Considering morbidity and financial impact on the health care system, it may be helpful to stratify patients who would most benefit from primary ICD treatment. The aim of this study was to assess the prevalence and identify the clinical predictors of appropriate ICD therapy in patients following implantation of an ICD in primary prevention for chronic heart failure. A monocenter retrospective analysis was performed and all patients undergoing implantation of ICD in primary prevention were included. Device interrogations were performed and appropriate therapies, either ATP or shock, were noticed. Over the 317 primary prevention patients undergoing ICD implantation, 203 had ischemic cardiomyopathy (ICM) and 114 had nonischemic dilated cardiomyopathy (NIDCM). At the median follow-up time 760±599 days, 56 (17,7%) had received appropriate ICD therapies. Average Figure: Predictors of appropriate ICD therapy LVEF was 26±6%. By univariate comparison, LVDD≥65mm (p=0,035) and lack of diuretic (p=0,024) were significant predictors for ICD therapy. ICM and NIDCM patients benefit equivalently from ICD implantation (p=0,941). By multivariate analysis, elderly patients ≥65y (HR 1,92, p=0,032), LVDD≥65mm (HR 2,01, p=0,022) and lack of diuretic (HR 0,31, p<0,001) were all significant independent predictors for ICD therapy. Absence of CRT device was closed to be significant (HR 0,53, p=0,062), but was significant in NIDCM population (p=0,007). Onset atrial fibrillation (p=0,027) and hospitalization for acute heart failure (p=0,002) were significantly associated with ICD-delivered therapy. ICD therapy occurred in 17,7% of primary prevention patients with both ICM and NIDCM. In multivariate analysis, age ≥65y, LVDD≥65mm and absence of diuretic were predictive factors for ICD therapy. Presence of CRT device was closed to be significant. There was no difference by considering heart failure etiology, ICM and NIDCM patients benefited from ICD equivalently.