Abstract 2290: Assessment of Left Ventricular Torsion Using Two Dimensional Speckle Tracking Echocardiography: Comparison with Tagged Cardiac Magnetic Resonance.
Background. LV torsion from helically oriented myofibers is a key parameter of cardiac performance. Until now, LV torsion could only be assessed using tagged cardiac magnetic resonance (cMR). Because of its high spatial and temporal resolution, speckle tracking echocardiography (STE) could be an alternative to cMR. STE offers the opportunity to track myocardial motion independently of both cardiac translation and angle-dependency. The aim of this study was to evaluate the accuracy and reproducibility of STE for the estimation of LV torsion using cMR as the reference standard.
Methods. Ten controls and 43 patients with a variety of cardiac disease underwent cMR and STE on the same day. STE datasets were analyzed using a prototype version of the 2DQ QLab software that allows to track speckles on a frame by frame basis in the endocardium and epicardium, and to derive LV torsion and twisting velocities. Care was taken to analyze cMR and STE data on similar short-axis slices, matched on basis of their end-diastolic internal dimensions. Inter- and intraobserver variabilities were estimated by two blinded observers for 20 patients. In 5 volunteers STE and cMR were repeated twice to assess test-retest reproducibility.
Results. Measurements of endocardial, midwall and epicardial torsion by cMR and STE did not differ significantly from each other (12.6 ± 5.9° vs. 12.5 ± 5.6°, 10.7 ± 4.7° vs. 9.7 ± 4.1°, and 8.9 ± 4.1° vs. 8.5 ± 3.8°, all p=ns) and were highly correlated (r=0.96, 0.88 and 0.79), with only small intertechniques biases (0.11 ± 3.4°, 0.98 ± 4.7° and 0.4 ± 5.28°). Peak twisting velocities, obtained by deriving systolic torsion over time, were also similar between cMR and STE (54 ± 18°/s and 63 ± 23°/s, p=ns) and were highly correlated (r=0.74). The intra- and interobserver agreement for peak LV torsion measurements, assessed by the intraclass correlation coefficient, was equally good for cMR (ICC=0.98 and 0.96; bias 0.3 ± 2.9 and 0.65 ± 3.1°) and for STE (ICC=0.98 and 0.96; bias 0.05 ± 2.8 and 0.13 ± 4.7°). Test-retest reproducibility was also excellent.
Conclusions. Our data show that, compared to cMR, STE allows LV torsion to be accurately and reproducibly measured. This should make LV torsion assessment more available in clinical and research cardiology.