Echocardiographic Examination
Comprehensive transthoracic echocardiography was performed using Philips IE 33 system (Philips Medical Systems, Bothell, WA, USA). Images were stored and analyzed using Syngo software platform (Siemens Medical Solutions, MI, US). Standard echocardiographic parameters of left atrial volume; LV size and systolic and diastolic function; LVOT and aortic valve (AV) gradients and AV area were measured by the primary reader (AC) under the guidance of an experienced echocardiographer (JG) according to the recommendations of American Society of Echocardiography (ASE) guidelines13,14.
For left ventricular global longitudinal strain analysis (GLS), Tomtec Cardiac Performance Analysis version 1.3.0.91 was used (Unterschliessheim, Germany). The software detects lateral and septal walls and divides each into three segments (basal, mid, and apical) to calculate the strain via speckle tracing. An average strain for entire LV in apical four chamber, apical two chamber, and apical three chamber views were used to calculate the GLS. Strain measurement was accepted after visual inspection and when the software demonstrated adequate tracking. If tracking was suboptimal, the endocardial border was manually retraced. Ten subjects were randomly selected to calculate the interobserver variability between the measurements of two independent investigators (AC, JG). Both investigators were blinded to each result.