Abstract 3147: Speckle Tracking Echocardiography Correctly Identifies Segmental Left Ventricular Dysfunction Induced By Scarring In A Rat Model Of Myocardial Infarction
Background: Speckle tracking echocardiography (STE) uses 2-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 remodeling and scarring of the left ventricle (LV) in a rat.
Methods: To assess relationship Scirc, Srad, and scar size, 2-dimensional echocardiographic LV short-axis images (12 MHz transducer, Vivid 7 echo machine) were collected in 25 Lewis rats 6 weeks after ligation of the left anterior descending artery and two sham-treated rats. Segmental fibrosis percent (%Fibrosis) was assessed from histologic LV cross-sections stained by Masson-trichrome. Six normal rats served as echocardiographic controls. Scirc and Srad were assessed by STE using Echopac PC software.
Results: Histologic data showed consistent scarring of anterior and lateral segments with variable extension to posterior and anteroseptal segments. Both Scirc and Srad significantly decreased after MI (p < 0.0001 for both), with decrease more significant in the MI regions than in the border zone or remote regions (p < 0.0001 vs. MI regions for both)(Figure⇓). Multiple regression showed that segmental Scirc were equally dependent on %Fibrosis and end-systolic diameter (p < 0.0001 for both), while segmental Srad were more dependent on end-systolic diameter (p < 0.0001) than on %Fibrosis (p = 0.01).
Conclusion: Speckle tracking echocardiography correctly identifies segmental left ventricular dysfunction induced by scarring in a rat model of myocardial infarction.