Global longitudinal strain: clinical use and prognostic implications in contemporary practice
Rachid Abou, Pieter van der Bijl, Jeroen J. Bax, Victoria Delgado
Abstract
### Learning objectives Non-invasive evaluation of left ventricular (LV) systolic function by echocardiography remains one of the most pivotal measures in clinical cardiology. Although conventionally quantified by means of LV ejection fraction (LVEF), it has become evident that this parameter is subject to a number of limitations. LVEF can be normal in the presence of impaired LV systolic function, since it does not reflect intrinsic myocardial contractility.1 In addition, LVEF is highly load-dependent and suffers from significant intraobserver and interobserver variability.2 Assessment of myocardial strain can potentially overcome many of the limitations of LVEF in assessing LV systolic function. Speckle tracking echocardiography permits assessment of myocardial strain in three spatial directions (longitudinal, radial and circumferential) independent of the angle of insonation of the ultrasound beam. Longitudinal strain is probably the most frequent type of strain used to characterise LV systolic function in clinical practice. This review article focuses on the practical aspects of measuring LV global longitudinal strain (GLS), reviews the clinical implications of impaired LV GLS strain and provides a glimpse into the future clinical applications of this technology. The LV myocardium consists of two helical, opposing layers of myocardial fibres (endocardial/right-handed and epicardial/left-handed) surrounding a circumferential, mid-ventricular layer. When these layers contract, the myocardium shortens in the longitudinal and circumferential directions and thickens in the radial direction (figure 1). The introduction of speckle tracking echocardiography has allowed for a more comprehensive analysis of LV systolic function when compared with LVEF by assessing myocardial deformation in these three directions. …