Anti-factor Xa and activated partial thromboplastin time strategies for unfractionated heparin dosing after HeartMate 3 left ventricular assist device implantation.

Abstract

No clear guidelines exist for perioperative anticoagulation management after durable left ventricular assist device insertion. In this study, we sought to compare outcomes between anti-factor Xa (FXa) and activated partial thromboplastin time (aPTT) in monitoring unfractionated heparin (UFH) dosing after HeartMate 3 (HM3) insertion. This is a single-center retrospective review of patients who received UFH after HM3 insertion between 01/2020-12/2022. Post-operative UFH dose was titrated by aPTT goal 45-60 sec (n = 53) or FXa goal 0.1-0.2 U/mL (n = 59). Baseline differences between cohorts were balanced by inverse probability treatment weighting. At baseline, unadjusted FXa patients were more likely to be white (47.5% vs. 35.8%, p < 0.001), INTERMACS 1-2 (69.5% vs. 47.2%, p = 0.013), have history of coronary artery disease (66.1% vs. 43.4%, p = 0.026), and lower eGFR (54.1 vs. 63.7 mL/min/1.73 m2, p = 0.029) compared to the aPTT group. After adjusting for several bleeding/thrombosis risk factors, 97.5% of FXa and 91.0% of aPTT patients reached therapeutic levels with comparable UFH duration and maximum dose. Moreover, in-hospital mortality (2.5% vs. 3.1%, p = 0.842), major bleeding events (4.2% vs. 9.2%, p = 0.360), and thromboembolic events (21.8% vs. 10.1%, p = 0.151) remained without significant differences between FXa and aPTT cohorts. There was a high degree of variability in FXa (r2 = 0.20) and aPTT (r2 = 0.22) values for any given UFH dose. No differences in frequency of bleeding or thromboembolic events were observed in this study between FXa versus aPTT cohorts after HM3 implantation. More longitudinal studies are warranted to determine whether or not one assay is superior to the other.