Background:

Hospitalized COVID-19 patients with hypoxemic respiratory failure may deteriorate despite invasive mechanical ventilation and thus require extracorporeal membrane oxygenation (ECMO) support. Unfractionated heparin (UFH) is the antithrombotic of choice, however, bivalirudin may offer more predictable pharmacokinetics resulting in consistent anticoagulant effects with lower bleeding and thrombotic occurrences. The aim of this study was to evaluate efficacy and safety outcomes in patients undergoing venovenous (VV) ECMO receiving bivalirudin or UFH-based anticoagulation.

Methods:

This retrospective, single-center, observational cohort study included patients with confirmed COVID-19 infection requiring VV ECMO support receiving anticoagulation with UFH or bivalirudin. Primary endpoints were time to reach therapeutic aPTT, percent time spent in aPTT range, and the occurrence of thrombotic events over the entire course of ECMO support. Secondary endpoints included the incidence of major/minor bleeding, the ability to wean off ECMO support, in-hospital mortality, and length of stay.

 Results:

Twenty-two patients were included in the study (n = 10 UFH, n = 12 bivalirudin). Time to therapeutic aPTT was achieved faster with UFH (10 h vs. 20 h). The percentage time spent within the goal aPTT range was similar between UFH and bivalirudin (50% vs. 52%). Thrombotic events were significantly higher in the UFH group (40% DVT, 40% PE, 80% oxygenator thrombus in ECMO machine, 10% ischemic stroke) versus bivalirudin (8% DVT, 17% PE, 33% oxygenator thrombus, no ischemic strokes) (CI 95%, p = 0.04). The overall bleeding incidence was higher in the UFH arm (90% vs. 75%). The mortality rate was 90% in the UFH group and 58% in the bivalirudin group. The length of stay was similar between the two study arms. 

Conclusion:

In hospitalized patients with COVID-19-associated acute respiratory distress syndrome (ARDS) on VV ECMO support, the use of bivalirudin showed to be a viable anticoagulation alternative in terms of efficacy compared to UFH and resulted in a favorable safety profile with lower rates of bleeding and thrombotic events.