Ischemic stroke and myocardial ischemia in clopidogrel users and the association with CYP2C19 loss-of-function homozygocity: a real-world study.

Reduced clopidogrel effectiveness in preventing recurrent myocardial ischemia following percutaneous coronary intervention has been demonstrated in CYP2C19 loss-of-function carriers. Less is known about the effect of CYP2C19 genotype on the effectiveness of clopidogrel for stroke prevention, particularly in Caucasians. This is a retrospective cohort study, in which we used the Clalit clinical database to follow genotyped clopidogrel initiators, for up to 3 years. Endpoint was a new primary discharge diagnosis of ischemic stroke; secondary endpoints were new primary discharge diagnoses of coronary angioplasty, myocardial infarction (MI), or a composite endpoint of: stroke, MI, or coronary angioplasty. After 3 years of follow up over 628 clopidogrel initiators, 2 out of 12 (16.7%) poor metabolizers, 9 out of 144 intermediate metabolizers (6.3%), and 29 out of 472 (6.1%) normal/rapid/ultrarapid metabolizers have been newly diagnosed with ischemic stroke. Poor metabolizer status was associated with higher risk for ischemic stroke, marginally significant in univariate analysis and in multivariable models; and higher risk for the composite outcome of stroke, myocardial infarction and coronary angioplasty, HR = 3.32 (1.35-8.17) p = 0.009, 2.86 (1.16-7.06) p = 0.02 (univariate and multivariate analyses, respectively). Poor metabolizer status was associated with higher risk for stroke HR = 5.80 (1.33-25.24) p = 0.019, HR = 4.13 (0.94-18.13) p = 0.06 (univariate and multivariate analyses, respectively) in patients who "survived" the first year, and were in the cohort 1-3 years. Caucasian treated with clopidogrel who are homozygote for the CYP2C19 loss-of function allele might be at increased risk for ischemic stroke, and for the composite outcome of ischemic stroke, myocardial infarction and coronary angioplasty.