Antiplatelet Therapy and Adverse Hematologic Events during Heart Mate II Support

Hematologic adverse events are common during continuous flow left ventricular assist device support; yet, their relation to antiplatelet therapy, including aspirin (ASA) dosing, is uncertain. Methods and Results-A single-center retrospective review of all patients supported by a continuous flow left ventricular assist device (Heart Mate II) from June 2006 to November 2014 was conducted. Patients were categorized into 3 groups: (1) ASA 81 mg+dipyridamole 75 mg daily (n=26) with a target international normalized ratio (INR) of 2 to 3 from June 2006 to August 2009; (2) ASA 81 mg daily (n=18) from September 2009 to August 2011 with a target INR of 1.5 to 2; and (3) ASA 325 mg daily from September 2011 to November 2014 with a target INR of 2 to 3 (n=70). Hemorrhagic and thrombotic outcomes were retrieved ≤365 days after implantation. Cumulative survival free from adverse events was calculated using Kaplan-Meier curves and Cox proportional hazard ratios were generated. Hemorrhagic events occurred in 6 patients on ASA 81 mg+dipyridamole (26%; 0.42 events per patient year; mean INR at event, 2.2), 4 patients on ASA 81 mg (22%; 0.38 events per patient year; mean INR at event, 2.0), and in 38 patients on ASA 325 mg (54%; 1.4 events per patient year; mean INR at event, 2.2); P=0.004. Patients on ASA 325 mg had a higher adjusted hazard ratio of 2.9 (95% confidence interval, 1.2-7.0 versus ASA 81 mg+dipyridamole; P=0.02) and 3.4 (95% confidence interval, 1.2-9.5 versus ASA 81 mg; P=0.02) for hemorrhagic events. Thrombotic events rates were not different between groups. Conclusions-High-dose ASA in Heart Mate II patients treated concomitantly with warfarin is associated with an increased hazard of bleeding but does not reduce thrombotic events.