Relationship between Aggressive Septal Ablation and Significant Left Atrial Appendage Activation Delay following Catheter Ablation of Persistent Atrial Fibrillation

  Objective  To elucidate the significant left atrial appendage activation following ablation of persistent atrial fibrillation, and explore its relationship with aggressive septal ablation.

  Methods  A total of 201 patients with persistent atrial fibrillation underwent catheter ablation from June 2007 to February 2009. Action mapping of left atrium was performed and the local potential of left atrial appendage was recorded at the end of the procedure. Transthroacic ultrasound was performed one month later to evaluate the function of left atrium.

  Results  Significant left atrial appendage activation delay was found in 23 out of 201 patients undergoing persistent atrial fibrillation ablation. Of these 23 patients, 14 patients suffered from this condition in their first were found at 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). The delay was found in another 9 patietns during their redo procedures (including two with biatrial activation dissociation), all of whom received extensive left septal complex fractionated elegrams ablation in their prior procedures (P=0.002). 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, which lasted 10.6 ±6.2 months.

  Conclusion  Septal line ablation and extensive septal complex fractionated elegrams ablation are correlated with significant left atrial activation delay or even biatrial activation dissociation, and should be performed with prudent consideration.