Background Atrial arrhythmias (AA) and heart failure (HF) are major causes of hospitalisation in adult congenital heart disease (ACHD). This study aimed to evaluate the temporal relationship between AA and HF onset, the association between HF and the success of radiofrequency ablation (RFA), and how HF influences outcomes in patients with AA.

Methods In this single-centre retrospective cohort study, data from 3995 patients with ACHD were analysed. Dates of first AA and HF presentations were documented, and outcomes of RFA, including acute and long-term success, were assessed. All-cause mortality was compared between patients with AA and those with both AA and HF.

Results The median age at last follow-up was 33 years (IQR 26–42). AA was observed in 348 patients (8.7%), and HF in 256 (6.4%). Among patients who developed both AA and HF (n=130), AA preceded HF in 79% of cases, with a median interval of 6 years (IQR 2–13) before HF diagnosis. In the remaining cases, AA occurred after HF diagnosis (median 2 years, IQR 1–6). RFA was performed in 119 patients (34.2%), 45 of whom had HF. Two years after RFA, 72% of patients were free from AA recurrence. Patients without HF had higher acute success rates (98% vs 90%) and lower recurrence rates (48% vs 76%) than those with HF. Patients with AA with HF had worse overall survival compared with those without HF.

Conclusions In patients with ACHD, AA frequently precedes HF by several years. RFA can be an effective treatment for AA, but acute success is lower and recurrence rate higher when HF is present.