Objective-To determine whether implantable cardioverter-defibrillator (ICD) treatment is beneficial in elderly patients with life threatening ventricular tachyarrhythmias. Design-Since January 1984, ICDs were implanted in 450 patients to evaluate surgical risk, complications and mean survival in relation to patient age; 81 patients (18%) were < 50 years at the time of ICD implant, 254 patients (56%) were between 51 and 64 years, and the remaining 115 (26%) were > 65 years. Epicardial lead systems were implanted in 209 patients (46%), while transvenous lead systems were implanted in 241 (54%). Results-13 patients (3%) died perioperatively, more often after epicardial (11 of 209 patients, 5%) than after transvenous ICD implantation (one of 241 patients, < 1%) (p < 0.05). During a mean (SD) follow up of 28 (24) months (range < 1 to 114 months), 90 patients (20%) died. Of these, nine (2%) died from sudden arrhythmic death; five (1%) died suddenly, probably as a result of non-arrhythmic causes; 55 (12%) died from other cardiac causes (congestive heart failure, myocardial infarction); and 21 (5%) died from noncardiac causes. The three, five, and seven year survival for arrhythmic mortality was 95% in patients < 50 years compared with a three year survival of 93% and a five and seven year survival of 91% in patients of 51 to 64 years, and a three, five, and seven year survival of 99% in patients > 65 years. 362 patients (80%) received ICD discharges (21 (43) shocks per patient), with a similar incidence among all three patient groups (< 50 years, 80%; 51 to 64 years, 81%; > 65 years, 79%). The time interval between ICD implant and the first ICD treatment was shorter in patients > 65 years (8 (8) months) than in patients between 51 and 64 years (11 (14) months) or < 50 years (11 (11) months) (p < 0.05). Survival time following first appropriate shock was 30 (24) months in patients < 50 years, 30 (26) months in patients of 51 to 64 years, and 19 (20) months in patients > 65 years. Conclusions-Elderly patients benefit from ICD treatment, and survive for a considerable time after the first treatment. Therefore, elderly patients should be considered candidates for ICD implantation if life threatening ventricular tachyarrhythmias are present. (Heart 1997;78:364-370) Keywords: cardioverter-defibrillator; heart failure; sudden death; ICD discharges; elderly patients Sudden cardiac death is one of the major causes of mortality in western countries, with an incidence of 500 000 per year in the United States and 400 000 per year in Europe. Recent controlled clinical trials with antiarrhythmic drugs have raised serious questions about the long term eYcacy and benefit of pharmacological treatment for ventricular tachyarrhythmias.3 4 As a result, nonpharmacological alternatives have gained increasing acceptance in the treatment of such patients.5 6 Clinical experience to date suggests that cardioverter-defibrillator (ICD) treatment is an acceptable approach for preventing sudden cardiac death, and more than 50 000 patient...