Anticoagulation with bivalirudin is associated with improved biocompatibility in patients supported on microaxial flow pumps

Objective: To evaluate whether an institutional shift from anticoagulation with heparin to bivalirudin in Impella 5.5 patients altered bleeding or thrombotic rates, transfusion dependency, or device biocompatibility. Methods: All patients supported by an Impella 5.5 between August 2022 and December 2024 were reviewed retrospectively. Heparin was used before December 2023, at which point the switch was made to bivalirudin. Groups were defined by anticoagulant initiated by postimplantation day 2, and patients with crossover or anticoagulation pauses for >2 days were excluded from the laboratory analyses. Baseline characteristics, anticoagulation details, complications, and clinical outcomes were compared between the heparin and bivalirudin groups. Biocompatibility was assessed via laboratory values recorded over the first 14 days of Impella support or until device explantation in patients supported for