Several studies have shown that high residual platelet reactivity during clopidogrel treatment is predictive of major cardiovascular events in patients undergoing percutaneous coronary intervention (PCI).
1-14 However, there is no standardized technique among ex vivo platelet function tests, and in studies using the same platelet function test, cutoff values for high on-treatment platelet reactivity established by receiver operating characteristic curve analysis are variable. Consequently, the hypothesis that the risk of thrombotic events increases markedly above a critical cut point of platelet reactivity on in vitro tests is not yet proven. Moreover, most studies have included heterogeneous populations with short follow-up, and few data exist for patients with acute coronary syndromes (ACS) undergoing an invasive procedure.