Serial assessment of MIBG scintigraphy in a case of DCM with heart failure improved by β-blocker therapy

We experienced a case of DCM (62-year-old man) improved by β-blocker (Metoprolol) therapy and studied time course of MIBG scintigraphy. We measured cardiac functions by UCG and ^99mTc cardiac pool imaging, and MIBG scintigraphy during 12 months of β-blocker therapy. In planar images we measured washout rate (WR) in total myocardium and regional washout rate (rWR) in 6 segments of myocardium. Cardiac function improved after 3 months of therapy. The WR did not improve until 6 months, but improved after 9 months (Before: 35.1%, 3 months after: 34.6%, 6 months after: 33.6%, 9 months after: 27.6%, 12 months after: 25.4%). rWR in inferoapical segment first improved at 3 months (Before: 40.1%, 3 months after: 35.1%), whereas rWR in antero-apical segment improved after 6 months and that in anterior segment improved after 9 months. These results suggest that the improvement of cardiac sympathetic nerve function in DCM treated with β-blocker was not identical in each myocardium region.