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.