Implantable Cardioverter Defibrillator in Nonischemic Versus Ischemic Cardiomyopathy: Real‐World Primary Prevention Study

BACKGROUND: The evidence in the primary prevention of sudden cardiac death (SCD) by using implantable cardioverter defibrillators (ICD) in patients with ischemic cardiomyopathy (ICM) is well-established but remains controversial for those with nonischemic cardiomyopathy (NICM). This study evaluates whether prognostic differences exist between ICM and NICM patients after ICD implantation. METHODS: Patients initially undergoing ICD implantation as primary SCD prevention were retrospectively enrolled from January 2017 to May 2023. Malignant ventricular arrhythmic and/or SCD were set as the primary endpoint, whereas all-cause mortality was the secondary endpoint. Patients were grouped by heart failure etiology (ICM vs. NICM) and then by primary endpoint events occurrence. Outcomes analyses were performed between the NICM and ICM patients. RESULTS: The final cohort had 342 patients, 213 (62.3%) with NICM and 129 (37.7%) with ICM. At a median follow-up of 23.0 (10.7, 33.2) months, 51 patients (14.9%) encountered primary endpoint events. No statistically significant disparities in primary endpoint events (log rank p = 0.413), all-cause death (log rank p = 0.208), cardiovascular mortality (log rank p = 0.218), or appropriate ICD therapy (log rank p = 0.250) between the two groups were indicated by Kaplan-Meier survival analysis. Moreover, the COX-adjusted models further demonstrated the absence of any significant differences between the two groups. CONCLUSION: In real-world settings, primary prevention of SCD with ICD implantation yields similar outcomes for ICM and NICM patients, including probabilities of SCD and/or malignant ventricular arrhythmias, all-cause mortality, appropriate ICD therapy, and cardiovascular mortality.