Assessment of subendocardial vs. subepicardial left ventricular rotation and twist using two-dimensional speckle tracking echocardiography: comparison with tagged cardiac magnetic resonance

The aim of this article is to evaluate the accuracy and reproducibility of two-dimesional speckle tracking echocardiography (2D-STE) for the estimation of left ventricular (LV) twist, using tagged cardiac magnetic resonance (cMR) as the reference standard, and to assess how much 2D-STE rotational parameters are affected by the level at which measurements are made within the LV. Forty-three patients with various heart diseases and 10 healthy volunteers underwent cMR and 2D-STE on the same day. With both methods, basal and apical time-rotation curves were generated at endocardial, midwall, and epicardial levels. By using the most apical cMR short-axis cross-section as a comparator, apical rotation was significantly underestimated by 2D-STE. When 2D-STE and cMR short-axis cross-sections were matched for their internal dimensions, measurements of endocardial, midwall, and epicardial twists no longer differ between cMR and 2D-STE (12.6 +/- 5.9 vs. 12.5 +/- 5.7 degrees, 10.5 +/- 4.6 vs. 9.7 +/- 4.1 degrees, and 8.9 +/- 4.0 vs. 8.4 +/- 3.7 degrees, respectively, all P = ns). Compared with tagged cMR, 2D-STE underestimates apical rotation and LV twist. This is related to the inability of 2D-STE to image the real LV apex in most of the patients. However, when 2D-STE and cMR data are compared at similar acquisition levels, both techniques provide similar values.