Use of apixaban in adults with congenital heart disease and atrial arrhythmias: The PROTECT-AR study.

BACKGROUND: Adults with congenital heart disease (ACHD) and atrial arrhythmias (AA) face an increased risk of thromboembolic events. Limited data exist on the use of non-vitamin K oral anticoagulants for thromboprophylaxis in 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 on routine apixaban treatment were included. The historical control group consisted of patients previously on vitamin K antagonist (VKA), who were analyzed prior to their transition to apixaban. The primary effectiveness endpoint was the composite of stroke or thromboembolism. The primary safety endpoint was major bleeding.

RESULTS: The study enrolled 218 ACHD patients with AA on apixaban, of which 73 were previous VKA users. The analysis covered 527 patient-years of prospective exposure to apixaban and 169 patient-years of retrospective exposure to VKA. The annualized rate of stroke or thromboembolism was 0.6% in the apixaban group and 1.8% in the VKA group (absolute difference - 1.2%; upper limit of one-sided 95% confidence interval [CI] 0.9%, lower than the predefined non-inferiority margin of +1.8%, Pnon-inferiority  < 0.001). The annualized rate of major bleeding was 1.5% in the apixaban group and 2.4% in the VKA group (hazard ratio 0.64; 95% CI 0.19-2.10, P = 0.48).

CONCLUSION: In ACHD patients with AA, routine apixaban use exhibited a non-inferior rate of stroke or thromboembolism compared to historical VKA use, alongside a similar rate of major bleeding.