Is High Platelet Reactivity Linked to Adverse Outcomes After Percutaneous Coronary Intervention?

Patients vary widely in their response to antiplatelet therapy. However, the value of platelet-reactivity testing to guide antiplatelet therapy after percutaneous coronary intervention (PCI) is much debated, and trials testing the approach have often been negative (e.g., NEJM JW Cardiol Nov 4 2012).

Now, we have prospective registry data from 8583 patients who each received at least one drug-eluting stent, as well as aspirin and clopidogrel, at one of about a dozen U.S. and European hospitals. The patients also underwent platelet-reactivity testing with the VerifyNow assay; their results were categorized according to arachidonic acid–induced and ADP-induced platelet aggregation for aspirin and clopidogrel, respectively. The maker of VerifyNow and several other companies funded the study.

By 1-year follow-up, definite or probable stent thrombosis had occurred in 0.8% of patients, myocardial infarction (MI) in 3.1%, clinically relevant bleeding in 6.2%, and death in 1.9%. In a propensity-adjusted multivariable analysis, high platelet reactivity while on clopidogrel was significantly associated with risks for stent thrombosis (hazard ratio, 2.49; P=0.001) and for MI (HR, 1.42; P=0.01); these associations were not found for aspirin. High platelet reactivity was inversely related to bleeding risk for both clopidogrel (HR, 0.73; P=0.002) and aspirin (HR, 0.65; P=0.04). Neither drug showed an association between high platelet reactivity and mortality risk.