Use of Apixaban in Children Awaiting Heart Transplantation

Objective: The use of apixaban in the pediatric cardiac population is expanding. We describe our apixaban dosing and monitoring strategy in children and young adults awaiting heart transplantation, along with outcomes related to bleeding and thrombosis during wait-list and early post-transplant periods. Methods: This study is a retrospective, single center analysis of all patients receiving apixaban while awaiting cardiac transplantation. Weight-based dosing was monitored with peak drug-specific anti-Xa chromogenic analysis. Significant post-operative bleeding defined by chest tube output or need for surgical intervention. Results: From September 2020 through December 2022, 19 patients, median age 13.5 years (6.1, 15.8 years), weighing 48.9 kg (15.4, 67.6) received apixaban while awaiting transplant. Indication for apixaban was prophylaxis (n=18, 3 with ventricular assist devices) and treatment of thrombus (n=1). There were no clinically relevant non-major or major bleeding, nor thrombotic events while awaiting transplant. The median time from last apixaban dose to arrival in the operating room was 23.2 hours (15.6-33.8), with median random apixaban level of 37 ng/ml (28.3, 59), 6.3 hours (4.8, 8.4) prior to arrival in the operating room. 32% of patients had significant post-operative bleeding based on chest tube output post-transplant or need for intervention. No patients meeting criteria for significant postoperative bleeding were thought to be attributable to apixaban. Conclusion: Careful use of apixaban can be safe and effective while awaiting heart transplant. There was no appreciable increase in perioperative bleeding. The use of apixaban is promising in providing safe, predictable and efficacious anticoagulation while avoiding additional patient stressors.