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

Abstract

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 (Scirc) and radial (Srad) strains to infarct-induced left ventricular (LV) remodeling and scarring of the LV in a rat. To assess the relationship among Scirc, Srad, and scar size, two-dimensional echocardiographic LV short-axis images (12 MHz transducer, 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 from histological LV cross sections stained by Masson trichrome. Ten normal rats served as echocardiographic controls. Scirc and Srad were assessed by STE. Histological data showed consistent scarring of anterior and lateral segments with variable extension to posterior and inferior segments. Both Scirc and Srad significantly decreased after myocardial infarction ( P < 0.0001 for both). As anticipated, Scirc and Srad were lowest in the infarcted segments. Multiple linear regression showed that segmental Scirc were similarly dependent on segmental fibrosis and end-systolic diameter ( P < 0.0001 for both), whereas segmental Srad 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.