Impact of right ventricular function on outcome in low-risk secondary tricuspid regurgitation according to effective regurgitant orifice area

Abstract Background The threshold value of the effective regurgitant orifice area (EROA) that identifies patients with secondary tricuspid regurgitation (STR) at high risk of events during follow-up remains unclear. Purpose Our study aimed to identify the threshold value of the EROA defining patients with STR at high-risk of events during follow-up and to evaluate the impact of right ventricular (RV) remodeling in modulating the outcome of low-risk STR patients according to EROA. Methods 513 consecutive outpatients with STR were included. Using the threshold value derived by spline curves, we divided our cohort into two groups: low- (EROA≤ 0.47cm2) and high- (EROA> 0.47cm2) risk STR patients. The endpoint was a composite of heart failure hospitalization and death. Results At 18±15 months from enrolment, 195 patients (38%) reached the endpoint. The Kaplan-Meier curves demonstrated a higher rate of events for high-risk patients (54±6% vs 30±7%, p <0.0001). EROA> 0.47 cm2 was associated with a 2-fold increased risk of experiencing the outcome (Hazard Ratio [HR]: 2.08, 95% Confidence Interval [CI] 1.56-2.77, p<0.0001). Patients with atrial STR had a significantly lower threshold value (0.44 cm²) than patients with ventricular STR (0.49 cm²). In multivariate Cox regression analysis, EROA remained independently associated with the composite endpoint (adjusted HR: 1.01, 95% CI 1.00-1.02, p<0.0001) both in the entire cohort and in high-risk patients. Patients with low-risk STR were associated with a dismal prognosis only if they had dilated or dysfunctioning RV. In patients with EROA≤ 0.47cm2, the event rate at two years for RV end-diastolic volume >90 mL/m2, RV end-systolic volume (RV ESV) >46 mL/m2, RV ejection fraction <45% and RV forward stroke volume/RV ESV< 0.40 were respectively: 42±4%, 51±4%, 44±4%, and 47±4%). Conclusions Our results refine the independent association between STR severity assessed by EROA and outcomes. In patients with low-risk STR, the assessment of RV function and RV-PA coupling may improve the patient’s risk prediction, demonstrating a clinically relevant link between STR severity and RV geometry and function.