(157) Assessment of Bivalirudin Dosing Protocol in Temporary Mechanical Circulatory Support

Introduction: Temporary mechanical circulatory support (tMCS), for use in patients with shock, offers essential circulatory and respiratory support. Activation of inflammatory pathways and blood interaction with nonendothelial surfaces can trigger a prothrombotic state. Unfractionated heparin is the most common anticoagulant in tMCS; however, direct thrombin inhibitors, such as bivalirudin, are increasingly utilized with partial thromboplastin time (PTT) as the standard monitoring parameter. A site-specific strategy was implemented to standardize use of bivalirudin, but uncertainty remains regarding dose adjustments based on PTT levels.

Methods: This retrospective cohort study, evaluating the impact of bivalirudin infusion rate adjustments on corresponding PTTs, included adult patients from January 2016 – January 2024 with tMCS anticoagulated with bivalirudin. The primary outcome was median change in PTT based on percent dosing changes. Secondary outcomes included percent of initial PTTs that were therapeutic stratified by bivalirudin dose and number of dose adjustments before reaching a first therapeutic PTT (tPTT).

Results: A total of 48 patients were included. The mean initial bivalirudin dose was 0.05656 mg/kg/hr. The median change in PTT (seconds) was 2.85, 2.5 and 3.5 in the 10%, 20% and 30% change groups, respectively. When compared, a 10%, 20% or 30% change in bivalirudin dose did not result in any differences in median change in PTT (p=0.368). Twenty-five patients (52%) had a tPTT on the first check. Of the 23 patients not therapeutic, 39% and 61% were subtherapeutic and supratherapeutic, respectively. Initial bivalirudin doses > 0.05 mg/kg/hr were not more likely to result in a tPTT at first draw (p=0.0581). The median number of overall adjustments to result in a tPTT was two (IQR 3). Renal replacement therapy during bivalirudin use occurred in 19 patients; however, it did not impact the first tPTT (OR 2.48; 95% CI 0.6832-9).

Conclusions: Despite a low total dose adjustment median, there may be opportunity to modify the infusion rate by a higher percentage based on PTT more consistently. More research is needed to determine optimal initial bivalirudin dose and infusion rate percent changes needed to maximize time in therapeutic range and to correlate this to clinical outcomes.