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 <14 days. Results: Among the 168 patients, 83 (49%) received heparin and 85 (51%) received bivalirudin. Baseline characteristics were similar in the 2 groups ( Conclusions: Systemic anticoagulation with bivalirudin in Impella 5.5 patients is associated with clinically meaningful improvements in postoperative thrombocytopenia and biocompatibility, with easier management, fewer insertion site bleeds, and more time within the target anticoagulation range.