Prevention of Non-Surgical Bleeding by Management of HeartMate II Patients Without Antiplatelet Therapy

This is a post-market clinical study of HM II patient management practices to be conducted in the United States. Subjects will be randomized in a 1:1 fashion to the following research drug groups: 1. Treatment Arm: Warfarin (INR target: 2.0-2.5, median: 2.25) + Placebo (1 pill/day) 2. Control Arm: Warfarin (INR target: 2.0-2.5, median: 2.25) + ASA Therapy (81mg/day) The study will investigate if subjects in the Treatment Arm experience a reduced incidence of non-surgical bleeding, without an increased risk of thromboembolic events.