Latest clinical data on testing for high on-treatment platelet reactivity.

Antiplatelet therapy is the cornerstone of treatment for patients with acute coronary syndromes and in those who are undergoing percutaneous coronary intervention (PCI). Clopidogrel, a second-generation thienopyridine antiplatelet agent, is currently used to prevent vascular complications in atherothrombotic patients, to prevent stent thrombosis in patients undergoing PCI, and in the long-term prevention of cardiovascular and cerebrovascular events. Unfortunately, despite treatment with clopidogrel, some patients continue to have cardiovascular events. This may be due in part to a suboptimal response to the drug, with minimal inhibition of platelet aggregation and/or high on-treatment platelet reactivity. Point-of-care testing of clopidogrel response, together with a reliable diagnostic cutoff, can identify patients with high on-treatment platelet reactivity and optimize their clinical management. This article reviews the impact of poor clopidogrel responsiveness on clinical outcomes, the major clinical studies using VerifyNow P2Y12 Assay® (Accumetrics, San Diego, CA) to assess on-clopidogrel platelet reactivity, and efforts to determine a reliable cutoff.