Significant Left Atrial Appendage Activation Delay Complicating Aggressive Septal Ablation during Catheter Ablation of Persistent Atrial Fibrillation

Background: This study aims to describe significant left atrial appendage activation following ablation of persistent atrial fibrillation, and explore its relationship with aggressive septal ablation. Methods and Results: Significant left atrial appendage activation delay was found in 23 out of 201 patients undergoing persistent atrial fibrillation ablation. Of them, 14 were found in their index procedures, of whom septal line ablation was performed in nine (odds ratio 15.2, 95% confidence interval 4.6–50.8, P < 0.001). Another nine were found during their redo procedures (including two with biatrial activation dissociation), all of whom received extensive left septal complex fractionated electrograms ablation in their prior procedures (P = 0.002). Electrocardiograph showed split P wave with the latter component merged into the QRS wave. Activation mapping demonstrated the earliest breakthrough of the left atrium changed to coronary sinus in 18 (85.7%) patients. After 1 month, the mitral A wave velocity was 18.2 ± 17.0 cm/s, and decreased significantly as compared with preablation (20.2 ± 19.1 vs 58.2 ± 17.9 cm/s, P = 0.037) in patients undergoing redo procedures. Fourteen (60.9%) remained arrhythmia‐free during follow‐up for 10.6 ± 6.2 months. Conclusion: Septal line ablation and extensive septal complex fractionated electrograms ablation are correlated with significant left atrial activation delay or even biatrial activation dissociation, and should be performed with prudent consideration. (PACE 2010; 33:652–660)