Could strain echocardiography help to assess systolic function in critically ill COVID-19 patients?

Abstract

Strain echocardiography enables the automatic quantification of the global longitudinal strain (GLS), which is a direct measure of ventricular shortening during systole. In the current context of overwhelmed ICUs and clinician shortage, GLS has the advantage to be quick and easy to measure by non-experts. However, little is known regarding its value to assess bi-ventricular systolic function in critically ill COVID-19 patients. Therefore, we designed a study to compare right and left ventricular GLS with classic echo-Doppler indices of systolic function, namely the ejection fraction for the left ventricle (LVEF) and the fractional area change (FAC), the tricuspid annular plane systolic excursion (TAPSE), and the tissue Doppler velocity of the basal free lateral wall (S') for the right ventricle. Eighty transthoracic echocardiographic evaluations done in 30 ICU patients with COVID-19 were analyzed. We observed a fair relationship (r = 0.73, p < 0.01) between LVEF and left ventricular GLS. The GLS cut-off value of - 22% identified a LVEF < 50% with a sensitivity of 63% and a specificity of 80%. All patients with a GLS > - 17% had a LVEF < 50%. Although statistically significant, relationships between FAC (r = 0.41, p < 0.01), TAPSE (r = 0.26, p < 0.05) and right ventricular GLS were weak. S' was not correlated with right ventricular GLS. In conclusion, left ventricular GLS was useful to assess left ventricular systolic function. However, right ventricular GLS was poorly correlated with FAC, TAPSE and S'. Further studies are needed to clarify what is the best method to assess right ventricular systolic function in ICU patients with COVID-19.

Keywords: COVID-19; Echocardiography; Global longitudinal strain; Point-of-care ultrasound; Speckle tracking; Systolic function.

Fig. 1

Top: Example of left ventricular (LV) global longitudinal strain (GLS) echocardiographic image and measurement. Bottom: Correlation between LV ejection fraction (LVEF) and LV GLS

Fig. 2

Left: Example of right ventricular (RV) global longitudinal strain (GLS) echocardiographic image. Right: Correlations between the right ventricular fractional area change (FAC), the tricuspid annular plane systolic excursion (TAPSE) and RV GLS