The Anturane Reinfarction Trial evaluated the effect of sulfinpyrazone (Anturane) (200 mg four times a day) vs placebo on cardiac mortality rates among patients recently recovered from an acute myocardial infarction. This study involved 1558 eligible patients who were observed for an average period of 16 months (maximum 2 years). The trial differed from studies on other platelet-active drugs in that it was designed as a clinical efficacy study rather than an "intent-to-treat" trial, and all patients were entered within a very narrow window, i.e., 25-35 days after infarction, which allowed for the drug to be evaluated against the natural history of mortality after an acute myocardial infarction. At the end of the trial, there were 105 analyzable cardiac deaths among eligible patients. 62 in the placebo group and 43 in the sulfinpyrazone group; this represented a reduction in mortality rate by sulfinpyrazone of 32% and was of borderline statistical significance (p = 0.044-0.058 using three methods of analysis). This reduction was attributable primarily to a significant reduction in sudden death (37 in the placebo group vs 22 in the sulfinpyrazone group, sudden death mortality reduction of 43%, p = 0.023-0.041). Interpretation of the data by time period and cause revealed that the effect of sulfinpyrazone was restricted to the prevention of sudden death during the high-risk period for this event, i.e., the first 6 months after trial entry (24 in the placebo group vs six in the sulfinpyrazone group, sudden death mortality reduction of 74%, p = 0.001-0.003).