[Two cases of dilated cardiomyopathy with the relationship between the effect of beta-blocker therapy and the changes of myocardial clearance of 123I-metaiodobenzylguanidine].

Two cases diagnosed dilated cardiomyopathy received beta-blocker therapy, and underwent 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy before and after the treatment. In case 1, symptoms and cardiac function were improved in 1 month and 4 months after the treatment (LVEF increased from 19% to 32% and 40%), and myocardial clearance of MIBG decreased from 50% to 27% and 29%. In case 2, both symptoms and cardiac function were not improved in 1 month and 3 months after the treatment (LVEF was changed from 11% to 10% and 13%), and myocardial clearance was not significantly different between before (50%) and after (1 month: 46%, 3 months: 50%) the treatment. It was indicated that myocardial clearance of MIBG might depend on the extent of the improvement of cardiac function and symptoms, and might reflect the effects of beta-blocker therapy.