Which role for antiplatelet and anticoagulant drugs in unstable angina pectoris?

Two large placebo-controlled, randomized, double-blind clinical trials have demonstrated the benefit of aspirin therapy in preventing myocardial infarction and death in patients with unstable angina. The Veterans Administration Cooperative Study of 1266 men hospitalized with unstable angina showed that 324 mg of aspirin daily for 12 weeks reduced the incidence of myocardial infarction by 51% (p = 0.001), and the data suggested a similar reduction in mortality. The Canadian McMaster University multicenter trial of 555 patients showed that treatment with 1300 mg of aspirin per day for a mean of 18 months reduced the incidence of cardiac death and nonfatal myocardial infarction together by 51% (p = 0.008). The reduction in death alone was 71% (p = 0.004). In the Canadian study there was no observed benefit of sulfinpyrazone. The Canadian trial confirmed the results of the VA Cooperative Study and showed statistical significance for reduction by aspirin of death as well as of myocardial infarction. It showed similar benefits in women as in men with unstable angina. The life-table curves for aspirin-treated and control patients continued to separate throughout the 2-year study period, demonstrating the value of continued treatment. The VA study showed no evidence of gastrointestinal side effects from 324 mg of aspirin daily administered in a buffered solution. Heparin therapy for unstable angina has appeared promising, but no properly conducted randomized trial has been accomplished.(ABSTRACT TRUNCATED AT 250 WORDS)