Antiplatelet drug resistance: not ready for prime time.

Antiplatelet drug therapy reduces vascular events in a wide range of patients. Although antiplatelet drug resistance is becoming well documented, a universal definition has not been established. This lack and the lack of standardized measures of platelet function make estimation of the prevalence of antiplatelet drug resistance difficult. Mounting evidence suggests that antiplatelet drug resistance is associated with adverse clinical outcomes, which have been assessed in patients with coronary artery disease, myocardial infarction, cerebrovascular disease, and peripheral vascular disease. Patients with antiplatelet drug resistance have significantly more vascular events than patients without such resistance. However, there are no guidelines for the treatment of antiplatelet drug resistance. Although point-of-care platelet-function testing makes screening for resistance feasible, routine screening should not be standard practice until data regarding the management of antiplatelet drug resistance are available.