Randomized, double-blind. Enrollment began in June 1987 when twenty-seven clinical centers began to randomize 4,400 post-myocardial infarction patients to placebo or treatment with encainide, flecainide, or moricizine. Prior to actual randomization, there was an open-label titration period to identify patients who responded to treatment. A total of 1,727 patients who responded were randomized: 1,455 to encainide, flecainide, or placebo, and 272 to moricizine or placebo. In April 1989, encainide and flecainide were discontinued because of increased total mortality and sudden arrhythmic death. CAST continued to compare moricizine to placebo in 1,300 patients for 18 months until August 1991 when the moricizine portion of the trial was stopped early because of excess deaths. The primary outcome variable in the full-scale trial was sudden cardiac death, with total mortality a secondary endpoint. Data analysis continued through March 1998.