Effect of right atrial isthmus ablation on the occurrence of atrial fibrillation - Observations in four patient groups having type I atrial flutter with or without associated atrial fibrillation

Background-The goal of this study was to test the hypothesis that the occur rence of atrial fibrillation (AF), in at least some patients with coexistin g type I atrial flutter (AFL), is based on macro-reentry around the tricusp id valve orifice, including the right atrial (RA) isthmus, by evaluation of AF recurrences after successful ablation of AFL. Methods and Results-Eighty-two consecutive patients with type I AFL, with o r without concomitant AF, underwent radiofrequency ablation (RFA) of the RA isthmus by an anatomical approach. The results were analyzed in 4 groups o f patients: group 1 (only AFL; 29 patients), group 2 (AFL >AF; 22 patients) , group 3 (AF >AFL; 15 patients), and group 4 (developing AFL while receivi ng class IC antiarrhythmic drug therapy for AF, the "class IC atrial flutte r"; 16 patients). In all groups, RFA of type I AFL was performed with a hig h (greater than or equal to 93%) procedural success rate. In group 1, only 2 patients (8%) had AF after (18 +/- 14 months) AFL ablation, These figures were 38% (20 +/- 14 months) and 86% (13 +/- 8 months) in groups 2 and 3, r espectively. Group 4 patients (4 +/- 2 months) had a 73% freedom of AF recu rrences with continuation of the class IC agent. Conclusions-The low incidence of new AF during long-term follow-up after RF A of type I AFL makes it unlikely that radiofrequency lesions promote the d evelopment of AF. The impact of isthmus ablation on AF recurrences differs according to the clinically predominant atrial arrhythmia and suggests a po ssible role of the RA isthmus in the occurrence of AF in some patients. Abl ation of class IC atrial flutter in patients with therapy-resistant AF is a novel approach to management of this patient subset. Careful classificatio n of AF patients plays a role in the selection of the site of ablation ther apy.