Catheter Ablation of Atypical Atrial Flutter and Atrial Tachycardia Within the Coronary Sinus After Left Atrial Ablation for Atrial Fibrillation Original Research Article

Objectives The goal of this study was to describe the prevalence and ablation of coronary sinus (CS) arrhythmias after left atrial ablation for atrial fibrillation (AF). Background The CS has been implicated in a variety of supraventricular arrhythmias. Methods Thirty-eight patients underwent mapping and ablation of atypical flutter that developed during (n = 5) or after (n = 33) ablation for AF. Also included were two patients with focal CS arrhythmias that occurred during an AF ablation procedure. A tachycardia was considered to be originating from the CS if the post-pacing interval in the CS matched the tachycardia cycle length and/or if it terminated during ablation in the CS. Results Among the 33 patients who developed atypical flutter late after AF ablation, 9 (27%) were found to have a CS origin. Overall, 16 of the 40 patients in this study had a CS arrhythmia. The tachycardia was macro-re-entrant in 14 patients (88%) and focal in two patients. Radiofrequency ablation with an 8-mm-tip catheter was successful in 15 patients (94%) without complication. In eight patients (50%), ≥45 W was required for successful ablation. Thirteen of the 15 patients (87%) with a successful ablation acutely remained arrhythmia-free during 5 ± 5 months of follow-up. Conclusions The musculature of the CS serves as a critical component of the re-entry circuit in approximately 25% of patients with atypical flutter after ablation for AF. The CS may also generate focal atrial arrhythmias that may play a role in triggering and/or maintaining AF. Catheter ablation of these arrhythmias in the CS can be performed safely.