Aspirin Plus Coumarin Versus Aspirin Alone in the Prevention of Reocclusion After Fibrinolysis for Acute Myocardial Infarction

Abstract

Background — Despite the use of aspirin, reocclusion of the infarct-related artery occurs in ≈30% of patients within the first year after successful fibrinolysis, with impaired clinical outcome. This study sought to assess the impact of a prolonged anticoagulation regimen as adjunctive to aspirin in the prevention of reocclusion and recurrent ischemic events after fibrinolysis for ST-elevation myocardial infarction. Methods and Results — At coronary angiography <48 hours after fibrinolytic therapy, 308 patients receiving aspirin and intravenous heparin had a patent infarct-related artery (Thrombolysis In Myocardial Infarction [TIMI] grade 3 flow). They were randomly assigned to standard heparinization and continuation of aspirin alone or to a 3-month combination of aspirin with moderate-intensity coumarin, including continued heparinization until a target international normalized ratio (INR) of 2.0 to 3.0. Angiographic and clinical follow-up were assessed at 3 months. Median INR was 2.6 (25 to 75th percentiles 2.1 to 3.1). Reocclusion (≤TIMI grade 2 flow) was observed in 15% of patients receiving aspirin and coumarin compared with 28% in those receiving aspirin alone (relative risk [RR], 0.55; 95% CI 0.33 to 0.90; P <0.02). TIMI grade 0 to 1 flow rates were 9% and 20%, respectively (RR, 0.46; 95% CI, 0.24 to 0.89; P <0.02). Survival rates free from reinfarction and revascularization were 86% and 66%, respectively ( P <0.01). Bleeding (TIMI major and minor) was infrequent: 5% versus 3% ( P =NS). Conclusions — As adjunctive to aspirin, a 3-month-regimen of moderate-intensity coumarin, including heparinization until the target INR is reached, markedly reduces reocclusion and recurrent events after successful fibrinolysis. This conceptual study provides a mechanistic rationale to further investigate the role of prolonged anticoagulation after fibrinolytic therapy.