Characterizing the recurrence of atrial arrhythmia following macro-reentrant atrial tachycardia ablation in adult patients with repaired tetralogy of Fallot.

Background: The recurrence of arrhythmia following catheter ablation of macro-reentrant atrial tachycardia (MRAT) in repaired tetralogy of Fallot (rTOF) is poorly understood. Objective: To better describe the incidence, mechanisms, and predictors of recurrent atrial arrhythmia following MRAT ablation in rTOF. Methods: Patients with rTOF ≥18 years of age who underwent radiofrequency ablation for MRAT (typical/cavotricuspid isthmus-dependent atrial flutter, incisional/scar-mediated MRAT, upper and lower-loop reentry, or left atrial MRAT) at Duke University Hospital from 1996 to 2023 were identified. The primary outcome examined was the first recurrence of atrial arrhythmia (MRAT, atrial fibrillation, or focal atrial tachycardia) lasting ≥30 seconds, captured on a 12-lead electrocardiogram, ambulatory monitor, or electrophysiologic study. Predictors of outcome were identified using Cox regression and Kaplan-Meier survival analyses. Results: Among 58 patients who met inclusion criteria, 39 (67.2%) developed the primary outcome over an average follow-up of 5.4 ± 5.5 years. Nine patients (15.5%) underwent repeat (second or third) ablation for recurrence of an index MRAT that was targeted during the initial ablation. Right atrial (RA) area (hazard ratio 1.60 per 10 cm Conclusion: Following MRAT ablation in rTOF, recurrence of atrial arrhythmia is common and often of distinct mechanism. RA size and the presence of other atrial arrhythmia at ablation may predict recurrence. Extended courses of post-ablation anti-coagulation may prove beneficial in this population.