Maximising Time in Therapeutic Range with Vitamin K Antagonists in LVAD Patients

Abstract

<h3>Purpose</h3> Time in Therapeutic range (TTR) is the percentage of time an anticoagulated patient has an INR between 2-3. While studies have demonstrated a link between low TTR, bleeding and thrombosis, the mean TTR in a VAD population is between 45 and 65%. We implemented a new anticoagulation protocol using point of care devices (POC, coagucheck©), with patient education and empowerment to control their own VKA (vitamin K antagonist) dosing. <h3>Methods</h3> Before discharge all VAD patients received anticoagulation education including drug and food interaction. Depending on INR stability, patients measured INR every 2-3 days and sent a text message to the VAD team for the appropriate VKA dose. After a minimum of 2 months post VAD, if the patient and team felt comfortable, VKA dosing was delegated to the patient. Patients updated the team weekly. <h3>Results</h3> Between February and October 2020, 24 patients were included (29% HM3, 71% HW, one Bi-VAD (HW)). Median follow-up was 131 days (IQR 88-163), cumulative follow up time was 3087day or 8.5 years. Median TTR was 90% (IQR 83-97), median INR 2.41 (IQR 2.2-2.4). INR was measured 3.6 times / week (IQR 3.3-3.8). In 15 cases (62%), the VKA dosing decision was delegated to the patient. Median TTR during patient management (96%, IQR 90-97) was significantly higher than the TTR during medical control (83%, IQR 78-88) (P<0.0001). There were no deaths, major bleeding events, pump thrombosis or strokes under patient management. Ten patients (41%) received one or more doses of enoxaparin (1mg/kg once a day) as bridge for INR < 1.8 for HW and 1.6 for HM3 pump. <h3>Conclusion</h3> A TTR higher than described in the literature is achievable in VAD patients using a POC device. If prerequisites are met, VAD patients can be empowered to control their VKA dosing with excellent TTR.