Myocardial sympathetic innervation in patients with impaired glucose tolerance: relationship to subclinical inflammation.
OBJECTIVE
This study was designed to assess cardiac adrenergic nerve activity, using iodine (I)-123-labeled metaiodobenzylguanidine (MIBG), in patients with impaired glucose tolerance (IGT) and to investigate its relation to circulating levels of proinflammatory cytokines.


METHODS
We studied 22 patients with IGT (aged 34-68 years) and 18 age-matched healthy controls, using I-123 MIBG cardiac imaging. The early (10 min) and late (4 h) heart to mediastinum MIBG uptake (H/M) ratio and washout were calculated. Levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-a), and its soluble receptor [soluble TNF receptor II (sTNFRII)] were measured by immunoassay of blood samples from patients and controls.


RESULTS
The early and late MIBG uptake was lower (both P<.001) and the WR was higher (P<.001) in patients than in controls. The analysis showed innervation defects in 20 of the 22 patients. Nearly half (45.4%) showed severe adrenergic innervation defects in both the inferior wall and the apex. Regarding cytokines, patients showed significantly elevated TNF-a (P=.005), sTNFRII (P<.001), and IL-6 (P<.001) levels compared to controls. IL-6 and sTNFRII were found to correlate with the WR (r=0.468, P=.028 and r=0.455, P=.034, respectively).


CONCLUSIONS
Patients with IGT show reduced MIBG cardiac uptake with a segmental pattern. The reduced cardiac sympathetic innervation was related to the elevated proinflammatory cytokine levels and could be considered an index of early atherosclerotic process in these patients.
Diakakis
Georgios F
GF
Department of Cardiology, Heraklion University Hospital, Crete, Greece.
Parthenakis
Fragiskos I
FI
Patrianakos
Alexandros P
AP
Koukouraki
Sofia I
SI
Stathaki
Maria I
MI
Karkavitsas
Nikos S
NS
Vardas
Panos E
PE
D019797:3-Iodobenzylguanidine; D000328:Adult; D000368:Aged; D005260:Female; D005951:Glucose Tolerance Test; D006321:Heart / Q000000981:diagnostic imaging / Q000294:innervation*; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000503:physiopathology*; D018836:Inflammation Mediators / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D009206:Myocardium; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000097:blood; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D018836:Inflammation Mediators; D015850:Interleukin-6; D019275:Radiopharmaceuticals; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; D019797:3-Iodobenzylguanidine