Normal ranges of right atrial strain by contemporary echocardiography software: a prospective comparative cohort study

BACKGROUND: Right atrial (RA) strains (RASr, RAScd, and RASct) are increasingly used in clinical and research settings, such as heart failure and pulmonary hypertension, but their feasibility and reference ranges across different strain software vendors are not well established. We aim to evaluate and compare two-dimensional RA strain values, reference ranges, and related factors across four strain software vendors in healthy subjects. METHODS: Healthy subjects (n = 100) undergoing echocardiography during January-April 2023 were prospectively studied, with equal numbers by age groups, gender, and GE versus Philips scans. RA strains were quantified using TomTec version 51.02 (Autostrain LA), EchoPAC version 206 (AFI-LA), Velocity-Vector Imaging (VVI) version 2.00, and Epsilon software (5.0.2.11295) for statistical analyses. RESULTS: Overall means and lower limits of normal (LLNs) of each type of RA strain by strain vendor, age group, sex, and scanner vendor were reported. For example, RASr (%) means and LLNs (95% confidence intervals) were 41.2 (38.5, 43.0) and 29.6 (26.5, 32.7) for TomTec, 35.9 (34.4, 37.3) and 27.0 (24.5, 29.5) for EchoPAC, 44.8 (42.3, 47.3) and 27.6 (23.3, 31.9) for VVI, and 38.9 (36.7, 41.0) and 25.5 (21.7, 29.3) for Epsilon, respectively. Linear mixed model regression showed EchoPAC and VVI had significantly lower RASr and higher RAScd magnitude than TomTec, with older age linked to lower RASr and RAScd magnitudes. CONCLUSION: TomTec and VVI were vendor-neutral for measuring RA strains, while EchoPAC worked only on GE scans. Normal values, lower limits of normal, and related factors for RA strain measurements by vendor were established for clinical use.