Implantable Cardioverter Defibrillators for Primary Prevention of Mortality in Patients With Nonischemic Cardiomyopathy: A Meta‐Analysis of Randomized Controlled Trials

BACKGROUND: Implantable cardioverter defibrillators (ICDs) improve survival in patients with heart failure due to ischemic cardiomyopathy, but their benefit in nonischemic cardiomyopathy (NICM) has been recently questioned. We performed a meta-analysis of randomized clinical trials to examine the effect of ICDs on total mortality and arrhythmic death in patients with NICM. We also examined the impact of age and cardiac resynchronization therapy (CRT) on the relative effect of ICD compared to control. METHODS AND RESULTS: We searched the MEDLINE and EMBASE databases for randomized trials evaluating the effect of ICD versus control in patients with NICM. Hazard ratios (HR) with 95% confidence interval (CI) were calculated using a random effects model. Six trials involving 2,967 patients were included (ICD, n = 1,553; control, n = 1,414). Based on the pooled estimate across the six studies, the use of ICD was associated with a significant reduction in total mortality (HR = 0.78, 95% CI 0.66-0.92; P = 0.003), as well as arrhythmic death (HR = 0.46, 95% CI 0.29-0.71; P = 0.0005) compared to control. ICD decreased total mortality in younger patients compared to control (HR = 0.63, 95% CI 0.46-0.86; P = 0.004), but not in older patients (HR = 0.97, 95% CI 0.56-1.68; P = 0.92). In patients with CRT, ICD reduced total mortality compared to control (HR = 0.78, 95% CI 0.65-0.95; P = 0.02), but not in patients with CRT (HR = 0.71, 95% CI 0.40-1.26). CONCLUSIONS: ICDs decrease total mortality and arrhythmic deaths in patients with NICM. The benefit of ICD appears to be dependent on age and concomitant use of CRT.