Clopidogrel Use in CYP2C19 Loss-of-Function Carriers with High Bleeding Risk after Percutaneous Coronary Intervention.

BACKGROUND It is not known whether clopidogrel use in cytochrome P450 (CYP) 2C19 loss-of-function (LOF) carriers with high bleeding risk (HBR) contributes to adverse outcomes after percutaneous coronary intervention (PCI).Methods and Results: This retrospective observational study included 618 consecutive patients with available CYP2C19 polymorphism information who underwent PCI between September 2014 and August 2021. Patients with HBR (319 [52%] met the Academic Research Consortium definition) were divided into 2 groups according to P2Y12inhibitor action, namely decreased (i.e., clopidogrel in CYP2C19 LOF carriers) and retained (i.e., clopidogrel in CYP2C19 LOF non-carriers or prasugrel regardless of CYP2C19 polymorphisms), and clinical outcomes at 1 year were compared using inverse probability-weighted Cox proportional hazard regression. The primary ischemic outcome (a composite of cardiovascular death, myocardial infarction, or ischemic stroke) was significantly higher in the decreased than retained group (10.2% vs. 3.0%; adjusted hazard ratio [aHR] 2.78; 95% confidence interval [CI] 1.40-5.52; P=0.004). The primary bleeding outcome (Bleeding Academic Research Consortium 3 or 5) did not differ significantly between the decreased and retained groups (3.4% vs. 6.9%, respectively; aHR 0.48; 95% CI 0.22-1.01; P=0.054). There were no interactions between the treatment groups and HBR status in primary ischemic and bleeding outcomes. CONCLUSIONS Among patients with HBR, clopidogrel use in CYP2C19 LOF carriers was significantly associated with increased ischemic events after PCI.