Department of Pharmacy, Aurora Health Care

Presentation Notes

Poster presented at: Aurora Scientific Day; May 22, 2019; Milwaukee, WI.


Background: In patients with a left ventricular assist devices (LVAD), long-term anticoagulation with a warfarin regimen is required to prevent thromboembolic events, including device thrombosis. Patients with LVAD frequently experience subtherapeutic international normalized ratio (INR) and/or interruption of anticoagulation. In these cases, bridge therapy should be considered, taking into account the balance between thrombotic and bleeding risk. Bridging strategies include anticoagulation with intravenous heparin and low-molecularweight heparin.

Purpose: To assist in the expansion of anticoagulation approaches for the LVAD population.

Methods: This is a retrospective, observational, single-center study of patients with LVAD. Patients were identified through the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) database. Patients implanted from January 2012 to December 2017 and who survived 30 days posthospitalization were followed until time of explant, transplant, or death. A bridging event is defined as the start of anticoagulation until 30 days post. Primary outcomes include thrombotic events and major bleeding events as reported in the INTERMACS registry. A generalized estimating equations model was used to analyze associations between baseline and temporal predictors of thrombotic and major bleeding events.

Results: A total of 156 patients were included. During followup time, 109 major bleeding events occurred, with 30 unique bridging events utilizing enoxaparin and 227 utilizing heparin. We adjusted for baseline predictors associated with major bleeding events. Therapeutic INR per protocol was associated with reduced risk of bleeding (relative risk [RR]: 0.47 [0.26– 0.87]; P=0.02). Compared to no bridging, patients bridged on heparin experienced significantly fewer bleeding events (RR: 0.43 [0.21–0.87]; P=0.02). There was no difference between patients bridged on enoxaparin compared to no bridging (RR: 0.91 [0.34–2.34]; P=0.85). Results on thrombotic events are pending.

Conclusion: Compared to patients who were not bridged, patients bridged with enoxaparin had no increase in bleeding events, whereas patients bridged with heparin experienced lower rates of bleeding. Although known bleeding risk factors were adjusted for, these results may be limited by physician discretion of bridging based on individual patient risk. Further data analysis will be conducted to identify independent bleeding and thrombotic risk factors to assist in anticoagulation practices in patients with LVAD.

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