BACKGROUND: Sudden death from cardiac causes remains a leading cause of death among patients with congestive heart failure(CHF). Treatment with amiodarone or an implantable cardioverter-defibrillator(ICD) has been proposed to improve the prognosis in such patients. METHODS: We randomly assigned 2521 patients with New York Heart Association(NYHA) class II or III CHF and a left ventricular ejection fraction(LVEF) of 35 percent or less to conventional therapy for CHF plus placebo(847 patients), conventional therapy plus amiodarone(845 patients), or conventional therapy plus a conservatively programmed, shock-only, single-lead ICD(829 patients). Placebo and amiodarone were administered in a doubleblind fashion. The primary end point was death from any cause. RESULTS: The median LVEF in patients was 25 percent; 70 percent were in NYHA class II, and 30 percent were in class III CHF. The cause of CHF was ischemic in 52 percent and nonischemic in 48 percent. The median follow-up was 45.5 months. There were 244 deaths(29 percent) in the placebo group, 240(28 percent) in the amiodarone group, and 182(22 percent) in the ICD group. As compared with placebo, amiodarone was associated with a similar risk of death(hazard ratio, 1.06; 97.5 percent confidence interval, 0.86 to 1.30; P=0.53) and ICD therapy was associated with a decreased risk of death of 23 percent(0.77; 97.5 percent confidence interval, 0.62 to 0.96; P=0.007) and an absolute decrease in mortality of 7.2 percentage points after five years in the overall population. Results did not vary according to either ischemic or nonischemic causes of CHF, but they did vary according to the NYHA class. CONCLUSIONS: In patients with NYHA class II or III CHF and LVEF of 35 percent or less, amiodarone has no favorable effect on survival, whereas single-lead, shock-only ICD therapy reduces overall mortality by 23 percent. BACKGROUND: Sudden death from cardiac causes remains a leading cause of death among patients with congestive heart failure (CHF). Treatment with amiodarone or an implantable cardioverter-defibrillator (ICD) has been proposed to improve the prognosis in such patients. METHODS: We randomly assigned 2521 patients with New York Heart Association (NYHA) class II or III CHF and a left ventricular ejection fraction (LVEF) of 35 percent or less to conventional therapy for CHF plus placebo (847 patients), conventional therapy plus amiodarone (845 patients) , or conventional therapy plus a conservatively programmed, shock-only, single-lead ICD (829 patients). Placebo and amiodarone were administered in a double blind fashion. The primary end point was death from any cause. RESULTS: The median LVEF in patients was 25%; 70 percent were in NYHA class II, and 30 percent were in class III CHF. The cause of CHF was ischemic in 52 percent and nonischemic in 48 percent. The median follow-up was 45.5 month s. There were 244 deaths (29 percent) in the placebo group, 240 (28 percent) in the amiodarone group, and 182 (22 percent) in the ICD group. As compared with placebo, amiodarone was associated with similar risk of death (hazard ratio, 1.06; 97.5 percent confidence interval, 0.86 to 1.30; P = 0.53) and ICD therapy was associated with a decreased risk of death of 23 percent (0.77; 97.5 percent confidence interval, 0.62 to 0.96; an absolute decrease in mortality of 7.2 percentage points after five years in the overall population. Results did not vary according to either either ischemic or nonischemic causes of CHF, but they did vary according to the NYHA class. CONCLUSIONS: In patients with NYHA class II or III CHF and LVEF of 35 percent or less, amiodarone has no favorable effect on survival, but single-lead, shock-only ICD therapy reduces overall mortality by 23 percent.