Real-world data for optimal single antiplatelet therapy during the chronic maintenance period after percutaneous coronary intervention: a nationwide study of Korea

Optimal single antiplatelet therapy (SAPT) during the chronic maintenance period after coronary stenting remains uncertain. Although HOST-EXAM demonstrated superiority of clopidogrel over aspirin, real-world evidence remains limited. Using the Korean Health Insurance Review and Assessment Service (HIRA) claims database, we identified 49,227 patients who completed 6–24 months of dual antiplatelet therapy after percutaneous coronary intervention (PCI) and then received SAPT (aspirin, n = 20,817; clopidogrel, n = 28,410). The efficacy outcome was a composite of myocardial infarction (MI) and ischemic stroke; the safety outcome was a composite of gastrointestinal (GI) bleeding and intracranial hemorrhage (ICH). Propensity score weighting was used to balance covariates between groups. Compared with aspirin, clopidogrel was associated with lower risks of MI (hazard ratio [HR] 0.88; 95% confidence interval [CI] 0.81–0.97) and the efficacy composite (HR 0.93; 95% CI 0.88–0.98). Risks of ischemic stroke and gastrointestinal bleeding were similar. Clopidogrel was associated with a lower risk of ICH (HR 0.81; 95% CI 0.69–0.94), while the overall safety composite did not differ (HR 1.00; 95% CI 0.92–1.08). In a nationwide contemporary PCI population, clopidogrel monotherapy was associated with lower ischemic risk, primarily driven by fewer MIs, with no difference in overall bleeding events despite a lower risk of ICH.