Sustained localized reentry within the left atrial appendage as a mechanism of recurrent arrhythmia following atrial fibrillation ablation

The current study investigated the electrophysiological characteristics and radiofrequency ablation in patients with localized reentry within the left atrial appendage during repeated ablation for recurrent atrial fibrillation (AF). A total of 76 patients (21 paroxysmal, 55 persistent) undergoing repeated catheter ablation for recurrent AF were enrolled in this study. Local reentry tachycardia within the left atrial appendage (LAA) was identified through combining activation and entrainment mapping. Left atriography was performed prior to radiofrequency ablation to identify the focus in the LAA. Three patients (1 paroxysmal, 2 persistent) with sustained atrial tachycardias (ATs) were identified during repeated ablation in this cohort. Combined activation and entrainment mapping were applied to localize the reentry. Postpacing interval-tachycardia cycle length differences were <30 msec at the possible site of reentry in varying segments with macro-reentry. This difference was only determined at the base of LAA for local reentry within the LAA. All 3 patients were free of atrial arrhythmias without any complications at the 6-month follow-up following the ablation in the LAA. Combining activation and entrainment mapping were necessary in approaching ATs within the LAA. Performing entrainments in opposite segments of possible loops were valuable in precluding macro-reentry. Focal ablation was safe and effective in this cohort. Therefore localized reentry within the LAA was not uncommon during repeat AF ablation. The present study may thus provide valuable information for clinicians to manage this type of arrhythmia.