From the Guidelines
Global longitudinal strain (GLS) on echocardiography checks for subtle abnormalities in heart muscle function, specifically measuring the percentage of shortening of the left ventricular myocardium throughout the cardiac cycle, providing an early and sensitive indicator of cardiac dysfunction. GLS works by tracking the movement of speckles in the myocardium using specialized software that analyzes how heart muscle fibers deform during contraction and relaxation, as described in the study by 1. This technique is particularly valuable for detecting subclinical cardiac damage in patients receiving cardiotoxic chemotherapy, those with hypertension or diabetes, and for early identification of cardiomyopathies before obvious symptoms develop, as supported by the findings of Sawaya et al 1 and Negishi et al 1.
The normal GLS values typically range from -18% to -22%, with less negative values indicating impaired function, and a ≥11% relative reduction in GLS is predictive of subsequent trastuzumab-associated cardiotoxicity, as shown in the study by Negishi et al 1. GLS is also advantageous because it's less dependent on loading conditions than ejection fraction and can detect dysfunction in hearts that appear to have normal overall pumping ability. Furthermore, the European Association of Cardiovascular Imaging recommends obtaining and reporting speckle tracking-derived GLS to provide quantitative analysis of LV longitudinal function, as stated in the expert consensus document by 1.
Some key points to consider when interpreting GLS results include:
- GLS <19% is predictive of subsequent cardiotoxicity, as demonstrated by Sawaya et al 1
- A 10% to 15% early reduction in GLS during therapy appears to be the most useful parameter for the prediction of cardiotoxicity, as discussed in the study by 1
- GLS can detect early myocardial changes during therapy, as consistently shown in a meta-analysis 1
- Abnormalities in strain parameters can also be seen several years after a cardiotoxic exposure, highlighting the importance of long-term monitoring, as reported in the study by 1.
From the Research
Global Longitudinal Strain on ECHO
- Global longitudinal strain (GLS) is a measure of left ventricular (LV) function that can be assessed using speckle-tracking echocardiography 2, 3, 4, 5, 6.
- GLS measures the deformation of the myocardium in the longitudinal direction, which can be used to detect LV dysfunction even in patients with preserved LV ejection fraction 2, 4.
- Studies have shown that GLS is closely correlated with LV ejection fraction (EF) and can be used to predict outcomes in patients with aortic stenosis and other cardiovascular diseases 3, 4.
- GLS can also be measured from contrast-enhanced echocardiographic images, which can be useful in patients with poor image quality 5.
- Abnormal GLS values have been associated with myocardial fibrosis and can be used to risk-stratify patients with aortic stenosis and preserved LVEF 4.
- GLS has also been used to detect LV dysfunction in long-term adult survivors of childhood lymphoma and acute lymphoblastic leukemia, even in those with apparently normal LV function 6.
Clinical Applications of GLS
- GLS can be used to guide heart failure management and to assess the effectiveness of treatments 2, 4.
- GLS can also be used to predict outcomes in patients with cardiovascular disease and to identify those at high risk of adverse events 3, 4.
- The use of GLS in clinical practice can help to improve patient outcomes and to reduce the risk of cardiovascular events 2, 3, 4, 5, 6.
Measurement of GLS
- GLS can be measured using speckle-tracking echocardiography, which involves tracking the movement of speckles in the myocardium over time 2, 3, 5.
- GLS can also be measured using feature-tracking cardiac magnetic resonance imaging (CMR) 3, 4.
- The measurement of GLS requires specialized software and expertise, but it can be performed in a clinical setting using standard echocardiography or CMR equipment 2, 3, 4, 5, 6.