DIFFUSE SLOW WASHOUT OF MYOCARDIAL TL-201 - A NEW SCINTIGRAPHIC INDICATOR OF EXTENSIVE CORONARY-ARTERY DISEASE

When coronary artery disease is extensive and of relatively uniform severity, regional myocardial hypoperfusion may be balanced during stress, precluding development of spatially relative perfusion defects. Assessment of the washout of 201Tl from myocardial regions may provide diagnostic assistance in these cases because washout analysis is spatially nonrelative and hypoperfused myocardial regions manifest a slow 201Tl washout rate. In 1265 consecutive patients having quantitatively analyzed stress-redistribution scintigraphy, 46 had a diffuse slow washout pattern with no or a maximum of 1 regional perfusion defect. Thirty-two underwent clinically indicated coronary angiography, and 23 (72%) of these were found to have 3 vessel or left main disease. Of 30 similar patients without a diffuse slow washout pattern and with no or a maximum of 1 perfusion defect, only 5 (17%) had extensive coronary disease. An independent relation between diffuse slow washout and extensive coronary disease was demonstrated by a Mantel-Haentzel chi-square analysis of a wide variety of other indexes of extensive disease. A diffuse washout abnormality, even in the absence of other scintigraphic, clinical or ECG indicators, carries a high predictive value for 3 vessel or left main coronary artery disease. The predictive value is maintained when the exercise level achieved is submaximal. Although an infrequent occurrence (3.6% of tested patients), a diffuse slow washout pattern without other scintigraphic indications of extensive coronary disease should lead to further diagnostic testing.