Abstract 6119: Ultrasound 2D Speckle Tracking Differentiates Stunned from Scarred Myocardium after Acute MI

Abstract

Background: The aim of this study was to evaluate 2D Speckle Tracking radial strain by ultrasound in stunned and scarred myocardium as defined by cardiac magnetic resonance (CMR) in a porcine reperfusion model of acute MI. Methods: Seven pigs underwent MI induction by 90′ mid-LAD balloon occlusion. CMR was performed in a 1.5 T magnet 4 days post-MI. For edema imaging a T2-weighted sequence was employed. Delayed enhancement (DE) images were acquired 10–15 minutes after the administration of 0.2 mmol/kg of Gd-DTPA using an inversion recovery gradient-echo sequence. Before CMR, echocardiographic short axis images of the LV were obtained at the basal, mid and apical levels. Echo and CMR images were matched and divided into 6 segments per slice. DE and edema were defined as those regions with signal intensity >3 SD of the mean signal of remote normal myocardium, and quantified as % of the LV. Stunned myocardium was defined as edema- DE. Radial strain was compared in segments containing predominantly normal myocardium (<10% edema; n=70), stunned myocardium [>25% (edema - DE); n=12] or predominantly scar (>75 % DE; n=19). Results: A total of 126 segments were analyzed. Radial strain was negatively correlated with the amount of edema (r=−0.41) and scar (r=−0.39, p<0.0001 for both). Radial strain was significantly lower in necrotic than in normal segments (p<0.001). Stunned segments showed intermediate degrees of myocardial deformation. (Figure ) Conclusions: Our study suggests that 2D Speckle Tracking radial strain can be a simple tool to differentiate stunned from scarred segments. This could be particularly useful in unstable patients after acute MI.