Indications for coronary revascularization and the postoperative evaluations using Tl-201 exercise myocardial scintigraphy and a bull's eye display

Tl-201 exercise myocardial scintigraphy and quantitative analysis using bull's eye display were performed in 31 cases (18 bypass cases, 13 PTCA cases) to determine the indications for coronary artery bypass surgery and PTCA, and to evaluate postoperative improvement. Regions of interest (ROI) corresponding to each revascularized area were created on a bull's eye display. Then the washout rates (WR) and % uptakes were expressed as percentages. Improvement was judged to have occurred if the revascularized coronary artery was patent and both the WR and % uptake returned to the normal range as determined from the examinations of 20 normal cases. The results were as follows : 1. The preoperative mean WR of the improved areas (30 vessels) was 19 ± 15 %, while that of the unimproved areas (15 vessels) was 35 ± 7 %. We assumed that the area was suitable for revascularization when the preoperative WR was less than 25 % which was in the lower limit of the normal range. Then, 18 vessels were judged to be suitable for surgery, and subsequent postoperative improvement was obtained in the 17 areas. 2. In 32 scintigraphically-improved areas, 30 vessels were angiographically patent, while five vessels were obliterated angiographically in 13 scintigraphically-unimproved areas (diagnostic validity was 76 % of all 45 vessels). 3. The exercise tolerance increased significantly (p < 0.01) from 8.7 ± 2.0 min to 11.6 ± 2.5 min in the improved cases in which all the revascularized areas were improved after revascularization. There was no change of the exercise tolerance (before: 9.4 ± 3.4 min, after: 9.4 ± 2.5 min) in the unimproved cases in which all the revascularized areas were unimproved. 4. Quantitative analysis was useful for objective evaluation, because the visual evaluation did not always agree with the quantitative evaluation. (J.P.N.)