Arrhythmic burden among asymptomatic patients with ischemic cardiomyopathy and an implantable cardioverter-defibrillator

Background: The clinical benefit of primary prevention implantable cardioverter-defibrillator (ICD)therapy in asymptomatic patients (New York Heart Association [NYHA]functional class I)with ischemic cardiomyopathy and left ventricular dysfunction is continually disputed. Objective: The purpose of this study was to evaluate the incidence of ventricular arrhythmias, mortality rates, and appropriate device therapies by NYHA class in a prospective national ICD registry. Methods: The study comprised 1670 consecutive patients with ischemic cardiomyopathy who were implanted with a primary prevention ICD and enrolled in the prospective national Israeli ICD Registry from 2010. The risk for clinical and arrhythmic events was assessed by NYHA class. Results: Asymptomatic patients (NYHA I)composed 19% of the study cohort. Comparison according to NYHA class showed that the highest mortality rate was in the NYHA III–IV group vs NYHA I and NYHA II (10.5% vs 5.4% and 5.8%, respectively; log rank P =.003). Conversely, cumulative incidence of appropriate ICD therapies, corrected for death as a competing risk, were higher among patients with NYHA I (11% vs 7%; P =.021). In a multivariate model, NYHA I vs ≥II remained independently associated with a significant 2-fold risk for appropriate ICD therapy (hazard ratio 2.03; 95% confidence interval 1.28–3.24). Conclusion: Our findings indicate that patients with ischemic cardiomyopathy without heart failure symptoms have a higher risk of appropriate ICD therapy compared with symptomatic patients after adjustment for the competing risk of death, suggesting possible incremental benefit of primary ICD implantation in this population.