Can global longitudinal strain predict reduced left ventricular ejection fraction in daily echocardiographic practice?

BACKGROUND

Transthoracic echocardiography (TTE) is the most commonly used method for measuring left ventricular ejection fraction (LVEF), but its reproducibility remains a matter of controversy. Speckle tracking echocardiography assesses myocardial deformation and left ventricular systolic function by measuring global longitudinal strain (GLS), which is more reproducible, but is not used routinely in hospital practice.

AIM

To investigate the feasibility of on-line two-dimensional GLS in predicting LVEF during routine echocardiographic practice.

METHODS

The analysis involved 507 unselected consecutive patients undergoing TTE between August 2012 and November 2013. Echocardiograms were performed by a single sonographer. Echogenicity was noted as good, moderate or poor. Simple linear regression was used to assess the relationship between LVEF and GLS, overall and according to quality of echogenicity. Receiver operating curve (ROC) analysis was used to identify the threshold GLS that predicts LVEF≤40%.

RESULTS

Mean LVEF was 64±11% and GLS was -18.0±4.0%. A reasonable correlation was found between LVEF and GLS (r=-0.53; P<0.001), which was improved when echogenicity was good (r=-0.60; P<0.001). GLS explained 28.1% of the variation in LVEF, and for one unit decrease in GLS, a 1.45 unit increase in LVEF was expected. Correlations between LVEF and GLS were -0.51 for patients in sinus rhythm (n=490) and -0.86 in atrial fibrillation (n=17). Based on ROC analysis, the area under the curve was 0.97 for GLS≥-14%, allowing detection of LVEF≤40% with a sensitivity of 95% and specificity of 86%.

CONCLUSION

Two-dimensional GLS is easy to obtain and accurately detects LVEF≤40% in unselected patients. GLS may be especially helpful when a suboptimal acoustic window makes LVEF measurement by Simpson's biplane method difficult and in atrial fibrillation patients with low heart rate variability.