The impact of abnormal conduction zone on outcomes after catheter ablation for atrial fibrillation

Background The abnormal conduction zone (ACZ) in the left atrium (LA) has attracted attention as an arrhythmia substrate in atrial fibrillation (AF). Purpose We investigated whether the ACZ affects outcomes after catheter ablation (CA) for AF. Methods We studied 78 patients (42 Non-paroxysmal AF, 49 males, and 68±10 years) who received CA for AF. High-density LA mapping during high right atrial pacing was constructed gaining than 2000 points (average 4377±846 points). Isochronal activation maps created at 5-ms interval setting. ACZ was identified by locating a site with isochronal crowding of ≥3 isochrones, and ≥8 isochrones were defined as the conduction block zone (CBZ) in a 4-mm diameter tag (conduction velocity were calculated as ≤27 cm/s and≤10 cm/s, respectively). Result Recurrent AF was detected in 25/78 patients (32%) during the follow-up period (9.2±3.0 month). ACZ and CBZ were distributed linearly, and ACZ was observed in 73 of 78 patients and 8 of these 73 patients had the CBZ. Univariate analysis revealed that elevated body mass index (26.2±3.8 vs. 24.3±3.3 kg/m2, P=0.0303), the higher prevalence of non-paroxysmal AF (72% vs. 45%, P=0.0272), larger LA diameter (47.6±6.6 vs. 42.1±6.9 mm, P=0.0014), and longer length of ACZ (79.7±45.1 vs. 52.9±35.7 mm, P=0.0058) were associated with recurrent AF after CA. On multivariate analysis, longer ACZ was independently associated with recurrent AF. Moreover, patients with longer ACZ (cutoff value: 84 mm) had a higher risk of recurrent AF than shorter ACZ (12/22; 55% vs 13/56; 23%, log-rank P=0.0024). Conclusion The length of ACZ was associated with recurrent AF after CA. Funding Acknowledgement Type of funding sources: None.