Variable platelet responsiveness to aspirin and clopidogrel: role of platelet function and genetic polymorphism testing.

Dual antiplatelet therapy with aspirin and clopidogrel is the standard treatment for patients with an acute coronary syndrome or percutaneous coronary intervention. However, at standard doses, many patients still experience an adverse cardiovascular event. Numerous studies have demonstrated that a laboratory assessment of platelet resistance to an antiplatelet medication is associated with adverse outcomes. The gold standard in assessing platelet function is light transmittance aggregometry. However, because of the time necessary to complete the test, the need for skilled technicians, and the associated costs, newer point-of-care tests have been developed to assess rapidly an individual's platelet responsiveness. Although numerous studies demonstrate an association with adverse outcomes and platelet resistance, currently no clinical trial results demonstrate a treatment strategy to mitigate the adverse outcomes associated with platelet resistance. Studies currently underway are evaluating treatment options for a laboratory assessment of platelet resistance, such as increasing the clopidogrel maintenance dose. Until such results are available, routine testing of platelet resistance to aspirin or clopidogrel should be used only in a research setting.