REgistry Of Catheter AbLation After Congenital Heart Disease Surgery(REAL-CHD Registry).

Background: Advances in surgical management have improved long-term survival in patients with congenital heart disease (CHD), leading to a growing population of adults with postoperative arrhythmias. However, contemporary data on catheter ablation practice and outcomes in patients with CHD remain limited. Methods: This multicenter, retrospective registry study included patients who underwent catheter ablation for postoperative CHD-related arrhythmias between April 2007 and December 2025 at 10 centers. CHD severity was classified as mild, moderate, or severe according to Japanese Circulation Society guidelines. Procedural characteristics, arrhythmia profiles, acute procedural outcomes, and complications were analyzed. Associations between age, disease severity, arrhythmia burden, and procedural success were evaluated using regression analyses. Results: A total of 1 719 patients were included. The number of ablation procedures increased over time across all CHD severity categories. Increasing age was associated with lower disease severity, whereas patients with severe CHD, particularly those after a Fontan repair, underwent ablation at younger ages. Procedural success decreased with increasing CHD severity (complete success: 92.5% in mild, 81.4% in moderate, and 71.4% in severe CHD) and with a greater number of induced arrhythmia types. Overall, procedure-related complications occurred in 2.3% of patients, with worsening heart failure being the most frequent non-vascular adverse event. Conclusion: In a large contemporary Japanese cohort, catheter ablation for postoperative CHD-related arrhythmias was increasingly performed and demonstrated acceptable safety. However, procedural success was lower in patients with more severe CHD and greater arrhythmia complexity, highlighting the need for specialized ablation strategies and careful periprocedural management in this growing population.