Reduced oxidative metabolic response in dysfunctional myocardium with preserved glucose metabolism but with impaired contractile reserve.
The recovery of function in myocardium defined as viable by (18)F-FDG PET may differ from that defined by dobutamine stress echocardiography (DSE). The aim of this study was to investigate the difference in the oxidative metabolic response between myocardial segments with preserved contractile reserve (CR) and those without CR, in segments with and without preserved glucose metabolism (GM), using (11)C-acetate PET.


METHODS
Twenty patients with previous myocardial infarction (left ventricular ejection fraction, 37.1% +/- 16.5%) underwent dynamic (11)C-acetate PET at rest and during dobutamine (7.5 microg/kg/min) infusion. GM was evaluated using (18)F-FDG PET and CR was evaluated using DSE. Dysfunctional segments were divided into 3 groups: group A (n = 26) with preserved CR and GM, group B (n = 15) without CR but with preserved GM, and group C (n = 41) without CR and without preserved GM.


RESULTS
Resting oxidative metabolism (k mono = monoexponential clearance rate) was preserved in group A and group B (0.052 +/- 0.011/min vs. 0.051 +/- 0.012/min, P = not significant) but was reduced in group C (0.040 +/- 0.015/min) (P < 0.03 vs. group A and group B). The change in k mono, as a measure of the metabolic response to low-dose dobutamine, was significantly higher in group A (0.018 +/- 0.012) than that in group B (0.0075 +/- 0.0096, P < 0.03) and group C (0.0080 +/- 0.012, P < 0.005).


CONCLUSIONS
Viable segments based on (18)F-FDG PET have preserved resting oxidative metabolism. However, segments without CR but with preserved GM show a reduction in the oxidative metabolic response to low-dose dobutamine infusion. The decrease in CR may be related to the reduction in the metabolic response to inotropic stimulation despite preservation of tissue viability on (18)F-FDG PET.
Yoshinaga
Keiichiro
K
Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.
Katoh
Chietsugu
C
Beanlands
Rob S B
RS
Noriyasu
Kazuyuki
K
Komuro
Kaoru
K
Yamada
Satoshi
S
Kuge
Yuji
Y
Morita
Koichi
K
Kitabatake
Akira
A
Tamaki
Nagara
N
D000085:Acetates / Q000493:pharmacokinetics*; D002244:Carbon / Q000493:pharmacokinetics*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism; D017682:Myocardial Stunning / Q000000981:diagnostic imaging* / Q000209:etiology / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics
D000085:Acetates; D019275:Radiopharmaceuticals; C438206:carbon-11 acetate; D002244:Carbon; D005947:Glucose; D010100:Oxygen