Importance of platelets and platelet response in acute coronary syndromes.

Platelet activation is one of the essential steps in the genesis and propagation of atherothrombosis. Accumulating clinical evidence suggests that an elevated platelet count, platelet activation, and platelet hyperreactivity (defined as residual platelet activity despite antiplatelet drug therapy) may be associated with adverse cardiovascular events in patients with acute coronary syndromes. Platelet function can be analyzed using various assays and measures of platelet activation. The best assays for measuring residual platelet activity in the setting of antiplatelet therapy are still being defined, as are their predictive values. Platelet aggregation remains the gold standard, but other testing methods offer advantages for specific applications, such as detecting overall platelet hyperreactivity in the presence of antiplatelet therapy or detecting inhibition of the adenosine diphosphate receptor P2Y(12). Standard testing protocols for platelet aggregation are needed to achieve consistency among studies.