A matter of proportions: a novel framework to classify functional tricuspid regurgitation

Abstract

Abstract Background Current approaches for the assessment of tricuspid regurgitation (TR) severity do not correct for right ventricular (RV) size. Similarly to what recently proposed for the left heart, we hypothesized that TR severity can be proportional or disproportional to RV dilation. Purpose To characterize the clinical features and the prognosis of patients with disproportionate vs proportionate functional TR (FTR). Methods A total of 345 patients (mean age: 70±12 years; 40% male) with significant (≥ moderate) FTR, preserved left ventricular systolic function and who did not undergo tricuspid valvular repair during follow-up were included. Proportional and disproportional FTR were defined according to the ratio between TR severity (vena contracta [VC] width) and RV size (tricuspid annulus [TA] diameter). A prognostic relevant cut-off for VC/TA was identified with spline curve analysis. The primary end-point was all-cause mortality and the event rates were compared between patients with proportionate and disproportionate FTR. Results The cut-off for disproportionate FTR associated with an increase in all-cause mortality was identified at 0.24 (Figure 1: left panel). According to this cut-off, 172 (50%) patients showed disproportionate FTR, while the remaining had proportionate FTR. Patients with disproportionate FTR were more frequently symptomatic, had smaller RV basal diameter, higher TR severity, greater left atrial volume, higher prevalence of mitral regurgitation, and higher pulmonary artery pressures compared to those with proportionate FTR. During a median follow-up of 61 (interquartile range, 28–101) months, 135 (39%) patients died. The cumulative 5-year survival rate was significantly worse in patients with disproportionate FTR (57% vs 74%, P=0.001; Figure 1: right panel) and on multivariable Cox regression analysis disproportionate FTR was independently associated with poor outcome (HR 1.56; 95% CI 1.06–2.29; P=0.023) together with age, coronary artery disease, renal impairment, reduced RV systolic function, and increased pulmonary artery pressures. Importantly, this novel framework outperformed the TR grading system recommended by current guidelines, which in this population was not able to effectively stratify the prognosis (HR for severe FTR vs moderate FTR 1.09; 95% CI 0.72–1.64; P=0.694). Conclusions In patients with significant FTR, characterization of TR severity in relation to RV size significantly improves risk-stratification since disproportionate FTR if left untreated is associated with worse prognosis compared with proportionate FTR. Figure 1 Funding Acknowledgement Type of funding source: None