2D- Speckle Tracking Strain Data
STE was conducted according to the recommendations of the American Society of Echocardiography and the European Association of Cardiovascular Imaging 16. Apical 4-, 3-, 2- chamber views for longitudinal deformation parameters of LV and parasternal short axis (PSAX) views from base to apex for circumferential deformation parameters of LV were obtained and stored for offline analysis in three consecutive cycles. Strain measurement was assessed offline from obtained 2D echocardiographic images using dedicated software with frame rates of ≥ 60 frame per second. Firstly, apical 3- chamber (A3C) was selected to determine aortic valve closure time. Endocardial and epicardial border were tracked automatically for A3C, and then automatic tracking of endocardial and epicardial borders were checked carefully. Furthermore, endocardial-epicardial tracking and analysis were performed for both apical 4- chamber (A4C) and apical 2- chamber (A2C). 2D-peak longitudinal systolic strain, peak longitudinal systolic strain rate (SRS), longitudinal early diastolic strain rate (SRE) and longitudinal late diastolic strain rate (SRA) were analyzed for the 17 segments from all of the apical views. The result of analysis was shown as either bullseye map (Figure 1A) and longitudinal strain, strain rate (SR) curves (Figure 1B, 1C). For circumferential strain analysis, apical, mid and basal PSAX views were selected. Endocardial and epicardial border were traced automatically for each segments and then contour tracing was checked and confirmed. The software calculated automatically circumferential systolic strain, circumferential peak SRS, circumferential SRE and circumferential SRA for each 16 segments from entire transmural LV of PSAX views. Like longitudinal strain analysis, the results of circumferential strain analysis was presented in a bullseye map or strain /SR curves.