Current echocardiographic indices for right ventricular function are inadequate to predict patient outcomes in chronic tricuspid regurgitation

Abstract Background/Introduction The presence of chronic tricuspid regurgitation (TR) can lead to pseudo-normalization of right ventricular (RV) functional indices on transthoracic echocardiography (TTE). Thus, the current cutoffs for RV free wall strain (FWS), functional area change (FAC), and tricuspid annular plane systolic excursion (TAPSE) (1) are not optimal for the volume overload associated with TR (2). Purpose We aimed to evaluate the sensitivity and specificity of the current cutoffs for RV FWS (>-23%), FAC (<35%), and TAPSE (<17 mm) in predicting adverse patient outcomes in a multi-centric population with chronic TR. We also evaluated whether interventricular septal shape was correlated with patient outcomes and aimed to develop cutoffs for this novel index. Methods We studied 753 patients (mean age 70.3 ± 15.0 years, 42.5% male) with >mild, medically managed TR who presented to our centers between 2018 and 2023. We measured TR grade (3), RV size, RV FWS, FAC, TAPSE, and eccentricity index (EI) for each patient (Figure 1). We subsequently tracked time to cardiac-related hospitalization or death, whichever came first. Using receiver operating characteristics (ROC), we estimated the area-under-the-curve (AUC) for RV FWS, FAC, and TAPSE as well as systolic and diastolic EI in predicting adverse patient outcomes. We used the modified Youden index (4) to analyze the current cutoffs for RV FWS, FAC, and TAPSE and specify novel cutoffs for all indices (including systolic and diastolic EI). Results Over a mean follow-up of 52 ± 16 months, there were 282 hospitalizations and 146 deaths across the 753 patients. AUC values for RV FWS, FAC, and TAPSE in predicting adverse clinical outcomes were 0.54, 0.62, and 0.54, respectively (p < 0.05 each, Figure 2A). Systolic and diastolic EI had the highest AUC (0.86 each, p < 0.0001) and were equivalent to one another in predicting adverse outcomes (Z-score = 0.0471, p = 0.9624) (Figure 2B). Sensitivity and specificity for the current cutoffs for RV FWS, FAC, and TAPSE are shown in Figure 2C. Using maximized Youden indices, the proposed cutoffs for normal RV FWS, FAC, TAPSE, systolic EI, and diastolic EI in chronic TR were ≤-24%, ≥38%, ≥22 mm, <1.3, and <1.3, respectively, which are all notably higher than the currently cutoffs (Figure 2C). Conclusions Given the pseudo-normalization of RV FWS, FAC, and TAPSE in chronic TR, waiting to intervene until these values become "abnormal" (per the current cutoffs) may in fact be too late. Our data suggest that the new cutoffs are needed to identify compensated RV function in the setting of TR. Moreover, interventricular septal shape (assessed via EI) predicts adverse patient outcomes with greater accuracy than conventional indices and should perhaps be incorporated in clinical decision-making.Figure 1.Eccentricity MeasurementFigure 2.ROC Curves for RV Indices