Altered myocardial substrate metabolism and decreased diastolic function in nonischemic human diabetic cardiomyopathy: studies with cardiac positron emission tomography and magnetic resonance imaging.
OBJECTIVE
This study was designed to evaluate myocardial substrate and high-energy phosphate (HEP) metabolism in asymptomatic men with well-controlled, uncomplicated type 2 diabetes with verified absence of cardiac ischemia, and age-matched control subjects, and to assess the association with myocardial function.


BACKGROUND
Metabolic abnormalities, particularly an excessive exposure of the heart to circulating nonesterified fatty acids and myocardial insulin resistance are considered important contributors to diabetic cardiomyopathy in animal models of diabetes. The existence of myocardial metabolic derangements in uncomplicated human type 2 diabetes and their possible contribution to myocardial dysfunction still remain undetermined.


METHODS
In 78 insulin-naive type 2 diabetes men (age 56.5 +/- 5.6 years, body mass index 28.7 +/- 3.5 kg/m(2), glycosylated hemoglobin A(1c) 7.1 +/- 1.0%; expressed as mean +/- SD) without cardiac ischemia and 24 normoglycemic control subjects (age 54.5 +/- 7.1 years, body mass index 27.0 +/- 2.5 kg/m(2), glycosylated hemoglobin A(1c) 5.3 +/- 0.2%), we assessed myocardial left ventricular (LV) function by magnetic resonance imaging, and myocardial perfusion and substrate metabolism by positron emission tomography using H(2)(15)O, carbon (11)C-palmitate, and 18-fluorodeoxyglucose 2-fluoro-2-deoxy-D-glucose. Cardiac HEP metabolism was assessed by phosphorous P 31 magnetic resonance spectroscopy.


RESULTS
In patients, compared with control subjects, LV diastolic function (E/A ratio: 1.04 +/- 0.25 vs. 1.26 +/- 0.36, p = 0.003) and myocardial glucose uptake (260 +/- 128 nmol/ml/min vs. 348 +/- 154 nmol/ml/min, p = 0.015) were decreased, whereas myocardial nonesterified fatty acid uptake (88 +/- 31 nmol/ml/min vs. 68 +/- 18 nmol/ml/min, p = 0.021) and oxidation (85 +/- 30 nmol/ml/min vs. 63 +/- 19 nmol/ml/min, p = 0.007) were increased. There were no differences in myocardial HEP metabolism or perfusion. No association was found between LV diastolic function and cardiac substrate or HEP metabolism.


CONCLUSIONS
Patients versus control subjects showed impaired LV diastolic function and altered myocardial substrate metabolism, but unchanged HEP metabolism. We found no direct relation between cardiac diastolic function and parameters of myocardial metabolism.
Rijzewijk
Luuk J
LJ
Diabetes Center, VU University Medical Center, Amsterdam, the Netherlands.
van der Meer
Rutger W
RW
Lamb
Hildo J
HJ
de Jong
Hugo W A M
HW
Lubberink
Mark
M
Romijn
Johannes A
JA
Bax
Jeroen J
JJ
de Roos
Albert
A
Twisk
Jos W
JW
Heine
Robert J
RJ
Lammertsma
Adriaan A
AA
Smit
Johannes W A
JW
Diamant
Michaela
M
D000368:Aged; D009202:Cardiomyopathies / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000378:metabolism; D003971:Diastole; D005947:Glucose / Q000378:metabolism*; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D016277:Ventricular Function, Left / Q000502:physiology*
D005947:Glucose; D006442:Glycated Hemoglobin