Park KW et al. – Enhanced clopidogrel response in smokers is reversed after smoking discontinuation, suggesting a causal relationship in addition to the previously reported association between smoking and enhanced clopidogrel response.

• From the prospective CROSS–VERIFY cohort, 810 subjects with repeated measurement of OPR at least 1 month apart were analysed.
• With smoking status ascertained at two time points, baseline and follow–up, study subjects were categorised into never smokers (n=628), smoking quitters (n=77) and persistent smokers (n=105).
• Dependent variables included OPR measured by the VerifyNow assay and the percentage of subjects with high OPR (HOPR).

• At baseline, current smokers showed significantly lower OPR compared with never smokers, with no significant differences in OPR between future quitters and future persistent smokers within current smokers.
• While the OPR of never smokers and persistent smokers did not change significantly during the follow–up, the mean OPR of quitters increased significantly by 19 P2Y12 reaction units (p=0.013).
• The frequency of HOPR showed similar results, with an 8–10% increase in smoking quitters in contrast to no significant changes in never and persistent smokers.
• Both mean OPR and the frequency of HOPR showed a linear inverse relationship with the amount of smoking.