CYP2C19*2 and *3 Polymorphisms Are Associated with High Post- Treatment Platelet Reactivity in Korean Patients with Acute Coronary Syndrome Undergoing Percutanous Coronary Intervention.

Background: Cytochrome P450 (CYP) 2C19 is an enzyme showing genetic polymorphism that may cause marked interindividual and interethnic variation in the metabolism and disposition of its substrates. CYP2C19*2 and CYP2C19*3 are the most common of CYP2C19 polymorphisms, and show phenotypic poor metabolism. Recent data have shown that the CYP2C19*2 loss-of-function allele is associated with a marked decrease in platelet response to clopidogrel in healthy controls and Caucasian patients with acute coronary syndrome. However, It is unknown whether CYP2C19 *3, which is frequently noted in Asian, is also associated with platelet response to clopidogrel. Therefore, this study was conducted to analyze the effect of CYP2C19 *2 and *3 polymorphisms on high post-treatment platelet reactivity (HPPR) on clopidogrel in Korean patients with acute coronary syndrome, as a representative of Asian populations.

Methods: The study included 136 consecutive patients undergoing percutanous coronary intervention (PCI). Adenosine diphosphate (ADP)-induced platelet aggregation by light transmittance aggregometry (LTA) and the VerifyNow P2Y12 assay (Ultegra rapid platelet function assay; Accumetrics Inc., USA) were assessed after a loading dose and after the maintenance dose of clopidogrel before discharge. CYP2C19 genotype was analyzed by Snapshot method.

Results: The genotypic distributions of CYP2C19*1/*1, *1/*2, *1/*3, *2/*2, and *2/*3 were 57 (41.9%), 47 (34.6%), 12 (8.8%), 14 (10.3%), 6 (4.4%), and 6(4.4%), respectively. The frequencies of CYP2C19 mutant alleles in Korean were higher than Caucasians. The CYP2C19*2 and CYP2C19*3 polymorphisms were significantly associated with persistent higher platelet aggregation by LTA, and lower inhibition of platelet reactivity by VerifyNow P2Y12 assay after clopidogrel than CYP2C19*1 genotype. The CYP2C19*2 and *3 alleles were more frequent in clopidogrel hyporesponsiveness, defined by persistent HPPR (5 uM ADP-induced platelet aggregation >50%; p = 0.01).

Conclusions: This study suggests that the CYPC19*2 and *3 alleles influence clopidogrel hyporesponsiveness after clopidogrel in Asian patients with acute coronary syndromes undergoing PCI. These findings can have a significant impact on the future design of pharmacognetic antiaggregant strategies for acute coronary syndrome on antiplatelet treatment.