['Platelet inhibition by clopidogrel is highly variable and the elevated platelet activity will increase the risk of major adverse cardiovascular events after percutaneous coronary intervention (PCI). CYP2C19 loss-of-function (LOF) alleles and risk factors of coronary heart disease (CAD) were reported to be associated with the low response of clopidogrel.', 'This study was carried out to analyze the contributions of CYP2C19 polymorphisms and risk factors to the various clopidogrel responses in Chinese patients with stable CAD after PCI.', 'The platelet reactivity index (PRI) was measured in 145 patients who underwent PCI using the vasodilator-stimulated phosphoprotein assay. Gene chip hybrid tests were used to analyze the genetic polymorphisms of CYP2C19.', 'With a cutoff value of 50% in PRI, 20.67% (31/145) of the patients were defined to be clopidogrel resistant. With respect to the normal *1, *2, and *3 LOF CYP2C19 alleles, patients were classified into three metabolism phenotypes: 39.31% were extensive, 47.59% were intermediate, and 13.10% were poor metabolizers (PMs). Of the enrolled patients, 53.82 and 9.66%, respectively, were carriers of *2 and *3 alleles. There was a significant difference in PRI between PM and either extensive or intermediate metabolizers (P<0.05). In all, 36.84% of the patients with the PM phenotype were clopidogrel resistant. Carriers of two CYP2C19 LOF alleles, BMI, and the presence of type 2 diabetes were three independent risk factors for clopidogrel resistance.'] Do cYP2C19 polymorphisms and coronary heart disease risk factors synergistically impact clopidogrel response variety after percutaneous coronary intervention?