Association of the right atrioventricular coupling and right atrial stiffness with outcome in patients with severe secondary tricuspid regurgitation and preserved right ventricular function

Background In patients with secondary tricuspid regurgitation (STR), adverse remodeling of both the right atrium (RA) and right ventricle (RV) has been associated with clinical outcomes. Although typically assessed in isolation, these two chambers interact closely. The concept of right atrioventricular coupling (RAVC) has recently emerged, yet its prognostic significance in STR remains unexplored. Purpose To evaluate the association between RAVC and a composite endpoint of all-cause mortality and heart failure hospitalization (HHF) using two echocardiographic indices, in patients with severe STR and preserved RV systolic function: 1)Speckle-tracking–derived RAVC (RAVCSTE), defined as the ratio of RA longitudinal strain (RALS) to RV free-wall strain—lower values suggest impaired RA contribution to RV filling despite preserved RV systolic function. 2)RA stiffness index, calculated as the ratio of RA volume index to RALS—reflecting atrial remodeling relative to deformation capacity. Methods This retrospective analysis included 239 patients with severe STR (mean age 78 ± 11 years; 53% with atrial STR) and RVEF > 45% who underwent comprehensive 2D, 3D, Doppler, and speckle-tracking echocardiography. STR severity was determined using the recommended multiparametric approach incorporating qualitative, semi-quantitative, and quantitative criteria. Results After a mean follow-up of 18±15 months, 115 patients reached the composite endpoint of HHF and all-cause death. On spline curve modeling the cut-off values associated with an excess event rate within the overall study population were: 0.82 for RVACSTE and 4.6 for RA stiffness index. Kaplan-Meier analysis demonstrated significantly lower event-free survival among patients with RVACSTE ≤ 0.82 and RA stiffness index ≥ 4.6 mL/% (p<0.005, for both) (Figure1). However, at Cox multivariable analysis, after adjusting for RV function, left ventricular ejection fraction, pulmonary artery systolic pressure and STR regurgitant volume, only RVACSTE (p<0.003), but not RA stiffness index (p=0.558), was independently associated with outcomes. Conclusions In patients with severe STR and preserved RV systolic function, impaired RVAC and identify individuals at heightened risk of death or HHF. This novel echocardiographic markers may enhance risk stratification and guide clinical decision-making.