Altered acoustic reflectance on two-dimensional echocardiography as an early predictor of myocardial infarct size.

P6 area of increased acoustic reflectance was readily observed by 2-dimensional echocardiography (2-D echo) in the acutely ischemic canine myocardium. Fifteen mongrel dogs subjected to closed-chest coronary artery occlusion were used to test the hypothesis that these areas of altered acoustic reflectance were predictors of subsequent myocardial infarction (MI). Each dog was studied by 2-D echo in short-axis views of the left ventricle at 4 levels before and after coronary artery occlusion. The dogs were killed after 48 hours and heart sections were stained with triphenyltetrazolium chloride to identify the areas of necrosis. Four sections were then selected, approximating the same location within the left ventricle as the short-axis views taken for 2-D echocardiographic analysis. The in vivo 2-D echocardiographic examination revealed alteration of acoustic reflectance immediately after coronary occlusion, which detected the presence of MI with a sensitivity of 92% and a specificity of 90%. The extent of altered acoustic reflectance seen by echo correlated closely (r = 0.81) with the extent of MI detected by triphenyltetrazolium staining of the excised heart. Altered acoustic reflectance seen by 2-D echo immediately after coronary artery occlusion reflects acute ischemic changes and may be an early predictor of MI size.