Adverse Events in HVAD vs. HM3 Patients under Outpatient Bridging with Low-Molecular Weight Heparin for Subtherapeutic Anticoagulation

Abstract

<h3>Purpose</h3> The standard of care in patients with durable left-ventricular assist devices combines antiplatelet with anticoagulation therapy. Current guidelines recommend use of intravenous (IV) unfractionated heparin as bridge to therapeutic INR-values in the postoperative period. However, management of subtherapeutic INR in the ambulatory setting is not yet clearly defined by guidelines. The protocol at our center proposes the use of unfractionated heparin perioperatively and low-molecular weight heparin in outpatients. Therefore, we aimed to analyse outcomes in patients with continuous-flow LVAD (CF-LVAD). <h3>Methods</h3> In this single-center retrospective trial all patients after CF-LVAD implantation at our center were included between 1/2015 and 12/2020 (n=110 patients; HVAD n=80, HM3 n=30). Patients were followed up from initial discharge after LVAD implantation until death, heart transplantation or end of the observation period (9/2021). Bridging for subtherapeutic INR (≤ 0.4 below target INR) were provided with enoxaparin in a therapeutic dose adapted to weight and renal function. Only patients with an INR > 0.4 below target INR were admitted to hospital for bridging with IV unfractionated heparin. Bleeding events leading to hospital admission, cerebrovascular events and pump thromboses were evaluated and provided in percent of study population and/or events per patient year (eppy). <h3>Results</h3> Follow-up covers a total of 214.2 patient years. Overall mortality was 18.2 %. Bleeding events occurred in 42.7 %, of which GI bleeding constituted the largest group with 21.8 % (HVAD: 0.25 eppy; HM3: 0.05 eppy). Stroke/TIA/PRIND occurred in 5.5 % of the patients (HVAD: 0.07 eppy; HM3: 0.01 eppy; in total: 0.03 eppy). Intracerebral hemorrhage (overall 0.04 eppy) occurred 6.3 times more often in HVAD patients. Pump thrombosis occurred in 8.2 % of all CF-LVAD patients and was limited to HVAD (0.13 eppy). <h3>Conclusion</h3> Current studies tend to promote the use of low molecular weight heparins, especially enoxaparin for outpatient anticoagulation bridging in case of subtherapeutic INRs. However, in most cases old generation CF-LVADs were studied. Our study includes a relevant number of HM3 devices. Overall, the adverse event rates presented herein suggest feasibility of low-molecular weight heparin bridging in patients with HM3 devices.