Atrial flutter catheter ablation in adult patients with repaired tetralogy of Fallot: Mechanisms and outcomes of percutaneous catheter ablation in a consecutive series

Background: Prior investigators note successful ablation of both typical cavotricuspid isthmus-dependent and scarrelated macroreentrant right atrial flutters (AFL) in adult patients with repaired tetralogy of Fallot (TOF). However, an analysis of the mechanisms (including a description of a uniform approach to diagnose such mechanisms), and clinical outcomes of catheter ablation in a consecutive series of adult patients with AFL late after surgical TOF repair has not been previously reported. Methods: Background clinical data and follow-up were evaluated in a consecutive series of TOF patients evaluated from September 2001 to June 2008. Results: We report a prevalence of sustained, symptomatic AFL in patients with repaired TOF equal to 20% (28/140 patients), and of recurrent, drug-refractory and/or severely symptomatic AFL to be 11% (16/140 patients). The AFLs manifested variable cycle lengths ranging from215 to 525 ms. Underlying mechanisms were: (1) cavotricuspid (CTI)-dependent, counterclockwise atrial flutter (n=8 patients); (2) non-CTI-dependent macroreentrant scar-related AFL (n=6 patients); and (3) both CTI- and non-CTI-dependent macroreentrant AFL (n=2 patients). Recurrent arrhythmias occurred in six patients, five of whom were successfully treated with repeat ablation. After a mean follow-up of 23 months, 15 of 16 patients were alive and free of sustained AFL. Conclusions: AFL late after surgical TOF repair occurs in 20% of such patients. In more than half of these patients, the AFLs are drug-refractory and/or severely symptomatic. Despite the presence of congenital heart disease treated with prior cardiac surgery and AFLs with variable atrial cycle lengths, the CTI-dependent mechanism underlies approximately half of the sustained, symptomatic AFLs.