(1) Background: In patients suffering from heart failure, the main causes of death are either he-modynamic failure, or ventricular arrhythmias. The only tool to significantly reduce arrhythmic sudden death is the implantable cardioverter defibrillator (ICD), but not all patients benefit to the same extend of these devices. (2) Methods: The primary outcome of this single center study was defined as cardiovascular death in patients with ischemic and non-ischemic heart failure who have benefited from ICD therapy. The secondary outcomes were death from any cause, sudden cardiac death, ICD-related therapies (appropriate antitachycardia pacing or shock therapy for ventricular tachycardia or fi-brillation) and recurrences of ventricular tachyarrhythmias. (3) Results: A total of 403 consecutive ICD recipients – symptomatic heart failure patients with ICD for the primary prevention of sudden cardiac death – were included retrospectively: 59% is-chemic cardiomyopathy (ICMP) and 41% non-ischemic cardiomyopathy (NICMP). Within a median follow-up period of 36 months, the incidence of cardiovascular mortality was not signif-icantly different in patients with NICMP and ICMP: the primary outcome had occurred in 9 pa-tients (5.4%) in the NICMP group and in 14 patients (5.9%) in the ICMP group (hazard ratio 1; 95%confidence interval [CI] 0.45 to 2.28; p =0.97). All-cause mortality occurred in 14 of 166 pa-tients (8.4%) in NICMP group and 18 of 237 patients (7.6%) in ICMP group. Sudden cardiac death occurred in 2 patients (1.2%) in the NICMP group and in 4 patients (1.7%) in the ICMP group (hazard ratio 0.71; 95% CI, 0.13 to 3.88; P=0.69). The rate of appropriate device therapies was comparable in both groups. (4) Conclusion: In this study, ICD implantation for primary prevention of sudden cardiac death in patients with symptomatic systolic heart failure was associated with similar rates of cardiovas-cular and all-cause mortality in patients with ischemic heart disease, and in patients with heart failure from other causes. NICMP and ICMP showed comparable rates of recurrent ventricular tachyarrhythmias and appropriate ICD therapies.