Electrophysiological predictors of susceptible atrial substrate for the onset and recurrence of atrial fibrillation

Background: The atrial electroanatomic substrate is an essential component in the pathogenesis of atrial fibrillation (AF). However, the electrophysiological markers of susceptible atria for AF are not well-characterized. This study aimed to assess atrial conduction indices on surface electrocardiogram (ECG) and intracardiac electrogram (EGM) as predictors of initiation and recurrence of AF after successful ablation.

Methods: We studied all consecutive patients who underwent electrophysiological study and catheter ablation for AF (study group) or atrioventricular nodal reentrant tachycardia (AVNRT) (control group) from 2013 to 2018. Atrial conduction indices were measured on ECG and EGM during the electrophysiology study. Clinical data was obtained from the medical record.

Results: A total of 387 patients with AF (mean age 63 years, 31% female) were studied and compared to 94 patents in control group. The initiation of AF was associated with significant prolongation of atrial conduction indices on ECG and EGM (p < 0.05). During a mean follow up of 5 ± 2 years, recurrence of AF (48%) after successful ablation occurred in patients with prolonged P wave duration, left atrial (LA) conduction interval, proximal to distal coronary sinus (pCS-dCS) interval, and P wave to dCS interval (p < 0.05). Machine learning modeling determined that pCS-dCS interval, QRS duration, and LA duration in leads V1 and II are most impactful conduction indices in association with AF recurrence.

Conclusion: Prolonged atrial conduction intervals, particularly LA (pCS-dCS), indicate susceptible substrate for the onset and the recurrence of AF after ablation. LA conduction indices can facilitate early detection and management of AF.