Left Atrial Appendage Fibrosis and 3-Year Clinical Outcomes in Atrial Fibrillation After Endoscopic Ablation: A Histologic Analysis

Background. Interest has been increasing in the study of atrial fibrosis, an important mechanism in atrial matrix remodeling. However, histopathologic evaluation of atrial fibrosis in non-valvular atrial fibrillation (NVAF) has been limited. This study aimed to analyze the histologic relationship between atrial fibrosis and development or recurrence of NVAF after endoscopic ablation. Methods. Patients (n = 136) with NVAF undergoing endoscopic ablation and 10 patients in sinus rhythm were enrolled in this study. Left atrial appendage was harvested from all patients. Collagen volume fraction (CVF) and fibrosis biomarkers were evaluated. Linear regression analysis was performed to determine the correlation between clinical variables and atrial fibrosis. The association between atrial fibrosis and NVAF recurrence was evaluated with the Cox proportional hazards model. Results. A significant difference was found in the degree of atrial fibrosis between patients with NVAF and sinus rhythm (CVF: median 15 [interquartile range (IQR), 13-17] vs median 6.5 [IQR, 5-10.25]; P < .001, respectively). Factors independently associated with CVF in multivariate linear regression analysis included longer duration of NVAF and larger left atrial diameter. Among 136 patients with ablation, 19 (13.9%) had recurrent NVAF. In multivariate Cox regression analysis, CVF (hazard ratio [HR] 1.093; 95% confidence interval [CI], 1.007-1.186; P = .033) and left atrial diameter (HR for 3-mm change 1.240; 95% CI, 1.004-1.531; P = .046) were independent risk factors for NVAF recurrence. Conclusions. Atrial fibrosis in NVAF is not only associated with left atrial diameter and duration of atrial fibrillation but also with recurrence after ablation. Atrial fibrosis may be a future therapeutic target for reduction of recurrence after endoscopic ablation. (C) 2020 by The Society of Thoracic Surgeons.