Clinical Value of a Novel Three-Dimensional Echocardiography–Derived Index of Right Ventricle–Pulmonary Artery Coupling in Tricuspid Regurgitation

Background: Echocardiographic surrogates of right ventricle–to–pulmonary artery (RV-PA) coupling have been reported to be associated with outcomes in patients with secondary tricuspid regurgitation (STR). However, pulmonary artery systolic pressure (PASP) is difficult to estimate using echocardiography in patients with severe STR. The aim of the present study was to evaluate the predictive power of a surrogate of RV-PA coupling obtained using right ventricular (RV) volumes measured on three-dimensional echocardiography. Methods: One hundred eight patients (mean age, 73 ± 13 years; 61% women) with moderate or severe STR were included. Results: At a median follow-up of 24 months (interquartile range, 2-48 months), 72 patients (40%) had reached the composite end point of death of any cause and heart failure hospitalization. RV-PA coupling was computed as the ratio between RV forward stroke volume (SV) (i.e., RV SV − regurgitant volume) and RV end-systolic volume (ESV). RV forward SV/ESV was significantly more related to the composite end point than RV ejection fraction (area under the curve, 0.85 [95% CI, 0.78-0.93] vs 0.73 [95% CI, 0.64-0.83], respectively; P = .03). A value of 0.40 was found to best correlate with outcome. On multivariate Cox regression, RV forward SV/ESV, tricuspid annular plane systolic excursion/PASP, and RV free wall longitudinal strain/PASP were all independently associated with the occurrence of the composite end point when added to a group of parameters including STR severity (severe vs moderate), atrial fibrillation, pulmonary arterial hypertension, right atrial volume, RV end-diastolic volume, and RV free wall longitudinal strain. RV forward SV/ESV < 0.40 (HR, 3.36; 95% CI, 1.49-7.56; P < .01) carried higher related risk than RV free wall longitudinal strain/PASP < −0.42%/mm Hg (HR, 3.1; 95% CI, 1.26-7.84; P = .01) and tricuspid annular plane systolic excursion/PASP < 0.36 mm/mm Hg (HR, 2.69; 95% CI, 1.29-5.58; P = .01). RV ejection fraction did not correlate independently with prognosis when added to the same group of variables. Conclusions: RV forward SV/ESV is associated with the risk for death and heart failure hospitalization in patients with STR.