The concept of disproportionate tricuspid regurgitation: a cardiac computed tomography-based outcome study

Background The concept of a disproportionate regurgitant lesion compared to the ventricular size has been widely investigated for prognostic purposes in functional mitral regurgitation patients. However, it has never been explored in the context of tricuspid regurgitation (TR) so far. Purpose To define and assess the prognostic role of disproportionate TR compared to right ventricular (RV) volumes in a cohort of severe TR patients evaluated by cardiac computed tomography (CCT). Methods Comprehensive clinical, echocardiographic and CCT data were collected from consecutive severe TR patients who had CCT measurements of both RV volumes and tricuspid valve anatomical regurgitant orifice area (AROA), a novel CCT parameter to quantify TR which we recently associated with outcome1 (Figure 1, panel A). The AROA/RV end-diastolic volumes indexed (RVEDVi) ratio was used to assess the relationship between proportionate/disproportionate TR with the outcome of interest, which was all-cause under medical management. Results We included 174 patients (median age 83 years, median RV ejection fraction 46%). Spline curve analysis showed that increasing values of AROA/RVEDVi ratio associated with progressive risk of outcome occurrence, and the prognostic cut-off associated with hazard ratio (HR) >1 was >0.74 (Figur 1, panel B1). Baseline characteristics were not significant for age, Euroscore II and biventricular ejection fraction (EF), but patients with high AROA/RVEDVi (disproportionate TR) had higher pulmonary artery systolic pressure, larger tricuspid reg. volumes and worse CCT-derived RV free-wall longitudinal strain compared to patients with low AROA/RVEDVi (proportionate TR, all p-values <0.05). After a median follow-up of 2.3 years, patients with disproportionate TR had significantly worse survival (Figure 1, panel B2), univariably and after multivariable analysis in two models adjusted for both clinical characteristics (adjusted HR 2.11, 95% confidence interval 1.19-3.75, p-value =0.01) and imaging variables (adjusted HR 2.01, 95% confidence interval 1.11-3.66, p-value =0.02). Exploratory secondary analysis for the 43 patients (24%) treated with transcatheter edge-to-edge repair (T-TEER), showed that disproportionate TR patients had similar achievements of TR reduction >2+ grades compared to those with proportionate TR (72% vs 63%, p-value= 0.210), despite larger median maximum coaptation gap (7 vs 11 mm, p-value<0.001). Conclusions CCT-based assessment of AROA/RVEDV ratio identifies a higher mortality risk cohort in which TR severity becomes disproportionate to RV remodeling. Larger studies are necessary to confirm our hypothesis that prognostic impact of TR severity is modulated by the degree of RV remodeling.