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

Introduction: Children with congenital and acquired heart disease are at risk of thrombotic events. Anticoagulation decisions are made assessing the underlying bleeding and thrombosis risk factors for each individual patient. Until recently, standard thromboprophylaxis in cardiology patients included low molecular weight heparin, Vitamin K antagonists and / or acetylsalicic acid. In comparison, direct oral anticoagulants (DOACs) bear many advantages and have been trialled in paediatric patients both for indications of thrombosis treatment and for thromboprophylaxis in the past few years. Apixaban has been shown to be both effective and safe in paediatric patients with underlying cardiac disease in a recent phase 2 clinical trial and in observational studies, but patient numbers and experience are still limited [1] [2] [3] [4] [5].

Method: This is a single-center retrospective cohort study. Apixaban was introduced as thromboprophylaxis for cardiac patients at our centre in 2022; dosing was approximated to the SAXOPHONE clinical trial, with the only available formulation being tablets of 2.5 or 5 mg. No laboratory monitoring was available. Paediatric patients with underlying cardiac disease aged<18 years who were prescribed apixaban were identified from the institution’s clinical information system. Patient demographics, therapy duration, occurrence of thrombotic events, major and clinically relevant non-major (CRNM) bleeding events were extracted from patient charts.

Results: Fifty-five patients who received apixaban from 10/2022 to 09/2024 were identified. Indications for start of thromboprophylaxis with apixaban and underlying cardiac conditions are shown in [Fig. 1]. Patient demographics are shown in [Fig. 2]. Patients were treated with apixaban for a total of 17’194 patient days (=47.1 patient years). Overall, 13 patients (=24%) were switched from previously established VKA to apixaban thromboprophylaxis. Two thrombotic events were recorded: One patient presented with a melody valve thrombosis and hypovolemic shock due to gastroenteritis, and the other presented with a melody valve thrombosis and simultaneous endocarditis. The incidence of thrombotic events was 0.04 per 1’000 patient days. No major or CRNM bleeding events were recorded.

Fig. 1  A: Indication for apixaban in cardiac patients; B: Distribution of underlying cardiac diseases

Fig. 2  Patient demographics of paediatric patients with underlying cardiac disease who were prescribed apixaban for thromboprophylaxis.

Conclusion: The use of apixaban for thromboprophylaxis in this patient cohort was safe with no major or CRNM bleeding events, and a very low incidence of thrombotic events. Both thrombotic events were accompanied by other thrombotic risk factors namely gastroenteritis, dehydration, hypovolemic shock and endocarditis. Taking this into account, apixaban as thromboprophylaxis is deemed safe and effective in this patient population – even when dosed in a higher dose than previous observational studies, and without laboratory monitoring. In sum, this study adds to the growing body of real-world evidence that apixaban is a feasible alternative of thromboprophylaxis in paediatric patients with congenital and acquired heart disease.

Acknowledgements: AB is supported by research grants from the “Claus Cramer Foundation”, “Filling the gap program” and “Walter and Gertraud Siegenthaler Foundation” from the University of Zurich, Switzerland.

Publikationsverlauf

Artikel online veröffentlicht:
13. Februar 2025

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