Influence of smoking on CYP2C19 genetic variants and clopidogrel efficacy in patients with minor stroke or transient ischaemic attack.

Amongst patients with minor stroke or transient ischaemic attack, marginal significant interactions between CYP2C19*2 and CYP2C19*3 allele carrier status and clopidogrel efficacy were found in smokers but not in non-smokers. Amongst smokers, clopidogrel plus aspirin might decrease the recurrence rate of stroke in non-carriers of *2 and *3 alleles of CYP2C19 compared with aspirin alone. However, caution should be taken to interpret our findings in view of several limitations in our study.