The role of left atrial muscular bundles in catheter ablation of atrial fibrillation.
OBJECTIVE
We sought to investigate the imaging of the left atrial (LA) muscular bundle and the relationship between the bundle and inducibility of tachyarrhythmia after pulmonary vein isolation (PVI).


BACKGROUND
Noninducibility is used as a clinical end point of atrial substrate ablation after PVI. However, little is known about the role of the LA muscular bundles in tachyarrhythmia after PVI.


METHODS
Forty-three consecutive patients with paroxysmal atrial fibrillation who underwent catheter ablation were included. Bi-atrial isochronal mapping was performed with the NavX system (St. Jude Medical Inc., St. Paul, Minnesota) during sinus rhythm. After 4 PVI, inducible organized LA flutter with or without transforming to atrial fibrillation (AF) (LA flutter/AF) was ablated with additional lines at the roof and/or mitral isthmus.


RESULTS
The existence of bilateral muscular bundles was an independent predictor of LA flutter/AF after PVI (p = 0.02). Patients with LA flutter/AF after PVI had a greater index of the double potentials (5.4 +/- 3.4% vs. 2.8 +/- 1.8%, p = 0.006) and interpotential interval (33 +/- 5 ms vs. 29 +/- 4 ms, p = 0.02) than without LA flutter/AF. The muscular bundles were identified in 28% patients using 16-slice multidetector computed tomography, which were identical to the isochrone map. Patients with noninducible LA flutter/AF after PVI plus the additional linear ablation had a lower recurrence rate as compared with the patients without it (19% vs. 75%, p = 0.02).


CONCLUSIONS
Left atrial muscular bundles may provide a conduction block line and barrier, which is important for the formation of LA flutter/AF after PVI. The noninducibility of LA flutter/AF achieved after additional linear ablation may contribute to a better outcome in RF ablation of paroxysmal atrial fibrillation.
Chang
Shih-Lin
SL
Division of Cardiology and Cardiovascular Research Center, National Yang-Ming University, School of Medicine, Taipei, Taiwan.
Tai
Ching-Tai
CT
Lin
Yenn-Jiang
YJ
Wongcharoen
Wanwarang
W
Lo
Li-Wei
LW
Lee
Kun-Tai
KT
Chang
Sheng-Hsiung
SH
Tuan
Ta-Chuan
TC
Chen
Yi-Jen
YJ
Hsieh
Ming-Hsiung
MH
Tsao
Hsuan-Ming
HM
Wu
Mei-Han
MH
Sheu
Ming-Huei
MH
Chang
Cheng-Yen
CY
Chen
Shih-Ann
SA
D000328:Adult; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006325:Heart Atria / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D011667:Pulmonary Veins / Q000601:surgery