Multimodality Quantitative Assessment of Left Atrial Remodeling Characteristics Using Echocardiography and LGE-CMR in Isolated Degenerative Mitral Regurgitation: Association With Atrial Fibrillation

Background Although atrial fibrillation (AF) frequently coexists with degenerative mitral regurgitation (DMR), imaging assessment of left atrial (LA) fibrosis in this population remains limited. We integrated echocardiographic and cardiac magnetic resonance (CMR) late gadolinium enhancement (LGE) parameters to characterize LA remodeling features in isolated DMR and assess its association with AF. Methods In this retrospective study, consecutive patients with moderate-to-severe or severe isolated DMR who underwent echocardiography and CMR, including cine and LGE sequences, between February 2025 and January 2026 were included. Patients with other left-sided valvular disease of mild or greater severity or cardiomyopathy were excluded to isolate a population of "pure" DMR patients, and LALGE percentage was calculated as LALGE area divided by left atrial wall area. Imaging parameters were compared according to AF status and evaluated using logistic regression and receiver operating characteristic (ROC) analysis. Multimodality models were constructed to assess the combined discriminative value of echocardiographic and CMR parameters. Results Among 46 patients with DM (71.7% male, 62.0 years of age), 17 (37.0%) had AF. Compared with patients without AF, AF patients were older (P=0.005) and had lower LA reservoir strain [LASr; adjusted odds ratio (OR) 0.86; 95% confidence interval (CI) 0.76-0.94; P<0.001], higher left atrioventricular coupling index (LACI; adjusted OR per 10-percentage-point increase, 1.48; 95% CI, 1.18-2.23; P<0.001), larger LALGE area (adjusted OR 1.20; 95% CI, 1.07-1.41; P<0.001), higher LALGE percentage (adjusted OR 1.19; 95% CI, 1.02-1.42; P=0.025). Among single parameters, LACI showed the highest area under the curve (AUC 0.85, 95% CI 0.72-0.99; cutoff 58.59%), whereas LALGE area showed an AUC of 0.78 (95% CI 0.61-0.94; cutoff 13.73 cm2). Among all models, LASr combined with LALGE percentage achieved the highest AUC (0.91, 95% CI 0.80-1.00), with sensitivity 76.5%, specificity 96.6%, positive predictive value 92.9%, and negative predictive value 87.5%. In serum biomarker analysis, patients with AF had significantly higher levels of C-terminal telopeptide of type I collagen (CITP) than those without AF (P=0.009). Follow-up data were available for 45 patients (97.8%), with a median follow-up duration of 9.2 months (IQR, 7.7-12.2 months). Conclusions In patients with DMR, AF was associated with more advanced LA structural remodeling, impaired LA function, and higher CMR LGE burden. Echocardiographic LA functional parameters, when combined with LALGE measures, may provide complementary information for the discrimination of AF. Given the exploratory nature of this study, the findings require external validation.