LAUSR

Background: Septal left atrial flutter has been described de novo and has been associated with lower catheter ablation success rate. Objective: To describe the electrophysiological characteristics and results of catheter ablation in patients with septal atrial flutter presenting after atrial fibrillation (AF) ablation. Methods: We retrospectively reviewed patients who presented with atrial flutter after PVI at 3 different centers. These included patients who had undergone surgical ablation and extensive catheter ablation for AF. Results: The study included 13 patients with septal atrial flutter. 6 patients presented after surgical ablation (including LAA clipping). All patients had undergone PVI and posterior wall isolation. Figure shows the 12 lead ECG and 3D electroanatomic map in one patient after surgical ablation of AF. The 12 lead ECG shows positive P waves in inferior leads, flat in I and avL with early precordial transition. The 3D map shows early activation on both sides of the septum with early meets late on septal side of the mitral annulus. The voltage map showed lack of voltage in posterior wall. Entrainment mapping was helpful in identifying both sides of the septum including septal mitral annulus, anterior roof and coronary sinus as part of the circuit. Catheter ablation was acutely successful in terminating flutter in 70% of the patients. The cycle length prolonged in the remaining patients. There was early recurrence leading to success rate of 50% after single ablation. Conclusion: Septal flutter after extensive catheter ablation and surgical ablation for AF is associated with low voltage in posterior wall. It involves a large circuit including both sides of the septum, anterior roof and CS.