This is a prospective, double-blind, placebo-controlled trial to determine the effect of antiarrhythmic drug therapy on mortality in patients with congestive heart failure and ventricular arrhythmia. Patients will be assigned to receive either amiodarone or placebo. Eligible patients include those with ischemic and nonischemic congestive heart failure and with > or = 10 ventricular premature beats per hour. All patients must have shortness of breath with minimal exertion or paroxysmal nocturnal dyspnea, a left ventricular internal dimension (LVIDd) by echocardiogram of > or = 55 mm or a cardiothoracic ratio of > 0.5 and an ejection fraction of < or = 40%. All patients will receive vasodilator therapy, unless they find it intolerable. Patients will be entered into the study for 2.5 years and followed for an additional 2 years. Drug therapy will be continued for all patients throughout the entire study unless adverse reactions occur that necessitate individualized treatment. The expectation is that 674 patients will be entered into the study from 25 participating centers. This sample size will allow for the detection of a 33% decrease in 2-year mortality (20% vs 30%) in the treated patients compared with those in the placebo group, with a power of 0.90 and a 2-sided alpha level of 0.05. Intermittent Holter monitoring, radionuclide ventriculograms, pulmonary function tests, echocardiograms, and blood tests, including arterial blood gases, will be required for each patient.(ABSTRACT TRUNCATED AT 250 WORDS)