Radiofrequency Catheter Ablation of Atrial Tachyarrhythmias in Adults with Repaired Congenital Heart Disease: Constraints from Multiple and New Arrhythmic Foci

Background: Radiofrequency catheter ablation (RFCA) for atrial tachyarrhythmias in postoperative congenital heart disease (CHD) patients has a low success rate and a high recurrence rate. This study explores the reasons for these constraints. Methods: A total of 49 consecutive postoperative CHD patients who received RFCA for atrial tachyarrhythmias between 1993 and 2010 were enrolled. Results: Overall, there were 86 RFCA procedures performed, 32 with the conventional method and 54 using CARTO-guided mapping. The interval between the operation and the first ablation was 13 years. Isthmus-dependent atrial flutter (AFL) was the most common type of tachycardia (37, 76%), followed by intra-atrial re-entry tachycardia (IART; 37%), and ectopic atrial tachycardia (EAT; 31%). By applying CARTO-guided mapping, the success rate was elevated compared to that of conventional ablation (84% vs. 56%, p = 0.006), but there was no improvement in the recurrence rate (22% vs. 28%, p = 0.75). Multiple atrial tachyarrhythmias occurred in 26 (53%) patients, and 17 presented during the initial electrophysiological study. The presence of multiple arrhythmias during the initial study predicted ablation failure or multiple ablations (11/17 vs. 3/32, p < 0.001). Among the 15 patients with new tachyarrhythmias, EAT and IART predominated. However, applying antiarrhythmia agents immediately following ablation may decrease arrhythmia recurrence (1/10 vs. 14/25, p = 0.02). Conclusions: Although electroanatomical mapping improves the results of RFCA in atrial tachyarrhythmias, the recurrence rate remains high because of multiple and new atrial tachyarrhythmias. Therefore, short-term pharmacological treatment following RFCA for positive remodeling should be considered.