Impact of Non-Valvular Atrial Fibrillation on Mitral Valve Anatomic Features: A Study of Three-Dimensional Mitral Valve by Transesophageal Echocardiography and Automatic Analysis Software

Background/Aim: Mitral regurgitation (MR) is frequently observed in non-valvular atrial fibrillation (NVAF) patients and is a significant risk factor for its progression. This study aims to investigate the three-dimensional anatomical characteristics of the mitral valve (MV) in patients with different types of NVAF to elucidate the underlying mechanisms of MR. Methods: A retrospective analysis was conducted on 82 paroxysmal atrial fibrillation patients (PAF group) and 66 persistent atrial fibrillation patients (PerAF group) who underwent real-time three-dimensional transesophageal echocardiography (RT 3D-TEE) before initial ablation. Additionally, 30 patients undergoing RT 3D-TEE for the assessment of patent foramen ovale were selected as the control group. Basic echocardiographic variables were measured, left atrioventricular volume and strain parameters were calculated using automated software (Dynamic-HeartModel and AutoStrain). MV anatomic features were analyzed using the 4D-MV Assessment software (TomTec Imaging Systems). Results: The maximum left atrial volume (LAVmax) was highest in the PerAF group, followed by the PAF and control groups, with statistically significant differences (p < 0.01). Left atrial reservoir strain (LASr) showed an opposite trend, being the lowest in the PerAF group (p < 0.01). The proportion of moderate to severe MR was significantly higher in the PerAF group (27.3%) compared to the PAF group (11.0%) (p < 0.01). Compared to controls, the AF groups exhibited mitral annular (MA) dilation, flattening of the MA plane, and increased leaflet area (all p < 0.05). Correlation analysis between effective regurgitant orifice area (EROA) and left atrioventricular structure and function parameters, as well as various annular parameters, showed that EROA was significantly correlated with left ventricular end-diastolic volume (LVEDV), LAVmax, LASr, anterior and posterior diameter, annular area, ratio of annular height to commissural diameter (AH/CD ratio), posterior leaflet area, posterior leaflet length, and the C-shaped annulus length (all p < 0.05). Conclusions: Significant remodeling of the MV apparatus occurs in NVAF patients, with more pronounced changes in PerAF patients, contributing to a higher incidence of moderate to severe MR. RT 3D-TEE-based MV automated assessment offers significant advantages in accurately diagnosing MV remodeling and supporting the evaluation of MR in NVAF patients.