OBJECTIVES: The beneficial effects of implantable cardioverter defibrillators (ICDs) in primary and secondary prevention patients are well established. However, relative scarcity of data exists regarding long-term follow-up outcomes of this population in the context of tertiary hospitals-ICD implantation centres beyond randomized clinical trials borders. The aim of the study was to exhibit “real-world” data and possible differences on mortality and ICD therapies between secondary and primary prevention ICD recipients. METHODS: : All patients treated with an ICD, regardless of the underlying cardiac pathology, at the island of Crete were included in the current analysis. The study population was grouped by the type of prevention (secondary or primary) for sudden cardiac death. The primary endpoint was all-cause mortality. The secondary endpoint was the occurrence of device therapy (appropriate or inappropriate). RESULTS: A total of 854 (88.6% men) ICD recipients were included. Of these, 623 (73%) patients received an ICD for primary prevention of sudden cardiac death and 231 (27%) patients for secondary prevention. During a mean follow-up of 12,4 +/-7,8 years, 177 (20.7%) patients died. The incidence of mortality was 35,5% for secondary prevention patients and 15.2% for primary prevention patients (p<0.001). Ventricular arrhythmia triggered appropriate therapy in 91 (39,4%) secondary prevention patients. Accordingly the number of primary prevention patients that received appropriate therapy was 126 (20,2%). A comparable risk for inappropriate shocks was observed. CONCLUSIONS: During long-term follow-up, primary prevention patients exhibited a lower risk for all-cause mortality. Both groups showed similar occurrence of inappropriate shocks but secondary prevention patients showed a higher rate of appropriate therapy.