Role of clopidogrel in unstable angina and non-ST-segment elevation myocardial infarction: from literature and guidelines to practice.

Clinical trials are the backbone of treatment paradigm shifts and guideline development. In terms of acute coronary syndromes, the American College of Cardiology and the American Heart Association (ACC-AHA) have developed extensive guidelines to assist the practitioner in the appropriate use of drugs including antiischemic, anticoagulant, and antiplatelet agents. Clopidogrel, an adenosine 5'-diphosphate antagonist, is one such drug. Unfortunately, consensus guidelines are limited by the design of the clinical trials they reference. Clopidogrel trials have examined various outcomes in patients for a limited time frame, making longer term use of the drug difficult to justify. An ongoing study, estimated to be completed in 2005, is evaluating the long-term use of clopidogrel in high-risk patients. Aspirin, however, has become a lifelong therapy for many patients, based on clinical trials and medical experience. Patient-specific risk factors, the drugs' safety profiles, and costs, in addition to the ACC-AHA guidelines, must all be considered by clinicians when selecting the appropriate agent and its duration of use.