Impaired myocardial blood flow reserve in subjects with metabolic syndrome analyzed using positron emission tomography and N-13 labeled ammonia.
OBJECTIVE
Coronary vasomotor response might be impaired in metabolic syndrome (MS); however, the precise abnormality has not been elucidated. The aim of this study was to assess coronary-vasomotor response in MS subjects using N-13 labeled ammonia and positron emission tomography.


RESULTS
Myocardial blood flow (MBF) was measured at rest and during adenosine infusion in MS subjects (n = 13, MS group) with no definite evidence of heart disease and in subjects without MS (n = 14, non-MS group). Coronary vascular resistance (CVR) was calculated by dividing the mean aortic blood pressure by MBF. Myocardial blood flow reserve (MFR) was calculated as the ratio of the MBF during adenosine infusion to that during rest. Blood chemical parameters were measured to evaluate their relationship with MFR. During adenosine infusion, MBF was lower (p = 0.0085) and CVR higher (p = 0.0128) in the MS group than in the non-MS group and MFR was significantly lower in the MS group than in the non-MS group (2.13 +/- 0.99 vs. 3.38 +/- 0.95, p = 0.0027). Multivariate analysis demonstrated that the homeostasis model assessment-insulin resistance (p < 0.05) and the presence of hypertension (p < 0.05) were independent determinants of MFR.


CONCLUSIONS
The results indicate that MFR was impaired in MS subjects, suggesting that an abnormal coronary microvascular response occurred in these subjects. This abnormality may have been partially due to insulin resistance and hypertension.
Teragawa
Hiroki
H
Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical Sciences, Minami-ku, Hiroshima, Japan. hteraga@hiroshima-u.ac.jp
Morita
Koichi
K
Shishido
Hiroki
H
Otsuka
Nobuaki
N
Hirokawa
Yutaka
Y
Chayama
Kazuaki
K
Tamaki
Nagara
N
Kihara
Yasuki
Y
D000641:Ammonia; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000503:physiopathology; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008875:Middle Aged; D009590:Nitrogen Radioisotopes; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography
D009590:Nitrogen Radioisotopes; D000641:Ammonia