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Antiplatelet therapy with aspirin and systematic anticoagulation with warfarin reduce cardiovascular morbidity and mortality after myocardial infarction when given alone. In the Coumadin Aspirin Reinfarction Study (CARS), we aimed to find out whether a combination of low-dose warfarin and low-dose aspirin would give superior results to standard aspirin monotherapy without excessive bleeding risk.

We used a randomised double-blind study design. At 293 sites, we randomly assigned 8803 patients who had had myocardial infarction, treatment with 160 mg aspirin, 3 mg warfarin with 80 mg aspirin, or 1 mg warfarin with 80 mg aspirin. Patients took a single tablet daily, and attended for prothrombin time (PT) measurements at weeks 1, 2, 3, 4, 6, and 12, and then every 3 months. Patients were followed up for a maximum of 33 months (median 14 months).

The primary event was …