The Canadian Amiodarone Myocardial Infarction Trial (CAMIAT) is a multicenter, triple-blind, randomized, placebo-controlled trial. Eligible patients are those found on 24-hour ambulatory electrocardiographic monitoring within 6-45 days of acute myocardial infarction to have ventricular premature depolarizations (VPDs) that are frequent (> or = 10/hr) or repetitive (> or = 1 three-beat run of ventricular tachycardia). Consenting patients are randomized to amiodarone or placebo with an oral loading dose of 10 mg/kg/day for 2 weeks; maintenance dose is 300-400 mg/day for 3.5 months, 200-300 mg/day for 4 months, and 200 mg/day for 5 or 7 days/week for 16 months. Patients are followed by alternate telephone and clinical visit at 2-month intervals for 24 months. The principal outcome is a composite of presumed arrhythmic death or resuscitated ventricular fibrillation. Outcomes are determined by an external validation committee. The anticipated rate of arrhythmic death is 7.5% over 2 years; the sample size is 1,200 patients. CAMIAT began in June 1990 and is anticipated to conclude enrollment by June 1994 and follow-up by June 1995. Recruitment rate is about 92% of projected.