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- Open Access
Stress P-31 MR spectroscopy for detection of myocardial microvascular disease in Latino type-1 diabetes mellitus patients
© Pohost et al; licensee BioMed Central Ltd. 2010
Published: 21 January 2010
Diabetes mellitus (DM) have an increased incidence of coronary artery disease. However, diabetics are also known to have microvascular disease involving the kidneys, the peripheral nerves and the retina. Accordingly, in view of the multisystem involvement of microvascular disease, involvement of the myocardium is clearly feasible. We have previously used 31P MRS to detect microvascular disease. We observed that a decrease in phosphocreatine (PCr), adenosine triphosphate (ATP), PCr/ATP ratio with stress myocardial 31P MRS suggests myocardial ischemia in the absence of coronary artery stenosis.
The present study aims to determine if there are metabolic changes in the myocardium in patients with type-1 DM that could suggest myocardial microvascular disease by using stress 31P MR spectroscopy.
Latino patients with T1DM of greater than 10 years in duration were selected from a registry of more than 2,000 Type-1 DM patients at USC. They are younger and have a lower incidence of large vessel coronary artery disease. A comprehensive history and physical examination were obtained and all subjects underwent a metabolic panel, urinalysis and a funduscopic examination.
MRI &31P MRS
MR examinations were performed using a 3 T MR scanner. Both ejection fraction and high energy phosphates (HEP) were evaluated during rest and stress. The cine MR imaging was performed using a 2D-FIESTA sequence to evaluate ventricular function during rest and stress. Three set of 31P MRS spectra were obtained at rest, stress and recovery from the 15 mm-thick double-oblique slice which mainly covers anterior left ventricle and septum.
Thirteen of 45 subjects showed a significant decrease in PCr/ATP during stress whereas seven normal controls showed no significant decrease. No significant change in ejection fraction during stress was observed. The significant drop was observed more frequently in the patients with retinopathy than without (p = 0.01). More than 10% difference in change of PCr/ATP ratio is anticipated with adequate power (>0.80) in diabetics with retinopathy when compared with other groups such as normal control or diabetics with no retinopathy.
In a subgroup of Type-1 DM patients, non-invasive stress 31P MRS can identify abnormal cardiac HEP metabolism that is likely microvascular in origin and predicts myocardial ischemic response. This abnormal response probably occurs earlier than retinal or renal involvement. This ischemic response in DM patients is unlikely to have epicardial CAD, but suggestive of microvascular dysfunction/disease and ultimately possible cardiomyopathy.
This study was supported by NIH R01 HL073412.
This article is published under license to BioMed Central Ltd.