Abstract 16088: Comparison of Aspirin and Clopidogrel Therapy With Clopidogrel Alone Use Following Coronary Stent Implantation in Patients With Acute Myocardial Infarction

Introduction: Dual antiplatelet (DAP) therapy with aspirin and a thienopyridine following coronary stenting is superior to aspirin alone use in reducing cardiovascular events in both acute coronary syndrome and stable angina. However, there is a doubt whether DAP therapy is more effective and safer than clopidogrel alone use in secondary prevention. Hypothesis: We assessed the hypothesis that we compared retrospectively clopidogrel alone use with DAP therapy in acute myocardial infarction (MI) patients treated with coronary stent. Methods: From the Korean MI registry, we selected a total of 13,348 patients who underwent coronary stent implantation and were discharged on clopidogrel alone use (n = 85, 0.6%) and DAP therapy (n = 13,263, 99.4%). Propensity score matching was used and two cohorts of 1:5 nearest neighbor matched patients were obtained to eliminate biased estimates. The primary endpoint was the composite of major adverse cardiac events (MACE; all-cause death, MI, or revascularization) at one-year. Results: In the two matched cohorts of clopidogrel alone use (n = 85) and DAP therapy (n = 425), there was no difference in all-cause death (3.1 vs. 3.5%, p = 0.82), cardiovascular death (2.1 vs. 2.4%, p = 0.892), MI (1.6 vs. 1.2%, p = 0.75), revascularization (6.6 vs. 8.2%, p = 0.583), and the composite of cumulative MACE (11.3 vs. 12.9%, p = 0.665) at median follow-up period of 11.8 months. Compared to DAP therapy, clopidogrel alone use was not associated with increased risk of all-cause death (hazard ratio [HR] 1.11, 95% confidence interval [CI] 0.314-3.93, p = 0.871), MI (HR 0.38, 95% CI 0.17-11.2, p = 0.763), revascularization (HR 0.808, 95% CI 0.353-1.851, p = 0.615), and the composite of MACE (HR 1.129, 95% CI 0.585-2.178, p = 0.717) at one-year. Conclusions: This observational study showed that clopidogrel alone use following coronary stenting was not associated with increased mortality and worse clinical outcomes at one-year compared to DAP therapy in patients with acute MI. Further studies are needed to support this observational result.