Comparison of Antiplatelet Monotherapies After Percutaneous Coronary Intervention According to Clinical, Ischemic, and Bleeding Risks

Background: Clopidogrel was superior to aspirin monotherapy in secondary prevention after percutaneous coronary intervention (PCI). Objectives: The purpose of this study was to evaluate the benefits of clopidogrel across high-risk subgroups Methods: This was a post hoc analysis of the HOST-EXAM (Harmonizing Optimal Strategy for Treatment of coronary artery diseases-EXtended Antiplatelet Monotherapy) trial that randomly assigned patients who were event free for 6 to 18 months post-PCI on dual antiplatelet therapy (DAPT) to clopidogrel or aspirin monotherapy. Two clinical risk scores were used for risk stratification: the DAPT score and the Thrombolysis In Myocardial Infarction Risk Score for Secondary Prevention (TRS 2°P) (the sum of age ≥75 years, diabetes, hypertension, current smoking, peripheral artery disease, stroke, coronary artery bypass grafting, heart failure, and renal dysfunction). The primary composite endpoint was a composite of all-cause death, nonfatal myocardial infarction, stroke, readmission because of acute coronary syndrome, and major bleeding (Bleeding Academic Research Consortium type ≥3) at 2 years after randomization. Results: Among 5,403 patients, clopidogrel monotherapy showed a lower rate of the primary composite endpoint than aspirin monotherapy (HR: 0.73; 95% CI: 0.59-0.90). The benefit of clopidogrel over aspirin was consistent regardless of TRS 2°P (high TRS 2°P [≥3] group: HR: 0.65 [95% CI: 0.44-0.96]; and low TRS 2°P [<3] group: HR: 0.77 [95% CI: 0.60-0.99]) (P for interaction = 0.454) and regardless of DAPT score (high DAPT score [≥2] group: HR: 0.68 [95% CI: 0.46-1.00]; and low DAPT score [<2] group: HR: 0.75 [95% CI: 0.59-0.96]) (P for interaction = 0.662). The association was similar for the individual outcomes. Conclusions: The beneficial effect of clopidogrel over aspirin monotherapy was consistent regardless of clinical risk or relative ischemic and bleeding risks compared with aspirin monotherapy.