Assessment of the severity of coronary artery disease by thallium-201 washout rate after dipyridamole infusion--a coronary hemodynamic and metabolic study.

This study examined the relationship between the myocardial washout rate (WR) of thallium-201 (201Tl) in dipyridamole scintigraphy and both coronary flow reserve (CFR) and myocardial lactate extraction rate (LER) after dipyridamole infusion in 31 patients with coronary artery disease (CAD) without myocardial infarction and 16 control patients. Patients with CAD demonstrated significantly lower WR (21 +/- 17 vs 43 +/- 10%, 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 significantly 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 chest 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 +/- 21 vs 11 +/- 9%, p < 0.001) than did CAD patients without chest pain. CAD patients with dipyridamole-induced ST depression demonstrated significantly 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 CAD patients without ST depression. These results suggest that the myocardial washout rate of 201Tl after dipyridamole infusion reflects the severity of coronary artery disease as assessed by coronary hemodynamics, myocardial metabolism, symptoms and electrocardiography.