Myocardial glucose metabolism assessed by positron emission tomography and the histopathologic findings of microvessels in syndrome X.
BACKGROUND
Syndrome X has been recognized as a disease that is primarily reflected in the cardiac microvasculature. Myocardial metabolism in this condition has been studied, but not in relation to small vessel pathology.


RESULTS
In order to examine the relationship between myocardial metabolism and small vessel pathology, 24 consecutive patients with syndrome X (7 men, 17 women; mean age 58 years) were evaluated by the thallium exercise stress test, positron emission tomography using F-18 fluoro-deoxyglucose (FDG), and an endomyocardial biopsy. All patients showed either diffuse or focal increase in the myocardial uptake of FDG, but only 17 patients (71%) showed hypoperfused areas with partial or complete redistribution in the thallium study. Quantification of myocardial FDG uptake revealed that the value in syndrome X patients was 10-fold higher than in controls (p<0.0001). Histopathological examination revealed that in syndrome X there is an extensive increase in smooth muscle cells and thickening of the vascular wall, even in capillary vessels, and the small vessel lumen was markedly narrowed. There was a significant inverse correlation between FDG myocardial uptake and the microvessel luminal area.


CONCLUSIONS
In syndrome X patients, myocardial FDG uptake is increased extensively, which is strongly associated with narrowed myocardial microvasculature.
Osamichi
Satake
S
Department of Cardiology, Kanazawa Medical University, Ishikawa, Japan. o-satake@kanazawa-med.ac.jp
Kouji
Kajinami
K
Yoshimaro
Ishikawa
I
Tadashi
Ueda
U
Hiroichi
Tsugawa
T
Seiyu
Kanemitsu
K
Shinji
Okubo
O
Noboru
Takekoshi
T
D000328:Adult; D000368:Aged; D017023:Coronary Angiography; D003331:Coronary Vessels / Q000378:metabolism / Q000473:pathology; D005080:Exercise Test; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D017566:Microvascular Angina / Q000378:metabolism* / Q000473:pathology* / Q000628:therapy; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology*; D019275:Radiopharmaceuticals / Q000378:metabolism; D013794:Thallium Radioisotopes / Q000378:metabolism; D014055:Tomography, Emission-Computed
D019275:Radiopharmaceuticals; D013794:Thallium Radioisotopes; D019788:Fluorodeoxyglucose F18; D005947:Glucose