Uncovering right ventricular impairment in severe TR: Insights from novel volumetric indices

BACKGROUND Accurate assessment of right ventricular (RV) performance is crucial in patients with severe tricuspid regurgitation (TR). Conventional RV ejection fraction (RVEF) may overestimate RV systolic function because it does not account for regurgitant volume in severe TR. This study aimed to evaluate the prognostic value of two novel CMR-derived indices of RV function-a volumetric surrogate of RV-pulmonary artery (PA) coupling (Vol RV-PA Coupling Index) and effective RV ejection fraction (effective RVEF), which accounts for regurgitant volume-compared with conventional RVEF. METHODS In this multicentre study, 289 patients with severe TR (mean age 71 ± 11 years, 66% women) underwent comprehensive CMR assessment and long-term follow-up. The primary endpoint was the first occurrence of all-cause death or heart failure hospitalisation. A pre-specified secondary analysis evaluated an expanded composite endpoint including all-cause death, heart failure hospitalisation, or tricuspid valve intervention (TVI). A subgroup of 50 patients underwent repeat CMR after TVI. RESULTS During follow-up, 106 patients (37%) reached the primary endpoint. Both the Vol RV-PA Coupling Index and effective RVEF were independently associated with the primary endpoint and significantly improved risk discrimination beyond conventional RVEF (Δ Harrell's C-index 0.056 and 0.043, respectively; both p < 0.01). Similar findings were observed for the expanded composite endpoint. Following TVI, both indices improved significantly and were associated with mortality during post-intervention follow-up. CONCLUSIONS Vol RV-PA Coupling Index and effective RVEF are complementary CMR-derived markers of RV performance that provide incremental prognostic information beyond conventional RVEF in patients with severe TR. Their improvement after TVI further supports their potential role for longitudinal assessment of RV performance.