Speckle-tracking analysis based on 2D echocardiography does not reliably measure left ventricular torsion

Purpose Worldwide left ventricular (LV) twist is measured by 2D speckle tracking acquiring apical short axis at a LV level where papillary muscles are no longer visible; however, we hypothesized that this methodological recommendation is not enough accurate to obtain a reliable measurement of apical rotation. Methods We measured twist and untwist rate in 30 healthy subjects by following the earlier method. By 3D echocardiography, we identified two LV apex levels: (i) 3D Apex, defined as the last apical slice at which LV cavity was visible; (ii) 2D Apex, defined as the level where diameters are equal to those of apical LV short axis used for twist analysis in the same subject. The ratio between the distance of 2D Apex and 3D Apex from LV base was calculated and expressed as percentage (2D Apex/3D Apex). Results 2D Apex/3D Apex was strongly related to the magnitude of twist and untwisting rate (r=0 center dot 82, P<0 center dot 001; r=0 center dot 46, P=0 center dot 015, respectively). The only determinant of twist was 2D Apex/3D Apex (r2=0 center dot 68; r=0 center dot 82; F ratio: 52 center dot 6, P<0 center dot 001); whereas untwisting rate was influenced by 2D Apex/3D Apex and age (r2=0 center dot 42; r=0 center dot 65; F ratio: 7 center dot 7; P=0 center dot 003 for 2D Apex/3D Apex; and P=0 center dot 011 for age). Conclusions Left ventricular apical level acquisition, even when recorded in a standard manner, determines variability of twist mechanics measurements. Thus, current anatomical markers used to identify LV apex for twist analysis are not reliable and need different standardization. 3D echocardiography may help in such standardization.