Should CYP2C19 Genotyping Be Recommended as a Straight Forward Approach to Optimize Clopidogrel Utilization in Patients with Ischemic Stroke Complicated by Type 2 Diabetes Mellitus?

BACKGROUND: There have been few studies on CYP2C19 genotypes and clopidogrel response associated with ischemic stroke (IS), especially IS complicated by type 2 diabetes mellitus (T2DM). This study aimed to investigate the possible association between CYP2C19 polymorphisms and high on-treatment platelet reactivity (HTPR) in IS patients with T2DM in China. PATIENTS AND METHODS: A total of 426 consecutive IS patients with T2DM were enrolled in this case-control study and they were divided into HTPR group and non-HTPR group according to the ADP-induced platelet inhibition (PIADP) assessed by thromboelastography (TEG). Genotypes were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Various clinical and demographic data were also recorded. The association between CYP2C19 genetic variants and platelet function was assessed. RESULTS: Carriers of CYP2C19*2 heterozygous and mutant homozygous genotypes showed significantly lower PIADP than non-carriers (27.2% vs 38.3%, p < 0.001; 27.41% vs 38.3%, p = 0.012, respectively). Compared with the control group, the CYP2C19*2 A allele was more frequent in the HTPR group (34.51% vs 25.82%, p = 0.002). The carriage of CYP2C19*2 mutant allele was significantly associated with increased risk of HTPR (odds ratio (OR) = 1.94, 95% confidence interval (CI) = 1.32–2.85). There was no significant correlation between CYP2C19*3 or *17 genotypes and HTPR risk. CONCLUSION: CYP2C19*2 mutant allele was associated with attenuated platelet response to clopidogrel and increased risk of HTPR in IS patients with T2DM, suggesting that CYP2C19*2 polymorphism might be an important predictor of HTPR in this high-risk population.