2.3 Strain echocardiography examination
The images were acquired at the left parasternal short axis views, apical long axis, apical four‐chamber, and apical two‐chamber views. All off‐line analyses were performed by an investigator experienced in speckle tracking analysis using the Q-lab workstation version 10.8.5(Phillip Medical Systems). The investigator was blinded to the patient’s management and outcome information. The endocardium was defined by manual tracing and the region of interest (ROI) was adjusted to the compact myocardium thickness. Default settings for smoothing and drift compensation were used. We evaluated longitudinal and circumferential strain. LV longitudinal strain analysis was performed on apical view. Circumferential strain was performed on short-axis views of three segments; basal, mid and apex.Care was taken to ensure that the basal short-axis at the level of mitral valve, and the apical plane distal to the papillary muscle. The region of interest width was adjusted first, to include the entire endocardium. From the analysis, we received 18 regional longitudinal strain (RLS) and circumferential strain (RCS). These allowed us to calculate the segmental longitudinal and circumferential strain and the global longitudinal strain (GLS) and circumferential strain (GCS) as well. Using the same software, the LA endocardial border was traced in the apical 4-chamber view and apical 2-chamber view, care was taken to exclude the appendage and pulmonary veins from the LA cavity. Then, a composite LA longitudinal strain (LAGLS) curve throughout the cardiac cycle was generated. The frame rate of 58 ±3 frames/sec was obtained for the LV and LA strain analysis.