Mechanical adaptation of the right ventricle to increased volume overload associated with secondary tricuspid regurgitation

Abstract Funding Acknowledgements Type of funding sources: None. Background Right ventricular (RV) function is strongly associated with the prognosis of patients with secondary tricuspid regurgitation (STR). However, the mechanical adaptations (contraction pattern) of the RV to volume overload associated with STR remain to be clarified. Purpose To investigate the changes in RV contraction pattern associated with the increase in severity of STR and to analyse whether the assessment of each RV motion component of RV ejection fraction (RVEF) (longitudinal, radial, and anteroposterior) adds prognostic value in patients with STR. Methods Consecutive patients with STR who underwent clinically indicated transthoracic echocardiography were enrolled in a multi-center prospective observational study. The primary outcome was defined as heart failure hospitalization or cardiac death. 3-dimensional echocardiography studies were performed at baseline and the ReVISION software package (Argus Cognitive, Inc, Lebanon, NH) was used to quantify the contribution of the longitudinal, radial, and anteroposterior motion components to total RVEF (Figure). Results We enrolled 172 patients (43% men, age: 75±15 years), followed for a median of 9 months. The patients were divided in two groups by STR severity (non-severe n=125, severe n=47). The characteristics of patients with massive/torrential STR (n=12) vs. "only" severe STR (n=35) were also assessed. RV end-diastolic volume index (r=0.33, p<0.001) and the longitudinal component of RVEF demonstrated significant correlation with STR severity (r=-0.22, p<0.01), while total RVEF did not (r=0.14; p = NS). The anteroposterior component of RVEF was the only parameter showing relatively strong correlation with left ventricular ejection fraction (r=0.39; p<0.001). RVEF was comparable between non-severe and severe patients (49±10 vs. 49±11%, p = NS). In patients with severe STR, the radial and also anteroposterior component of RVEF were comparable to non-severe STR patients, while the longitudinal component was significantly lower in severe STR (19±6 vs.17±7%, p<0.05; shown on Figure). Notably, in patients with massive/torrential STR, the radial contribution markedly decreased (27±8 vs. 20±9%, p<0.05), with consequently reduced global RVEF (52±9 vs. 41±12%, p<0.01) (Figure). In a multivariable Cox regression, using parameters proved to be significant in the univariable analysis, longitudinal component of total RVEF was a significant and independent predictor of outcome (hazard ratio, 0.947 [CI, 0.903–0.992], P= 0.022). Conclusions Patients with severe STR demonstrate significant morphological and functional RV remodeling with chamber enlargement and maintained RVEF, but a significant decrease in the longitudinal component of RVEF. In patients with massive/torrential STR, the radial mechanism markedly deteriorates, leading to decreased global RVEF. The longitudinal component of RV motion demonstrated independent prognostic value in patients with STR.