Low-molecular-weight heparin for anti-coagulation after left ventricular assist device implantation

Anti-coagulation is required in patients with left ventricular assist devices (LVADs). We evaluated the feasibility of low-molecular-weight heparin (LMWH) for initiation of anti-coagulation and transitioning to oral anti-coagulation after LVAD implantation.

This single-center study included 78 consecutive patients who underwent either Thoratec HeartMate II LVAD (n = 27) or HeartWare ventricular assist device (HVAD, n = 51) implantation. The LMWHs enoxaparin (n = 50) and dalteparin (n = 28) were used. LMWH was started within 24 hours post-operatively in 79.5% of patients. No anti-coagulation was given before starting LMWH therapy. LMWH activity was monitored by determination of anti-factor Xa levels in plasma.

The majority of patients (80.7%) had peak anti-Xa activity within the defined range of efficacy of 0.2 to 0.4 IU/ml by the second day of treatment. Mean effective peak anti-Xa activity was 0.28 ± 0.06 IU/ml. Mean duration of anti-coagulation with LMWH was 25.8 ± 18 days. Ischemic strokes were observed in 3 patients (3.8%), with a total of 4 events. Three events occurred while on LMWH, and 1 event occurred during follow-up on oral anti-coagulation. There was 1 fatal stroke. No pump thrombus was observed. Major bleeding was observed in 5 patients (6.4%), with a total of 6 events. Gastrointestinal bleeding was the most common complication (n = 3). There were no fatal bleeding events.

LMWH in the setting of LVAD shows rapid and constant biologic efficacy. Anti-coagulation with LMWH appears feasible after LVAD implantation. These findings support further evaluation of LMWH as an alternative to unfractionated heparin in this patient cohort.