Use of exercise thallium scintigraphy to assess extent of ischaemic myocardium in patients with left anterior descending artery disease.

Open Access
Publisher Website
Google Scholar
Abstract
The extent of jeopardized myocardium in patients with severe left anterior descending disease was examined. The jeopardized myocardium was defined by the number of perfusion defects in the distribution of the left anterior descending artery depicted on exercise 201Tl images. One segment in each of the 3 projections represented the distribution of this vessel, i.e., the anterolateral segments in the anterior projection, the anteroseptal segment in the left anterior oblique projection and the anterior segment in the lateral projection. Forty-five patients with .gtoreq. 70% diameter narrowing in the left anterior descending artery and abnormal exercise images in the distribution of this vessel were selected. There were 17 patients with isolated left anterior descending artery disease and 28 patients with multivessel disease including the left anterior descending artery. Fifteen patients (33%) had 1 perfusion defect (4 patients with isolated disease and 11 patients with multivessel disease); 17 patients (38%) had 2 perfusion defects (6 with isolated disease and 11 with multivessel disease); and 13 patients (29%) had 3 perfusion defects (7 with isolated disease and 6 with multivessel disease). The anteroseptal segment was the most common segment to become ischemic during execise and was abnormal in 40 of the 45 patients (89%). The anterior segment in 27 patients (60%) was next, and the anterolateral segment in 20 patients (44%) the least common. The number of defects did not correlate with the site of disease of the left anterior descending artery (proximal vs. distal to the 1st septal and 1st diagonal branches); the degree of left anterior descending narrowing (70-99% vs. total occlusion); collaterals; left ventricular asynergy; or the presence of isolated left anterior descending disease in contrast with multivessel disease. Variations in the extent of perfusion abnormalities seen in patients with disease of the left anterior descending artery suggest that these patients do not constitute a homogeneous group. Future studies designed to study the effect of medical or surgical treatment in such patients may be more meaningful if the extent of jeopardized myocardium, as defined by exercise 201Tl imaging, is incorporated as a variable in group comparison. Apparently the number of perfusion defects do not predict the site of the lesion of the left anterior descending artery in relation to its 1st septal and diagonal branches.