Prior Antiplatelet Exposure and Clinical Outcomes Among Korean Patients With Acute Myocardial Infarction.

Abstract

BACKGROUND: The impact of prior antiplatelet exposure on outcomes of acute myocardial infarction remains unclear, particularly in East Asian populations with distinct antithrombotic response profiles. METHOD(S): This retrospective cohort study analyzed 29 281 patients with acute myocardial infarction from 2 nationwide Korean registries. After excluding patients with atrial fibrillation, prior coronary artery disease, heart failure, cerebrovascular accident, or thrombolysis and those discharged on oral anticoagulants, 21 304 patients were categorized into previous-user and nonuser groups. Propensity score matching was performed to adjust for baseline differences. The primary outcome was 3-year major adverse cardiac and cerebrovascular events. RESULT(S): Previous users were older and had more comorbidities and angiographic complexity. Unadjusted analysis showed higher major adverse cardiac and cerebrovascular event rates in previous users, but the difference attenuated after propensity score matching in both the overall matched (adjusted hazard ratio [HR], 0.967 [95% CI, 0.850-1.100]) and selected population (adjusted HR, 1.036 [95% CI, 0.847-1.267]). All-cause death remained slightly elevated in the overall matched cohort (HR, 1.204 [95% CI, 1.004-1.443]) but not in the selected population. In-hospital outcomes and platelet reactivity findings supported the high-risk profile of prior users. CONCLUSION(S): Prior antiplatelet exposure was associated with a higher-risk clinical phenotype among patients with acute myocardial infarction, but this relationship was not independent after adjustment for baseline differences. These findings should be interpreted as hypothesis generating and underscore the importance of individualized antithrombotic strategies tailored to risk profiles, particularly in East Asian populations.