Antiplatelet and antithrombotic therapy in unstable angina.

In 4 well-controlled clinical trials, aspirin reduced the incidence of coronary events in unstable angina. The benefits were present during the acute, subacute and more chronic phases of the disease and were independent of the doses and of other protocol differences. This benefit of aspirin can be extended to some, but not all, other antiplatelet drugs. In 4 clinical trials, heparin used acutely added substantial benefit to the management of unstable angina, reducing the event rate and also the incidence of refractory angina more than aspirin. The long-term benefit of antithrombin therapy remains to be more thoroughly investigated. Despite these successes, the failure rate of aspirin and of heparin remains high, justifying a continuing search for more potent and safe antiplatelet and antithrombotic drugs.