Measurement of Left Ventricular Indices
In terms of the methodology for echocardiographic imaging, the majority of studies followed recommendations from the American Society of Echocardiography (11), with two studies following recommendations from the European Association of Cardiovascular Imaging (12), for two-dimensional echocardiographic measurements including LVEDD and LVEF. LV-GLS was measured using software from different vendors including TomTec Imaging systems, GE Echopac workstation, X-Strain and Syngo Vector Imaging which increased the variability of absolute strain values. All studies had reported mean LV-GLS values derived from offline measurements made in the standard three apical views by at least two operators. Despite different software used, all algorithms for strain assessment appeared to utilise similar approaches where the endocardial borders were manually traced throughout the cardiac cycle. Longitudinal strain was assessed in all 17 longitudinal LV segments, and the segmental values were averaged to give the mean LV-GLS.