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

Background Recurrence of arrhythmia following catheter ablation of macroreentrant 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/cavotricuscpid isthmus-dependent atrial flutter, incisional/scar-mediated MRAT, upper and lower-loop reentry, or left-atrial MRAT) at Duke University Hospital from 1996-2023 were identified. The primary outcome examined was first recurrence of atrial arrhythmia (MRAT, atrial fibrillation, or focal atrial tachycardia [FAT]) lasting ≥30 seconds, captured on 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 that 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 initial ablation. Right atrial (RA) area (HR 1.60 per 10 cm 2 increase; 95% CI 1.15-2.22; p<0.01) and the presence of atrial fibrillation or FAT (HR 3.43; 95% CI 1.25-9.44; p=0.02) at ablation were predictive of the primary outcome. RA area ≥26.0 cm 2 was associated with decreased arrhythmia-free survival (p=0.02). 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 anticoagulation may prove beneficial in this population.