Echocardiographic Evaluation of Myocardial Function in Standardbreds During the First Year of Race Training

Several studies have shown the effect of training on myocardial deformation parameters in human athletes. The aim of this prospective, longitudinal study was echocardiographic evaluation of myocardial velocities and deformation in horses during the first year of training. Twelve Standardbred yearlings were examined using tissue Doppler imaging (TDI) and two-dimensional speckle tracking (2D-ST) during the first year of race training (short axis of left and right ventricle). The first examination was performed before the beginning of training (n = 12). At the last time point, horses were fully trained and had participated in their first races (n = 10). Radial myocardial velocities were evaluated using color (c-) and pulsed-wave (PW-)TDI in the left ventricular free wall, the interventricular septum (IVS) and the right ventricular free wall from a right parasternal short-axis image. Strain and strain rate were evaluated using 2D-ST in the LW and IVS using offline analysis of the 2D grayscale images. The radial, systolic myocardial velocities in the left ventricle (LVFW) increased significantly over the year in both c- and PW-TDI. In addition, the early diastolic velocity in the LW (in cTDI) and IVS (in c- and PW-TDI) and the systolic velocity in the IVS (in cTDI) increased significantly. The 2D-ST revealed significant increases of the radial systolic and early diastolic strain rate in the IVS and of the late diastolic strain rate in the LW. Training and aging/growing had both an impact on echocardiography.