Abstract 262: Aspirin vs. Warfarin Therapy Outcomes for Non-Valvular Atrial Fibrillation Patients with Moderate Stroke Risk

Background: The American College of Cardiology Foundation and American Heart Association guidelinerecommends aspirin 81-325 mg or warfarin use for Non-Valvular Atrial Fibrillation (NVAF) patients with one risk factor for stroke. This study evaluated outcomes associated with antithrombotic treatment among NVAF patients with CHADS2=1 in an integrated healthcare system. Methods: Patients age ≥18 years newly diagnosed with NVAF with a CHADS2 score=1 at diagnosis were identified between 01/01/2006-12/31/2011 within Kaiser Permanente Southern California’s membership and followed until 12/31/2012. The rate of stroke or systemic embolism (SE) and major bleeding events per 100 person-years were evaluated for: 1) aspirin (ASA) only, 2) warfarin time in therapeutic range (TTR) ≥55%, 3) warfarin TTR <55%, and 4) no antithrombotic therapy. The 55% threshold was selected as the lower bound of reported means from previous studies. Results: Among 7,899patients with CHADS2=1, 336 stroke and 34 SE events were observed duri...