Global Longitudinal Strain (GLS) Calculator

Global Longitudinal Strain (GLS): Explanation and Clinical Context Global Longitudinal Strain (GLS) by speckle-tracking echocardiography measures the percentage deformation (shortening) of the left ventricular myocardium in the longitudinal direction during systole. GLS is reported as a negative percentage (for example, −20% represents greater shortening than −15%) and is a sensitive measure of longitudinal systolic function that often detects subclinical dysfunction earlier than left ventricular ejection fraction (LVEF). GLS values vary by vendor, software version, age, sex, and loading conditions; therefore comparisons should ideally be performed with the same acquisition and analysis pipeline.

Contemporary guideline/consensus thresholds commonly used in adults designate GLS magnitude >18% (i.e., GLS < −18%) as normal, 16–18% as borderline, and <16% (i.e., GLS > −16%) as abnormal or reduced — thresholds meant for clinical interpretation with the caveats noted above. Several large cohort studies and meta-analyses have shown that progressively less negative (worse) GLS is associated with higher risk of adverse outcomes (including mortality, heart failure hospitalization and cardiotoxicity), with many analyses reporting an approximate relative change in hazard per 1% absolute worsening of GLS (often in the range of ~4–12% per 1% depending on the cohort and endpoint). These associations support the complementary prognostic value of GLS beyond LVEF in multiple clinical settings, but absolute risk estimates should be individualized and used alongside clinical context, biomarkers, and other imaging parameters.