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Three-dimensional electroanatomic mapping of the coronary veins during cardiac resynchronization therapy implant: feasibility and possible applications
Abstract
Purpose:
Left ventricular (LV) electrical activation pattern could determine optimal LV lead placement site during cardiac resynchronization therapy (CRT) device implant. We sought to determine the feasibility of using EnSite NavX™ electroanatomic mapping system (St. Jude Medical Inc., St. Paul, MN) to assess LV electrical activation during CRT implant.
Methods:
Patients (n = 32; NYHA III, LVEF <35%, QRSd >120 ms) underwent NavX™ mapping during CRT implant. Left bundle branch block (LBBB) was present during sinus rhythm in group A (n = 17), whereas LBBB was induced by permanent RV apical pacing in group B (n = 15). Following coronary sinus (CS) cannulation, a coil tip 0.014-in. guidewire was introduced into all available CS branches as a mapping electrode. Each patient's unipolar activation map was successfully constructed within 10 min, using the onset of surface QRS as reference.
Results:
LV activation patterns were complex and varied in both groups. Earliest activation was usually apical, but latest activation was more heterogenous. The lateral or posterolateral branches were the sites of latest activation in 47% of group A and 73% of group B. An LV lead positioned conventionally by a physician blinded to the mapping data was concordant with the latest activated segment in 18% of group A and none of group B patients.
Conclusions:
Electroanatomic mapping of the CS tributaries is feasible and clinically practicable. Mapping revealed heterogenous conduction patterns that vary between patients in each group and between groups. An LV lead empirically placed in a lateral branch rarely paces the optimal, latest activated vein segment.
... Guidewire Method for Measuring Local LV Electrical Activation Time using three-dimensional (3D) mapping systems in conjunction with a guidewire, [5][6][7] and with LV pacing leads 8 ; however, this method is limited in that it can only be used by those electrophysiology (EP) laboratories with access to such systems and those who can afford the additional cost and time associated with 3D mapping. To determine if QLV measurements can be made before lead selection and without a 3D mapping system, electrogram recordings were made using a guidewire and a standard EP laboratory recording system, and then compared with recordings obtained from permanent LV pacing electrodes implanted at the same site. ...
... Studies that have prospectively measured QLV have thus far used 3D mapping systems or have moved the permanent LV pacing lead from site to site. [5][6][7][8]12 The present study describes a simplified method to measure QLV intervals using a unipolar guidewire during CRT implantation that does not require pairing with a 3D mapping system or repeated maneuvering of an LV pacing lead. The QLV measured with the guidewire corresponds closely with the value measured following placement of the lead. ...
The timing of local activation at left ventricular (LV) pacing leads is measured from the onset of the QRS complex to the peak of the LV electrogram (QLV). Pacing from the sites of late activation is associated with higher response rates to cardiac resynchronization therapy (CRT). Prior studies have measured QLV from permanent pacing leads, or have used electroanatomic mapping systems. The current study compares QLV measurements made with a guidewire to those collected from permanent LV pacing leads positioned at the same venous site without the use of electroanatomic mapping systems. In this study, 20 patients undergoing CRT implantation (14 males, mean QRS: 164.0 ms) had QLV measurements taken using a guidewire. QLV and LV electrogram duration measurements were made at LV pacing sites, and were repeated after positioning the permanent LV pacing lead at the same site. There was no difference in QLV measurements obtained using a guidewire and those obtained using the permanent pacing lead placed at the same site (p = 0.569). QLV measurements obtained with a guidewire and the permanent LV pacing lead at the same site, respectively, were strongly correlated (r = 0.965; p < 0.001). The median absolute difference in electrogram duration was 7.0 ms (p = 0.55). The average time required to make QLV measurements using the guidewire was 11.7 minutes [standard deviation (SD): 6.8]. The average total fluoroscopy time for the entire CRT implant procedure was 10.9 minutes (SD: 5.1). In light of these results, it can be suggested that a guidewire can be used to prospectively measure LV prior to selection or placement of a permanent pacing lead without the use of an electroanatomic mapping system.
... Coronary venous EAM has proven itself as a safe technique requiring reasonable procedural times. 6,16 All procedures in our study occurred without complications, and image integration did not prolong the implantation time, mainly because constructing the DE-CMR mesh, the most time-consuming aspect, was performed before the procedure. ...
... Coronary venous EAM requires practice by electrophysiologists, although it can be performed within reasonable times when performed by those with adequate skill. 6,16 The integration process in our study was complicated because 2 anatomies were fused and DE-CMR images were acquired during end-diastole but EAM generation was not ECG triggered. Nevertheless, rotation errors were minimized by mapping the RV apex and CS ostium, creating additional matching points on both geometries. ...
Background: Placing the left ventricular (LV) lead at a site of late electrical activation remote from scar is desired to improve cardiac resynchronization therapy (CRT) response.
Objective: To integrate coronary venous electro-anatomic mapping (EAM) with delayed enhancement cardiac magnetic resonance (DE-CMR) enabling LV lead guidance to the latest activated vein remote from scar.
Methods: Eighteen CRT candidates with focal scar on DE-CMR were prospectively included. DE-CMR images were semi-automatically analyzed. Coronary venous EAM was
performed intra-procedurally and integrated with DE-CMR to guide LV lead placement
real-time. Image integration accuracy and electrogram (EGM) parameters were
evaluated offline.
Results: Integration of EAM and DE-CMR was achieved using 8.9±2.8 anatomical landmarks and with an accuracy of 4.7±1.1mm (mean±SD). Maximal electrical delay ranged between 72−197ms (57−113% of QRS duration) and was heterogeneously located among individuals. In twelve patients the latest activated vein was located outside scar and placing the LV lead in the latest activated vein remote from scar was
accomplished in ten and prohibited in two patients. In the other six patients the latest activated vein was located in scar and targeting alternative veins was considered. Unipolar voltages were on average lower in scar compared to non-scar (6.71±3.45 vs. 8.18±4.02 mV (median±IQR), p<0.001), but correlated weakly with DE-CMR scar extent (R -0.161, p <0.001), and varied widely among individual patients.
Conclusion: Integration of coronary venous EAM with DE-CMR can be used during CRT implantation to guide LV lead placement to the latest activated vein remote from scar, possibly improving CRT.
... The feasibility of such an approach has been explored by a number of studies. 7,8,13,14 Consistent with the earlier reports, the study by Niazi et al. involving 32 patients found that sites of latest LV activation were variable, and that the LV lead which was positioned conventionally by a physician blinded to the mapping data was concordant with the latest activated segment in only a small proportion of patients. 13 In a more recent study involving 25 patients, Rad et al., using EAM of the coronary sinus venous system (figure), also found considerable variability in site of latest LV activation, being located anterolaterally in 18 patients and inferolaterally in 6 patients (1 patient had limited coronary venous anatomy which precluded assessment). ...
... 7,8,13,14 Consistent with the earlier reports, the study by Niazi et al. involving 32 patients found that sites of latest LV activation were variable, and that the LV lead which was positioned conventionally by a physician blinded to the mapping data was concordant with the latest activated segment in only a small proportion of patients. 13 In a more recent study involving 25 patients, Rad et al., using EAM of the coronary sinus venous system (figure), also found considerable variability in site of latest LV activation, being located anterolaterally in 18 patients and inferolaterally in 6 patients (1 patient had limited coronary venous anatomy which precluded assessment). 14 In this study, a quarter of the patients had phrenic nerve stimulation at the optimal site, which might have been overcome in the current day by the use of multipolar LV leads (which were not available at time of study) or perhaps LV endocardial pacing. ...
Biventricular devices play an important adjunctive role in the treatment of heart failure. However, biventricular device implantation is associated with significant radiation exposure and a high proportion of non-response to cardiac resynchronization therapy (CRT). The use of electroanatomic mapping (EAM) during biventricular device implantation may help overcome these issues. This article will review the literature on the role of EAM in biventricular device implantation.
... Therefore, new CS cannulation strategies are required to increase the resynchronization efficiency and to diminish the duration and risks of the operation. Three-dimensional electroanatomic mapping or sensor based electromagnetic tracking systems might be beneficial for CS lead implantation [9,10]. Both techniques are limited in usability to due the higher costs and availability in catheter laboratories without electrophysiology. ...
Objectives:
The aim of this study was to compare conventional versus steerable catheter guided coronary sinus (CS) cannulation in patients with advanced heart failure undergoing cardiac resynchronization therapy (CRT).
Background:
Steerable catheter guided coronary sinus cannulation could reduce fluoroscopy time and contrast medium use during CRT implantation.
Methods:
176 consecutive patients with ischemic and non-ischemic heart failure undergoing CRT implantation from January 2008 to December 2012 at the University Hospital of Cologne were identified. During the study period two concurrent CS cannulation techniques were used: standard CS cannulation technique (standard-group, n = 113) and CS cannulation using a steerable electrophysiology (EP) catheter (EPCath-group, n = 63). Propensity-score matched pairs of conventional and EP-catheter guided CS cannulation made up the study population (n = 59 pairs). Primary endpoints were total fluoroscopy time and contrast medium amount used during procedure.
Results:
The total fluoroscopy time was 30.9 min (interquartile range (IQR), 19.9-44.0 min) in the standard-group and 23.4 min (IQR, 14.2-34-2 min) in the EPCath-group (p = 0.011). More contrast medium was used in the standard-group (60.0 ml, IQR, 30.0-100 ml) compared to 25.0 ml (IQR, 20.0-50.0 ml) in the EPCath-group (P<0.001).
Conclusions:
Use of steerable EP catheter was associated with significant reduction of fluoroscopy time and contrast medium use in patients undergoing CRT implantation.
Nowadays, fluoroscopy is the standard tool used to help physicians during pacing lead implantation. However, its use entails significant radiation exposure for physicians and especially for patients. For the first time, the present case report describes the use of the electro‐anatomical mapping (EAM) navigation system KODEX‐EPD for cardiac resynchronization therapy (CRT) implantation. These findings suggest that CRT implantation guided by the KODEX‐EPD system is feasible and safe with the minimization of X‐ray and dye exposure. CRT‐D electroanatomic mapping system.
Three‐dimensional (3D) reconstruction by means of electroanatomic mapping (EAM) systems, allows for the understanding of the mechanism of focal or re‐entrant arrhythmic circuits, which can be identified by means of dynamic (activation and propagation) and static (voltage) color‐coded maps. However, besides this conventional use, EAM may offer helpful anatomical and functional information for tissue characterisation in several clinical settings. Today, data regarding electromechanical myocardial viability, scar detection in ischaemic and nonischaemic cardiomyopathy and arrhythmogenic right ventricle dysplasia (ARVC/D) definition are mostly consolidated, while emerging results are becoming available in contexts such as Brugada syndrome and cardiac resynchronisation therapy (CRT) implant procedures. As part of an invasive procedure, EAM has not yet been widely adopted as a stand‐alone tool in the diagnostic path. We aim to review the data in the current literature regarding the use of 3D EAM systems beyond the definition of arrhythmia. This article is protected by copyright. All rights reserved
Introduction
Studies have shown an association between outcome in cardiac resynchronization therapy (CRT) and longer interventricular delay at the site of the left ventricular (LV) lead. Targeted LV lead placement at the latest electrically activated segment increases LV function further as compared with standard treatment. We aimed to determine reproducibility and repeatability of identifying latest electrically activated segment during mapping of all available CS branches in patients receiving CRT.
Methods
We included 35 patients who underwent CRT implantation with protocolled mapping guided LV lead implantation aiming for the site of latest electrical activation. Three different doctors experienced in electrophysiology and implantation of CRT devices independently measured time interval from the local bipolar right ventricular (RV) electrogram (EGM) to the local unipolar LV EGM at all mapped sites (RV‐LV). The segment with the latest electrical activation was defined as target segment (TS) and the CS tributary containing TS was defined as target vein (TV). Weighted Kappa statistics with 95% confidence intervals were computed to assess intra‐and inter‐observer agreement for TS and TV.
Results
We mapped 258 segments within 131 veins. Weighted kappa values for repeatability were 0.85 (0.81‐0.89) for TS and 0.92 (0.89‐0.93) for TV, and weighted kappa values of inter‐observer agreement ranged from 0.70 (0.61‐0.73) to 0.80 (0.76‐0.83) for TS and 0.73 (0.64‐0.78) to 0.86 (0.83‐0.89) for TV among all three observers.
Conclusion
The reproducibility and repeatability of identifying latest electrically activated segment during mapping of all available CS branches in patients receiving CRT ranges from good to very good.
This article is protected by copyright. All rights reserved.
The use of an electroanatomic navigation system in Cardiac Resynchronization Therapy (CRT) implantation is an increasingly used approach in the field of electrophysiology. The possibility to minimize X-ray exposure both for patients and for physicians is not the only most attractive aspect. Indeed it is feasible, safe, and allows to obtain more detailed information during the coronary sinus lead placement, in terms of both 3D anatomy and ventricular activation time. This procedure can improve the pacing site choice optimization, making CRT implantation an electrophysiological procedure.
Background
Variations of the coronary sinus tributaries might result in difficulties in left ventricle electrode insertion during cardiac resynchronizing therapy. Morphometric features of tributaries, especially angulation of the coronary sinus tributaries, are crucial for coronary sinus procedures.
Methods
This study was carried out on 200 formaldehyde‐fixed human hearts (22.0% females, mean age of 48.7 ± 15.6 years).
Results
The infero‐lateral aspect of the left ventricle was accessible from the coronary venous tree in 77.0% (in 35% from one, 29% from two, and 13.0% from three tributaries). The middle cardiac vein was present in all cases, with a diameter of 1.8 ± 0.5 mm, cannulation distance of 5.3 ± 3.2 mm and angle of 82.0 ± 12.8°. The infero‐lateral vein of the left ventricle varied greatly in number: single in 63.5%, multiple in 30.5%. The ostium diameter for a single vein was 1.3 ± 0.5 mm, cannulation distance was 21.1 ± 9.8 mm and the angle was 98.1 ± 13.5°. The left marginal vein was present in 39.5% with an ostium diameter of 0.9 ± 0.5 mm, cannulation distance of 46.0 ± 12.0 mm and angle of 92.0 ± 13.4°. Finally, the oblique vein of the left atrium was present in 71.0% with a diameter of 1.3 ± 0.8 mm, cannulation distance of 27.2 ± 9.4 mm and angle of 136.8 ± 16.6°.
Conclusions
This study shows the clinically relevant morphometric characteristic of coronary sinus tributaries. The middle cardiac vein is the most constant among coronary veins. However, it is usually not suitable for left ventricular pacing. The infero‐lateral vein of the left ventricle is highly variable in number, but its morphology makes it a suitable target for left ventricular lead placement.
This article is protected by copyright. All rights reserved
Background
Choice of left ventricular pacing vector (LVPV) affects the QRS-duration (QRSd) in patients with Cardiac Resynchronization Therapy (CRT). It is not known whether testing all LVPVs reduces QRSd compared to device-based “standard-programming”.
Methods
In patients implanted with CRT several ECGs were recorded for each usable LVPV (no phrenic nerve stimulation and threshold <3.5 V) and during “standard-programming” after device-based optimization of AV/VV delays.
Results
22 consecutive patients were included. Average QRSd reduction after CRT + “standard-programming” was 27.3 ± 22 ms. Additional QRSd-reduction was possible in 4 patients by changing the LVPV, and in 5 other patients after optimization of AV- and VV delays without changing LVPV.
Conclusions
Shortening of QRSd compared to “standard-programming” was possible approximately 40% of these patients treated with CRT by testing all LVPVs and re-optimizing AV/VV delays during follow-up. Studies of clinical effects are needed.
: Cardiac resynchronization therapy (CRT) is an established treatment in patients with symptomatic drug-refractory heart failure and broad QRS complex on the surface ECG. Despite the presence of either mechanical dyssynchrony or viable myocardium at the site where delivering left ventricular pacing being necessary conditions for a successful CRT, their direct assessment by techniques of cardiovascular imaging, though feasible, is not recommended in clinical practice by the current guidelines. Indeed, even though there is growing body of data providing evidence of the additional value of an image-based approach as compared with routine approach in improving response to CRT, these results should be confirmed in prospective and large multicentre trials before their impact on CRT guidelines is considered.
Implantation of cardiac resynchronization therapy (CRT) devices can be challenging, time consuming, and associated with high-dose X-Ray exposure. We present the technique in which an electromagnetic navigation system (MediGuideTM, St. Jude Medical) and an electro-anatomical three-dimensional mapping system (EnSite NavX, St Jude Medical) are usefully combined for implanting ICD-CRT devices with strong reduction of X-ray exposure, and for targeting the most delayed regions in the activation maps avoiding scars for optimal CRT response.
Objectives
The MultiPoint Pacing (MPP) trial assessed the safety and efficacy of pacing 2 left ventricular sites with a quadripolar lead in patients with heart failure indicated for a CRT-D device.
Background
Cardiac resynchronization therapy nonresponse is a complex problem where stimulation of multiple left ventricular sites may be a solution.
Methods
Enrolled patients were indicated for a CRT-D system. Bi-ventricular (Bi-V) pacing was activated at implant. Three months later, clinical response was assessed and the patient was randomized (1:1) to receive Bi-V pacing or MPP. Patients were followed for 6 months post-randomization and clinical response was again assessed.
Results
The CRT-D system was successfully implanted in 455 of 469 attempted implants (97%). A total of 381 patients were randomized to Bi-V or MPP at 3 months. The primary safety endpoint was met with freedom from system-related complications of 93.2%. The primary efficacy endpoint of the noninferiority comparison of nonresponder rates between the 2 arms was met. Patients randomized to MPP arm and programmed to pace from anatomically distant poles (MPP-AS) responded to therapy at significantly higher rates than MPP-other programmed settings (MPP-Other). Within this group, 87% were responders at 9 months, 100% designated as nonresponders at 3 months converted to responders at 9 months, and 54% experienced an incremental response compared to MPP-Other. Also within MPP-AS, 92% of patients with de novo CRT-D implant were classified as responders compared with patients with MPP-Other.
Conclusions
MPP is safe and effective for treating heart failure. The study met the pre-specified hypothesis that response to MPP is noninferior to Bi-V pacing with a quadripolar left ventricular lead. (MultiPoint Pacing IDE Study [MPP IDE]; NCT01786993)
Introduction:
Cardiac resynchronization therapy (CRT) device implantation guided by an electroanatomic mapping system (EAMS) is an emerging technique that may reduce fluoroscopy and angiography use and provide information on coronary sinus (CS) electrical activation. We evaluated the outcome of the EAMS-guided CRT implantation technique in a multicenter registry.
Methods:
During the period 2011-2014 we enrolled 125 patients (80% males, age 74 [71-77] years) who underwent CRT implantation by using the EnSite NavX system to create geometric models of the patient's cardiac chambers, build activation mapping of the CS and guide leads positioning. 250 patients undergoing traditional CRT implantation served as controls. Success and complication rates, fluoroscopy and total procedure times in the overall study population and according to center experience were collected. Centers that performed ≥10 were defined as highly experienced.
Results:
Left ventricular lead implantation was successful in 122 (98%) cases and 242 (97%) controls (p = 0.76). Median fluoroscopy time was 4.1 (0.3-10.4) minutes in cases versus 16 (11-26) minutes in controls (p<0.001). Coronary sinus angiography was performed in 33 (26%) cases and 208 (83%) controls (p<0.001). Complications occurred in 5 (4%) cases and 17 (7%) controls (p = 0.28). Median fluoroscopy time (median 11 vs. 3 minutes, p<0.001) and CS angiography rate (55% vs. 21%, p<0.001) were significantly higher in low experienced centers, while success rate and complications rate were similar.
Conclusions:
EAMS-guided CRT implantation proved safe and effective in both high- and low-experienced centers and allowed to reduce fluoroscopy use by ≈75% and angiography rate by ≈70%. This article is protected by copyright. All rights reserved.
Background:
implantation of the left ventricular (LV) lead in segments with delayed electrical activation may improve response to cardiac resynchronization therapy (CRT).
Objective:
to evaluate amount and regional distribution of LV electrical delay (LVED) in patients with or without left bundle branch block (LBBB).
Methods:
we enrolled 60 patients who underwent electroanatomic mapping system-guided CRT implantation. Activation mapping of the coronary sinus (CS) branches was performed using an insulated guide wire. LVED was defined as the interval between the beginning of the QRS on the surface ECG and the local electrogram and expressed as ms. or as percentage of the QRS duration (LVED%).
Results:
43 patients showed a LBBB and 17 a non-LBB ECG pattern. A total of 148 CS-branches (mean 2.5/patient, range 2-4) were mapped. LBBB patients showed higher maximum LVED [135ms. (108-150) vs. 100ms. (103-110), p<0.001] and LVED(%) [86% (79-89) vs. 72% (54-80), p<0.001] than no-LBBB patients. The maximum LVED was recorded in mid-basal antero-lateral or infero-lateral LV segments (traditional CRT targets) significantly more often in LBBB than in no-LBBB patients (85% vs. 59%, p=0.02). The number of CS branches showing LVED >50%, >75% and >85 ms was significantly higher in LBBB than in no-LBBB patients.
Conclusions:
patients with no-LBBB showed lower LVED and more heterogeneous electrical activation of the CS than patients with LBBB. This finding may contribute to lower rate of response to CRT of no-LBBB patients and suggests the use of activation mapping to guide LV lead placement.
The aim of the present study was to evaluate the relationship between left ventricular (LV) electrical delay, as measured by the QLV interval, and outcomes in a prospectively designed substudy of the SMART-AV Trial.
This was a multicentre study of patients with advanced heart failure undergoing cardiac resynchronization therapy (CRT) defibrillator implantation. In 426 subjects, QLV was measured as the interval from the onset of the QRS from the surface ECG to the first large peak of the LV electrogram. Left ventricular volumes were measured by echocardiography at baseline and after 6 months of CRT by a blinded core laboratory. Quality of life (QOL) was assessed by a standardized questionnaire. When separated by quartiles based on QLV duration, reverse remodelling response rates (>15% reduction in LV end systolic volume) increased progressively from 38.7 to 68.4% and QOL response rate (>10 points reduction) increased from 50 to 72%. Patients in the highest quartile of QLV had a 3.21-fold increase (1.58-6.50, P = 0.001) in their odds of a reverse remodelling response after correcting for QRS duration, bundle branch block type, and clinical characteristics by multivariate logistic regression analysis.
Electrical dyssynchrony, as measured by QLV, was strongly and independently associated with reverse remodelling and QOL with CRT. Acute measurements of QLV may be useful to guide LV lead placement.
Up to 30% of patients with heart failure do not respond to cardiac resynchronisation therapy (CRT). This may reflect placement of the coronary sinus lead in regions of slow conduction despite optimal positioning on current criteria.
To characterise the effect of CRT on left ventricular activation using non-contact mapping and to examine the electrophysiological factors influencing optimal left ventricular lead placement.
and results: 10 patients implanted with biventricular pacemakers were studied. In six, the coronary sinus lead was found to be positioned in a region of slow conduction with an average conduction velocity of 0.4 m/s, v 1.8 m/s in normal regions (p < 0.02). Biventricular pacing with the left ventricle paced 32 ms before the right induced the optimal mean velocity time integral and timing for fusion of depolarisation wavefronts from the right and left ventricular pacing sites. Pacing outside regions of slow conduction decreased left ventricular activation time and increased cardiac output and dP/dt(max) significantly.
In patients undergoing CRT for heart failure, non-contact mapping can identify regions of slow conduction. Significant haemodynamic improvements can occur when the site of left ventricular pacing is outside these slow conduction areas. Failure of CRT to produce clinical benefits may reflect left ventricular lead placement in regions of slow conduction which can be overcome by pacing in more normally activating regions.
Cardiac resynchronization reduces symptoms and improves left ventricular function in many patients with heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony. We evaluated its effects on morbidity and mortality.
Patients with New York Heart Association class III or IV heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony who were receiving standard pharmacologic therapy were randomly assigned to receive medical therapy alone or with cardiac resynchronization. The primary end point was the time to death from any cause or an unplanned hospitalization for a major cardiovascular event. The principal secondary end point was death from any cause.
A total of 813 patients were enrolled and followed for a mean of 29.4 months. The primary end point was reached by 159 patients in the cardiac-resynchronization group, as compared with 224 patients in the medical-therapy group (39 percent vs. 55 percent; hazard ratio, 0.63; 95 percent confidence interval, 0.51 to 0.77; P<0.001). There were 82 deaths in the cardiac-resynchronization group, as compared with 120 in the medical-therapy group (20 percent vs. 30 percent; hazard ratio 0.64; 95 percent confidence interval, 0.48 to 0.85; P<0.002). As compared with medical therapy, cardiac resynchronization reduced the interventricular mechanical delay, the end-systolic volume index, and the area of the mitral regurgitant jet; increased the left ventricular ejection fraction; and improved symptoms and the quality of life (P<0.01 for all comparisons).
In patients with heart failure and cardiac dyssynchrony, cardiac resynchronization improves symptoms and the quality of life and reduces complications and the risk of death. These benefits are in addition to those afforded by standard pharmacologic therapy. The implantation of a cardiac-resynchronization device should routinely be considered in such patients.
An important determinant of successful cardiac resynchronization therapy for heart failure is the position of the left ventricular (LV) pacing lead. The aim of this study was to analyze the impact of the LV lead position on outcome in patients randomized to cardiac resynchronization-defibrillation in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT) study.
The location of the LV lead was assessed by means of coronary venograms and chest x-rays recorded at the time of device implantation. The LV lead location was classified along the short axis into an anterior, lateral, or posterior position and along the long axis into a basal, midventricular, or apical region. The primary end point of MADIT-CRT was heart failure (HF) hospitalization or death, whichever came first. The LV lead position was assessed in 799 patients, (55% patients ≥65 years of age, 26% female, 10% LV ejection fraction ≤25%, 55% ischemic cardiomyopathy, and 71% left bundle-branch block) with a follow-up of 29±11 months. The extent of cardiac resynchronization therapy benefit was similar for leads in the anterior, lateral, or posterior position (P=0.652). The apical lead location compared with leads located in the nonapical position (basal or midventricular region) was associated with a significantly increased risk for heart failure/death (hazard ratio=1.72; 95% confidence interval, 1.09 to 2.71; P=0.019) after adjustment for the clinical covariates. The apical lead position was also associated with an increased risk for death (hazard ratio=2.91; 95% confidence interval, 1.42 to 5.97; P=0.004).
LV leads positioned in the apical region were associated with an unfavorable outcome, suggesting that this lead location should be avoided in cardiac resynchronization therapy. Clinical Trial Registration- URL: http://clinicaltrials.gov. Unique identifier: NCT00180271.
Cardiac resynchronization therapy has been increasingly used for patients with heart failure. However, unstable and dislocated coronary sinus leads reduce the effectiveness of this important intervention. Aim: To examine the long-term effects of coronary sinus side branch stenting on sensing and pacing parameters of the left ventricular leads.
A total of eight patients (six males; two females; mean age, 56.6 ± 14.4 years) whose coronary sinus lead dislocated during the procedure were included in the study. Targeted coronary sinus side branch stenting was performed to stabilize the leads. Sensing and pacing parameters including lead impedance, capture threshold, and R-wave amplitude were measured at implantation, first month, sixth month, and every 6-month period.
Mean follow-up period was 30.4 ± 7.4 months. At the time of implantation, lead impedance, capture threshold, and R-wave amplitude were 656 ± 162 Ω, 1.1 ± 0.5 V, and 13.0 ± 6.8 mV, respectively. No statistically significant mean lead impedance, capture threshold, and R-wave amplitude differences were observed between at the time of implantation and at the time of last follow-up (697 ± 164 Ω, 1.1 ± 0.5 V, 12.8 ± 6.9 mV, respectively).
In this long-term study, coronary sinus side branch stenting for the stabilization of dislocated leads seems to be effective.
Cardiac resynchronization therapy (CRT) has been shown to induce a spectacular effect on left ventricular (LV) function in certain patients. Our aim was to analyze and characterize the super-responders (SRs) to CRT using echocardiography in 186 patients with a conventional indication according to the European Society Cardiology guidelines. The investigation took place before and 6 months after implantation. CRT-SRs were defined by an improvement of the New York Heart Association functional class and LV ejection fraction to > or = 50% in absolute values associated with a relative LV end-systolic volume reduction of > or = 15%. Of the 186 patients, 18 (9.7%) were identified as CRT-SRs and had a significantly lower prevalence of ischemic etiology (11%), lower LV dimensions, lower left atrial volume, and greater global longitudinal strain at baseline. Receiver operating characteristics curves identified global longitudinal strain as the strongest parameter for predicting CRT-SRs, with a cutoff value of -12% (area under the curve 0.87, sensitivity 71%, and specificity 85%, p <0.01). In conclusion, in the present retrospective study, only a left atrial volume <55 ml and global longitudinal strain < or = -12% were independent predictors of CRT-SRs.
In patients with chronic systolic heart failure who undergo cardiac resynchronization therapy (CRT), improvements in left ventricular ejection fraction (LVEF) and reductions in left ventricular volume are generally modest. A minority of patients experience a dramatic response to CRT (super-responders), but the attributes associated with these patients have not been fully characterized.
The purpose of this study was to identify baseline clinical attributes of super-responders and to assess the survival benefit associated with this response.
We reviewed clinical, echocardiographic, and ECG data from a cohort of 233 patients undergoing new implantation of a CRT device between December 2001 and November 2006. All patients had a baseline LVEF < or =40% and New York Heart Association class II to IV symptoms on standard medical therapy. Patients whose absolute LVEF improved by > or =20% were termed super-responders. A multivariate model was constructed to determine factors predictive of super-response, and an assessment of mortality was made.
In this cohort of 233 patients, 32 (13.7%) met criteria for super-response. In univariate analysis, super-responders were more likely to be female and have a native left bundle branch block, lower preimplant brain natriuretic peptide and red cell distribution width levels, and smaller baseline left ventricular volumes with trends toward having more nonischemic cardiomyopathy and midventricular lead positions. In multivariate analysis, only left bundle branch block remained significantly associated with super-response. Super-responders had a considerably lower incidence of mortality compared to non-super-responders (9.4% vs 43.2%, P = .006) at mean follow-up of 5.5 +/- 1.2 years.
Baseline left bundle branch block is strongly associated with super-response to CRT. Super-responders derive better long-term outcomes with CRT than do non-super-responders.
The optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricle (LV) lateral or posterolateral wall. However, little is known about the impact of segmental pacing site on outcomes.
We assessed the impact of segmental LV lead position on CRT outcomes.
Patients (n = 115) undergoing CRT were followed prospectively. Segmental LV lead position along the longitudinal axis (apical, midventricle, or basal) was determined retrospectively by examining coronary sinus (CS) venograms and chest X-rays. The primary outcome was a combined endpoint of heart failure hospitalization, cardiac transplantation, or all-cause mortality. Secondary outcomes included change in New York Heart Association (NYHA) functional class and degree of LV reverse remodeling.
Patients were divided into two groups based on LV lead position: apical (n = 25) and basal/midventricle (n = 90). The apical group was older (72.9 +/- 8.9 vs. 66.5 +/- 13.3 years; P = .010) and more likely to have ischemic cardiomyopathy (77% vs. 52%, P <.001). During a mean follow-up of 15.1 +/- 9.0 months, event-free survival was significantly lower in the apical group: 52% vs. 79%, hazard ratio [HR] 2.7 (95% confidence interval [CI] 1.5-5.5, P = .006). The adverse impact of apical lead placement remained significant after adjusting for clinical covariates: HR 2.3 (95% CI 1.1-4.8, P = .03). The apical group also experienced less improvement in NYHA functional class and less LV reverse remodeling.
Apical LV lead placement is associated with worse CRT outcomes. Preferential positioning of LV leads in the basal/midventricle segments may improve outcomes.
The optimal left ventricular (LV) pacing site for cardiac resynchronization therapy (CRT) is unclear. The current study aims to explore the clinical significance of LV lead concordance to delayed contraction segment in CRT.
Concordant LV lead position was defined as the lead tip located by fluoroscopy at or immediately adjacent to the LV segment with latest contraction determined by tissue Doppler imaging. Echocardiographic and clinical outcomes among 101 consecutive patients with or without concordant LV lead positions were compared. There was no significant difference in changes in LV volumes and clinical parameters between patients with concordant (n = 46) or nonconcordant (n = 55) LV lead positions at 3 and 6 months. In multivariate analysis, the baseline asynchrony index (beta= 1.092, 95% CI: 1.050-1.114; P < 0.001), but not LV lead concordance, was the only independent predictor of LV reverse remodeling. By Cox regression analysis, ischemic etiology, and LV reverse remodeling, but not LV lead concordance, were independent predictors of mortality (beta= 2.475, 95% CI: 1.183-5.178; P = 0.016, and beta= 0.272, 95% CI: 0.130-0.567; P < 0.001, respectively), cardiovascular hospitalization (beta= 1.551, 95% CI: 1.032-2.333; P = 0.035, and beta= 0.460, 95% CI: 0.298-0.708; P < 0.001, respectively), and heart failure hospitalization (beta= 0.486, 95% CI: 0.320-0.738; P = 0.001 for LV reverse remodeling).
LV lead concordance to the delayed contraction segment may not be a major determining factor for favorable echocardiographic and clinical outcomes after CRT.
The aim of the current study was to evaluate echocardiographic parameters after 6 months of cardiac resynchronization therapy (CRT) as well as long-term outcome in patients with the left ventricular (LV) lead positioned at the site of latest activation (concordant LV lead position) as compared with that seen in patients with a discordant LV lead position.
A nonoptimal LV pacing lead position may be a potential cause for nonresponse to CRT.
The site of latest mechanical activation was determined by speckle tracking radial strain analysis and related to the LV lead position on chest X-ray in 244 CRT candidates. Echocardiographic evaluation was performed after 6 months. Long-term follow-up included all-cause mortality and hospitalizations for heart failure.
Significant LV reverse remodeling (reduction in LV end-systolic volume from 189 +/- 83 ml to 134 +/- 71 ml, p < 0.001) was noted in the group of patients with a concordant LV lead position (n = 153, 63%), whereas patients with a discordant lead position showed no significant improvements. In addition, during long-term follow-up (32 +/- 16 months), less events (combined for heart failure hospitalizations and death) were reported in patients with a concordant LV lead position. Moreover, a concordant LV lead position appeared to be an independent predictor of hospitalization-free survival after long-term CRT (hazard ratio: 0.22, p = 0.004).
Pacing at the site of latest mechanical activation, as determined by speckle tracking radial strain analysis, resulted in superior echocardiographic response after 6 months of CRT and better prognosis during long-term follow-up.
Benefit from cardiac resynchronization therapy (CRT) is likely influenced by the location of the left ventricular (LV) lead.
To evaluate the association of LV lead position with outcome after CRT.
Two-hundred and fifty patients with LV dysfunction, New York Heart Association (NYHA) class III (68%) or IV (32%) symptoms, and QRS durations > or =120 ms were followed for a median of 30 months post-CRT. LV lead position was categorized as anterior (n = 20, 8%), lateral (n = 128, 51%), or posterior (n = 102; 41%) using postero-anterior and lateral postoperative chest radiographs.
Median age was 69 years and most (68%) had ischemic LV dysfunction. Clinical response, defined by a > or =1 NYHA class reduction, was lower in patients with an anterior (30%) versus lateral (76%) or posterior (73%) lead position (p = 0.001). An anterior versus nonanterior position was independently associated with a two to three-fold higher risk for nonresponse to CRT, cardiovascular death, death from worsening heart failure or cardiac transplantation, and death from any cause. Repositioning of the LV lead from an anterior to a nonanterior position in seven patients who had not clinically responded to CRT after > or =6 months resulted in clinical improvement in all cases.
An anterior versus nonanterior LV lead position is independently associated with an increased likelihood of nonresponse to CRT and a higher risk of serious outcomes. Repositioning of an anteriorly placed LV lead to a nonanterior position should be considered in CRT nonresponders.
Background — Cardiac resynchronization therapy (CRT) improves systolic function in heart failure patients with ventricular conduction delay by stimulating the left ventricle (LV) or both ventricles (biventricular, BV). Optimal LV site selection is of major clinical interest for CRT device implantation; however, the dependence of hemodynamics on LV stimulation site has not been established. Thus, the objective of this study was to compare the hemodynamic response to CRT for 2 LV coronary vein sites: the free wall and anterior wall.
Methods and Results — A total of 30 patients (mean NYHA class, 2.7; mean QRS interval, 152 ms; mean PR interval, 194 ms) enrolled in the PATH-CHF-II trial were studied. CRT was administered with LV and BV stimulation in VDD mode at 4 AV delays. LV stimulation was at the lateral free wall or anterior wall, whereas right ventricular stimulation was fixed near the apex. LV+dP/dt max and aortic pulse pressure changes from baseline during CRT were compared for LV sites. Free wall sites with LV and BV stimulation yielded significantly larger LV+dP/dt max (14% versus 6%, P <0.001 for LV; 12% versus 5%, P <0.001 for BV) and pulse pressure (8% versus 4%, P <0.001 for LV; 9% versus 5%, P <0.001 for BV) compared with anterior sites. In one third of patients, CRT at free wall sites increased LV+dP/dt max , whereas it decreased at anterior sites over most AV delays.
Conclusion — CRT with LV free wall stimulation produced significantly better LV systolic performance compared with anterior stimulation. Further studies are warranted to prove the clinical superiority of the LV free wall as a site for long-term CRT.
Cardiac resynchronization therapy (CRT) for congestive heart failure patients with delayed left ventricular (LV) conduction is clinically beneficial in approximately 70% of patients. Unresolved issues include patient selection, lead placement, and efficacy of LV pacing alone. Being an electrical approach, detailed electrical information during CRT is critical to resolving these issues. However, electrical data from patients have been limited because of the requirement for invasive mapping.
The purpose of this study was to provide observations and insights on the variable electrophysiologic responses of the heart to CRT using electrocardiographic imaging (ECGI).
ECGI is a novel modality for noninvasive epicardial mapping. ECGI was conducted in eight patients undergoing CRT during native rhythm and various pacing modes.
In native rhythm (six patients), ventricular activation was heterogeneous, with latest activation in the lateral LV base in three patients and in the anterolateral, midlateral, or inferior LV in the remainder of patients. Anterior LV was susceptible to block and slow conduction. Right ventricular pacing improved electrical synchrony in two of six patients. LV pacing in three of four patients involved fusion with intrinsic excitation resulting in electrical resynchronization similar to biventricular pacing. Although generally electrical synchrony improved significantly with biventricular pacing, it was not always accompanied by clinical benefit.
Results suggest that (1) when accompanied by fusion, LV pacing alone can be as effective as biventricular pacing for electrical resynchronization; (2) right ventricular pacing is not effective for resynchronization; and (3) efficacy of CRT depends strongly on the patient-specific electrophysiologic substrate.
Intracardiac electrograms can be used to guide left ventricular (LV) lead placement during implantation of cardiac resynchronization therapy (CRT) devices. Although attempts often are made to ensure that the LV lead is positioned at a site of maximal electrical delay, information on whether this is useful in predicting the acute hemodynamic response and long-term clinical outcome to CRT is limited.
The purpose of this study was to assess the ability of intracardiac (electrogram) measurements made during LV lead placement in patients undergoing CRT for predicting acute hemodynamic response and long-term clinical outcome to CRT.
Seventy-one subjects with standard indications for CRT underwent electrogram measurements and echocardiograms performed in the acute phase of this study. The LV lead electrical delay was measured intraoperatively from the onset of the surface ECG QRS complex to the onset of the sensed electrogram on the LV lead, as a percentage of the baseline QRS interval. Echocardiographic assessment of the hemodynamic response to CRT was measured as an intra-individual percentage change in dP/dt over baseline (DeltadP/dt, derived from the mitral regurgitation Doppler profile) with CRT on and off. dP/dt was measurable in 48 subjects, and acute responders to CRT were defined as those with DeltadP/dt >or=25%. Long-term response was measured as a combined endpoint of hospitalization for heart failure and/or all cause mortality at 12 months. Time to the primary endpoint was estimated by the Kaplan-Meier method, with comparisons made using the log rank test.
LV lead electrical delay correlated weakly with DeltadP/dt of the combined group (n = 48, r = 0.311, P = .029) but was strongly correlated with DeltadP/dt in the nonischemic subgroup (n = 20, r = 0.48, P = .027). LV lead electrical delay (%) was significantly longer in acute responders (69.6 +/- 23.9 vs 31.95 +/- 11.57, P = .002) among patients with nonischemic cardiomyopathy. A reduced LV lead electrical delay (<50% of the QRS duration) was associated with worse clinical outcome within the entire cohort (hazard ratio: 2.7, 95% confidence interval: 1.17-6.68, P = .032) as well as when stratified into ischemic and nonischemic subgroups.
Measuring LV lead electrical delay is useful during CRT device implantation because it may help predict hemodynamic response and long-term clinical outcome.
Coronary sinus (CS) leads used for cardiac resynchronization have undergone development in the last years. However, dislocation rate remained high (5-9%). The aim of this study was to investigate the effectiveness and safety of stent implantation in a CS side vein to stabilize the left ventricular lead position after postoperative or intraoperative dislocation of the electrode.
Thirty-six patients (age: 64 +/- 9.7 years, 19 primary, 17 ischemic cardiomyopathy, NYHA class III: 30, IV: 6) were treated with stenting. The procedure was performed because of postoperative dislocation in seven patients, while dislocation was observed during the implantation in 29 cases. The electrode was repositioned into the desired position and a bare metal coronary stent was introduced via another guide wire. The stent was deposited at 5- to 15-mm proximal to the tip of the electrode with a pressure of 6 to 14 atmospheres. Control angiography showed no blood flow compromise in any of the side branches or in the coronary sinus. Control echocardiography did not show pericardial effusion due to stenting. During follow-up (11.5 +/- 5.5, 2-23 months), left ventricular pacing threshold increased from 2.2 to 5.6 V in one patient, but dislocation was not found by fluoroscopy. Clinically important pacing threshold increase was not detected in the other cases. Impedance measurements did not suggest lead insulation failure.
Stent implantation to stabilize the left ventricular lead position seems to be a useful and safe procedure in the treatment of patients with complicated coronary sinus anatomy or lead instability.
RV apical pacing (RVP) may be deleterious, possibly by simulating LBBB, i.e., prolonging QRS duration (QRSd) and LV activation (LVAT). However, determinants of electrical delays are unknown.
LV dysfunction (LVEF <or= 40%, HF) and pre-existing conduction system abnormalities may modulate RVP's effects, compared to LBBB.
RVP-induced QRSd and LVAT were compared in normal LV to HF, with normal QRS (<120 ms), RBBB, or LBBB. LVAT was estimated by interval from QRS onset to basal inferolateral LV depolarization.
During LBBB and RVP, LVAT/QRSd was >or=85%, i.e., LVAT indicated terminal LV depolarization. In normal LV, LVAT during intrinsic conduction (55 +/- 18 ms) was delayed by RVP (129 +/- 20 ms, n = 58, P < 0.001). RVP's effects were similar to LBBB (P = NS) and unaffected by baseline conduction disease. In HF overall, RVP-induced delays (QRSd 209 +/- 27, LVAT 186 +/- 26 ms, n = 102) were greater than RVP in normal LV (P < 0.001). When baseline conduction system disease was present, RVP's effects were exaggerated (RVP wide QRS [>120 ms]: QRSd 216 +/- 27, LVAT 191 +/- 20 ms, [n = 72] vs RVP normal QRS: QRSd 193 +/- 24, LVAT 169 +/- 24 ms, n = 31, P < 0.001). In patients with LBBB (n = 41), delays during intrinsic conduction (QRSd 163 +/- 29, LVAT 137 +/- 33 ms, n = 41) were enhanced by RVP (QRSd 218 +/- 28, LVAT 191 +/- 22 ms, P < 0.001). RVP's effects were similar in patients with LBBB and RBBB (P = NS).
RVP simulated LBBB in normal LV. In HF, RVP induced greater conduction delays than LBBB, enhanced by accompanying conduction disease. These variations may contribute to RVP's mixed clinical effects.
Conventional activation mapping in the dilated human left ventricle (LV) with left bundle-branch block (LBBB) morphology is incomplete given the limited number of recording sites that may be collected in a reasonable time and given the lack of precision in marking specific anatomic locations.
We studied LV activation sequences in 24 patients with heart failure and LBBB QRS morphology with simultaneous application of 3D contact and noncontact mapping during intrinsic rhythm and asynchronous pacing. Approximately one third of the patients with typical LBBB QRS morphology had normal transseptal activation time and a slightly prolonged or near-normal LV endocardial activation time. A "U-shaped" activation wave front was present in 23 patients because of a line of block that was located anteriorly (n=12), laterally (n=8), and inferiorly (n=3). Patients with a lateral line of block had significantly shorter QRS (P<0.003) and transseptal durations (P<0.001) and a longer distance from the LV breakthrough site to line of block (P<0.03). Functional behavior of the line of block was demonstrated by a change in its location during asynchronous ventricular pacing at different sites and cycle lengths.
A U-shaped conduction pattern is imposed on the LV activation sequence by a transmural functional line of block located between the LV septum and the lateral wall with a prolonged activation time. Assessment of functional block is facilitated by noncontact mapping, which may be useful for identifying and targeting specific locations that are optimal for successful cardiac resynchronization therapy.
Effect of left ventricular lead concordance to the delayed contraction segment on echocardiographic and clinical outcomes after cardiac resynchronization therapy
- J W Fung
- Y Y Lam
- Q Zhang
- G W Yip
- W W Chan
- G C Chan
- JW Fung