Inter-vendor variability in two-dimensional speckle tracking strain: a ten-year follow-up on the strain standardization task force inter-vendor comparison study
Authors: Balinisteanu A E , Duchenne J , Puvrez A , Wouters L , Bezy S , Youssef A , Minten L , Bekhuis Y , Papangelopoulou K , Cieplucha A , Cattapan I , Tostes P , Vinereanu D , Voigt J U 
Published: January 2025

Abstract

Background
Global longitudinal strain (GLS) derived from two-dimensional speckle-tracking echocardiography is feasible and accurate. However, in 2013, the landmark first Inter-Vendor Comparison Study showed significant differences of GLS results among vendors, providing a baseline for ongoing standardization efforts. In order to make tracking-based strain imaging a clinically accepted and useful parameter, it is of utmost importance to have interchangeable and accurate measurements from all vendors. This is a report of the EACVI Strain Standardization Task Force.

Purpose
To assess the current inter-vendor variability and reproducibility, to compare our results to the findings from 2013, and to identify potential improvements and convergence of GLS measurements during the past ten years.

Methods
372 echocardiographic examinations were performed in sixty-two subjects (50 male, age 56.1 ± 16.98) with a wide range of left ventricular (LV) function (ejection fraction from 30% to 64%) using ultrasound systems from six manufacturers. Each subject was scanned consecutively on all machines by a single assigned sonographer. For each subject, two sets of LV apical views were acquired in order to assess reproducibility in a true test-retest setting. We assessed mean GLS (GLSAV) as average peak systolic global strain from the three apical views on four vendor-specific and five vendor-independent software solutions. Three vendors provided old or research-use-only software solutions. Since there is no gold standard for GLS measurements in patients, we compared GLSAV of each vendor to the average of the GLS values from vendors that provided the latest version of their CE-marked clinical tracking software solutions (SWS). In contrast to 2013, we now measured both endocardial and mid/full-wall GLS as most companies provide now both parameters.

Results
Both endocardial and mid/full-wall GLS measurements from clinical SWS were comparable and within a very narrow range (maximum inter-vendor bias of 0.9% strain units). In 2013, the maximum absolute difference among clinical SWS providers was 3.7 % strain units. GLSAV of each software versus the mean of clinical SWS (Figure 1, Figure 2) showed significant correlation for most of the companies (r2 &gt;0.8, p&lt;0.001). Reproducibility of both mid/full and endocardial GLS was good, except for one company (relative mean error 6.7% and 6.3%, resp.) The latter was comparable to the findings from 2013.

Conclusions
In contrast to the situation ten years ago, there is substantial improvement in inter-vendor bias, with good agreement for companies that provide SWS for clinical use. In addition, most companies now allow mid/full-wall tracking, which had similarly good inter-vendor bias and reproducibility as endocardial GLS. Our data indicate that the efforts of the Strain Standardization Task Force have been fruitful. A continuing effort is needed until all software providers adhere to the task force consensus recommendations.
Figure 1
Figure 2