Context High on-treatment platelet reactivity is associated with atherothrombotic events following coronary stent implantation. Objective To evaluate the capability of multiple platelet function tests to predict clinical outcome. Design, Setting, and Patients Prospective, observational, single-center cohort study of 1069 consecutive patients taking clopidogrel undergoing elective coronary stent implantation between December 2005 and December 2007. On-treatment platelet reactivity was measured in parallel by light transmittance aggregometry, VerifyNow P2Y12 and Plateletworks assays, and the IMPACT-R and the platelet function analysis system (PFA-100) (with the Dade PFA collagen/adenosine diphosphate [ADP] cartridge and Innovance PFA P2Y). Cut-off values for high on-treatment platelet reactivity were established by receiver operating characteristic curve analysis.Main Outcome Measurement The primary end point was defined as a composite of all-cause death, nonfatal acute myocardial infarction, stent thrombosis, and ischemic stroke. The primary safety end point included TIMI (Thrombolysis In Myocardial Infarction) criteria major and minor bleeding.Results At 1-year follow-up, the primary end point occurred more frequently in patients with high on-treatment platelet reactivity when assessed by light transmittance aggregometry (11.

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carriage of the loss-of-function alleles CYP2C19*2 and CYP2C9*3 increases the risk on ST after PCI.

In this collaborative meta-analysis, the level of on-treatment platelet reactivity according to the P2Y(12) assay is associated with long-term cardiovascular events after percutaneous coronary intervention, including death, MI, and stent thrombosis.

is suitable to monitor clopidogrel responsiveness? A pharmacokinetic analysis on the active metabolite of clopidogrel. J Thromb Haemost 2010; 8: 482-8.Summary. Background: Multiple platelet function tests claim to be P2Y12-pathway specific and capable of capturing the biological activity of clopidogrel. Objectives: The aim of the present study was to determine which platelet function test provides the best reflection of the in vivo plasma levels of the active metabolite of clopidogrel (AMC). Patients/methods: Clopidogrel-naive patients scheduled for elective percutaneous coronary intervention (PCI) received a 600 mg loading dose of clopidogrel and 100 mg of aspirin. For pharmacokinetic analysis, blood was drawn at 0,20, 40, 60, 90, 120, 180, 240 and 360 min after clopidogrel loading and peak plasma concentrations (C max ) of the AMC were quantified with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Platelet function testing was performed at baseline and 360 min after the clopidogrel loading. Results: The VASP-assay, the VerifyNow P2Y12-assay and 20 lmol L )1 adenosine diphosphate (ADP)-induced light transmittance aggregometry (LTA) showed strong correlations with C max of the AMC (VASP: R 2 = 0.56, P < 0.001; VerifyNow platelet reactivity units (PRU): R 2 = 0.48, P < 0.001; VerifyNow %inhibition:R 2 = 0.47, P < 0.001). Agreement with C max of the AMC was less evident for 5 lmol L )1 ADP-induced LTA or whole blood aggregometry (WBA), whereas the IMPACT-R ADP test did not show any correlation with plasmalevels of the AMC. Conclusion:The flow cytometric VASP-assay, the VerifyNow P2Y12 assay and, although to a lesser extent, 20 lmol L )1 ADPinduced LTA correlate best with the maximal plasma level of the AMC, suggesting these may be the preferred platelet function tests for monitoring the responsiveness to clopidogrel.