High Atrial Defibrillation Threshold is Related to a Risk of Recurrence after Catheter Ablation For Long-Standing Persistent Atrial Fibrillation But Not for Persistent Atrial Fibrillation

Background: The atrial defibrillation threshold (ADFT) for internal cardioversion is theoretically related to the critical mass for sustaining atrial fibrillation (AF). Objective: This study aimed to investigate the association of ADFT for internal cardioversion with the outcome of catheter ablation for non-paroxysmal AF (non-PAF). Methods: We included 368 consecutive patients who underwent first-time catheter ablation for non-PAF. Based on the degree of ADFT recorded by the internal cardioversion before pulmonary vein isolation, we divided the patients into low ADFT (<20 J) and high ADFT (≥20 J) groups and analyzed the association between ADFT and atrial tachyarrhythmia recurrence. Results: There were 234 and 134 patients in the low and high ADFT groups, respectively. Of these, 39 patients (16.7%) and 41 (30.6%) patients, respectively, had atrial tachyarrhythmia recurrence during the 2.6 ± 1.0 year follow-up. The high ADFT group showed a significantly higher atrial tachyarrhythmia recurrence than the low ADFT group (p = 0.002). This finding was also noted in patients with long-standing persistent AF (p = 0.032) but not in patients with persistent AF (p = 0.159). The significant predictors of arrhythmia recurrence on multivariate analysis were high ADFT (p = 0.004) and long-standing persistent AF (p = 0.011). In multivariate analysis within the long-standing persistent AF group, only ADFT remained a significant risk factor for AF recurrence (p = 0.035). Conclusions: High ADFT of internal cardioversion was found to be a risk factor for post-catheter ablation recurrence in patients with long-standing persistent AF but not in those with persistent AF.