RT Journal Article
SR Electronic
T1 Decreased Myocardial β-Adrenergic Receptor Density in Relation to Increased Sympathetic Tone in Patients with Nonischemic Cardiomyopathy
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1777
OP 1782
DO 10.2967/jnumed.107.043794
VO 48
IS 11
A1 Takahiro Tsukamoto
A1 Koichi Morita
A1 Masanao Naya
A1 Masayuki Inubushi
A1 Chietsugu Katoh
A1 Kenichi Nishijima
A1 Yuji Kuge
A1 Hiroshi Okamoto
A1 Hiroyuki Tsutsui
A1 Nagara Tamaki
YR 2007
UL http://jnm.snmjournals.org/content/48/11/1777.abstract
AB Cardiac sympathetic function plays an important role in the regulation of left ventricular (LV) function and the pathophysiology of LV dysfunction. 11C-CGP-12177 (11C-CGP) has been used to assess myocardial β-adrenergic receptor (β-AR) density in vivo using PET. The aim of this study is to measure myocardial β-AR density in patients with nonischemic cardiomyopathy and to compare the measurements with various standard parameters of heart failure (HF), particularly with presynaptic function assessed by 123I- metaiodobenzylguanidine (123I-MIBG) imaging. Methods: 11C-CGP PET was performed on 16 patients with nonischemic cardiomyopathy and 8 age-matched healthy volunteers using a double injection method. A 11C-CGP dynamic scan for 75 min was performed after the injection of 11C-CGP with a high specific activity. After 30 min, 11C-CGP with a low specific activity was injected. The β-AR density of the whole LV was calculated on the basis of the graphical analysis method. Additionally, β-AR density was compared with LV ejection fraction (LVEF), sympathetic presynaptic function assessed using 123I-MIBG kinetics, and neurohormonal parameters. Results: The β-AR density of patients was significantly lower than that of healthy volunteers (3.80 ± 0.96 vs. 7.70 ± 1.92 pmol/mL; P < 0.0001). In the patients, β-AR density correlated significantly with LVEF (r = 0.62, P < 0.05). Furthermore, β-AR density correlated significantly with the 123I-MIBG washout rate (r = −0.68, P < 0.01) and delayed heart-to-mediastinum ratio (H/M ratio) (r = 0.61, P < 0.05). On the other hand, the correlation between β-AR density and early H/M ratio was not significant (r = 0.40, P = 0.13). The β-AR density of patients with severe HF (New York Heart Association functional [NYHA] class III) was significantly lower than that of those with NYHA functional class I or class II HF (3.24 ± 0.96 vs. 4.24 ± 0.73 pmol/mL; P < 0.05). Conclusion: A reduction in β-AR density measured by 11C-CGP PET was observed in patients with nonischemic cardiomyopathy. This downregulation may be due to the increased presynaptic sympathetic tone as assessed by 123I-MIBG imaging.