Electrophysiological Features of Atrial Tachyarrhythmias and Rhythm Outcome in Patients Receiving Repeat Catheter Ablation after Surgical Atrial Fibrillation Ablation plus Left Atrial Appendage Excision.

Introduction: Trans-thoracoscopic atrial fibrillation (AF) ablation combined with left atrial appendage excision (LAAE) is an alternative treatment approach for nonvalvular AF patients with a history of thromboembolic events. The primary objective of this research was to investigate the electrophysiological characteristics of recurrent atrial tachyarrhythmias and rhythm outcome in patients receiving repeat catheter ablation after surgical AF ablation plus LAAE.

Methods: Nonvalvular AF patients with previous thromboembolic events who underwent trans-thoracoscopic AF ablation plus LAAE and then received radiofrequency catheter ablation were enrolled. During the procedure, the reconnection of the left atrium (LA) and pulmonary veins (PVs) was investigated, and three-dimensional activation mapping of the LA and/or right atrium during atrial tachyarrhythmias was performed.

Results: From January 2014 to December 2021, 173 patients without a history of prior ablation underwent concurrent trans-thoracoscopic AF ablation and LAAE. A total of 74 patients experienced recurrent atrial tachyarrhythmias during a median follow-up period of 3.5 years (interquartile range [IQR]: 2.0 to 5.0 years) after the surgical procedure. A total of 22 patients with atrial tachyarrhythmias recurrence (11 males, aged 60 ± 9 years) underwent radiofrequency catheter ablation. Among them, 10 patients with recurrent AF were identified, and in two of them, non-PV triggers originated from the interatrial septum and the superior vena cava. Reconnected LA-PV conduction was detected in 12 patients, with a total of 27 PV gaps. Eighteen of these PV gaps were located at the roof or the bottom. Thirteen sustained atrial tachycardias (ATs) were mapped in 12 patients, including peri-mitral AT (n = 7), cavotricuspid isthmus-dependent AT (n = 3), remnant LAA-related micro-reentrant AT (n = 1), roof-dependent reentry AT (n = 1), and focal AT (n = 1). At a median follow-up of 9 months (IQR: 3-20 months) after the ablation procedure, the freedom rate from atrial tachyarrhythmias was 77%.

Conclusion: Reconnection of LA-PVs and macro-reentry ATs are common in repeat catheter ablation after surgical treatment for AF, with peri-mitral AT being the most frequently observed AT. PV gaps are most often located at the roof or bottom. Additionally, LAAE may contribute to arrhythmogenesis in certain patients. Catheter ablation targeting these mechanisms resulted in a favorable short- to mid-term rhythm outcome.