Left Atrial Strain Parameters
2D grayscale images of three cardiac cycles from apical four-chamber views were obtained with the help of conventional ultrasound, with a frame rate of 60–90 frames/s. The lateral and septal walls of the LA were continuously imaged without important dropouts. Two experienced cardiologists who were blinded to the study groups carried out the examinations. In order to calculate the strain rate and the LA strain, the off-line EchoPAc workstation was used by the researchers. As a reference point, the LA 2D-STE curves were acquired using the R-wave onset of the electrocardiogram. Following the manual definition of the endocardial border, the software automatically developed the tracing for each view. When the automatically acquired tracking segments were sufficient for the analysis, the researchers allowed the software to read the data. For insufficient tracking segments, manual adjusting or software parameters changing were performed.
As the average of six segmental values, strain rate parameters and global LA strain were evaluated. QRS onset speckle-tracking echocardiography analysis for LA; LA peak strain prior to mitral valve opening was taken as LA reservoir (LA-Res), and LA strain prior to atrial contraction (onset of the P-wave on electrocardiography) was taken as LA-conduit. LA strain rate throughout ventricular systole (LA-SRs), LA-SRe throughout ventricular passive filling and LA-SRa throughout active atrial contraction were measured as LA function parameters.