Use of Bivalirudin in Pediatric Patients on Ventricular Assist Device Support

Purpose Little reported data exist regarding bivalirudin anticoagulation in pediatric patients supported with ventricular assist devices (VAD). Methods Single center retrospective cohort study of all patients supported with VAD who received bivalirudin for anticoagulation from 10/2016 to 10/2018. Demographic variables and clinical features, including indication for bivalirudin, details of therapy, and complications were analyzed. Results Bivalirudin was utilized in 19 HeartWare and 4 Berlin EXCOR patients (23 runs in 19 unique patients) - 39% (9/23) male, median age 13.6yr (IQR 6.3 - 17.2yr). Indications included: initial anticoagulation after VAD in 34% (4 HeartWare, 4 Berlin EXCOR), rescue anticoagulation for sub-therapeutic heparin in 26% (6 HeartWare), wash-out for pump thrombosis based on log file analysis and laboratory findings of hemolysis in 26% (6 HeartWare), and anticoagulation after a new ischemic stroke (once neurologically stable) in 14% (3 HeartWare). The overall median duration of bivalirudin was 23 days (IQR 12 - 35 days). The median starting dose was 0.15 mg/kg/hr (IQR 0.1 - 0.15 mg/kg/hr), and the median target activated partial thromboplastin time (PTT) Hepzyme was 60 - 70 sec. The median initial lactate dehydrogenase level was 1213 IU/mL (IQR 599 - 2072 IU/mL), and the median initial plasma hemoglobin level was 40 mg/dL (IQR 30 - 110 mg/dL). The median time to reach goal anticoagulation parameters was 1 day (IQR 1-2 days), and the median therapeutic dose was 0.2 mg/kg/hr (IQR 0.15 - 0.20 mg/kg/hr). Two of the 6 patients who received bivalirudin infusion for washout of pump thrombosis did not achieve therapeutic PTT hepzyme levels, and underwent pump exchange. The remaining 4 patients had normalization of flow patterns on their log file downloads after bivalirudin. While on bivalirudin, 1 patient had a bleeding complication (mediastinal hematoma in HeartWare), while 3 patients had thrombotic complications (all on bivalirudin for primary anticoagulation after VAD implantation - 1 embolic stroke in Berlin EXCOR, 1 embolic stroke in HeartWare, 1 VAD thrombus in HeartWare). Conclusion In this small pediatric series, bivalirudin use for post-operative anticoagulation as well as pump thrombosis achieved therapeutic success in 91% (21/23) cases, with complications in 4 cases. Increasing use of bivalirudin will help elucidate its role in pediatric VAD management.