Background and objective: The CYP2C19*2 allele is associated with reduced clopidogrel bioactivation, increasing the risk of complications after percutaneous coronary intervention (PCI), particularly stent thrombosis. Recently published data suggests that CYP2C19*2 allele carriers have a higher risk for in-stent restenosis (ISR) after endovascular treatment. Very few studies have investigated the relationship between CYP2C19*2 and coronary ISR, with no significant association reported. The objective of this study was to assess the relationship between CYP2C19*2 allele carrier status and coronary ISR. Methods: Patients with previous PCI with stenting and who were scheduled for elective PCI after coronary angiogram were recruited from the cardiac catheterization suite over a 12-month period. The angiography report of each patient was perused to identify patients requiring PCI due to ISR. For patients with angiography-confirmed ISR, date of previous PCI to the restenosed stent was noted. CYP2C19*2 genotyping was undertaken using a TaqMan® Drug Metabolism assay. The association between CYP2C19*2 allele carrier status and incidence of coronary ISR within 1 year was assessed using Fisher’s exact test (p < 0.05 significance) and by calculating the odds ratio (OR) with a 95% confidence interval (CI). Results: Of the 82 patients with previous PCI, 29 (35.4%) had angiography-confirmed ISR (12 carriers, 17 noncarriers of CYP2C19*2). In 13 (44.8%) of these patients, the restenosed stent was deployed within 1 year and the patients were on clopidogrel therapy at the time of repeat PCI (8 carriers, 5 non-carriers of CYP2C19*2). The association between CYP2C19*2 allele carrier status and ISR within 1 year was not statistically significant (Fisher’s exact p = 0.067; OR: 4.80, 95% CI: 0.98–23.54, p = 0.053). Conclusions: Despite a higher proportion of CYP2C19*2 allele carriers exhibiting ISR within 1 year compared to non-carriers, the association was not statistically significant. This result may be attributed to the small sample size, and larger prospective studies are recommended to further assess this association.peer-reviewe
