Effect of Implantable Cardioverter-Defibrillators by Etiology of Heart Failure: A Propensity-Matched Mortality Analysis of the WARCEF Trial

Background There is a recent debate on whether the beneficial effect of implantable cardioverter-defibrillators (ICDs) may be attenuated in patients with non-ischemic cardiomyopathy (NICMP). Objectives We aim to assess whether ICD benefit differs between patients with NICMP and those with ischemic cardiomyopathy (ICMP), using data from the Warfarin versus Aspirin in Reduced Cardiac Ejection Fraction (WARCEF) trial. Methods We performed a post-hoc analysis using the WARCEF trial (N=2293; ICMP, n=991 vs. NICMP, n= 1314), where participants received optimal medical treatment. We developed a propensity score of having an ICD at baseline using 41 demographic and clinical variables, and created 1:2 propensity-matched cohorts for patients with ICD for ICMP (N=223 with ICD; N= 446 matched) and NICMP (N= 195 with ICD; N=390 matched). We constructed Cox proportional hazards model to assess the effect of ICD status on mortality for patients with ICMP and those with NICMP. Results During a median follow-up of 3.5 ± 1.8 years, 527 patients died. Presence of ICD was associated with a lower risk of all-cause death among those with ICMP (HR, 0.64; 95% CI, 0.45 to 0.92; P = 0.01) but not among those with NICMP (HR, 0.98; 95% CI, 0.64 to 1.51; P = 0.94). Conclusion Presence of ICD at baseline conveyed a survival benefit in those with ischemic cardiomyopathy, but not in those with non-ischemic cardiomyopathy.