Speckle-tracking echocardiography correctly identifies segmental left ventricular dysfunction induced by scarring in a rat model of myocardial infarction

Speckle-tracking echocardiography (STE) uses a two-dimensional echocardiographic image to estimate two orthogonal strain components. The aim of this study was to assess Sensitivity Of circumferential (S-circ) and radial (S-rad) strains to infarct-induced left ventricular (LV) reniodeling and scarring of the LV in a rat. To assess the relationship among S-circ, S-rad. and scar- size, two-dimensional echocardiographic LV short-axis images (12 MHz transducers, Vivid 7 echo machine) were collected in 34 Lewis rats 4 to 10 wk after ligation of the left anterior descending artery. Percent segmental fibrosis was assessed front histological LV cross sections stained by Masson trichrome. Ten normal rats served as echocardiographic Controls. S-circ, and S-rad were assessed by STE. Histological data showed consistent scarring of anterior and lateral segments with variable extension to Posterior and inferior segments. Both S-eire and S-rad significantly decreased after invocardial infarction (P < 0.0001 for both). As anticipated S-circ and S-rad were lowest in the infarcted segments. Multiple linear regression showed that segmental S-circ were similarly dependent on segmental fibrosis and end-systolic diameter (P < 0.0001 for both), whereas segmental S-rad measurements were more dependent on end-systolic diameter (P < 0.0001) than on percent fibrosis (P < 0.002). STE correctly identifies segmental LV dysfunction induced by scarring that follows myocardial infarction in rats.