Apixaban for thromboprophylaxis in paediatric cardiology patients: Real-world data from a single institution

Background Thrombosis is a major complication in children with congenital or acquired heart disease, contributing to significant morbidity and mortality. Direct oral anticoagulants (DOACs), including apixaban, are increasingly used for thromboprophylaxis in this population yet real-world paediatric data remain limited. Objectives To evaluate the safety and effectiveness of apixaban as thromboprophylaxis in paediatric cardiac patients receiving commercially available adult tablet formulations outside a clinical trial setting. Patients/methods This retrospective cohort study included patients aged ≤18 years with congenital or acquired heart disease who received apixaban at the University Children's Hospital Zurich from October 2022 to June 2025. Dosing was approximated to the SAXOPHONE trial using commercially available tablets that were split or crushed, without therapeutic laboratory monitoring. Outcomes included incident thrombosis (primary), major bleeding, clinically relevant non-major bleeding (CRNMB), and all-cause mortality. Results Sixty-seven patients were included with a median age of 4.6 years (IQR 3.3–9.8) and median apixaban exposure of 210 days (IQR 83–461), totalling 18,799 patient-days (51.5 patient-years). Single ventricle physiology was the most common underlying diagnosis (40/67, 60%) and Fontan circulation the most frequent indication (34/67, 51%). Two thrombotic events occurred (incidence rate 3.9 per 100 patient-years), both in the context of additional thrombotic risk factors. No major bleeding or CRNMB events were recorded. Conclusions Apixaban appeared safe and effective as thromboprophylaxis in this paediatric cardiology cohort, with no major or CRNMB and a low rate of thrombotic events. These findings add to the growing body of real-world evidence supporting DOAC use in children with cardiac disease.