STREI: a new index of right heart function in isolated severe tricuspid regurgitation by speckle-tracking echocardiography.

Aims: Right ventricular (RV) performance determines clinical management in severe tricuspid regurgitation (TR). Right atrial (RA) function complements RV assessment in TR. This study aimed to design a novel index by speckle-tracking echocardiography (STREI index) integrating RA and RV strain information and to evaluate the clinical utility of combining RV and RA strain for prediction of cardiovascular (CV) outcomes.

Methods And Results: Consecutive patients with at least (≥) severe TR evaluated in the Heart Valve Clinic (n = 300) were prospectively included. An additional independent TR cohort was included for external validation (n = 50). STREI index was developed with the formula: [2 ∗ RV-free wall longitudinal strain (RV-FWLS)] + reservoir RA strain (RASr). The composite endpoint included hospital admission due to heart failure and all-cause mortality. A total of 176 patients with ≥severe TR were finally included. STREI index identified a higher percentage of patients with RV dysfunction compared with conventional parameters. After a median follow-up of 2.2 years (interquartile range: 12-41 months), a total of 38% reached the composite endpoint. STREI values were predictors of outcomes independently of TR severity and RV dimensions. The combination of prognostic cut-off values of RASr (<10%) and RV-FWLS (>-20%) (STREI stratification) stratified four different groups of risk independently of TR severity, RV dimensions, and clinical status (adj HR per stratum 1.89 (1.4-2.34), P < 0.001). Pre-defined cut-off values achieved similar prognostic performance in the validation cohort (n = 50).

Conclusion: STREI index is a novel parameter of RV performance that independently predicts CV events. The combination of RA and RV strain stratifies better patients' risk, reflecting a broader effect of TR on right heart chambers.