Clinical Outcomes of High On-Treatment Platelet Reactivity in Koreans Receiving Elective Percutaneous Coronary Intervention (from Results of the CROSS VERIFY Study)

Platelet reactivity after clopidogrel therapy varies among patients. Whether clopidogrel response variability can predict clinical outcomes has not been verified in Asians. A prospective cohort was analyzed to evaluate clinical impact of clopidogrel response variability in patients who underwent elective percutaneous coronary intervention (PCI). A total of 809 consecutive patients receiving clopidogrel after elective PCI were followed for 1 year. On-treatment platelet reactivity (OPR) after clopidogrel therapy was measured with a point-of-care test, the VerifyNow P2Y12 assay. The primary end point was the composite of cardiac death and nonfatal myocardial infarction (MI) at 1 year. In this exclusively Korean cohort, the median OPR was 236 P2Y12 reactivity units. Using the definition of OPR >= 235 P2Y12 reactivity units as high OPR (HOPR), 50.3% of the cohort showed HOPR. The group with HOPR had significantly higher rates of cardiac death and spontaneous MI (2.5% vs 0.5%, p = 0.022) than the group without HOPR. Multivariate-adjusted analysis showed that HOPR was an independent predictor of the composite of cardiac death and nonfatal MI. The difference in major adverse cardiac events between the groups with and without HOPR was more profound in those without major cardiovascular disease, such as hypertension, diabetes mellitus, or dyslipidemia. In conclusion, HOPR to clopidogrel was significantly associated with cardiac death and spontaneous MI after elective PCI, suggesting that clopidogrel response variability may be a significant risk factor of hard end points in Koreans. (C) 2011 Elsevier Inc. All rights reserved. (Am J Cardiol 2011;108: 1556-1563)