743-2 Superiority of 3D Echo vs 2D Echo for Quantitating Wall Motion Abnormality as an Index of Myocardial Infarction Size

Two-dimensional echo estimations of the fraction of myocardium showing abnormal wall motion (AWM) are often used as an index of infarct size, to establish prognosis and guide therapy. However 2D echo methods rely on image plane and geometric assumptions which may not be valid when infarction affects ventricular shape. 3D echo reconstruction of the endocardial surface can eliminate the need for these assumptions. Purpose; To use 3D echo and 2D echo to quantitate AWM in experimental acute infarction, and to correlate the extent of AWM with the pathologic determination of infarct size.MethodsCoronary ligation was performed in 14 open chest dogs, and echo imaging performed after 6 hours. 3D echo used 7–8 spatially registered short axis cross-sections to measure % of endocardial surface showing AWM. Two 2D echo methods using multiple, non-spatially registered images were evaluated. Both compared summed endocardial length showing AWM to the total of the endocardial circumferences, expressed as %. Method #1 used 7-8 short-axis slices. Method #2 used basal, mid, apical short axis + apical 4-and 2-chamber views. Percent LV mass (% mass) infarcted was determined by a standard technique.Resultsregression of [x = echo %AWM] vs [y = %mass infarcted]Echo Methodr valueStandard Error of the EstimateEquationp value3D0.94±2.6%y =0.71x-1.81%<0.000120-#10.82±4.3%y =0.50x-0.66%0.001520-#2074±5,1%Y =0.47x-1.25%0.0058ConclusionThree-dimensional echocardiography is a more accurate means of non-invasively estimating myocardial infarct size in this animal model, compared to 2D echo methods