Real-world use of apixaban for the treatment and prevention of thrombosis in children with cardiac disease

Direct oral anticoagulants use in pediatric cardiology is poorly defined.We present the largest experience of apixaban use in children with heart disease, using weight- and level-based dosing.Retrospective single-center analysis of cardiac patients ≤19 years treated with apixaban. Patients were evaluated for safety (clinically relevant non-major [CRNM] or major bleeding; thrombotic events) and effectiveness (thrombus improvement by imaging). Peak drug-specific anti-Xa chromogenic assay results ("apixaban levels") were analyzed.Over 3 years (5/2018-9/2021), 219 children, median age 6.8 years (0.3-19), median weight 20.8 kg (4.8-160) received apixaban, totaling 50,916 patient days. Of them, 172 (79%) warranted thromboprophylaxis and 47 (21%) thrombosis treatment (with 10 arterial, 19 venous, 15 intracardiac, and 3 pulmonary). The median initial peak apixaban level was 165 ng/mL (23-474; n = 125) in the prophylaxis subgroup and 153 ng/mL (30-450; n = 33) in the treatment subgroup; dosage was adjusted in response to levels in 25% of the patients. There were 4 bleeding safety events (3 CRNM; 1 major, hemoptysis complicating empyema); the serious bleeding event rate was 2.9 per 100 patient-years of apixaban. Minor bleeding events (42) were noted in 18 patients, with an additional 2 having leukopenia, 1 transaminitis, and 3 rashes. An improvement in thrombosis was seen in 95% of the treated patients with available follow-up imaging (37/39 patients).Apixaban use was feasible with a low rate of adverse events across a diverse pediatric cardiac population using commercially available tablets dosed to weight and adjusted based on peak apixaban levels.