). ...
... This result was validated using multivariable regression analysis and implied that depressed LVEF could contribute to poor postoperative respiratory function, consistent with the findings of earlier studies [33,34]. Importantly, our study indicated that there was no association between depressed LV function prior to surgery and surgical mortality, consistent with results from other trials [35][36][37][38]. Within patients with reduced LVEF and moderate to severe IMR, the additional mitral valve repair beyond CABG could also improve survival [39]. ...
... The benefits of performing mitral interventions beyond CABG have been demonstrated in several studies. A randomized clinical trial of additional mitral valve repair for moderate IMR patients found greater improvements in oxygen consumption, MR severity, and LV remodeling [37]. In another trial, concomitant mitral valve repair resulted in better NYHA functional class, LV dimensions, LV function, and pulmonary artery pressure [38]. ...
Background
Numerous studies have examined the therapeutic effects of mitral valve repair during revascularization on moderate ischemic mitral regurgitation (IMR), as well as the incremental benefit of subvalvular repair alongside an annuloplasty ring. However, the impact of depressed left ventricular (LV) function on the surgical outcome of patients with moderate IMR has been rarely investigated. The aims of this single-center, retrospective, observational study were firstly to evaluate short- and medium-term outcomes in this patient group after undergoing mitral valve repair during revascularization, and secondly to assess the impact of depressed LV function on surgical outcomes.
Methods
A total of 272 eligible patients who had moderate IMR and underwent concomitant mitral valve repair and revascularization from January 2010 to December 2017 were included in the study. These patients were categorized into different groups based on their ejection fraction (EF) levels: an EF <40% group (n = 90) and an EF ≥40% group (n = 182). The median time course of follow-up was 42 months and the shortest follow-up time was 30 months. This study compared in-hospital outcomes (major postoperative morbidity and surgical mortality) as well as midterm outcomes (moderate or more mitral regurgitation, all-cause mortality, and reoperation) of the two groups before and after propensity score (PS) matching (1:1).
Results
No significant difference was observed in surgical mortality between groups (8.9% vs. 3.3%, p = 0.076). More patients in the EF <40% group developed low cardiac output (8.9% vs. 2.7%, p = 0.034) and prolonged ventilation (13.3% vs. 5.5%, p = 0.026) compared to the EF ≥40% group. Propensity score (PS) matching successfully established 82 patient pairs in a 1:1 ratio. No significance was discovered between the matched cohorts in terms of major postoperative morbidity and surgical mortality, except for prolonged ventilation. Conditional mixed-effects logistic regression analysis revealed that EF <40% had an independent impact on prolonged ventilation (odds ratio (OR) = 2.814, 95% CI 1.321–6.151, p = 0.031), but was not an independent risk factor for surgical mortality (OR = 2.967, 95% CI 0.712–7.245, p = 0.138) or other major postoperative morbidity. Furthermore, the two groups showed similar cumulative survival before (log-rank p = 0.278) and after (stratified log-rank p = 0.832) PS matching. Cox regression analysis suggested that EF <40% was not related to mortality compared with EF ≥40% (PS-adjusted hazard ratio (HR) = 1.151, 95% CI 0.763–1.952, p = 0.281).
Conclusions
Patients with moderate IMR and EF <40% shared similar midterm outcomes and surgical mortality to patients with moderate IMR and EF ≥40%, but received prolonged ventilation more often. Depressed LV function may be not associated with surgical or midterm mortality.
... However, when moderate or worse MR is observed prior to coronary revascularization or aortic valve surgery, it is presently debated whether MVR/P should be performed at the time of surgery and whether the correction of MR impacts survival (5,6). The risks of not performing concurrent MVR/P, including persistent secondary MR and the need for cardiac reoperation, loss of potential long-term benefits in survival, and functional status, need to be balanced against the operative and postoperative morbidity and mortality of concomitant MVR/P (3,(5)(6)(7)(8)(9). Further, concomitant MVR/P may significantly improve the risk-benefit profile for later transcatheter aortic valve replacement (TAVR) compared to surgical AVR. ...
... Further, concomitant MVR/P may significantly improve the risk-benefit profile for later transcatheter aortic valve replacement (TAVR) compared to surgical AVR. However, well-conducted trials have failed to demonstrate improved mortality after concomitant MVR/P for moderate MR (7,8,10), and thus, the value of concomitant MVR/P for secondary MR during CABG surgery is still debated. Current Guidelines of the American Association for Thoracic Surgery state that "In patients with moderate IMR undergoing CABG, MV repair with an undersized complete rigid annuloplasty ring may be considered" with Class of Recommendation (COR) IIb, Level of Evidence (LOR) B (11). ...
... Pairwise comparison of survival between patients with more-than-moderate MR who underwent MVR/P or did not showed statistical significance when adjusted for two comparisons (P = 0.028), which was explained by mortality in the first 2 postoperative years. The benefit of MVR/P concomitant with CABG for moderate MR has been examined in randomized trials (7,8,10), several observational studies (17)(18)(19), and meta-analyses . Consensus indicates no survival benefit from concomitant MVR/P with CABG, as we also observed, but studies of survival after concomitant AVR or AVR/CABG are few (23) and limited in scope. ...
Objectives
It is uncertain whether concurrent mitral valve repair or replacement for moderate or greater secondary mitral regurgitation at the time of coronary artery bypass graft or aortic valve replacement surgery improves long-term survival.
Methods
Patients undergoing coronary artery bypass graft and/or aortic valve replacement surgery with moderate or greater secondary mitral regurgitation were reviewed. The effect of concurrent mitral valve repair or replacement upon long-term mortality was assessed while accounting for patient and operative characteristics and mitral regurgitation severity.
Results
Of 1,515 patients, 938 underwent coronary artery bypass graft or aortic valve replacement surgery alone and 577 underwent concurrent mitral valve repair or replacement. Concurrent mitral valve repair or replacement did not alter the risk of postoperative mortality for patients with moderate mitral regurgitation (hazard ratio = 0.93; 0.75–1.17) or more-than-moderate mitral regurgitation (hazard ratio = 1.09; 0.74–1.60) in multivariable regression. Patients with more-than-moderate mitral regurgitation undergoing coronary artery bypass graft-only surgery had a survival advantage from concurrent mitral valve repair or replacement in the first two postoperative years ( P = 0.028) that did not persist beyond that time. Patients who underwent concurrent mitral valve repair or replacement had a higher rate of later mitral valve operation or reoperation over the five subsequent years (1.9% vs. 0.2%; P = 0.0014) than those who did not.
Conclusions
These observations suggest that mitral valve repair or replacement for more-than-moderate mitral regurgitation at the time of coronary artery bypass grafting may be reasonable in a suitably selected coronary artery bypass graft population but not for aortic valve replacement, with or without coronary artery bypass grafting. Our findings are supportive of 2021 European guidelines that severe secondary mitral regurgitation “should” or be “reasonabl[y]” intervened upon at the time of coronary artery bypass grafting but do not support 2020 American guidelines for performing mitral valve repair or replacement concurrent with aortic valve replacement, with or without coronary artery bypass grafting.
... Thus, initially, most patients with moderate IMR did not undergo MV intervention at the time of CABG [24], and these patients required MV surgery at a delayed point in time. Importantly, other randomized studies before the CTSN trial had demonstrated an improvement in left ventricular function with concomitant MV repair [25][26][27][28]. The presence of IMR was shown to be independently related to death after myocardial infarction [2]. ...
... Nonetheless, the efficacy of adding MV repair at the time of CABG is well demonstrated by Fattouch K et al. [25] and Chen et al. [26], who showed an improvement of the functional class of left ventricular ejection fraction and a decrease of regurgitation grade, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, pulmonary artery pressure and left atrial size when compared with CABG alone. Moreover, CABG alone left more patients with heart failure symptoms at rest and during exercise. ...
... Moreover, CABG alone left more patients with heart failure symptoms at rest and during exercise. Although combined CABG and MV repair has no effect on survival at short-term follow-up, it was suggested that the positive trends that were evident were likely to become more significant with time (20,26,30). ...
Objective:
Long-term outcomes of mitral valve (MV) repair versus MV replacement for ischemic mitral regurgitation (IMR) in patients undergoing either prior (PCR) or concomitant coronary revascularization (CCR) by surgery (CABG) or intervention (PCI) are uncertain.
Methods and results:
Of 446 patients receiving MV surgery for IMR between July 2006 and December 2010, 125 patients-87 CCR (69.1%) and 38 PCR (30.9%)-were eligible for inclusion in the study. Survival was higher in CCR versus PCR at long-term follow-up (78.83% vs. 57.9%, p = 0.016). The incidence of MACCE was lower in the CCR compared to PCR at both hospital discharge (34.11% vs. 63.57%, p = 0.003) and at follow-up (34.11% vs. 65.79%, p = 0.0008). Patients receiving CABG or CABG with PCI in PCR had higher mortality risks after MV surgery than CCR patients (X2 = 6.029, p = 0.014 and X2 = 6.466, p = 0.011, respectively). Whereas in the PCR group, MV repair and MV replacement achieved similar survival probability (X2 = 1.551, p = 0.213), MV repair in the CCR group led to improved survival compared to MV replacement (X2 = 3.921, p = 0.048). In MV replacement, LAD-CABG improved survival compared to LAD-PCI (U = 15,000.00, Z = -2.373 p = 0.018), and a substantial impact of arterial IMA-LAD grafting was revealed in the Cox-regression analysis (HR 0.334, CI: 0.113-0.989, p = 0.048) as opposed to venous-LAD grafting (HR 0.588, CI: 0.166-2.078, p = 0.410).
Conclusion:
Early treatment of IMR concomitant to coronary revascularization enhances long-term survival compared to delayed MV surgery after PCR. MV repair is not superior to MV replacement when performed late after coronary revascularization; however, MV repair leads to better survival than MV replacement when performed concomitantly with CABG with arterial LAD revascularization.
... Some experts believe that revascularization alone for moderate ischemic mitral regurgitation, due to improvements in global and regional left ventricular function and geometry after CABG, can decrease rates of mitral regurgitation [5,6]. On the other hand, some experts support restrictive mitral annuloplasty repair at the time of CABG to decrease the degree of mitral regurgitation, preventing further adverse remodeling and reducing the risk of heart failure [7,8]. Nonetheless, incorporating mitral valve repair (MVR) into CABG requires exposing the heart through open-heart surgery, resulting in a longer period of aortic cross-clamping and cardiopulmonary bypass, both of which can raise the risk of complications during the perioperative period [9]. ...
... It remains uncertain whether the reduced occurrence of mitral regurgitation after the combined procedure confers any clinical advantages. Several studies have indicated that simultaneous mitral valve surgery results in functional improvements [8,10], while others have found no benefits in terms of symptoms or survival associated with the incorporation of mitral valve surgery into CABG [11,12]. Several new studies have been conducted since the last meta-analysis that compared the survival and cardiologic outcomes of patients who underwent CABG alone versus CABG with MVR for those with moderate ischemic mitral regurgitation [13]. ...
... Forest plot comparing risk of mortality between two groups CABG: Coronary artery bypass surgery Sources: References[7,8,12,[15][16][17][18]20,21] ...
The aim of this meta-analysis was to compare clinical outcomes between those who underwent coronary artery bypass grafting (CABG) alone and CABG with mitral valve repair (MVR) in patients with moderate ischemic mitral regurgitation. The present study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two authors performed a comprehensive search of international databases, including PubMed, EMBASE, and the Cochrane Library, for relevant studies published from inception to March 1, 2023. The search was performed again before the submission of the manuscript on March 20, 2023. Primary outcomes assessed in the present meta-analysis included early mortality and long-term mortality. Secondary outcomes assessed in the present meta-analysis included change in New York Heart Association (NYHA) score from baseline, change in ejection fraction (EF) from baseline (%), and major cardiovascular events (MACE). A total of 13 studies were included in the present meta-analysis. Out of 13 included studies, four were randomized control trials (RCTs) and nine were retrospective cohort studies.
The pooled analysis showed that early mortality was significantly lower in patients in the CABG group compared to the CABG+MVR group (risk ratio [RR]: 0.47, 95% confidence interval [CI]: 0.31, 0.70). Long-term mortality was also lower in patients who underwent CABG compared to patients in the CABG+MVR group. However, the difference was statistically insignificant (RR: 0.88, 95% CI: 0.77, 1.02). No significant differences were reported in the EF score between patients who underwent CABG and patients who underwent CABG plus MVR (mean difference [MD]: 0.40, 95% CI: -1.90, 2.69). NYHA score was significantly lower in patients in the CABG+repair group compared to the CABG alone group (MD: 0.39, 95% CI: 0.06, 0.72).
In conclusion, our meta-analysis suggests that concomitant MVR during CABG may not improve clinical outcomes in patients with moderate ischemic mitral regurgitation. Further clinical trials are needed to investigate this intervention in more detail.
... These studies, which randomized 301 patients with moderate IMR to undertake isolated CABG or CABG plus MAP, showed that moderate or severe residual MR was more frequently observed in patients undergoing CABG alone, but showed no difference between the two procedures in LV reverse remodeling, mortality, overall adverse events, and readmissions at two years after operation. On the other hand, these results contradicted other previous studies 13,14) . Fattouch and colleagues reported the first prospective, randomized study of moderate IMR, comparing patients with undergoing CABG alone or CABG plus MAP for an average of 32 months 13) . ...
... They showed that the addition of MAP to CABG significantly improved LV reverse remodeling, severity of MR, and NYHA functional class compared with CABG alone. Similarly, the Randomized Ischemic Mitral Evaluation (RIME) trial 14) , which was another randomized study of moderate IMR, demonstrated that oxygen consumption, severity of MR, plasma B-type natriuretic peptide levels, and LV reverse remodeling were improved in patients assigned to CABG plus MVs compared to those assigned to CABG alone. These studies proved the beneficial effects of CABG plus MVs in patients with moderate IMR by showing that concomitant mitral valve restoration not only reduced the degree of severity of mitral valve regurgitation, but also provided an improvement in the NYHA functional class. ...
... Since the mechanisms of IMR are various and complicated 1,2) , patients' characteristics at baseline might be heterogeneous and imbalanced among these studies. For example, when comparing the three clinical trials mentioned above, in the study by Fattouch and colleagues 13) and in the RIME trail 14) , patients had significantly higher rates of previous MI and larger LV size, and remodeling was more advanced than in the CTSN trial 12) at baseline. Postoperative echocardiogram showed that the degree of reverse LV remodeling was greater in the first two studies than in the CTSN trial. ...
Objectives Ischemic mitral valve regurgitation (IMR) in patients undergoing coronary artery bypass grafting (CABG) is associated with worse long-term outcomes. This study aimed to assess the impact of mitral valve repair with CABG in patients with moderate IMR.
Materials This observational study enrolled 3,215 consecutive patients from the Juntendo CABG registry with moderate IMR and multivessel coronary artery disease who underwent CABG between 2002 and 2017.
Methods The CABG alone and CABG with mitral valve surgery (MVs) groups were compared. The propensity score was calculated for each patient. Long-term all-cause death, cardiac death, and major adverse cardiac and cerebrovascular events (MACCEs) were compared.
Results Our database had 101 patients who underwent CABG with moderate IMR. Propensity score matching selected 40 pairs for final analysis. MVs was associated with increased risks of postoperative atrial fibrillation, blood transfusion, and longer hospitalization. Long-term outcomes, including all-cause mortality, cardiac mortality, and the incidence of MACCEs were similar.
Conclusion Surgical treatment of moderate IMR combined with CABG was related to increased risk of several non-fatal short-term complications when compared to CABG alone, with similar long-term outcomes. Further studies are needed to determine the effects of MVs in patients with moderate IMR and severe coronary artery disease.
... 3,4 In patients with moderate ischemic MR, the Randomized Ischemic Mitral Evaluation (RIME) Trial reported that adding CABG to MV annuloplasty leads to improved outcomes when compared to CABG alone. 5 Atrial fibrillation (AF) is present in 30%-50% of patients undergoing mitral valve surgery and is associated with long-term mortality and morbidity. 6 Surgical ablation for AF during MV surgery has been demonstrated to be an effective method of lowering the incidence of AF (6). ...
... Nevertheless, the study did report that the addition of MV annuloplasty to CABG might improve left ventricular reverse remodelling, MR severity, and functional capacity when compared to CABG alone. 5 The current evidence clearly contrasts our data which demonstrated 50.4% of the surgeons reporting the indication for intervention on the ischaemic MV in patients CABG to be moderate mitral regurgitation with ERO >20 mm^2 and regurgitant volume >30 mL. 22 In cases where MV surgery was decided to be carried out concomitantly to CABG, surgeons preferred mitral valve replacement if predictors of repair failure were identified (47.2%) and downsizing annuloplasty ring (46.1%), demonstrating a variability in practice. ...
Introduction
In recent years, major findings on concomitant procedures and anticoagulation management have occurred in Mitral Valve (MV) surgery. Therefore, we sought to evaluate the current practices in MV interventions across Europe.
Methods
In October 2021, all national cardio-thoracic societies in the European region were identified following an electronic search and sent an online survey of 14 questions to distribute among their member consultant/attending cardiac surgeons.
Results
The survey was completed by 91 consultant/attending cardiac surgeons across 12 European countries, with 78% indicating MV repair as their specialty area. 57.1% performed >150 operations/year and 71.4% had 10+ years of experience. Concomitant tricuspid valve repair is performed for moderate tricuspid regurgitation (TR) by 69% of surgeons and for mild TR by 26.3%, both with annular diameter >40 mm. 50.6% indicated ischaemic MV surgery in patients undergoing CABG if moderate mitral regurgitation with ERO >20 mm ² and regurgitant volume >30 mL, and 45.1% perform it if severe MR with ERO >40 mm ² and regurgitant volume >60 mL. For these patients the preferred management was: MVR if predictors of repair failure identified (47.2%) and downsizing annuloplasty ring only (34.1%). For atrial fibrillation (AF) in cardiac surgery, 34.1% perform ablation with biatrial lesion and 20% with left sided only. 62.6% perform concomitant Left Atrial Appendage (LAA) Occlusion irrespective of AF ablation with a left atrial clip. A wide variability in anticoagulation strategies for MV repair and bioprosthetic MV valve was reported both for patients in sinus rhythm and AF.
Conclusion
These results demonstrate a variable practice for MV surgery, and a degree of lack of compliance with surgical intervention guidelines and anticoagulation strategy.
... The 16 studies [4][5][6][7][8][9][10][11][12][13][15][16][17][18]20 reported perioperative mortality after surgery, and the results showed statistical heterogeneity (p = 0.06, I 2 = 38%), so the random effect model was used for meta-analysis. The results showed that there was no significant difference in perioperative mortality between CABG group and CMVs Group (odds ratio [OR] = 0.88, 95% confident interval [CI] [0.54, 1.44], p = 0.62) (Fig. 2). ...
... The 11 studies 3,5,6,8,9,[14][15][16]19 reported the survival rate of 1 year after operation, and the results of each study were not statistically heterogeneous (p = 0.85, I 2 = 0%), so the fixed effect model was used for meta-analysis. The results showed that there was no significant difference in 1-year survival rate between CABG group and CMVs Group (OR = 1.03, 95% CI [0.80, 1.32], p = 0.82) (Fig. 3). ...
... On the other hand, The RIME trial [30] studied 73 ischemic moderate mitral insufficiency patients who were grouped into either isolated CABG or combined surgery groups and despite the early termination of the trial due to slow patient enrollment, the trial did show some benefits in the combined group as regard the peak oxygen consumption, incompetence volume, the left ventricle ESVI, and the natriuretic peptide concentrations in blood. This was different from our study which did not show any remarkable benefits in either group with similar outcomes after a 1-year observation. ...
... This was different from our study which did not show any remarkable benefits in either group with similar outcomes after a 1-year observation. Also, the trial showed an increased rate of IABP use in the combined surgery group and this was similar to our results but without any significance regarding our candidates [30]. In our study, we noticed higher numbers of patients with recurrent moderate mitral incompetence (33.3 %) in the isolated CABG group after 1-year observation compared with 26.7 % in the combined surgery group, but the clinical correlation of these results to our candidates including the daily activities, symptoms of heart failure, severe recurrent insufficiency that needs intervention, postoperative mortalities, and the major complications fail to provide any difference which is significant among the studied groups. ...
... Существуют исследования, согласно которым коррекция МР при ее ишемической форме, совместно с реваскуляризацией миокарда, оправдана [11,12]. ...
... Так, при субанализе результатов исследования STICH было показано преимущество в выживаемости у группы пациентов, которым была выполнена пластика митрального клапана с КШ по сравнению с группой, подвергшейся только реваскуляризации миокарда [11]. Исследование RIME показало, что даже пациентам со средней степенью МР аннулопластика, выполненная с КШ, может снизить уровни гормона BNP, улучшить функциональный класс хронической сердечной недостаточности и обратное ремоделирование ЛЖ, то есть ключевой аспект патогенеза ишемической МР, по сравнению с одним только КШ [12]. ...
Mitral regurgitation is one of the prevalent entities among valvular defects in the adult population. In approximately half of the patients, the etiology of this defect is directly related to obstructive coronary artery disease. As a rule, the high perioperative risk in such patients is the main reason for the refusal to perform traditional open interventions. According to the available literature, the first experience of successful simultaneous percutaneous coronary intervention and transcatheter mitral valve repair “edge-to-edge” with the MitraClip G4 device is presented in a 77-year-old patient with severe mitral regurgitation who had previously suffered myocardial infarction and paroxysmal atrial fibrillation. The advantages of such an approach to treatment are demonstrated, and the need for its further study for systemic implementation is actualized.
... According to some studies, mitral valve annuloplasty may remove MR after CABG surgery. However, CABG + mitral valve annuloplasty can cause recurrent MR without improving long-term survival (9)(10). CABG + mitral valve operations may increase morbidity and death in high-risk moderate IMR patients compared to CABG alone (11). ...
Background: Approximately 13-59% of myocardial infarction patients develop ischemic mitral regurgitation, impacting left ventricular function and increasing mortality risk. Optimal management of moderate ischemic mitral regurgitation remains controversial, raising the question of whether adding mitral valve surgery to coronary artery bypass graft (CABG) has an overall advantage over revascularization or not. Objective: To investigate the early and mid-term comparison between the two techniques. Subjects and Methods: This randomized clinical trial was conducted at Assuit University Heart Hospital, on 50 patients randomized into two groups: Group A: 25 patients underwent CABG and Group B: 25 patients had CABG and mitral valve repair. Inclusion criteria was multi-vessel coronary artery disease, moderate ischemic mitral regurge (MR). All patients were subjected to full history taking, routine physical, laboratory investigations and transthoracic echocardiography. Intraoperative data was collected. Early outcomes included MR degree, and left ventricular (LV) diameters and function, ICU stay duration, and in-hospital mortality. Mid-term outcomes included MR degree, LV diameter and function. Results: Groups had similar age and gender distribution. Repair procedures showed longer ischemic and operative times than CABG alone (P≤0.0001 and P=0.0012). Early post-operative, repair reduced MR significantly (P≤0.0001). At six months follow-up, CABG group had more rate of improvement than repair group (P≤0.0001). Conclusions: In moderate ischemic mitral regurgitation with multi-vessel ischemic heart disease, adding mitral valve repair to CABG may reduce mitral regurgitation severity early and at six months compared to CABG alone. However, CABG alone offers shorter ischemic times and operative durations.
... In addition, the operation Table 2. Comparison of operation-relevant data between the OPCABG and CABG+MVP groups after IPTW. [10][11][12][13][14] . In this study, OPCABG was used in all CABG groups. ...
Objective
To compare the efficacy of isolated off-pump coronary artery bypass grafting (OPCABG) and of coronary artery bypass grafting (CABG) plus mitral valve plasty (MVP) in treating coronary heart disease with moderate ischemic mitral regurgitation to find a better surgical method.
Methods
Clinical data of 822 patients diagnosed with coronary heart disease and moderate ischemic mitral regurgitation were analyzed retrospectively. Patients were divided into the OPCABG and CABG+MVP groups according to surgical methods. Baseline data of both groups were corrected, and clinical efficacy of the two surgical methods was analyzed and compared using the propensity score inverse probability of treatment weighting (IPTW) method.
Results
There were no significant differences in the use of mammary artery grafts, number of grafts, and blood product consumption between the two groups (P>0.05) after IPTW. However, the CABG+MVP group had a significantly longer operation time than the OPCABG group (4.13 ± 0.85 hours vs. 5.65 ± 1.02 hours, P<0.001). No statistically significant differences in postoperative major adverse cardiac and cerebrovascular events were observed between the two groups. However, the intra-aortic balloon pump rate was higher in the CABG+MVP group than in the OPCABG group (12.3% vs. 25.0%, P=0.012). Although CABG+MVP can improve ischemic mitral regurgitation significantly (95.4% vs. 81.2%, P<0.001), there were no significant differences in the cumulative survival rate and the incidence of major adverse cardiac and cerebrovascular events between the groups (P>0.05) after IPTW.
Conclusion
CABG+MVP may not provide more advantage in patients with coronary heart disease and moderate ischemic mitral regurgitation.
... In patients with moderate SIMR, RMA should be used in combination with CABG surgery if there is extensive post-infarct scarring, especially if SVR is required due to accentuated geometric ventricular deformation such as apical leaflet tethering (10,25,42,110). For patients with ischemic SIMR and a positive LV remodelling, CABG surgery alone is advised (14,22,23). Grayburn et al. (103,104) and Bartko et al. (20,21) identified and discussed a population of patients with proportionate MR who present with a highly dilated left ventricle, worse LV function and remodelling, and are therefore more challenging to manage. ...
Background and Objective
Surgery for mitral valve disease is a developing area with a wide range of surgical options. There is growing evidence on the best approach for secondary ischemic mitral regurgitation (SIMR) when the pathology is within the ventricle. The goal of this literature review is to provide a comprehensive comparison of surgical treatments for SIMR.
Methods
The initial screening process included PubMed, Medline and Embase to identify randomized controlled trials, propensity-matched observational series, meta-analyses and unmatched observational series. The terms used were ‘mitral valve disease’, ‘secondary mitral regurgitation’, ‘secondary ischemic mitral regurgitation’, ‘functional mitral regurgitation’, ‘restrictive mitral annuloplasty’, ‘subvalvular repair’, ‘Trans Catheter Edge to Edge Repair and echocardiography coupled with secondary mitral regurgitation’, ‘secondary ischemic mitral regurgitation’, and ‘functional mitral regurgitation’. Six strategies have been identified for treating SIMR. These include mitral valve replacement (MVR), restrictive mitral annuloplasty, surgical revascularisation (with and without mitral annuloplasty), subvalvular procedures [papillary muscle (PM) approximation, PM relocation, ring and string procedure], procedures directly targeting the mitral valve (edge-to-edge repair and anterior leaflet enlargement), and transcatheter heart valve therapy.
Key Content and Findings
There is a deficiency of robust empirical data to enable meaningful comparisons between MVR, mitral valve repair (including subvalvular repair), and transcatheter mitral valve procedure. This review will definitively analyze the current outcomes of transcatheter mitral valve procedure using the edge-to-edge mitral valve repair technique and standard surgical mitral valve procedures in patients with secondary mitral regurgitation (MR). In addition, the seminar highlights the role of left ventricular assist devices in managing SIMR. It discusses the advantages and limitations of each intervention.
Conclusions
Currently, there is no consensus on the optimal management strategy for patients with SIMR. Therefore, a multidisciplinary cardiac team should manage patients with secondary MR to ensure the best outcome by matching the ideal intervention with the patient.
... In patients with moderate secondary ischemic MR in the setting of multivessel coronary artery disease, mitral valve repair may be performed at the time of CABG (22)(23)(24). The Cardiothoracic Surgical Trials Network (CTSN) conducted a multicenter, randomized trial comparing CABG alone with combined CABG and mitral valve repair in patients with moderate ischemic MR. ...
... Limited evidence is available regarding ischemic MR with patients eligible for myocardial revascularization. [27][28][29][30] However, even these randomized trials did not confirm or were not designed to demonstrate a survival benefit of simultaneous MV and coronary bypass surgery. The main limitation of surgery in patients with SMR is that none of the available approaches is curative. ...
Objective
This study compares early and long-term outcomes following mitral valve (MV) repair and replacement in patients with mitral regurgitation (MR) and reduced left ventricular ejection fraction (LVEF).
Methods
Patients with primary or secondary MR and LVEF <50% who underwent MV replacement or repair (with/without atrial septal defect closure and/or atrial fibrillation ablation) between 2005 and 2017 at our center were retrospectively analyzed using unadjusted and propensity score matching techniques (42 pairs).
Results
A total of 356 patients with either primary (n = 162 [45.5%]) or secondary MR (n = 194 [54.5%]) and LVEF <50% underwent MV repair (n = 293 [82.3%]) or replacement (n = 63 [17.7%]) during the study period. In-hospital mortality was 0.3% (repair) and 1.6% (replacement) in the unmatched cohort (P = .32); there were no in-hospital deaths after matching. Estimated survival was 72.8% (repair) versus 50.1% (replacement) at 8 years in the unmatched (P < .001), and 64.3% (repair) versus 50.7% (replacement) in the matched groups (P = .028). Eight-year cumulative incidence of reoperation was 7.0% and 11.6% in unmatched (P = .28), and 9.9% and 12.7% in matched (P = .69) repair and replacement groups, respectively. Markedly reduced LVEF (<40%) was among the independent predictors of long-term mortality (hazard ratio, 1.7; 95% CI, 1.2-2.4; P = .002). In secondary MR, MV repair showed an 8-year survival benefit over replacement (65.1% vs 44.6%; P = .002), with no difference in reoperation rate (11.6% [repair] vs 17.0% [replacement]; P = .11).
Conclusions
MV repair performed in primary or secondary MR and reduced LVEF provides superior long-term results compared with replacement. Severe LV dysfunction is a significant predictor of reduced survival following MV surgery.
... There was also a trend toward higher complication rates in the CABG plus MVR group, although the differences were not significant. The results support the addition of MVR to CABG in patients with moderate ischemic MR undergoing CABG, but the benefits of the combined procedure must be balanced against possible increased risk of morbidity in the perioperative period [12,13] . ...
... В настоящее время предпочтение отдается реконструктивным вмешательствам на МК [9,11]. В то же время ряд исследователей публикует данные, свидетельствующие о повышении послеоперационных осложнений и летальности при выполнении сочетанных операций на МК и аортокоронарного шунтирования (АКШ) [12]. Таким образом, до сих пор не существует универсальной тактики лечения этой группы пациентов. ...
Objective : To evaluate long-term outcomes of mitral valve annuloplasty using an autologous pericardial strip (“soft support ring” type) and a rigid support ring in combination with coronary artery bypass graft (CABG) in patients with ischemic mitral regurgitation.
Materials and methods : We carried out retrospective and prospective analyses of the treatment outcomes in 90 patients with coronary heart disease (CHD) and ischemic mitral regurgitation. Ischemic mitral regurgitation (grade 2 or above) was an inclusion criterion for patients with CHD. Exclusion criteria were as follows: nonischemic mitral regurgitation, acute myocardial infarction, progressive angina pectoris, and repeated heart interventions. The patients were divided into 2 groups. Patients from group 1 underwent CABG with mitral regurgitation correction using a strip of glutaraldehyde-treated autologous pericardium (“soft support ring” type) according to our own method, whereas patients from group 2 underwent CABG with mitral regurgitation correction using a rigid support ring. The analysis revealed that the groups were comparable in all the studied parameters.
Results : There was no statistically significant difference in the number of postoperative complications and hospital mortality between the groups. According to the analyzed data obtained at the time of discharge, all the patients had grade 0-1 mitral regurgitation, which shows a complete restoration of the mitral valve function after annuloplasty. In addition, there was a statistically significant decrease in the end-diastolic volume and an increase in ejection fraction, which is a sign of reverse left ventricular (LV) remodeling. The mean follow-up was 44±7.4 months. No deaths were reported during the follow-up. The results of the examination in the long-term period did not reveal negative dynamics in most patients compared with the findings in the early postoperative period. The LV size also did not change significantly, and the ejection fraction demonstrated an upward trend. One patient in each group had a recurrence of grade 3 mitral regurgitation.
Conclusions : The immediate outcomes showed no recurrence of mitral regurgitation, a low number of intraoperative and postoperative complications, and pronounced reverse LV remodeling. We observed stable results in the long-term follow-up: only one patient in each group had a recurrence of mitral regurgitation. Reverse LV remodeling persisted throughout the follow-up. There were no significant differences between the groups in any parameter, which indicates that the developed annuloplasty method is not inferior to the traditional technique with a rigid support ring.
... Studies in the table focus on both ischemic and non-ischemic V-FMR, encompassing a wide range of patient profiles. 12,13,[27][28][29][30][31][32][33][34][35][36][37] Surgical approaches include mitral valve repair and mitral valve replacement. Ischemic V-FMR studies report relatively older patient populations, with mean ages ranging from 62 to 70 years, while non-ischemic V-FMR studies show slightly higher mean ages of 64-71 years. ...
The treatment of functional mitral regurgitation (FMR) has evolved dramatically in recent years and remains dynamic. Generally, the treatment of FMR involves a combination of medication optimization and surgical or transcatheter interventions. The use of transcatheter edge-to-edge repair has been increasing for FMR. This less invasive approach allows for transcatheter mitral valve repair, avoiding open heart surgery. On the other hand, surgical mitral valve repair techniques, such as annuloplasty, still play a crucial role in managing FMR. Simultaneous surgical ablation for atrial fibrillation or left atrial appendage closure can be performed. Surgical interventions also encompass concomitant operations, including addressing commonly coexisting secondary tricuspid valve pathology or performing coronary artery bypass grafting, which is relevant, especially in the case of ischemic mitral regurgitation. The management of FMR involves a multidisciplinary heart team consisting of cardiologists, cardiac surgeons, and other specialists. This collaborative approach aims to tailor treatment strategies to individual patients, considering survival and the quality of life.
... Trials have consistently demonstrated a reduction in left ventricle dimension after MV operations. 15,16 Further investigation on the proportionality of MR may identify a subgroup with proportionate MR that may yield benefits from MVoperations, in contrast to disproportionate MRs benefitting from transcatheter edge-to-edge repair focused on the treatment of the leaflet apparatus. ...
Objective
Ischemic mitral regurgitation is prevalent and associated with high surgical risk. With the less-invasive option of transcatheter edge-to-edge repair, the optimal patient selection for mitral valve operation for ischemic mitral regurgitation remains unclear. We sought to identify high-risk features in this group to guide patient selection.
Methods
Using the Cardiothoracic Surgery Trial Network's severe ischemic mitral regurgitation trial data, we identified patient and echocardiographic characteristics associated with an increased risk of 2-year mortality using the support vector classifier and Cox proportional hazards model. We identified 6 high-risk features associated with 2-year survival. Patients were categorized into 3 groups, each having 1 or less, 2, or 3 or more of the 6 identified high-risk features.
Results
Among the 251 patients, the median age was 69 (Q1 62, Q3 75) years, and 96 (38%) were female. Two-year mortality was 21% (n = 53). We identified 6 high-risk preoperative features: age 75 years or more (n = 69, 28%), prior sternotomy (n = 49, 20%), renal insufficiency (n = 69, 28%), gastrointestinal bleeding (n = 15, 6%), left ventricular ejection fraction less than 40% (n = 131, 52%), and ventricular end-systolic volume index less than 50 mL/m² (n = 93, 37%). In patients who had 1 or less, 2, and 3 or more high-risk features, 90-day mortality was 4.2% (n = 5), 9.9% (n = 4), and 20.0% (n = 10), respectively (P = .006), and 2-year mortality was 10% (n = 12), 22% (n = 18), and 46% (n = 23) (P < .001), respectively.
Conclusions
We developed the 3-strike score by identifying high-risk preoperative features for mitral valve surgery for ischemic mitral regurgitation. Patients having 3 or more of such high-risk features should undergo careful evaluation for surgical candidacy given the high early and late mortality after mitral valve operations.
... It was suggested in several studies that isolated coronary artery bypass grafting (CABG) surgery may reduce the degree of IMR by improving left ventricular function (2) . Some researchers recommend mitral annuloplasty repair at the time of CABG to directly reduce the degree of IMR (3,4) . However, the addition of mitral valve repair to CABG may increase operative morbidity and mortality rates. ...
Introduction: The aim of this study was to assess the efficacy of isolated coronary artery bypass grafting (CABG) on preoperatively existing mild-to-moderate chronic ischemic mitral regurgitation.
Patients and Methods: A retrospective analysis was conducted on 30 patients who had coronary artery disease and chronic ischemic mitral regurgitation, and underwent isolated CABG at the Department of Cardiovascular Surgery, Kocaeli University, between January 2012 and February 2014. Preoperative demographic and clinical characteristics, as well as postoperative outcomes, were evaluated. The degree of IMR, left ventricular ejection fraction (LVEF), left ventricular end-systolic dimension (LVESD), left ventricular end-diastolic dimension (LVEDD), and left atrial dimension (LAD) were assessed preoperatively, and at the postoperative 12 th month.
Results: There was no mortality during the early postoperative period. There were statistically similar measurements for LVEF, LVESD, LVEDD, and LAD between preoperative and postoperative periods (p> 0.05). However, a decrease in the degree of IMR was detected during the specified periods (p< 0.05).
Conclusion: Isolated CABG can be safely performed in patients with mild/moderate chronic ischemic mitral regurgitation. The efficacy of isolated CABG was demonstrated to improve the degree of mitral regurgitation in selected patients based on echocardiographic measurements.
... While the negative prognostic effect of ischemic FMR is well recognized, the impact of surgical repair of MR on LV remodeling and outcomes is still controversial, especially in patients with severely reduced LV function, who are poor candidates for surgery [28][29][30]. Theoretically, the less invasive MitraClip procedure may be considered as an alternative to surgery in high-risk patients. In fact, recent trials suggest that MitraClip therapy improves quality of life and may even reduce mortality among patients with severe chronic ischemic MR [4,6]. ...
Aims
Acute mitral regurgitation (MR) in the setting of myocardial infarction (MI) may be the result of papillary muscle rupture (PMR). This condition is associated with high morbidity and mortality. We aim to evaluate the feasibility of transcatheter edge‐to‐edge mitral valve repair (TEER) in this acute setting.
Methods and results
We analysed data from the International Registry of MitraClip in Acute Mitral Regurgitation following acute Myocardial Infarction (IREMMI) of 30 centres in Europe, North America, and the middle east. We included patients with post‐MI PMR treated with TEER as a salvage procedure, and we evaluated immediate and 30‐day outcomes. Twenty‐three patients were included in this analysis (9 patients suffered complete papillary muscle rupture, 9 partial and 5 chordal rupture). The patients' mean age was 68 ± 14 years. Patients were at high surgical risk with median EuroSCORE II 27% (IQR 16, 28) and 20 out of 23 (87% were in cardiogenic shock). All patients were treated with vasopressors, and 17 out of 23 patients required mechanical support. TEER procedure was performed on the median 6 days after the index MI date IQR (3, 11). Procedural success was achieved in 87% of patients. The grade of MR was significantly decreased after the procedure. MR reduction to 0 or 1 + was achieved in 13 patients (57%), to 2 + in 7 patients (30%), P < 0.01. V‐Wave was reduced from 49 ± 8 mmHg to 26 ± 10 mmHg post‐procedure, P < 0.01. Sixteen out of 23 patients (70%) were discharged from hospital and 5 of them required reintervention with surgical mitral valve replacement. No additional death at 1 year was documented.
Conclusions
TEER is a feasible therapy in critically ill patients with PMR due to a recent MI. TEER may have a role as salvage treatment or bridge to surgery in this population.
... Adding the additional context of LVSD, OPCAB in the modern era has been associated with comparable, if not better, early survival than on-pump CABG [59] , with potentially higher five-year mortality, potentially due to suboptimal longitudinal management rather than surgical strategy [60] . The merit of OPCAB in women with reduced LVEF remains to be explored. ...
Revascularization through percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) is used to manage left ventricular systolic dysfunction (LVSD) due to coronary artery disease (CAD). This review provides an overview of coronary revascularization for CAD with reduced left ventricular ejection fraction (LVEF), focusing on disparities in management. CABG provides more complete revascularization, and lower long-term all-cause mortality and reintervention and MI rates compared to PCI in patients with LVSD and CAD. Consequently, CABG is recommended as the primary revascularization therapy for CAD with reduced LVEF, with PCI being reserved for patients who are high-risk or have unfavorable coronary anatomy. Although LVSD increases revascularization risk, differential outcomes can be attributed to patients’ biological, behavioral, and socioeconomic factors as well as health system deficiencies. Women and racially and/or ethnically minoritized patients often present with progressive disease and greater comorbidity, experience delays in diagnosis and treatment, and have higher morbidity and mortality rates post-revascularization. These disparities may be explained by biological differences compounded by social determinants of health. Patients with CAD with LVSD pose unique medical challenges, which may be further complicated by disparities in care. Increased representation of minoritized patients in cardiovascular trials is needed to elucidate these differences and their long-term impact.
... The evidence for the role of surgical repair in SMR is mixed with some studies demonstrating symptomatic benefit with MV repair in conjunction with coronary artery bypass grafting (CABG). 52,53 However, surgery does not provide a clear mortality benefit. [54][55][56] There are disparities in surgical outcomes for treatment of SMR as well; a small study of 251 patients with severe ischemic MR identified that female patients had a higher mortality rate and worse quality of life than male counterparts after MV surgery. ...
Mitral regurgitation is the most common valvular disease, particularly in older adults. Recent literature has consistently supported that there are significant differences in mitral regurgitation outcomes between male and female patients and that this is likely multifactorial. Numerous sex differences in anatomy and pathophysiology may play a role in delayed diagnoses, referrals, and treatments for female patients. Despite the recognition of these discrepancies in the literature, many guidelines that steer clinical care do not incorporate these factors into society recommendations. Identifying and validating sex-specific diagnostic parameters and increasing the representation of female patients in trials of new mitral regurgitation treatment modalities are key factors in improving outcomes for female patients.
... Retrospective studies have shown that patients with severe FMR also have significant symptomatic limitations (OR = 1.8, 95% CI 1.1 to 2.8, p = 0.01) and hospitalization for decompensated heart failure (HR = 1.7, 95% CI 1.2 to 2.5, p = 0.004) compared to patients without FMR [28]. Surgical data suggest improvements in functional status, LV end-systolic volume index, mitral regurgitant volume, and BNP at one year in patients with FMR undergoing CABG with mitral valve replacement when compared to those undergoing CABG alone [29]. Recent AHA/ACC guidelines list a class-IIa recommendation for mitral valve surgery in symptomatic patients with severe FMR undergoing CABG [4]. ...
Advanced heart failure is often accompanied by perturbations in cardiac chamber or valve geometries which result in worsening cardiac function and hemodynamics. Once limited to surgical procedures, recent developments in minimally invasive percutaneous techniques have demonstrated efficacy in patients with both reduced and preserved ejection fraction who are at an elevated surgical risk for perioperative events. This review highlights a subset of the interventions available in clinical practice or in development for the treatment of these valvular and structural alterations.
... Fattouch et al. [22] found that concomitant MVR was associated with improved EF, LV dimensions, and symptoms, while there was no difference in short-term survival. Similarly, Chan and colleagues [23] reported improved outcomes after MVR in their randomized clinical trial comparing CABG vs. CABG and MVR. The difference in outcomes between randomized trials and retrospective studies could be attributed to the strict inclusion criteria and the exclusion of high-risk patients. ...
Background:
Ischemic mitral regurgitation (IMR) or functional MR intensity with or without repair increases the risk of coronary artery bypass grafting (CABG), and if the contaminant is undertaken, it doubles the risk of the surgery. This study aimed to characterize patients with concomitant CABG and mitral valve repair (MVR) and assess the surgical and long-term outcomes.
Methods:
We conducted a cohort study from 2014 to 2020 on 364 patients who underwent CABG. A total of 364 patients were enrolled and divided into two groups. Group I (n= 349) included patients with isolated CABG, and Group II included patients who underwent CABG with concomitant mitral valve repair (MVR) (n= 15).
Results:
Regarding preoperative presentation, most patients were male: 289 (79.40%), hypertensive 306 (84.07%), diabetic 281 (77.20%), dyslipidemic 246 (67.58%), presenting with NYHA classes III-IV: 200 (54.95%), and upon angiography, found to have the three-vessel disease: 265 (73%). Regarding their age mean± SD and Log EuroSCORE median (Q1-Q3), they had a mean age of 60.94± 10.60 years and a median score of 1.87 (1.13-3.19). The most prevalent postoperative complications were low cardiac output 75 (20.66%), acute kidney injury (AKI) 63 (17.45%), respiratory complications 55 (15.32%), and atrial fibrillation (AF) 55 (15.15%). Regarding long-term outcomes, most patients reported class I NYHA 271 (83.13%) and an echocardiographic decrease in MR severity. Patients with a CABG + MVR were significantly younger (53.93± 15.02 vs. 61.24± 10.29 years; P= 0.009), had a lower ejection fraction (33.6 [25-50] vs. 50 [43-55] %; p= 0.032), and had a higher prevalence of LV dilation (32 [9.17%]). EuroSCORE was significantly higher in patients with mitral repair (3.59 [1.54-8.63] vs. 1.78 (1.13-3.11); P= 0.022). The mortality percentage was higher with MVR but did not attain statistical significance. Intraoperative CPB and ischemic durations were longer in the CABG + MVR group. Furthermore, neurological complications were higher in patients with mitral repair (4 (28.57%) vs. 30 (8.65%), P= 0.012). The study’s follow-up duration median was 24 (9-36) months. The composite endpoint occurred more frequently in older patients (HR: 1.05 [95% CI: 1.02-1.09]; 0.001), patients with low ejection fraction (HR: 0.96 [95% CI: 0.93-0.99]; P= 0.006) and in patients with preoperative myocardial infarction (MI) (HR: 2.3 [95%: 1.14- 4.68]; P= 0.021).
Conclusion:
Most IMR patients benefited from CABG and CABG + MVR, as evident by NYHA class and echocardiographic follow-up. CABG + MVR had a higher Log EuroSCORE risk with increased intraoperative cardiopulmonary bypass (CPB) and ischemic durations, which may have played a role in increasing the incidence of postoperative neurological complications. On follow-up, no differences were reported between the two groups. However, age, ejection fraction, and a history of preoperative MI were identified as factors affecting the composite endpoint.
... Однако, согласно большому экспертному заключению ведущих кардиохирургов в 2019 г., тактика лечения пациентов с ФМН является крайне спорной и вызывает много дебатов даже в ведущих кардиоторакальных ассоциациях [5]. Во многом это связано с рекомендациями Европейского общества кардиологов (European Society of Cardiology, ESC), Европейской ассоциации кардиоторакальной хирургии (European Association for Cardio-Thoracic Surgery, EACTS), Американской ассоциации сердца (American Heart Association, AHA), Американского кардиологического колледжа (American College of Cardiology, ACC), Американской ассоциации торакальной хирургии (The American Association for Thoracic Surgery, AATS), которые основаны на результатах обсервационных исследований с про-тиворечивыми результатами при единичных рандомизированных контрольных исследованиях, которые представлены только МН ишемического генеза (Randomized Ischaemic Mitral Evaluation, RIME; Cardiothoracic Surgical Trials Network, CTSN, 2014-2016) [14][15][16][17][18][19][20][21][22][23]. В связи с этим у пациентов со вторичной МН практически отсутствует алгоритм лечения. ...
p>The optimal treatment strategy for secondary mitral regurgitation of type IIIb (A. Carpentier classification) remains debatable. The use of a standard surgical technique for treating secondary mitral regurgitation and undersized ring annuloplasty demonstrates suboptimal results in several patients (about 30% of the patients exhibit postoperative hemodynamically significant mitral regurgitation with the absence of effective reverse remodelling of the left ventricle). Such suboptimal results are associated with the unification of only the mitral valve reconstruction technique, irrespective of the state of the left ventricle (degree of dysfunction, dilatation, tethering/tenting, and papillary muscle displacement); this is not entirely justified because of the disease complexity (valve and ventricular), and it is crucial to influence both the components of the disease. Particularly, modern researchers are inclined toward the need of using additional reconstructive interventions on the subvalvular structures that contribute to a more effective reverse remodelling of the left ventricle.
Here, we present a review of recent studies on the surgical treatment of functional mitral insufficiency of type IIIb (A. Carpentier classification) with effects on the subvalvular structures (pupillary muscle relocation and approximation).
Revised 19 April 2020. Revised 5 May 2020. Accepted 28 May 2020.
Funding: The study did not have sponsorship.
Conflict of interest: Authors declare no conflict of interest.</p
Aim
To evaluate the benefits of off-pump coronary artery bypass grafting (OPCABG) in patients with coronary artery disease and concomitant mitral valve (MV) regurgitation.
Methods
The study included 50 patients with coronary artery disease and concomitant MV disease who underwent simultaneous CABG and correction of MV regurgitation. Patients were divided into 2 groups: group 1 (n = 26) included patiens with on- pump CABG (ONCABG), group 2 (n = 24) included patiens with OPCABG.
Results
In the OPCABG group there was shorter aortic cross-clamping time (85,5 [71,25; 105,25] vs 119 [99,25; 132,25] min, compared with the ONCABG group, p < 0,05), shorter duration of CPB (136,5 [119,25; 158,5] vs 168,5 [142,75; 186,25] min, p < 0,05), and overall duration of the operation (292,5 [252,5; 360] vs 340 [287,5; 385] min, respectively, p = 0,15). Moreover, in this group there was a lower need for transfusion of blood and its components: freshly frozen plasma (2[2;3]vs3[3;3],p<0,05),RBCmass(2[1;2]vs2[2;2], respectively,p= 0,4), and lower number of bed-days during hospital stay (20 [13,5; 26,25] vs 23,5 [17,5; 26] days, p < 0,05).
Conclusion
Off-pump CABG in patients with combined valvular pathology is a safe and reproducible technique that provides shorter aortic cross-clamping time, on-pump time and operation duration. The need for blood transfusion and the length of hospital stay are reduced as well.
Keywords
Coronary artery bypass grafting • Mitral valve • Coronary artery disease • Myocardial revascularization • Cardiopulmonary bypass
Introduction:
Deciding whether to perform coronary artery bypass grafting (CABG) alone or in combination with mitral valve repair is a common dilemma encountered by surgeons when treating patients with ischemic mitral regurgitation, a common condition related to coronary artery disease. Although ischemic mitral regurgitation after CABG has been linked to unfavorable results, the benefits of including mitral valve repair are still unknown. This discrepancy led us to undertake a systematic review and meta-analysis to determine whether combining CABG with mitral valve surgery leads to better clinical results than CABG alone.
Evidence acquisition:
Studies comparing the results of CABG versus CABG with mitral valve replacement were searched in the databases of PubMed and Google Scholar. There were six randomized clinical trials included in this study.
Evidence synthesis:
We analyzed 852 patients' data. There were no significant variations between patients who acquired CABG alone or CABG+(MVR) in terms of their risk of death at one year, stroke, atrial fibrillation, or hospitalization for heart failure. For recurrent/residual mitral regurgitation; it revealed an RR=5.42, 95% CI, 0.77 to 37.98, and a P-value of =0.065. According to the analysis of study heterogeneity, no apparent heterogeneity was identified in the outcomes of death after one year, stroke, atrial fibrillation, or hospitalization for heart failure. However, the outcome of recurrent or residual mitral regurgitation showed significant variation (I2=66%).
Conclusions:
Patients who underwent CABG alone versus CABG plus MVR did not differ significantly from one another. However, the comparison of CABG alone with CABG plus MVR underlines the need for customized treatment plans based on the unique characteristics of each patient.
Cardiovascular disease is an important cause of morbidity and mortality in Malaysia. Heart Failure (HF), the end stage of most diseases of the heart, is a common medical problem encountered in primary care and is an important cause of hospital admissions and readmissions with a significant impact on hospital expenditure. As the population ages, the prevalence of HF is expected to increase.
The 1st Clinical Practice Guidelines (CPG) in HF was published in 2000 with revisions in 2007, 2014 and 2019. Since then, there have been many new developments in this field. Thus, the publication of this 5th edition is timely. This CPG stresses on the early implementation and optimization of the “Foundational HF” medications. It also proposes a structured multidisciplinary strategy for the seamless care of patients with HF between hospital and primary care.
This CPG was drawn up by a committee appointed by the National Heart Association of Malaysia and Ministry of Health. It comprises cardiologists, nephrologists, family medicine and general physicians and pharmacists from the government, private sectors, and the public Universities.
The mitral valve is an architecturally intricate structure, the pathology of which is broadly divided into regurgitation or stenosis, any of which can lead to congestive heart failure. Herein we describe the operative management of these disease processes, which requires a solid familiarity of the intimate relationships of the mitral valve with its surrounding structures, a clear understanding of the varying etiologies of valvular pathology, and a grasp of the natural history of disease progression.
This study retrospectively evaluated the mid-term outcomes of surgical aortic valve replacement (SAVR) using a stented porcine aortic valve bioprosthesis (Mosaic; Medtronic Inc., Minneapolis, MN, USA) with concomitant mitral valve (MV) repair. From 1999 to 2014, 157 patients (median [interquartile range] age, 75 [70–79] years; 47% women) underwent SAVR with concomitant MV repair (SAVR + MV repair), and 1045 patients (median [interquartile range] age, 76 [70–80] years; 54% women) underwent SAVR only at 10 centers in Japan as part of the long-term multicenter Japan Mosaic valve (J-MOVE) study. The 5-year overall survival rate was 81.5% ± 4.1% in the SAVR + MV repair group and 85.1% ± 1.4% in the SAVR only group, and the 8-year overall survival rates were 75.2% ± 5.7% and 78.1% ± 2.1%, respectively. Cox proportional hazards analysis showed no significant difference in the survival rates between the two groups (hazard ratio, 0.87; 95% confidence interval, 0.54–1.40; P = 0.576). Among women with mild or moderate mitral regurgitation who were not receiving dialysis, those who underwent SAVR + MV repair, were aged > 75 years, and had a preoperative left ventricular ejection fraction of 30–75% tended to have a lower mortality risk. In conclusion, this subgroup analysis of the J-MOVE cohort showed relevant mid-term outcomes after SAVR + MV repair.
Echocardiography is pivotal in the evaluation and management of valvular heart disease. Conventionally, echocardiographic assessment of any valve disease is performed at rest. However, as valvular heart disease is a dynamic entity, evaluation only at rest is not sufficient to assess the true hemodynamic severity of the valve lesion. For this reason, stress echocardiography (SE) serves as a useful diagnostic modality. By permitting evaluation under hemodynamic stress, it provides incremental diagnostic and prognostic information which has significant therapeutic implications. Further, exercise SE also permits correlation of the symptoms with the severity of the underlying valve disease. This information is crucial as the development of symptoms is a Class I indication for intervention in valve disorders. These benefits coupled with the easy availability and safety of SE should lead to its more routine application in the management of the patients with valvular heart disease. The present review describes the technical aspects and the clinical utility of SE in the evaluation and management of mitral valve disease.
Objective:
Functional mitral regurgitation (FMR) is associated with increased mortality and has been considered a marker for advanced heart disease, yet the value of mitral valve repair (MVr) in this population remains unclear. This study aims to evaluate the impact of reducing FMR burden through surgical MVr on survival.
Methods:
Patients with severe FMR who underwent MVr with an undersized, complete, rigid, annuloplasty between 2004-2017 were assessed (n=201). Patients were categorized based on grade of recurrent FMR (0-4). Time-to-event Kaplan-Meier (KM) estimations of freedom from death or reoperation were performed using the log-rank test. Cox proportional hazards models evaluated all-cause mortality and reported in hazards ratios (HR) and 95% confidence intervals (CI).
Results:
Patients were categorized by postoperative recurrent FMR: 45% (91/201) of patients had grade 0, 29% (58/201) grade 1, 20% (40/201) grade 2, 2% (4/201) grade 3, and 4% (8/201) grade 4. The cumulative incidence of reoperation with death as a competing risk was higher in patients with grades ≥3 recurrent FMR compared to grades ≤2 (44.6% vs. 14.6%, subhazard ratio 3.69 [95% CI, 1.17-11.6]; p=0.026). Overall freedom from death or reoperation was superior for recurrent FMR grades ≤2 compared to grades ≥3 (log-rank p<0.001). Increasing recurrent FMR grade was independently associated with mortality (HR 1.30 [95% CI, 1.07-1.59] p=0.009).
Conclusions:
Reduced postoperative FMR grade resulted in an incrementally lower risk of death or reoperation after MVr. These results suggest that achieving a durable reduction in FMR burden improves long-term survival.
Severe secondary mitral regurgitation carries a poor prognosis with one in five patients dying within 12 months of diagnosis. Fortunately, there are now a number of safe and effective therapies available to improve outcomes. Here, we summarise the most up-to-date treatments. Optimal guideline-directed medical therapy is the mainstay therapy and has been shown to reduce the severity of mitral regurgitation in 40–45% of patients. Rapid medication titration protocols reduce heart failure hospitalisation and facilitate earlier referral for device therapy. The pursuit of sinus rhythm in patients with atrial fibrillation has been shown to significantly reduce mitral regurgitation severity, as has the use of cardiac resynchronisation devices in patients who meet guideline-directed criteria. Finally, we highlight the key role of mitral valve intervention, particularly transcatheter edge-to-edge repair (TEER) for management of moderate-severe mitral regurgitation in carefully selected patients with poor left ventricular systolic function, with a number needed to treat of 3.1 to reduce heart failure hospitalisation and 5.9 to reduce all-cause death. To slow the rapid accumulation of morbidity and mortality, we advocate a proactive approach with accelerated medical optimisation, followed by management of atrial fibrillation and cardiac resynchronisation therapy if indicated, then, rapid referral to the Heart Team for consideration of mitral valve intervention in patients with ongoing symptoms and at least moderate-severe mitral regurgitation. Mitral TEER has been shown to be ‘reasonably cost-effective’ (but not cost-saving) in the UK in selected patients, although TEER remains underused with only 6.5 procedures per million population (pmp) compared with Germany (77 pmp), Switzerland (44 pmp) and the USA (32 pmp).
Patients with heart failure with reduced ejection fraction who have secondary mitral regurgitation (SMR) have poorer outcomes and quality of life than those without SMR. Guideline-directed medical therapy is the cornerstone of SMR treatment. Careful evaluation of landmark trials using mitral transcatheter edge-to-edge repair in SMR has led to an improved understanding of who will benefit from percutaneous interventions with emphasis on a multidisciplinary approach. The success with mitral transcatheter edge-to-edge repair in SMR has also spurred the evaluation of its role in populations that were not initially studied, such as end-stage heart failure and cardiogenic shock. A spectrum of transcatheter devices in development and clinical trials promise to further provide a growing array of management options for heart failure with reduced ejection fraction patients with symptomatic SMR.
Background
Operative indication of the additional mitral repair for moderate ischemic mitral regurgitation (MR) in the setting of coronary artery bypass grafting (CABG) is still unclear.Methods
This study was designed as the nation-wide multi-center retrospective analysis with additional survival data. CABGs without past heart surgery registered in 2014 and 2015 were included. Concomitant surgery other than tricuspid or arrhythmia surgery, mitral replacement, and off-pump cases, was excluded. Grade 1 or 4 MR, and ejection fraction < 20 or > 50 were excluded. Additional questionnaire was sent to each hospital, regarding the pathology of MR and clinical outcomes. Additional data were registered between May 28, 2021 and Dec 31, 2021, and the primary outcomes were all-death and cardiac death. The secondary outcomes were heart failure and cerebrovascular event requiring admission, mitral re-intervention. Patients underwent on-pump CABG (CABG only group 221 cases) and CABG with mitral repair (CABG + Mitral repair group 276 cases) were enrolled.ResultsAfter Propensity score matching, 362 cases (CABG only 181cases vs CABG + mitral repair 181 cases) were matched. Cox regression model showed no statistical difference in the long-term survival between CABG alone group and combined procedure group (p = 0.52). Cardiac death (p = 1.00), heart failure (p = 0.68), and cerebrovascular event (p − 0.80) requiring admission were not different between groups as well. The incidence of mitral re-intervention was very few (2 cases in CABG only group, 4 cases in CABG + mitral repair group).Conclusions
In patients with moderate ischemic MR, additional mitral repair to CABG did not improve long-term survival, freedom from heart failure, or cerebrovascular event.
Objective. To determine the impact of the mitral valve insufficiency in patients, suffering ischemic heart disease with lowered contractility of left ventricle and methods of its treatment.
Materials and methods. During 01.01.2015-31.12.2018 yrs period in the Amosov National Institute of Cardiovascular Surgery there were conducted 2267 consecutive operations of coronary shunting, of them 190 (8.4%) - in patients, suffering the ischemic heart disease with lowered contractility of left ventricle. Reduction of the output fraction of left ventricle down to 35% and lower have served as criterion of inclusion of the patients into the Group. There were 170 (89.5%) men and 20 (10.5%) women. The patients’ age have constituted 29 - 83 yrs old, (61.1 ± 8.9) yrs old at average.
Results. In 47.9% of the patients the lowering of the left ventricle contractility after myocardial infarction was followed by occurrence of regurgitation on a mitral valve. At the same time it was noted, that the regurgitation value have had correlated with degree of the left ventricle contractility lowered: in reduction of values of the left ventricle output fracture down to 25% and lower a moderate regurgitation on a mitral valve was registered up to 2 times, a significant one - in 2.5 times, and the pronounced one - in 1.5 times more frequently, than in values of the left ventricle output fracture, exceeding 25%. Occurrence of a mitral insufficiency in 18.7% patients was caused by direct damage of valvular apparatus, while in 81.3% patients the consequences of the heart cavities were present in disorder of contractile function of myocardium. Presence of postinfarction mitral insufficiency enhances the risk of an acute cardiac insufficiency in 1.7 times and necessitates intraoperative correction in values of the regurgitation fraction over 30%.
Conclusion. The own data obtained witness, that noncorrected mitral insufficiency in the ischemic heart disease worsens significantly the postoperative period course after performance of coronary shunting, enhancing rate of an acute cardiac, respiratory and renal insufficiency. Thus, taking into account a negative impact of concomitant mitral valve insufficiency on efficacy of surgical interventions in the lowered contractility of left ventricle the need emerges to perform complex reconstructive intervention in patients, suffering ischemic heart disease with lowered contractility of left ventricle.
Objective
Ischemic mitral regurgitation (IMR) is associated with increased risks of mortality and heart failure. However, the optimal management of moderate IMR remains controversial. We conducted a meta-analysis to appraise whether moderate IMR should be corrected during coronary artery bypass grafting (CABG).
Methods
We searched PubMed, Embase, and Cochrane databases from its inception up to 15 October 2022 for studies that assessed CABG alone versus CABG with mitral valve (MV) surgery in patients with moderate IMR. The primary outcome was perioperative mortality.
Results
Four randomized controlled trials and three observational studies with propensity-matched data including 1209 patients assessing CABG alone ( n = 598) versus CABG with MV surgery ( n = 611) were included. Compared to CABG alone, the addition of MV surgery did not significantly increase perioperative mortality (RR, 1.01; 95% CI, 0.52–1.96; p = 0.98) and stroke (RR, 2.14; 95% CI, 0.97–4.72; p = 0.06), whereas a longer cardiopulmonary bypass duration (MD, 54.91; 95% CI, 42.13–67.68; p < 0.01) and an increased incidence of renal failure were observed in the combined-procedure group. At follow-up, the addition of MV surgery was significantly associated with reduced rates of residual MR (RR, 0.26; 95% CI, 0.13–0.51; p < 0.01) and NYHA class III-IV (RR, 0.54; 95% CI, 0.37–0.78; p < 0.01). However, there was no difference in either mid-term mortality (RR, 1.05; 95% CI, 0.65–1.70; p = 0.82) or late mortality (RR, 91; 95% CI, 0.49–1.71; p = 0.78) between the CABG alone group and the combined-procedure group.
Conclusions
In patients with moderate IMR, the addition of MV surgery to CABG did not increase perioperative mortality. Despite the reduced rates of moderate MR and NYHA class III-IV at follow-up, the addition of MV surgery did not translate in a reduction in mid-term or late mortality.
BACKGROUND
Recent guidelines regarding the treatment of moderate or severe ischemic mitral regurgitation (IMR) in patients undergoing coronary artery bypass grafting (CABG) have changed. This study assessed the real-world impact of changing guidelines on the management of IMR during CABG over time. We hypothesized that the utilization of mitral valve repair for IMR would decrease over time, while mitral valve replacement for severe IMR would increase.
METHODS
Patients undergoing CABG in a statewide collaborative database (2011-2020) were stratified by severity of IMR. Trends in mitral valve repair or replacement were evaluated. To account for patient differences, propensity matched analyses were used to compare patients with and without mitral intervention.
RESULTS
A total of 11,676 patients met inclusion criteria including 1,355 (11.6%) with moderate IMR, and 390 (3.3%) with severe IMR. The proportion of patients undergoing mitral intervention for moderate IMR decreased over time (2011: 17.7%, 2020: 7.5%, p-trend 0.001), while mitral replacement for severe IMR remained stable (2011 11.1%, 2020: 13.3%, p-trend 0.14). Major morbidity was higher among patients with moderate IMR who underwent mitral intervention (29.1% vs 19.9%, p=0.005). In a propensity analysis of 249 well-matched pairs, there was no difference in major morbidity (29.3% with mitral intervention vs. 23.7% without, p=0.16) or operative mortality (1.2% vs. 2.4%, p=0.5).
CONCLUSIONS
Consistent with recent guideline updates, patients with moderate IMR were less likely to undergo mitral repair. However, the rate of replacement for severe ischemic MR did not change. Mitral intervention during CABG did not increase operative mortality or morbidity.
Introduction
Although randomized trial data exist for 2-y outcomes comparing isolated coronary artery bypass grafting (CABG) versus CABG with concomitant mitral valve repair (CABG + MVr) for the treatment of moderate ischemic mitral regurgitation (IMR), longer term outcomes are unclear. This study evaluated the longitudinal outcomes of isolated CABG for moderate IMR.
Methods
Patients with moderate IMR undergoing isolated CABG from January 2010 to February 2018 at a single institution were included. Outcomes included longitudinal freedom from heart failure readmission, survival, rates of persistent mitral regurgitation (MR), and freedom from mitral valve reinterventions. A subanalysis was conducted comparing CABG versus CABG + MVr. Multivariable Cox regression was used for risk adjustment.
Results
A total of 528 patients with moderate IMR underwent isolated CABG. Postoperatively, 26% of patients had at least moderate MR at 1-mo follow-up, although at 5 y progression to severe MR was rare (2.2%) as were mitral valve reinterventions (0.2%). Survival at 30 d (95.8%), 1 y (89.6%), and 5 y (76.6%) was acceptable. Furthermore, the freedom from readmission for heart failure was also acceptable at 30 d (92.6%), 1 y (79.9%), and 5 y (65.0%) postoperatively. In a subanalysis comparing CABG versus CABG + MVr, unadjusted and risk-adjusted survival, freedom from heart failure readmissions, mitral valve reinterventions, and degrees of MR were comparable between the groups at all intervals (all P > 0.05).
Conclusions
The majority of patients with moderate IMR can undergo isolated CABG with acceptable rates of heart failure readmissions, survival, progression to severe MR, and the need for subsequent mitral interventions. These data support the use of isolated CABG in patients with moderate IMR.
In this paper, a neural inverse model controller to achieve maximum power tracking for wind energy conversion systems (WECS's) employing a double-fed induction generator (DFIG) is proposed. Changes on the firing angle of the inverter can control the operation point of the generator. This purpose complies with a neural network (NN) controller. Its feasibility and effectiveness are demonstrated by simulation results of a typical turbine/generator pair.
As a result of increasing environmental concern, the impact of conventional electricity generation on the environment is being minimized and efforts are being made to generate electricity from renewable sources. One way of generating electricity from renewable sources is to use wind turbines that convert the energy contained in owing air into electricity. The major contributions of this paper are as follows: 1) The math-
ematical model of a prototype of a wind turbine is presented. This mathematical model is obtained by using the Euler Lagrange method and the circuits theory. The data of a prototype are used for the simulations of the obtained model. The prototype is a windward wind turbine of three blades. 2) An observer to see the angular position of a blade and the angular velocity of a blade using the armature current in the wind turbine is proposed, and this observer is important because it is easy to have the measure of the third, but it is difficult to have the measure of the first and the second. 3) It is proven that the state error of the observer applied to the nonlinear model is exponentially stable. The stability of the proposed observer is based on the solution of the Lyapunov method.
The framework of adaptive control applied to a wind turbine is presented. The wind turbine is adaptively controlled to achieve a balance between two objectives, power maximization and minimization of the generator torque ramp rate. An optimization model is developed and solved with a linear weighted objective. The objective weights are autonomously adjusted based on the demand data and the predicted power production. Two simulation models are established to generate demand information. The wind power is predicted by a data-driven time-series model utilizing historical wind speed and generated power data. The power generated from the wind turbine is estimated by another model. Due to the intrinsic properties of the data-driven model and changing weights of the objective function, a particle swarm fuzzy algorithm is used to solve it.
This paper presents a multiobjective optimization model of wind turbine performance. Three different objectives, wind power output, vibration of drive train, and vibration of tower, are used to evaluate the wind turbine performance. Neural network models are developed to capture dynamic equations modeling wind turbine performance. Due to the complexity and nonlinearity of these models, an evolutionary strategy algorithm is used to solve the multiobjective optimization problem. Data sets at two different frequencies, 10 s and 1 min, are used in this study. Computational results with the two data sets are reported. Analysis of these results points to a reduction of wind turbine vibrations potentially larger than the gains reported in the paper. This is due to the fact that vibrations may occur at frequencies higher than ones reflected in the 10-s data collected according to the standard practice used in the wind industry.
In this work, a novel data-driven control approach, model-free adaptive control, is presented based on a new dynamic linearization technique for a class of discrete-time single-input and single-output nonlinear systems. The main feature of the approach is that the controller design depends merely on the input and the output measurement data of the controlled plant. The theoretical analysis shows that the approach guarantees the bounded input and bounded output stability and tracking error monotonic con- vergence. The comparison experiments verify the effectiveness of the proposed approach. Index Terms—Adaptive control, compact form dynamic lin- earization (CFDL), data-driven control, model-free adaptive control (MFAC), partial form dynamic linearization (PFDL), pseudo-partial derivative (PDD), three-tank system.
In wind energy conversion systems, one of the operational problems is the changeability and discontinuity of wind. In most cases, wind speed can fluctuate rapidly. Hence, quality of produced energy becomes an important problem in wind energy conversion plants. Several control techniques have been applied to improve the quality of power generated from wind turbines. Pitch control is the most efficient and popular power control method, especially for variable-speed wind turbines. It is a useful method for power regulation above the rated wind speed. This paper proposes an artificial neural network-based pitch angle controller for wind turbines. In the simulations, a variable-speed wind turbine is modeled, and its operation is observed by using two types of artificial neural network controllers. These are multi-layer perceptrons with back propagation learning algorithm and radial basis function network. It is shown that the power output was successfully regulated during high wind speed, and as a result overloading or outage of the wind turbine was prevented.
Neural networks (NNs) have numerous applications to online processes, but the problem of stability is rarely discussed. This is an extremely important issue because, if the stability of a solution is not guaranteed, the equipment that is being used can be damaged, which can also cause serious accidents. It is true that in some research papers this problem has been considered, but this concerns continuous-time NN only. At the same time, there are many systems that are better described in the discrete time domain such as population of animals, the annual expenses in an industry, the interest earned by a bank, or the prediction of the distribution of loads stored every hour in a warehouse. Therefore, it is of paramount importance to consider the stability of the discrete-time NN. This paper makes several important contributions. 1) A theorem is stated and proven which guarantees uniform stability of a general discrete-time system. 2) It is proven that the backpropagation (BP) algorithm with a new time-varying rate is uniformly stable for online identification and the identification error converges to a small zone bounded by the uncertainty. 3) It is proven that the weights' error is bounded by the initial weights' error, i.e., overfitting is eliminated in the proposed algorithm. 4) The BP algorithm is applied to predict the distribution of loads that a transelevator receives from a trailer and places in the deposits in a warehouse every hour, so that the deposits in the warehouse are reserved in advance using the prediction results. 5) The BP algorithm is compared with the recursive least square (RLS) algorithm and with the Takagi-Sugeno type fuzzy inference system in the problem of predicting the distribution of loads in a warehouse, giving that the first and the second are stable and the third is unstable. 6) The BP algorithm is compared with the RLS algorithm and with the Kalman filter algorithm in a synthetic example.
Mitral and tricuspid are increasingly prevalent. Doppler echocardiography not only detects the presence of regurgitation but also permits to understand mechanisms of regurgitation, quantification of its severity and repercussions. The present document aims to provide standards for the assessment of mitral and tricuspid regurgitation.
Surgical ventricular reconstruction is a specific procedure designed to reduce left ventricular volume in patients with heart failure caused by coronary artery disease. We conducted a trial to address the question of whether surgical ventricular reconstruction added to coronary-artery bypass grafting (CABG) would decrease the rate of death or hospitalization for cardiac causes, as compared with CABG alone.
Between September 2002 and January 2006, a total of 1000 patients with an ejection fraction of 35% or less, coronary artery disease that was amenable to CABG, and dominant anterior left ventricular dysfunction that was amenable to surgical ventricular reconstruction were randomly assigned to undergo either CABG alone (499 patients) or CABG with surgical ventricular reconstruction (501 patients). The primary outcome was a composite of death from any cause and hospitalization for cardiac causes. The median follow-up was 48 months.
Surgical ventricular reconstruction reduced the end-systolic volume index by 19%, as compared with a reduction of 6% with CABG alone. Cardiac symptoms and exercise tolerance improved from baseline to a similar degree in the two study groups. However, no significant difference was observed in the primary outcome, which occurred in 292 patients (59%) who were assigned to undergo CABG alone and in 289 patients (58%) who were assigned to undergo CABG with surgical ventricular reconstruction (hazard ratio for the combined approach, 0.99; 95% confidence interval, 0.84 to 1.17; P=0.90).
Adding surgical ventricular reconstruction to CABG reduced the left ventricular volume, as compared with CABG alone. However, this anatomical change was not associated with a greater improvement in symptoms or exercise tolerance or with a reduction in the rate of death or hospitalization for cardiac causes. (ClinicalTrials.gov number, NCT00023595.)
Cardiovascular magnetic resonance (CMR) is increasingly used to assess patients with mitral regurgitation. Its advantages include quantitative determination of ventricular volumes and function and the mitral regurgitant fraction, and in ischemic mitral regurgitation, regional myocardial function and viability. In addition to these, identification of leaflet prolapse or restriction is necessary when valve repair is contemplated. We describe a systematic approach to the evaluation of mitral regurgitation using CMR which we have used in 149 patients with varying etiologies and severity of regurgitation over a 15 month period.
Following standard ventricular cine acquisitions, including 2, 3 and 4 chamber long axis views and a short axis stack for biventricular function, we image movements of all parts of the mitral leaflets using a contiguous stack of oblique long axis cines aligned orthogonal to the central part of the line of coaptation. The 8–10 slices in the stack, orientated approximately parallel to a 3-chamber view, are acquired sequentially from the superior (antero-lateral) mitral commissure to the inferior (postero-medial) commissure, visualising each apposing pair of anterior and posterior leaflet scallops in turn (A1-P1, A2-P2 and A3-P3). We use balanced steady state free precession imaging at 1.5 Tesla, slice thickness 5 mm, with no inter-slice gaps. Where the para-commissural coaptation lines curve relative to the central region, two further oblique cines are acquired orthogonal to the line of coaptation adjacent to each commissure. To quantify mitral regurgitation, we use phase contrast velocity mapping to measure aortic outflow, subtracting this from the left ventricular stroke volume to calculate the mitral regurgitant volume which, when divided by the left ventricular stroke volume, gives the mitral regurgitant fraction. In patients with ischemic mitral regurgitation, we further assess regional left ventricular function and, with late gadolinium enhancement, myocardial viability.
Comprehensive assessment of mitral regurgitation using CMR is feasible and enables determination of mitral regurgitation severity, associated leaflet prolapse or restriction, ventricular function and viability in a single examination and is now routinely performed at our centre. The mitral valve stack of images is particularly useful and easy to acquire.
In this work, a novel model-free adaptive control based freeway ramp metering strategy with feedforward iterative learning is proposed. The modularized controller design with feedforward iterative learning controller added on to the feedback model free adaptive control (MFAC) controller makes use of the periodicity of the traffic flow effectively and improves the controller performance greatly. With rigorous analysis, the proposed control scheme guarantees the asymptotic convergences along the iteration axis. Intensive simulations show the effectiveness of the proposed strategy.
It is well-known that robustness refers to the ability dealing with unknown uncertainties or unmodeled dynamics of the model-based control theory. However, this kind of robustness no longer has any significance for model free or data-driven control theory because the controller is designed only using I/O data of the controlled plant. In this paper, a novel robustness of the model free control or data-driven control is presented when the system is controlled by the model free adaptive control (MFAC) scheme. It is assumed that an MFAC scheme is implemented via a network control system and that data dropout occurs due to a failing sensor, actuator or network failure, resulting in what it is called intermittent MFAC. The stability of such a MFAC scheme is analyzed by the statistical approach. It is shown that the MFAC system is still stable when data dropout occurs, and the data dropout impacts the convergence speed.
In this paper, we present several considerations centered around the data-driven system approaches. We briefly explore three main issues: the evolving relationship between off-line and on-line data processing methods, the complementary relationship between the data-driven and model-based methods, and the perspectives of data-driven system approaches. Instead of offering solutions to data-driven system problems, which is impossible at the present level of knowledge and research, in this article we aim at categorizing and classifying open problems, exploring possible directions that may offer alternatives or potentials for the four key fields of interests: control, decision making, scheduling, and fault diagnosis.
A doctor could say that a patient is sick while he/she is healthy or could say that the patient is healthy while
he/she is sick, by mistake. So it is important to generate a system that can give a good diagnosis, in this case for abnormal eye movements. An abnormal eye movement is when the patient wants to move the eye to up or down and the eye does not move or the eye moves to other place. In this paper, a method for the pattern recognition is used to provide a better diagnosis for patients related with the abnormal eye movements. The real data of signals of two eye movements (up and down) of patients are obtained using a mindset ms-100 system. A new method that uses one intelligent algorithm for online pattern recognition is proposed. The difference between the proposed method and the previous works is that, in other works, both behaviors (up
and down) are trained with one intelligent algorithm, while in this work, up behavior is trained with one intelligent algorithm and down behavior is trained with other intelligent algorithm; it is because the multi-output system can always be decomposed into a collection of single-output systems with the advantage to use different parameters for each one if necessary. The intelligent algorithm used by the proposed method could be any of the following: the adaline network denoted as AN, the multilayer neural network denoted as
NN, or the Sugeno fuzzy inference system denoted as SF. So the comparison results of the proposed method using each of the intelligent algorithms for online pattern recognition of two eye movements are presented.
A novel Sensitivity Compensating Control (SCC) approach is proposed in a data-driven model based platform and combined with an Extended External Reset Feedback (EERF) method to handle sensitivity, input saturation, and accurate process model requirement problems associated with application of Generic Model Control (GMC). Two versions of Adaptive GMC (AGMC) are proposed using linear-in-parameters time-series models with time-varying parameters for higher relative degree systems, and are used in the formulation of SCC and EERF approaches. The steps involved in the proposed approach consist of defining a new process, control law and set point such that the determined control action drives the original process to its desired set point. The performance of the proposed control algorithms is illustrated by application to a benchmark multi-product polymerization reactor control challenge problem. The proposed approaches are applicable to chemical engineering systems exhibiting input sensitivity.
This article reviews the design of algorithms for wind turbine pitch control and also for generator torque control in the case of variable speed turbines. Some recent and possible future developments are discussed. Although pitch control is used primarily to limit power in high winds, it also has a significant effect on various loads. Particularly as turbines become larger, there is increasing interest in designing controllers to mitigate loads as far as possible. Torque control in variable speed turbines is used primarily to maximize energy capture below rated wind speed and to limit the torque above rated. Once again there are opportunities for designing these controllers so as to mitigate certain loads. In addition to improving the design of the control algorithms, it is also possible to use additional sensors to help the controller to achieve its objectives more effectively. The use of additional actuators in the form of individual pitch controllers for each blade is also discussed. It is important to be able to quantify the benefits of any new controller. Although computer simulations are useful, field trials are also vital. The variability of the real wind means that particular care is needed in the design of the trials. Copyright
In this paper, we propose a new H¥{\mathcal H_\infty} weight learning algorithm (HWLA) for nonlinear system identification via Takagi–Sugeno (T–S) fuzzy Hopfield neural networks
with time-delay. Based on Lyapunov stability theory, for the first time, the HWLA for nonlinear system identification is presented
to reduce the effect of disturbance to an H¥{\mathcal{H}_{\infty }} norm constraint. The HWLA can be obtained by solving a convex optimization problem which is represented in terms of linear
matrix inequality (LMI). An illustrative example is given to demonstrate the effectiveness of the proposed identification
scheme.
Keywords
H¥{\mathcal{H}_{\infty}} nonlinear system identification–Weight learning algorithm–Takagi–Sugeno fuzzy Hopfield neural networks–Linear matrix inequality (LMI)–Lyapunov stability theory
In this paper, a speed-adaptive reduced-order observer for sensorless vector control of doubly fed induction generators (DFIGs) is proposed. The observer is a simulation of the rotor current dynamic model with feedback of the estimation error and a speed-adaptation loop. Feedback and adaptation gains are designed based on the closed-loop observer model. A parameter sensitivity analysis reveals that this observer is robust against machine parameter variations in the normal operating regions. Simulation results demonstrate desired steady-state and dynamic performance of this sensorless control approach for DFIG-based variable-speed wind turbines.
A multistage data-driven neuro-fuzzy system is considered for the multiobjective trajectory planning of Parallel Kinematic Machines (PKMs). This system is developed in two major steps. First, an offline planning based on robot kinematic and dynamic models, including actuators, is performed to generate a large dataset of trajectories, covering most of the robot workspace and minimizing time and energy, while avoiding singularities and limits on joint angles, rates, accelerations, and torques. An augmented Lagrangian technique is implemented on a decoupled form of the PKM dynamics in order to solve the resulting nonlinear constrained optimal control problem. Then, the outcomes of the offline-planning are used to build a data-driven neuro-fuzzy inference system to learn and capture the desired dynamic behavior of the PKM. Once this system is optimized, it is used to achieve near-optimal online planning with a reasonable time complexity. Simulations proving the effectiveness of this approach on a 2-degrees-of-freedom planar PKM are given and discussed.
A data-driven fuzzy approach is developed for solving the motion planning problem of a mobile robot in the presence of moving obstacles. The approach consists of devising a general method for the derivation of input–output data to construct a fuzzy logic controller (FLC) off-line. The FLC is constructed based on the use of a recently developed data-driven and efficient fuzzy controller modeling algorithm, and it can then be used on-line by the robot to navigate among moving obstacles. The novelty in the presented approach, as compared to the most recent fuzzy ones, stems from its generality. That is, the devised data-derivation method enables the construction of a single FLC to accommodate a wide range of scenarios. Also, care has been taken to find optimal or near optimal FLC solution in the sense of leading to a sufficiently small robot travel time and collision-free path between the start and target points. Furthermore, since the algorithm has been shown efficient in the representation of non-linear control functions, in terms of combating noise and possessing a good generalization capability, these aspects are also tested in this practical control problem. Comparison of the results with those obtained by fuzzy-genetic and another hybrid and data-driven design approach is also done.
The heart, lungs and hemoglobin form the body's gas transport system, which links the atmosphere and its supply of O2 with tissue, while simultaneously providing for the elimination of the metabolic end-product, CO2, into the atmosphere. The transport of these respiratory gases must be in accordance with metabolic need. This is particularly evident during the physiologic stress of isotonic exercise, when the O2 requirements and CO2 production of skeletal muscle are increased. The monitoring of these respiratory gases during exercise, referred to as cardiopulmonary exercise testing (CAR-PET), can be used to assess heart and lung function in patients with cardiovascular or lung disease or both. Chronic cardiac failure (CCF) may be defined in physiologic terms as that circumstance in which the heart fails to provide tissue with O2 at a rate commensurate with aerobic requirements. In patients with CCF, CAR-PET represents a noninvasive means to determine aerobic capacity (that is, maximal O2 up-take) and anaerobic threshold during incremental treadmill exercise. It can also provide an objective measure of the severity of failure, the functional status of the patient and the heart's pump reserve. By using additional measurements of ventilation, arterial O2 saturation and, in selected cases, hemodynamic monitoring, the nature and severity of cardiovascular and pulmonary disease may be evaluated.
This paper focuses on a control application of optimization in wind power systems. An optimal control structure for variable speed fixed pitch wind turbines is presented. The optimality of the whole system is defined by the trade-off between the energy conversion maximization and the control input minimization that determines the mechanical stress of the drive train. The frequency separation of the short-term and the long-term variations, adopted in the wind modelling, has resulted in a two-loop control structure. The optimal problem is treated within a complete linear quadratic stochastic approach, whose effectiveness was tested on an electromechanical wind turbine simulator.
Operation of variable speed wind turbine generator (WTG) in the above-rated region characterized by high turbulence intensities demands a trade-off between two performance metrics: maximization of energy harvested from the wind and minimization of damage caused by mechanical fatigue. This paper presents a learning adaptive controller for output power leveling and decrementing cyclic loads on the drive train. The proposed controller incorporates a linear quadratic Gaussian (LQG) augmented by a neurocontroller (NC) and regulates rotational speed by specifying the demanded generator torque. Pitch control ensures rated power output. A second-order model and a stochastic wind field model are used in the analysis. The LQG is used as a basis upon which the performance of the proposed paradigm in the trade-off studies is assessed. Simulation results indicate the proposed control scheme effectively harmonizes the relation between rotor speed and the highly turbulent wind speed thereby regulating shaft moments and maintaining rated power.
Wind energy technology has experienced important improvements this last decade. The transition from fixed speed to variable speed wind turbines has been a significant element of these improvements. It has allowed adapting the turbine rotational speed to the wind speed variations with the aim of optimizing the aerodynamic efficiency. A classic controller that has slow dynamics relative to the mechanical dynamics of the drive train is implemented in commercial wind turbines. The objective of the work related in this paper has been to evaluate the implementation, on a test bench, of a controller whose dynamics can be adjusted to be faster and to compare in particular its aerodynamic efficiency with the conventional controller. In theory, the higher dynamics of the non-classic controller has to lead to a better efficiency. A 180 kW wind turbine whose simulation model has been validated with field data is emulated on an 18 kW test bench. The emulator has also been validated. Test bench trials are a very useful step between numerical simulation and trials on the real system because they allow analyzing some phenomena that may not appear in simulations without endangering the real system. The trials on the test bench show that the non-conventional controller leads to a higher aerodynamic efficiency and that this is offset by higher mechanical torque and electric power fluctuations. Nevertheless, the amplitudes of these fluctuations are relatively low compared to their rated values.
It is well-known that conventional control theories are widely suited for applications where the processes can be reasonably described in advance. However, when the plant’s dynamics are hard to characterize precisely or are subject to environmental uncertainties, one may encounter difficulties in applying the conventional controller design methodologies. In this case, an alternative design is a model-free learning adaptive control (MFLAC), based on pseudo-gradient concepts with compensation using a radial basis function neural network and optimization approach with differential evolution technique presented in this paper. Motivation for developing a new approach is to overcome the limitation of the conventional MFLAC design, which cannot guarantee satisfactory control performance when the nonlinear process has different gains for the operational range. Robustness of the MFLAC with evolutionary-neural compensation scheme is compared to the MFLAC without compensation. Simulation results for a nonlinear chemical reactor and nonlinear control valve are given to show the advantages of the proposed evolutionary-neural compensator for MFLAC design.
To achieve maximum power point tracking (MPPT) for wind power generation systems, the rotational speed of wind turbines should be adjusted in real time according to wind speed. In this paper, a Wilcoxon radial basis function network (WRBFN) with hill-climb searching (HCS) MPPT strategy is proposed for a permanent magnet synchronous generator (PMSG) with a variable-speed wind turbine. A high-performance online training WRBFN using a back-propagation learning algorithm with modified particle swarm optimization (MPSO) regulating controller is designed for a PMSG. The MPSO is adopted in this study to adapt to the learning rates in the back-propagation process of the WRBFN to improve the learning capability. The MPPT strategy locates the system operation points along the maximum power curves based on the dc-link voltage of the inverter, thus avoiding the generator speed detection.
A data-driven approach for maximization of the power produced by wind turbines is presented. The power optimization objective is accomplished by computing optimal control settings of wind turbines using data mining and evolutionary strategy algorithms. Data mining algorithms identify a functional mapping between the power output and controllable and non-controllable variables of a wind turbine. An evolutionary strategy algorithm is applied to determine control settings maximizing the power output of a turbine based on the identified model. Computational studies have demonstrated meaningful opportunities to improve the turbine power output by optimizing blade pitch and yaw angle. It is shown that the pitch angle is an important variable in maximizing energy captured from the wind. Power output can be increased by optimization of the pitch angle. The concepts proposed in this paper are illustrated with industrial wind farm data.
An intelligent statistical approach is proposed for monitoring the performance of multivariate model predictive control (MPC) controller, which systematically integrates both the assessment and diagnosis procedures. Model predictive error is included into the monitored variable set and a 2-norm based covariance benchmark is presented. By comparing the data of a monitored operational period with the “golden” user-predefined one, this method can properly evaluate the performance of an MPC controller at the monitored operational stage. Characteristic direction information is mined from the operating data and the corresponding classes are built. The eigenvector angle is defined to describe the similarity between the current data set and the established classes, and an angle-based classifier is introduced to identify the root cause of MPC performance degradation when a poor performance is detected. The effectiveness of the proposed methodology is demonstrated in a case study of the Wood–Berry distillation column system.
Unfalsified control is a data-driven, plant-model-free controller design method, which recursively falsifies controllers that fail to meet the specified performance requirement. In ellipsoidal unfalsified control, the region of controllers that are unfalsified, the unfalsified set, is described by an ellipsoid. Due to the combination of the performance requirement and controller structure, the approximate update of the unfalsified set can be computed analytically, resulting in a computationally cheap algorithm. Conditions for stability of ellipsoidal unfalsified control are presented, and the effectiveness of the proposed algorithm is shown in a simulation.
An evolutionary computation approach for optimization of power factor and power output of wind turbines is discussed. Data-mining algorithms capture the relationships among the power output, power factor, and controllable and non-controllable variables of a 1.5 MW wind turbine. An evolutionary strategy algorithm solves the data-derived optimization model and determines optimal control settings. Computational experience has demonstrated opportunities to improve the power factor and the power output by optimizing set points of blade pitch angle and generator torque. It is shown that the pitch angle and the generator torque can be controlled to maximize the energy capture from the wind and enhance the quality of the power produced by the wind turbine with a DFIG generator. These improvements are in the presence of reactive power remedies used in modern wind turbines. The concepts proposed in this paper are illustrated with the data collected at an industrial wind farm.
The power factor and torque of wind turbines are predicted using artificial neural networks (ANNs) based on experimental data which have been collected for seven prototype vertical Savonius rotors tested in a wind tunnel. In this research, the rotors with different configurations were located in the wind tunnel and the tests were repeated 4–6 times in order to reduce errors. Since the Reynolds number has a negligible effect on power ratio, therefore tip speed ratio (TSR) is the main input parameter to be predicted in neural network. Also, the rotor’s power factor and torque were simulated for different tip speed ratios and different blade angles. The simulated results show a strong capability for providing reasonable predictions and estimations of the maximum power of rotors and maximizing the efficiency of Savonius turbines. According to artificial neural nets simulations and the experimental results, increasing tip speed ratio leads to a higher power ratio and torque. For all the tested rotors, a maximum and minimum amount of torque has happened at angle of 60o and 120o, respectively.
The wind power production spreading, also aided by the transition from constant to variable speed operation, involves the development of efficient control systems to improve the effectiveness of wind systems. This paper presents a data-driven design methodology able to generate a Takagi–Sugeno–Kang (TSK) fuzzy model for maximum energy extraction from variable speed wind turbines. In order to obtain the TSK model, fuzzy clustering methods for partitioning the input–output space, combined with genetic algorithms (GA), and recursive least-squares (LS) optimization methods for model parameter adaptation are used.The implemented TSK fuzzy model, as confirmed by some simulation results on a doubly fed induction generator connected to a power system, exhibits high speed of computation, low memory occupancy, fault tolerance and learning capability.
We assessed changes in left ventricular (LV) volume and function and in regional myocardial wall stress in noninfarcted segments after restrictive mitral annuloplasty (RMA) with or without surgical ventricular restoration (SVR).
Thirty-nine patients with ischemic cardiomyopathy (ejection fraction ≤ 0.35) and severe mitral regurgitation (≥ 3) were studied before and 2.8 months after surgery with cine-angiographic multidetector computed tomography (cine-MDCT). Eighteen underwent RMA alone (RMA group) and 21 underwent RMA and SVR (RMA+SVR group). In addition to measuring conventional parameters (LV end-diastolic volume index [LVEDVI], LV end-systolic volume index [LVESVI], and LV ejection fraction), we evaluated the regional circumferential end-systolic wall stress and mean circumferential fiber shortening in both the basal and mid-LV regions using 3-dimensional cine-MDCT images. LV end-diastolic and end-systolic volume indexes were significantly greater in the RMA+SVR group than in the RMA group preoperatively, but these values did not differ significantly postoperatively. LV end-diastolic and end-systolic volume indexes decreased significantly, by 21% and 27% after RMA and by 35% and 42% after RMA and SVR, and the percent reductions in LV end-diastolic and end-systolic volume indexes were significantly larger in the RMA+SVR group. Regional end-systolic wall stress decreased and circumferential fiber shortening increased significantly in the noninfarcted regions after RMA with or without SVR.
RMA plus SVR showed a potentially greater reduction of LV end-diastolic and end-systolic volume indexes than RMA alone. In selected patients with more advanced LV remodeling, concomitant SVR may favorably affect the LV reverse-remodeling process induced by RMA.