Use of Enoxaparin in Patients After Implantation of Left Ventricular Assist Device

Anticoagulation After LVAD Implantation is Essential

More than 2,500 devices are implanted annually in patients with left-side HF. LVADs are used as a last-resort therapy or temporarily for patients awaiting heart transplants. One of the most common complications of LVAD is device thrombosis and increased bleeding risk due to anticoagulant therapy.

Anticoagulation is typically initiated within 24 hours after LVAD implantation, with warfarin being the first-line medication in this indication. It usually takes a few days to achieve effective INR, thus requiring bridging with another form of anticoagulation. According to recent recommendations, heparin is used for bridging, with LMWH being a possible alternative.

Study Methodology and Process

A retrospective analysis evaluated 250 patients who received LVAD between January 2017 and December 2018. Participants were divided into two groups. The first group used unfractionated heparin (UFH) postoperatively, while the second used enoxaparin. UFH was administered via continuous infusion according to a standardized protocol with an initial bolus according to the attending physician, targeting an activated partial thromboplastin time (aPTT) between 60 and 80 seconds. Enoxaparin was given at a dose of 0.5 mg/kg every 12 hours to achieve anti-Xa levels of 0.2–0.4 IU/ml and aPTT of 60–80 seconds. The administration of UFH or LMWH was stopped once an INR of 2–2.5 was achieved; warfarin was typically started on the first postoperative evening.

Patients were followed during hospitalization and for three months post-procedure. Efficacy was judged by the time to the occurrence of ischemic or hemorrhagic cerebrovascular events, while safety was assessed by the occurrence of bleeding complications. Severe bleeding was defined as any obvious bleeding or unexplained acute drop in hemoglobin levels requiring a transfusion of at least one red cell concentrate. The secondary outcome was the length of hospital stay.

Study Findings

The 250 patients were monitored during hospitalization, with 246 continuing in the study post-discharge. Patients using UFH were older (56.1 ± 11.96 years vs. 51.9 ± 15.3 years; p = 0.02), more frequently male (82% vs. 67%; p = 0.03), and had a higher incidence of paroxysmal atrial fibrillation (41% vs. 16%; p = 0.005). Chronic kidney insufficiency was more common in the enoxaparin group (41.9% vs. 15.9%; p < 0.01).

During hospitalization, no significant difference was found between the two groups concerning cerebrovascular events (odds ratio [OR] 0.67; 95% confidence interval [CI] 0.07–6.39; p = 0.73) and bleeding complications (OR 0.91; 95% CI 0.27–3.04; p = 0.88). Similarly, three months post-LVAD implantation, the bleeding risk was OR 0.85 (95% CI 0.31–2.34; p = 0.76) and the incidence of cerebrovascular events was extremely low. The hospital stay was shorter in the enoxaparin group (4 days; p = 0.03).

Discussion and Conclusion

LMWHs are often used to bridge the period until target INR is achieved when administering warfarin. Their advantages include rapid onset of action, predictable anticoagulant effect, and the possibility of self-administration without monitoring, even at home.

This study is the first to compare the safety and efficacy of enoxaparin with UFH in patients after LVAD implantation. The results indicated that enoxaparin could be a suitable and safe alternative to UFH in this indication. Additionally, the use of enoxaparin significantly reduced the hospital stay. Further clinical studies with a larger patient cohort are necessary to confirm these findings.

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Source: Shah Z., Mastoris I., Acharya P. et al. The use of enoxaparin as bridge to therapeutic INR after LVAD implantation. J Cardiothorac Surg 2020; 15 (1): 329, doi: 10.1186/s13019-020-01373-y.