Head-to-Head Comparison of Global Longitudinal Strain Measurements among Nine Different Vendors The EACVI/ASE Inter-Vendor Comparison Study

Background: This study was planned by the EACVI/ASE/Industry Task Force to Standardize Deformation Imaging to (1) test the variability of speckle-tracking global longitudinal strain(GLS) measurements among different vendors and (2) compare GLS measurement variability with conventional echocardiographic parameters. Methods: Sixty-two volunteers were studied using ultrasound systems from seven manufacturers. Each volunteer was examined by the same sonographer on all machines. Inter- and intraobserver variability was determined in a true test-retest setting. Conventional echocardiographic parameters were acquired for comparison. Using the software packages of the respective manufacturer and of two software-only vendors, endocardial GLS was measured because it was the only GLS parameter that could be provided by all manufactures. We compared GLS(AV) (the average from the three apical views) and GLS4(CH) (measured in the four-chamber view) measurements among vendors and with the conventional echocardiographic parameters. Results: Absolute values of GLS(AV) ranged from 18.0% to 21.5%, while GLS4(CH) ranged from 17.9% to 21.4%. The absolute difference between vendors for GLS(AV) was up to 3.7% strain units (P < .001). The interobserver relative mean errors were 5.4% to 8.6% for GLS(AV) and 6.2% to 11.0% for GLS4(CH), while the intraobserver relative mean errors were 4.9% to 7.3% and 7.2% to 11.3%, respectively. These errors were lower than for left ventricular ejection fraction and most other conventional echocardiographic parameters. Conclusion: Reproducibility of GLS measurements was good and in many cases superior to conventional echocardiographic measurements. The small but statistically significant variation among vendors should be considered in performing serial studies and reflects a reference point for ongoing standardization efforts.