Association of right atrioventricular coupling and right atrial stiffness indices with outcomes in secondary tricuspid regurgitation patients

AIMS: In secondary tricuspid regurgitation (STR) patients, the clinical value of right atrioventricular coupling (RAVC) and right atrial (RA) stiffness indices has never been evaluated. Accordingly, we explored the association with a composite outcome of all-cause mortality or heart failure hospitalization of (i) RAVC index obtained either with speckle tracking echocardiography (RAVCSTE) or as the ratio between RA volume (RAV) and right ventricular (RV) stroke volume (RAVCVOL) and (ii) RA stiffness index calculated as the ratio between RAV index and RA longitudinal reservoir strain (RALS). METHODS AND RESULTS: 513 patients with mild-to-severe STR (75 ± 13 years, 58% severe) were included. After a mean follow-up of 18 ± 15 months, 195 patients (38%) reached the composite endpoint. On spline curve modelling, the cut-off values associated with increased 2-year event rates were (i) < 0.82 for RAVCSTE (reduced values of the ratio between RALS and RV free wall strain indicating impaired coupling, the RA not supporting effectively the RV filling, despite a good systolic function of the RV); (ii) > 1.23 for RAVCVOL (higher values suggesting greater RA remodelling relative to RV stroke volume and altered coupling); (iii) > 4.6 for RA stiffness index (higher values indicating a diminished RA compliance to filling). However, in multivariable Cox regression analyses and hierarchical χ2 analyses, only RAVCVOL maintained a significant association with the outcome (P < 0.05). CONCLUSION: In STR patients, RAVC and RA stiffness indices are associated with the risk of events, with RAVCVOL yielding the strongest association.