P6384High proportion of ischemic strokes may be due to low adherence to oral anticoagulation guidelines among patients with atrial fibrillation and stroke risk factors

Background: Oral anticoagulation is highly effective for preventing stroke in patients with atrial fibrillation (AF) and stroke risk factors. However, the proportion of ischemic strokes occurring in patients with AF who did not adhere to guideline recommendations for anticoagulation is not well understood. Purpose: We sought to analyze oral anticoagulation utilization among patients with a recent ischemic stroke and a prior diagnosis of AF in an effort to better understand the potential for stroke prevention through better guideline adherence. Methods: Using deidentified Optum EHR data from 2011–2016, we included cardiovascular disease patients with ischemic stroke (ICD-9 codes 433.x/434.x/436.x or ICD-10 codes I63.x/I65.x/I66.x) and a prior history of AF. Subsequent analysis was limited to those indicated for oral anticoagulation (i.e., CHADS2 scores ≥2). Anticoagulant prescription in the year prior to the index ischemic stroke was assessed as a function of CHADS2 score. Results: A total of 46,230 ischemic stroke patients with a prior history of AF were identified. Among these, 34,657 (75.0%) had CHADS2 scores ≥2 prior to the index stroke – a group where existing guidelines give strong recommendation to anticoagulate. While anticoagulant utilization was low across all evaluated CHADS2 scores, it was lowest among patients with CHADS2 scores of 2 or 3 prior to the index stroke (27.2% and 36.9%, respectively, line graph). Patients with these CHADS2 scores accounted for the 84.8% of anticoagulant-eligible patients (bar graphs).