ASSESSMENT OF THE SEVERITY OF CORONARY-ARTERY DISEASE BY TL-201 WASHOUT PLATE AFTER DIPYRIDAMOLE INFUSION - A CORONARY HEMODYNAMIC AND METABOLIC STUDY

This study examined the relationship between the myocardial washout ra te (WR) of thallium-201 (Tl-201) in, dipyridamole scintigraphy and bot h coronary flow reserve (CFR) and myocardial lactate extraction rate ( LER) after dipyridamole infusion in 31 patients with coronary artery d isease (CAD) without myocardial infarction and 16 control patients. Pa tients with CAD demonstrated significantly lower WR (21+/-17 vs 43+/-1 0%, p<0.001), lower CFR (128+/-82 vs 242+/-89%, p<0.001) and lower LER (-2+/-20 vs 10+/-10%, p<0.05) than did the control patients. WR was s ignificantly correlated with CFR (r=0.50, p<0.001) and LER (r=0.41, p< 0.01) in all of the patients. CAD patients with dipyridamole-induced c hest pain demonstrated significantly lower WR (14+/-20 vs 27+/-12%, p< 0.05), lower CFR (97+/-71 vs 162+/-82%, p<0.05) and lower LER (-13+/-2 1 vs 11+/-9%, p<0.001) than did CAD patients without chest pain. CAD p atients with dipyridamole-induced ST depression demonstrated significa ntly lower WR (14+/-20 vs 29+/-8%, p<0.05), lower CFR (105+/-79 vs 170 +/-73%, p<0.05) and lower LER (-8+/-21 vs 11+/-10%, p<0.01) than did C AD patients without ST depression. These results suggest that the myoc ardial washout rate of Tl-201 after dipyridamole infusion reflects the severity of coronary artery disease as assessed by coronary hemodynam ics, myocardial metabolism, symptoms and electrocardiography.