Validation of three-dimensional echocardiography for quantifying the extent of dyssynergy in canine acute myocardial infarction: Comparison with two-dimensional echocardiography

Objectives. This study was designed to compare the accuracy of three- and two-dimensional echocardiography for quantifying the extent of abnormal wall motion in experimental acute myocardial infarction, as correlated with the pathologic determination of infarct size. Background. Two-dimensional echocardiographic estimations of the fraction of myocardium showing abnormal wall motion are often used as an index of infarct size even though they rely on image plane positioning and geometric assumptions that may not be valid. Three-dimensional echocardiographic reconstruction of the endocardial surface eliminates the need for these assumptions and may improve echocardiographic estimates of infarct size. Methods. Coronary ligation was performed in 14 open chest dogs, and echocardiographic imaging of the ventricle was performed 6 h later. Three-dimensional echocardiography used seven or eight spatially registered short-axis images to measure percent of endocardial surface and mass showing abnormal wall motion. Three two-dimensional echocardiographic methods using multiple, nonspatially registered images were evaluated. One method used seven or eight short-axis slices and a summation of discs algorithm for computing surface area. The second method used the same images and a conical model for the left ventricle. The third used basal, middle and apical short-axis plus apical four- and two-chamber views comparing summed endocardial lengths showing abnormal wall motion with the total of the endocardial dimensions, expressed as percent. The percent of left ventricular mass and surface area infarcted was determined by staining with triphenyltetrazolium chloride. Results. Three-dimensional echocardiographic measurements of endocardial surface area correlated more closely with infarct mass (r = 0.94, SEE ±3.6%) than did the two-dimensional method using the summation of discs algorithm (r = 0.85, SEE ±6.6%), the summation of conical sections algorithm (r = 0.82, SEE ±5.4%) or the method using summed endocardial lengths (r = 0.79, SEE ±7.4%). Limits of agreement analysis comparing mass showing abnormal wall motion with anatomic infarct mass and surface area showing abnormal wall motion with anatomic infarct surface area showed the smallest limits for three-dimensional echocardiography. Conclusions. Three-dimensional echocardiography is a more accurate means of noninvasively estimating myocardial infarct size in this canine model than two-dimensional echocardiography.