One strain to rule them all? Inter-vendor variability in global longitudinal strain—progress made, challenges remain

This editorial refers to ‘Vendor differences in 2D-speckle tracking global longitudinal strain: an update on a 10-year standardization effort’, by A. Balinisteanu et al., https://doi.org/10.1093/ehjci/jeaf155. More than a decade ago, the European Association of Cardiovascular Imaging (EACVI) and the American Society of Echocardiography (ASE) launched an ambitious effort: to bring echocardiographic strain into reproducible, vendor-neutral clinical practice. At the time, global longitudinal strain (GLS) was gaining traction as a sensitive biomarker of myocardial function, outperforming ejection fraction in detecting subtle dysfunction across conditions like cardio-oncology, cardiomyopathies, and valvular disease. Yet enthusiasm was tempered by a nagging problem: significant variability in GLS values across software platforms and vendors. Without standardization, clinicians and researchers faced inconsistent thresholds and questionable reliability in longitudinal follow-up data. The landmark 2015 inter-vendor study by the EACVI-ASE Strain Standardization Task Force revealed a bias of up to 3.7% strain units between platforms—a gap too wide for clinical comfort.1 For a parameter with a normal reference range of −16% to −24%,2 such variability was far from trivial, especially because the relative impact of bias becomes more pronounced in the lower range, where clinical decisions are often made. This prompted a collaborative effort to harmonize measurement techniques and promote interoperability. In the years since, the task force has issued technical consensus documents, coordinated collaborative studies, and encouraged adoption of standardized definitions and protocols.3