Abstract 2574: Accuracy of Apical Rotation by Two-dimensional Speckle Tracking Echocardiography is Influenced by Apical Slice Location.
Background : During the cardiac cycle, there is a systolic twist and an early diastolic untwist about LV long axis, because of opposite rotation of the basal and apical segments. Previous studies showed that speckle tracking echocardiography (STE) allows to measure the rotation of these segments and thereby to assess global LV torsion. Unfortunately, STE does not always allow visualization of the real apex, thus raising concerns about the reliability of LV torsion data using this approach.
Methods : We compared LV apical rotation by tagged magnetic resonance (cMR) and STE in 30 patients with normal regional and global systolic function. With cMR, rotation was measured on serial contiguous 10 mm thick short-axis (SAX) sections, whereas with STE, it was only obtained on the most apical available SAX section. cMR and STE were compared using either the most apical cMR SAX slice or the cMR slice that best matched the end-diastolic internal dimensions of the available STE slice.
Results : LV rotation measured by cMR decreased from apex to base (Fig 1⇓). When using the best matched cMR SAX slice, cMR and STE were well correlated (r=0.7, Fig 2⇓, black dots). By contrast, when using the most apical cMR SAX slice, the correlation between cMR and STE was lost (Fig 2⇓, white dots). By comparing end-diastolic internal dimensions, the level of the STE slice was found to be at the real apex in 10% of pts, and at 10, 20 and 30 mm below the apex in 27%, 50% and 13% of pts, respectively.
Conclusion : Although STE allows to measure LV apical rotation, it rarely does so at the level of the real apex. This results in an almost systematic and mostly unpredictable underestimation of apical rotation.