Retrospective Evaluation of Inpatient Warfarin Management Practices in Patients Immediately Following Left Ventricular Assist Device Implantation

Abstract

Background: The International Society for Heart and Lung Transplantation recommends patients receive warfarin and aspirin following left ventricular assist device (LVAD) placement. Optimal warfarin management in this population has not been well established. Objectives: The objectives of this study were to evaluate warfarin practices in patients immediately post-LVAD implantation. Methods: This single-center, retrospective cohort study included patients 18 years and older following LVAD placement from August 1, 2012 to April 1, 2020. The primary outcome was to assess patient-specific risk factors affecting time to therapeutic range. Secondary outcomes included bleeding events, thrombotic events, and warfarin dosing patterns. Results: Of 104 included patients, 91% reached the therapeutic range at a median of 8 days. A higher proportion of patients started on 3.5 mg or higher reached therapeutic international normalized ratio (INR) and faster (96% vs 90%; 8 vs 5 days) compared to lower doses. Univariate analysis of associations with reaching therapeutic INR range included initial warfarin dose, cumulative warfarin, and warfarin dosing changes, whereas HAS-BLED and CHA₂DS₂VAC were associated with slower time to therapeutic INR. Overall, 44% of patients met Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) bleeding criteria. There were a total of 12 thrombotic events and no pump thrombotic events. Total weekly warfarin dosing was significantly lower post-LVAD (24.3 mg vs 35 mg, P = 0.0009). In addition, warfarin requirements were statistically higher after the first week of therapy (4.0 mg vs 2.89 mg, P < 0.0001). Conclusion: Based on the results, consider warfarin starting dose between 2.5 and 4 mg for patients on LVAD therapy, while balancing patient-specific risks for bleeding.