Abstract 15341: A Prospective Study on the Safety and Effectiveness of Apixaban for the Prevention of Thromboembolism in Adults With Congenital Heart Disease and Atrial Arrhythmias: The PROTECT-AR Study

Abstract

Introduction: In adults with congenital heart disease (ACHD), atrial arrhythmias (AA) confer an increased risk of thromboembolic events. Limited data exist on non-vitamin K oral anticoagulant (NOAC) treatment for ACHD. We aimed to assess the effectiveness and safety of apixaban in ACHD patients with AA. Methods: PROTECT-AR (NCT03854149) was a prospective, multicenter, observational study conducted from 2019 to 2023. ACHD patients with atrial fibrillation, atrial flutter, or intra-atrial re-entrant tachycardia, who were routinely treated with apixaban, were included. The primary efficacy endpoint was the composite of stroke or thromboembolism. The primary safety endpoint was major bleeding. Patients who were previously on vitamin K antagonists (VKAs) before transitioning to apixaban served as a historical control group. Results: In total, 218 patients with ACHD and AA on apixaban (previous VKA users 34.9%) were included (mean age 51±17 years; 45.9% male; predominantly moderate complexity). Over a mean follow-up of 2.4±1.3 years, the rate of stroke or thromboembolism was 0.57% [95% confidence interval (CI): 0.15-1.55] and the rate of major bleeding was 1.52% [95%CI: 0.71-2.88] per patient-year, respectively. In the subset of patients who were previously on VKA, the risk of the primary endpoints did not differ significantly between apixaban and VKA-treatment periods (Figure). Conclusion In ACHD patients with AA on routine apixaban treatment, the risk of major thromboembolic and bleeding events was low. Among prior VKA users, the risk of adverse events during the apixaban-treatment period was comparable to that during the VKA-treatment period. Prospective studies directly comparing NOAC and VKA-treated patients are needed.