Percutaneous coronary intervention (PCI) with stent implantation is the preferred reperfusion strategy for treatment of acute myocardial infarction (AMI). Despite advances in both devices and pharmacological support for AMI patients undergoing PCI, the risk of recurrent ischemic events has been higher than that of elective PCI. Among therapeutic options for surmounting clopidogrel hyporesponsiveness, higher loading doses and maintenance doses of clopidogrel achieved significant enhancements in the speed of onset and intensity of inhibition and these approaches have been widely adapted in clinical practice. Interestingly, recent studies found that carriers of the loss-of-function hepatic cytochrome (CYP) 2C19 allele had significantly lower levels of the active metabolite of clopidogrel, diminished platelet inhibition, and a higher rate of major adverse cardiovascular events than did non-carriers, in the setting of PCI and acute coronary syndrome (ACS). These findings raise the need of solutions to overcome enhanced post-clopidogrel platelet reactivity by the influence of the loss-of-function CYP2C19 allele. Increasing the dose of clopidogrel, new potent P2Y12 antagonists (such as prasugrel), or other antiplatelet drugs such as cilostazol may be alternative antiplatelet regimens in patients with the loss-of-function CYP variant. A recent study demonstrated that adjunctive cilostazol to dual antiplatelet therapy (triple antiplatelet therapy) intensified platelet inhibition as compared with a high maintenance-dose (MD) of 150 mg/day. Therefore, triple antiplatelet therapy could also be an alternative antiplatelet therapy to improve platelet inhibition and clinical outcomes in carriers of CYP2C19 mutant allele.

The purpose of this study was to determine the impact of adjunctive cilostazol on platelet inhibition in carriers and non-carriers of the loss-of-function CYP2C19 allele. The investigators compared the enhanced inhibition of platelet aggregation by adjunctive cilostazol 100 mg twice daily versus high-MD clopidogrel 150 mg/day in AMI patients treated with emergent coronary stenting, according to the CYP2C19 polymorphism.