Aspirin plus either dipyridamole or ticlopidine is effective in preventing recurrent myocardial infarction. Secondary Prevention Group.

The efficacy of combining antiplatelet agents with low doses of aspirin to prevent cardiac events in patients with myocardial infarction was examined. A total of 1,083 patients with prior myocardial infarction were randomly divided into those who were (618) and were not (465) treated with antiplatelet agents, and observed for 12.5 +/- 18.5 months. Those treated with antiplatelet agents included 113 patients treated with aspirin (50 mg) plus dipyridamole (150 mg/day), 253 treated with aspirin (50 mg) plus ticlopidine (200 mg/day), and 252 treated with only 1 of the 3 antiplatelet agents. Cardiac events, including fatal or nonfatal recurrent myocardial infarction, death by congestive heart failure, and sudden death, occurred in 34 patients (7.3%) in the nontreatment group and in 19 patients (3.1%; p < 0.01) in the treatment group; odds ratio 0.40, 95% confidence interval 0.23-0.71. There were only 2 cardiac events (1.8%) in the aspirin + dipyridamole group (p < 0.05 vs nontreatment group: odds ratio 0.28: 0.08-1.03), and 5 such events (2.0%) in the aspirin + ticlopidine group (p < 0.01; odds ratio 0.28: 0.11-0.69). Subgroup analysis to exclude differences in the patients' background confirmed the efficacy of these antiplatelet agents. We conclude that combined treatment with low doses of aspirin plus either dipyridamole or ticlopidine is effective in preventing cardiac events in patients who have had prior myocardial infarction.