Factors Associated with Atrial Functional Tricuspid Regurgitation Severity: A Comprehensive Three-dimensional Echocardiographic Study

Background Geometric alterations in the tricuspid annulus (TA) are common in atrial functional tricuspid regurgitation (A-FTR), and may reflect structural and dynamic changes that contribute to disease severity. Methods and Results Comprehensive two-dimensional and 3D echocardiographic analyses were performed in 216 patients with A-FTR. Geometric parameters included indexed TA area, sphericity index, and tenting volume. Dynamic parameters included TA area fraction, TA excursion, and unfavorable TA dynamics. A-FTR groups. Indexed TA area and tenting volume increased significantly with A-FTR severity (all P<0.001). Severe A-FTR showed a higher prevalence of unfavorable TA dynamics (55.8%, P=0.013) compared to mild (33.3%) and moderate (32.1%) groups. No significant differences were observed in TA area fraction and excursion across groups. In multivariable analysis, indexed TA area (aOR: 1.216, 95% CI: 1.166–1.267, P<0.001), tenting volume (aOR: 1.150, 95% CI: 1.099–1.204, P<0.001), and unfavorable TA dynamics (aOR: 1.309, 95% CI: 1.089–1.572, P=0.005) were independently associated with A-FTR severity. TA geometry correlated with both RA (β=0.841, P<0.001) and RV (β=0.748, P<0.001) volumes, while unfavorable dynamics were associated only with RV volume (β=0.166, P=0.027). Conclusion 3D remodeling and unfavorable TA dynamics independently correlated with A-FTR severity. TA geometry was linked to RA volume, while dynamics reflected RV remodeling. These findings support a potential sequential mechanism, highlighting the value of comprehensive 3D assessment.