Two-Year Outcomes of Primary Prophylactic Use of Defibrillators for Ischemic and Non-Ischemic Cardiomyopathy　― Propensity Score-Matched Analysis From the Nippon Storm Study

Background: In 2016, the DANISH study reported negative results regarding the efficacy of implantable cardioverter-defibrillators (ICDs) in patients with non-ischemic cardiomyopathy (NICM) and reduced left ventricular ejection fraction (LVEF). In this study we determined the efficacy of using ICDs for primary prophylaxis in patients with NICM.Methods and Results: We selected 1,274 patients with underlying cardiac disease who were enrolled in the Nippon Storm Study. We analyzed the data of 451 patients with LVEF ≤35% due to NICM or ischemic cardiomyopathy (ICM) who underwent ICD implantation for primary prophylaxis (men, 78%; age, 65±12 years; LVEF, 25±6.4%; cardiac resynchronization therapy, 73%; ICM, 33%). After propensity score matching, we compared the baseline covariates between groups: NICM (132 patients) and ICM (132 patients). The 2-year appropriate ICD therapy risks were 27.7% and 12.2% in the NICM and ICM groups, respectively (hazard ratio, 0.390 [95% confidence interval, 0.218–0.701]; P=0.002).Conclusions: This subanalysis of propensity score-matched patients from the Nippon Storm Study revealed that the risk of appropriate ICD therapy was significantly higher in patients with NICM than in those with ICM.