Atrial Fibrillation Burden and Early Mitral Valve Remodelling in Patients Without Significant Mitral Regurgitation: A 3D Transesophageal Echocardiographic Study

Background The progression of mitral valve (MV) remodelling in atrial fibrillation (AF) patients without significant mitral regurgitation (MR) remains poorly characterized. We aimed to determine whether AF burden—paroxysmal versus persistent—differentially affects MV annular geometry, leaflet morphology, and functional dynamics using three‐dimensional transesophageal echocardiography (3D‐TEE). Methods In prospective cross‐sectional observational study, 46 consecutive AF patients without significant MR (paroxysmal AF: n = 18; persistent AF: n = 28) underwent comprehensive 3D transesophageal echocardiography. Offline semi‐automated quantitative analysis (4D MV Assessment, TomTec) was performed to assess mitral annular dimensions and geometry, leaflet morphology (area and angulation), and functional parameters including tenting volume, coaptation depth, and dynamic annular motion. Results Despite comparable demographics, persistent AF patients had larger LA diameter (45.4 ± 7.1 vs. 40.3 ± 6.3 mm; p = 0.05), lower LVEF (45.5 ± 15.4 vs. 56.5% ± 15.2%; p = 0.042), and greater LV end‐systolic dimension (41.3 ± 9.7 vs. 33.1 ± 9.4 mm; p = 0.018). 3D‐TEE demonstrated significant annular enlargement in persistent AF: larger AP diameter (3.92 ± 0.53 vs. 3.60 ± 0.47 cm; p = 0.042), AL‐PM diameter (3.74 ± 0.50 vs. 3.49 ± 0.34 cm; p = 0.048), 3D annular area (11.98 ± 3.19 vs. 10.34 ± 2.05 cm 2 ; p = 0.038), and 2D annular area (9.78 ± 2.83 vs. 8.27 ± 1.87 cm 2 ; p = 0.035). Anterior leaflet area was larger (8.93 ± 2.07 vs. 7.60 ± 2.02 cm 2 ; p = 0.036) and distal anterior leaflet angle was reduced (16.97 ± 5.03 vs. 20.76 ± 6.40°; p = 0.042). Annular shape, tenting parameters, coaptation depth, and dynamic motion were preserved in both groups. Conclusion Persistent AF was associated with early mitral annular enlargement, anterior leaflet remodelling, impaired LV function, and LA dilation, even in the absence of significant MR. However, the higher heart rate in persistent AF, unrecorded AF duration, and lack of data on prior rhythm‐control therapy limit attribution of these changes to AF burden alone. These findings are hypothesis‐generating and require confirmation in prospective studies accounting for these potential confounders.