Combined Atrial Functional Mitral and Tricuspid Regurgitation in Atrial Fibrillation: Prevalence, Associated Factors, and Three-Dimensional Valve Remodeling

Background/Objectives: Atrial fibrillation (AF) may cause functional mitral regurgitation (MR) and tricuspid regurgitation (TR) through atrial remodeling and annular dilation. However, the prevalence and structural characteristics of combined MR/TR in AF are not well defined. We aimed to determine the prevalence, clinical profile, and factors associated with combined clinically significant MR and TR in AF patients. Methods: In this prospective observational study (REMO-FIB), 175 consecutive AF patients underwent comprehensive transesophageal echocardiography with three-dimensional mitral valve analysis. After excluding organic MR and significant aortic valve disease, 125 patients were analyzed. Patients were classified into four groups according to the presence of moderate/severe MR and/or TR. Multivariable logistic regression evaluated factors associated with the combined phenotype. Results: Among 125 patients, 53 (42.4%) had no significant MR/TR, 33 (26.4%) had isolated MR, 11 (8.8%) had isolated TR, and 28 (22.4%) had combined MR/TR. Compared with patients without regurgitation, those with combined MR/TR had higher symptom burden (EHRA class, p = 0.036), more heart failure (92.9% vs. 67.9%, p = 0.048), larger left (47.0 vs. 42.0 mm, p = 0.002) and right atria (42.0 vs. 38.0 mm, p < 0.001), higher pulmonary artery pressure (40.0 vs. 28.0 mmHg, p = 0.004), and lower left ventricular ejection fraction (47.5% vs. 55.0%, p = 0.006). Three-dimensional analysis showed larger mitral annular perimeter (129.0 vs. 121.0 mm, p = 0.009), greater annular area (12.7 vs. 11.1 cm2, p = 0.014), longer anterior leaflet length (26.5 vs. 24.0 mm, p < 0.001), and greater tenting area (2.1 vs. 1.4 cm2, p = 0.002). Factors independently associated with the combined phenotype were female sex (OR 4.60, p = 0.015), lower ejection fraction (OR 0.47 per SD, p = 0.005), and larger right atrial diameter (OR 1.85 per SD, p = 0.037). Model discrimination was good (AUC 0.81). Conclusions: Combined moderate/severe MR and TR affects over one-fifth of AF patients without organic valve disease and is associated with advanced biatrial remodeling, adverse symptoms, and heart failure. Comprehensive assessment of both atrioventricular valves should be considered in AF.