Point-of-care testing of clopidogrel-mediated platelet inhibition and risk for cardiovascular events after coronary angiography with or without percutaneous coronary intervention

High-on-treatment platelet reactivity (HPR) during antiplatelet treatment with clopidogrel is associated with increased risk for adverse cardiovascular events after percutaneous coronary intervention (PCI). Recent studies have indicated that the point-of-care platelet function test Plateletworks can predict such events. The objectives were to investigate the incidence of HPR, to identify correlating variables, and to assess if platelet function testing could predict adverse cardiovascular events. Observational, prospective, single-center study of 491 patients on clopidogrel and aspirin who underwent coronary angiography with or without PCI between October 2006 and May 2011. Platelet reactivity was measured with adenosine diphosphate-induced single-platelet function testing (Plateletworks). A cutoff of 82.3% aggregation was established and used to define HPR. Patients were followed for 3 months, and the primary end-point was myocardial infarction. Secondary end-points included stent thrombosis, death, rehospitalization, and a composite of myocardial infarction, death, and stent thrombosis. One hundred and ninety-six of the 491 patients had HPR. This group had a higher BMI (P < 0.001), and had more often received their clopidogrel loading dose within 6-24 h before coronary angiography (P = 0.001). At 3 months follow-up, the event rates of myocardial infarction and rehospitalization, respectively, were higher in HPR patients [5.1 vs. 1.7%, odds ratio (OR) 3.12, 95% confidence interval (CI) 1.05-9.27, P = 0.03; and 23.0 vs. 14.2%, OR 1.80, CI 1.13-2.86, P = 0.01, respectively]. Testing with Plateletworks identified patients at increased risk of myocardial infarction and rehospitalization within 3 months after coronary angiography with or without PCI.