BACKGROUND: Two-dimensional echocardiography is useful for estimating the extent of infarct-related wall motion abnormalities. Such estimation, however, is based on a few selected views and extrapolated for the whole left ventricle (LV). This approach does not provide us with the actual amount of dysfunctional myocardium. Volume-rendered three-dimensional echocardiography (3DE) might overcome these limitations. In this study we explored (1) how well volume-rendered 3DE delineates regional dysfunction of the infarcted LV and (2) how well dysfunctional myocardial mass quantified by 3DE reflects the actual anatomic infarct mass. METHODS AND RESULTS: 3DE was performed before and 3 hours after coronary occlusion in 16 dogs. With the LV viewed in equidistant short-axis slices, the region of dysfunction was demarcated, and the dysfunctional myocardial mass was derived from this. With triphenyltetrazolium chloride staining, anatomic infarct regions were delineated, dissected, and weighed. The anatomic infarct mass was 16.3+/-7.7 g (mean+/-SD) (range, 6.4 to 31.4 g); the dysfunctional mass estimated by 3DE was 17.4+/-9.1 g (range, 5.2 to 39.0 g). The mean difference was 1.0 g. The correlation between dysfunctional mass (y) and infarct mass (x) was y=l.lx-0.6, r=.93 (P<.0001). The percentage of LV involved in infarction was 18.2+/-5.8% (range, 9.1% to 26.1%); the percentage of LV involved in regional dysfunction was 18.3+/-6.9% (range, 7.9% to 31.2%). The mean difference was 0.1%. The correlation between percentage of LV involved in infarction (x) and percentage of LV involved in dysfunction (y) was y=1.0x-1.1, r=.92 (P<.0001). CONCLUSIONS: Volume-rendered 3DE crisply displays regional dysfunction of infarcted LV. 3DE-measured dysfunctional mass accurately reflects the anatomic infarct mass.