Bachmann's Bundle-Related Atrial Tachycardias Following Catheter Ablation of Persistent Atrial Fibrillation

Background: Atrial tachycardias (AT) after radiofrequency ablation (RFA) of atrial fibrillation (AF) may utilize Bachmann's bundle (BB). Due to their epicardial location, these ATs remain poorly understood. Objective: To describe the electrophysiologic and anatomic basis of BB-related ATs. Methods: The region of BB was defined as the anterior left atrium (LA) immediately outside the right superior pulmonary vein. A BB-dependent AT was defined as an arrhythmia that originated from (focal) or involved the BB region (reentrant). Results: Among 1611 patients with persistent AF undergoing ablation, 32 patients (2%) (age 69 ± 9, male n = 22, LA size 47 ± 6 mm, ejection fraction 55 ± 13%) with BB ATs were included. Twenty-nine (91%) had undergone prior ablation for persistent AF (average, 2.0 ± 1.3 procedures). The mechanism of BB ATs was focal (n = 7, 22%) or macro-reentry (n = 25, 78%). RFA eliminated all focal and ultimately reentrant ATs in 15 of the 32 patients; RFA was required at the right atrial (RA) projections of BB among eight of the latter patients. The electrogram at the successful site was devoid of local voltage in four patients. In nine patients with redo procedure, recurrent BB-AT was found in five (56%). After 2.3 ± 1.4 years of follow-up, 22 of the 32 patients (69%) remained free of atrial arrhythmias. Conclusion: The region of the BB bundle may be responsible for focal and reentrant tachycardias following RFA of persistent AF. Given its epicardial location, sequential ablation from the LA and RA may be required, even at sites that might be devoid of local voltage.