CYP2C19 Metabolizer Status and Clopidogrel Efficacy in the Secondary Prevention of Small Subcortical Strokes (SPS3) Study

Background The role of the CYP 2C19 genotype on clopidogrel efficacy has been studied widely, with data suggesting reduced clopidogrel efficacy in loss‐of‐function variant carriers taking clopidogrel after percutaneous coronary intervention; however, data are limited regarding the association between CYP 2C19 genetic variants and outcomes in stroke patients. We investigated whether CYP 2C19 metabolizer status affects the risk of recurrent stroke or major bleeding in subcortical stroke patients taking dual antiplatelet therapy with aspirin and clopidogrel. Methods and Results CYP 2C19*2 and CYP 2C19*17 were genotyped in 522 patients treated with dual antiplatelet therapy from the Secondary Prevention of Small Subcortical Strokes ( SPS 3) study. CYP 2C19 metabolizer status was inferred from genotype, and associations with the risk of recurrent stroke and major bleeding were assessed in the overall cohort and by race/ethnic group with logistic regression modeling. In the overall cohort, there were no differences in outcomes by CYP 2C19 metabolizer status (recurrent stroke, odds ratio 1.81 [95% CI 0.76 to 4.30]; major bleeding, odds ratio 0.67 [95% CI 0.22 to 2.03]). In white participants, those with CYP 2C19 intermediate or poor metabolizer status had higher odds of recurrent stroke (odds ratio 5.19 [95% CI 1.08 to 24.90]) than those with extensive or ultrarapid metabolizer status, but there was no evidence of difference in major bleeding. Conclusions There were significant differences in recurrent stroke by CYP2C19 genotype‐inferred metabolizer status in white subcortical stroke patients receiving dual antiplatelet therapy with aspirin and clopidogrel, consistent with cardiovascular studies on CYP 2C19 and clopidogrel; however, the bleeding risk that led to early termination of the antiplatelet arm of the SPS 3 trial does not appear to be explained by CYP 2C19 genotype. This study was relatively underpowered; therefore, these findings should be interpreted with caution and warrant replication. Clinical Trial Registration URL : www.clinicaltrials.gov . Unique identifier: NCT 00059306.