Echocardiographic measures of myocardial deformation by speckle-tracking technologies: The need for standardization?

Background: Multiple vendor-specific two-dimensional speckle-tracking echocardiographic algorithms with which to characterize myocardial mechanics are commercially available. The purpose of this study was to compare global longitudinal strain (GLS) results between two independent software vendors using a neutral image platform. Methods: A convenience sample of 100 prospectively collected patients was evaluated. Subjects with more than two left ventricular endocardial segments poorly delineated were excluded. GLS was obtained from the apical four-chamber, three-chamber, and two-chamber views using two independent speckle-tracking echocardiographic software packages (EchoInsight version 1.5.0 and Image-Arena version 4.5). Linear regression analysis and paired t tests were used to compare GLS results. Intraclass correlation coefficients and Bland-Altman plots were used for assessments of reliability. Results: The "out-of-the-box" mean GLS was -12.99 ± 2.38% using EchoInsight and -16.87 ± 2.84% using Image-Arena (mean difference, 3.87 ± 2.42%; P =.0001). Agreement between the software packages was moderate (intraclass correlation coefficient, 0.43; 95% confidence interval, 0.32-0.55). Using uniform variables to derive GLS (Lagrangian strain measured in systole and diastole at the endocardium and averaging the peak segmental strain curves), EchoInsight GLS was -16.17 ± 2.90% and Image-Arena GLS was -16.87 ± 2.84% (mean difference, 0.70 ± 2.75%; P =.02), with an intraclass correlation coefficient of 0.70 (95% confidence interval, 0.52-0.79). Conclusions: Image-Arena GLS results were consistently different (more negative) than EchoInsight measures out of the box but became similar when information used to derive GLS was uniform. The evolution of measures of myocardial mechanics into routine clinical practice will require vigilance and standardization of the various techniques, necessitating independent validation of commercially available speckle-tracking echocardiographic products.