Strain analysis:
We assessed strain parameters by speckle-tracking echocardiography. LV global longitudinal strain (GLS) was computed from apical four-chamber, two-chamber, and long-axis views using the 18-segment model.26 GLS was defined as the peak negative strain during systole.
LA strain was obtained from LA-focused apical four-chamber 2D views at frame rates >60 frames per second. The LA border was traced along the endocardium from one side of the mitral annulus to the other, and a region of interest was automatically defined, then adjusted manually as recommended to fit the thickness of the LA wall.27 The software divided the LA into six segments, scoring tracking quality with the possibility of manual correction. Zero strain reference was set at LV end-diastole, defined by the frame prior to mitral valve closure. LA strain values were computed as the average of accepted atrial segments averaged over three heart cycles and stated as LA reservoir strain (LASr), LA conduit strain (LAScd), and LA contractile strain (LASct).27 SD-TPS was calculated as the mean value of the time-to-peak strain in the six atrial segments. SD-TPS was calculated separately in three consecutive loops, and an average of these values is reported. In addition to crude SD-TPS in ms, SD-TPS was also corrected by the cycle length and expressed as a percentage of the cardiac cycle SD-TPS (%) = (\(\frac{SD-TPS(ms)}{Cycle\ length(ms)}\ X\ 100\)). A higher value of SD-TPS reflects a higher degree of LA MD (Figure 2).