Outcomes and Prognostic Impact of Prophylactic Oral Anticoagulation in Anterior ST‐Segment Elevation Myocardial Infarction Patients With Left Ventricular Dysfunction

BACKGROUND: The contemporary role of prophylactic anticoagulation following extensive anterior wall ST‐segment myocardial infarction (STEMI) is unclear. METHODS AND RESULTS: We evaluated anterior STEMI patients with left ventricle dysfunction (left ventricular ejection fraction ≤40%) (“high risk”), categorized by prophylactic warfarin use, within a regional STEMI. Patients with pre‐existing atrial fibrillation were excluded. The primary outcome was an adjusted (for Global Registry of Acute Coronary Events risk score) 1‐year composite of recurrent ischemia, stroke/transient ischemic attack/systemic embolism, or all‐cause death. Of the 2032 STEMI admissions, 436 (21.5%) were high risk. After excluding 19 (4.4%) patients with definite left ventricle thrombus and 21 (4.8%) in‐hospital deaths (2 had left ventricle thrombus), prophylactic warfarin was utilized in 236/398 (59.3%) high‐risk survivors. Prescriptions were comparable across sex, but recipients were on average younger (58.5 years versus 64.0 years, P<0.001) and lower risk (Global Registry of Acute Coronary Events risk: 163 versus 181, P<0.001). No association on the adjusted ischemic composite (23.3% versus 25.3%, odds ratio 0.96, 95% CI 0.60–1.55) or thromboembolic events (2.1% versus 1.2%, odds ratio 1.99, 95% CI 0.38–10.51) was observed, but reduced 1‐year all‐cause mortality was noted (2.5% versus 8.6%, odds ratio 0.30, 95% CI 0.11–0.81); numerically higher major bleeding was observed at 1 year (2.5% versus 1.2%, odds ratio 2.17, 95% CI 0.43–10.96). CONCLUSIONS: A high utilization of prophylactic warfarin occurs in anterior STEMI patients with left ventricle dysfunction, yet appears to provide no additional benefit on the ischemic composite. The association with lower all‐cause mortality, but higher bleeding, calls for an improved understanding of its role in high‐risk STEMI.