Effect of QRS morphology on clinical event reduction with cardiac resynchronization therapy: Meta-analysis of randomized controlled trials
ABSTRACT Cardiac resynchronization therapy (CRT) is effective in reducing clinical events in systolic heart failure patients with a wide QRS. Previous retrospective studies suggest only patients with QRS prolongation due to a left bundle-branch block (LBBB) benefit from CRT. Our objective was to examine this by performing a meta-analysis of all randomized controlled trials of CRT.
Systematic searches of MEDLINE and the Food and Drug Administration official website were conducted for randomized controlled CRT trials. Trials reporting adverse clinical events (eg, all-cause mortality, heart failure hospitalizations) according to QRS morphology were included in the meta-analysis.
Four randomized trials totaling 5,356 patients met the inclusion criteria. In patients with LBBB at baseline, there was a highly significant reduction in composite adverse clinical events with CRT (RR = 0.64 [95% CI (0.52-0.77)], P = .00001). However no such benefit was observed for patients with non-LBBB conduction abnormalities (RR = 0.97 [95% CI (0.82-1.15)], P = .75). When examined separately, there was no benefit in patients with right-bundle branch block (RR = 0.91 [95% CI (0.69-1.20)], P = .49) or non-specific intraventricular conduction delay (RR = 1.19 [95% CI (0.87-1.63)], P = .28). There was no heterogeneity among the clinical trials with regards to the lack of benefit in non-LBBB patients (I(2) = 0%). When directly compared, the difference in effect of CRT between LBBB versus non-LBBB patients was highly statistically significant (P = .0001 by heterogeneity analysis).
While CRT was very effective in reducing clinical events in patients with LBBB, it did not reduce such events in patients with wide QRS due to other conduction abnormalities.
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ABSTRACT: Women have been under-represented in trials of cardiac resynchronization therapy-defibrillators (CRT-D). Previous studies suggest that women benefit from CRT-D at shorter QRS duration than men and that there may be no benefit of CRT-D in patients without left bundle branch block (LBBB) regardless of patient sex. We compared sex-specific death risk in 75 079 patients with New York Heart Association class III or IV heart failure, reduced left ventricular ejection fraction, and prolonged QRS duration (≥120 ms) receiving either CRT-D or implantable cardioverter defibrillator in subgroups according to QRS morphology and 10-ms increments in QRS duration. We applied propensity score weighting to control for differences between treatments. Among patients with LBBB, women receiving CRT-D had a lower relative death risk than those receiving an implantable cardioverter-defibrillator (absolute difference, 11%; hazard ratio=0.74 [95% confidence interval, 0.68-0.81]). In men, the lower mortality with CRT-D versus implantable cardioverter defibrillator was less pronounced (absolute difference, 9%; hazard ratio=0.84 [0.79-0.89]; sex×device interaction P=0.025). In those without LBBB, the mortality difference was modest and did not differ between women and men (absolute difference, 3%; hazard ratio=0.88 [0.79-0.97] in women and absolute difference, 2%; hazard ratio=0.95 [0.91-0.998] in men; interaction P=0.17). In subgroups according to QRS duration, CRT-D was associated with better survival in both sexes with LBBB and QRS ≥130 ms, whereas there was no clear relation between QRS duration and survival in patients without LBBB regardless of patient sex. In a large real-world population CRT-D was associated with a lower mortality risk in both sexes with LBBB, although more pronounced among women. Only among those with LBBB, both sexes had better survival with longer QRS duration. The mortality differences in patients without LBBB were attenuated in both sexes. © 2015 American Heart Association, Inc.Circulation Cardiovascular Quality and Outcomes 02/2015; DOI:10.1161/CIRCOUTCOMES.114.001548 · 5.66 Impact Factor
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ABSTRACT: Whether stenting or coronary artery bypass grafting (CABG) is the best revascularization strategy in patients with multivessel disease has been a heavily debated controversy. The trials comparing the two methods were unfortunately underpowered for mortality. Moreover, results of clinical trials appeared to contradict with each other. Because CABG is unequivocally a more cumbersome method, stenting became commonly preferred in the absence of evidence for mortality difference. Meta-analysis is a powerful tool, especially when several high-quality randomized trials are available on the same issue. In these instances, meta-analyses can overcome the power limitation of the individual trials. Our recent meta-analysis reveals that, as compared to stenting, CABG leads to unequivocal reductions in mortality and myocardial infarctions in patients with multivessel disease. These benefits are seen regardless of whether patients are diabetic or not and also do not depend on whether bare-metal or drug-eluting stents are used.Current Cardiology Reports 02/2015; 17(2):558. DOI:10.1007/s11886-014-0558-4
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ABSTRACT: The temporal effect of heart failure (HF) hospitalization occurring at different time periods before implantation has not yet been studied in detail. The aim of the present study was to investigate the potential association between time from last HF hospitalization to device implantation and effects on subsequent outcomes and benefit from cardiac resynchronization therapy with a defibrillator (CRT-D). Multivariate Cox models were used to determine the temporal influence of previous HF hospitalization on the end point of HF or death within all left bundle branch block implantable cardioverter-defibrillator (ICD) and CRT-D patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT) trial (n = 1,250) and to evaluate the clinical benefit of CRT-D implantation, comparing CRT-D patients with ICD patients within each previous HF hospitalization group. The patients with previous HF hospitalization ≤12 months before device implantation had the greatest incidence of HF or death during 4-year follow-up (31%), while those with previous HF hospitalization >12 months and those with no previous HF hospitalization had similar lower rates of HF or death (22% and 24%, respectively). All patients treated with CRT-D derived significant clinical benefit compared with their ICD counterparts, regardless of time of previous hospitalization (hazard ratios 0.38 [no previous hospitalization], 0.49 (≤12 months), and 0.45 (>12 months); p for interaction = 0.67). In conclusion, in the present study of patients with mild HF with prolonged QRS intervals and LBBB, a previous HF hospitalization ≤12 months was associated with increased risk for HF or death compared with >12 months and no previous HF hospitalizations. The clinical benefit of CRT-D was evident in all patients regardless of time from last HF hospitalization to implantation compared with ICD only. Copyright © 2015 Elsevier Inc. All rights reserved.The American Journal of Cardiology 02/2015; DOI:10.1016/j.amjcard.2015.02.029 · 3.43 Impact Factor