Interatrial Septal Thickness as a Marker of Structural Remodeling of the Left Atrium in Patients with Atrial Fibrillation

Background: Although periatrial adipose tissue, especially in interatrial septum, has been known to be related with atrial fibrillation (AF) chronicity, the association between interatrial septum thickness (IST) and atrial remodeling has not been elucidated. Objective: The aims of the present study are to determine whether IST correlates with structural remodeling of the left atrium (LA), and to identify whether it predicts clinical outcome after Catheter ablation (CA) for AF. Methods: We consecutively enrolled 104 patients undergoing CA for AF [paroxysmal AF (PAF)=82, persistent AF (PeAF)=22]. An echocardiography and voltage mapping using NavX system were performed. LA was divided into 6 segments and the mean voltage for each region was determined by averaging the bipolar voltage of the points. IST and integrated backscatter signal (IBS) reflecity of interatrial septum were assessed. Results: IST was significantly correlated with the mean voltage of LA (r=-0.537, p<0.001), IBS reflecity (r=0.476, p<0.001), LA volume index (LAVI) (r=0.203, p=0.038), and CHA2RD2-VASc score (r=0.348, p<0.001). During the mean follow-up of 17 months after a single ablation procedure, 27 subjects (26.0%, PAF=20, PeAF=7) had arrhythmia recurrence. Multivariate analysis revealed that LAVI, IBS, and IST were independent predictors for AF recurrence after CA. Conclusion: IST was a reliable noninvasive parameter for structural remodeling of the LA and might predict thromboembolic risk.