acipimox and Myocardial-Infarction

The use of 18F-fluorodeoxyglucose (FDG) imaging with single photon emission computed tomography (SPECT) has been introduced recently to assess myocardial viability. Several centres have now gained experience with cardiac FDG SPECT imaging, and this report is a summary of the currently available FDG SPECT data. Three studies have compared FDG SPECT with FDG positron emission tomography and demonstrated good agreement between them. Initial results in patients undergoing revascularization suggest that FDG SPECT can predict improvement in contractile function after revascularization. Although the initial results are promising, larger studies are needed to determine the precise role of FDG SPECT in the assessment of myocardial viability.

Topics: Cardiotonic Agents; Deoxyglucose; Dobutamine; Echocardiography; Exercise Test; Fluorodeoxyglucose F18; Glucose; Humans; Hypolipidemic Agents; Myocardial Contraction; Myocardial Infarction; Myocardial Reperfusion; Myocardium; Predictive Value of Tests; Pyrazines; Radiopharmaceuticals; Sensitivity and Specificity; Tomography, Emission-Computed, Single-Photon

The rat myocardial infarction (MI) model is widely used to study left ventricular (LV) remodeling. In this study, acipimox-enhanced (18)F-Fluorodeoxyglucose (FDG) gated-positron emission tomography (PET) was assessed for characterizing and predicting early remodeling in the rat infarct model. Nineteen Wistar rats had surgical occlusion of the left anterior descending coronary artery and 7 were sham-operated. PET was scheduled 48 h and 2 weeks later for quantifying MI area and LV function. Segments with <50% of FDG uptake had histological evidence of MI (74 ± 9% decrease in parietal thickness, fibrosis development). At 48 h, MI area was large (>35% of LV) in 6 rats, moderate (15-35% of LV) in 8 rats, limited (<15% of LV) in 5 rats and absent in the 7 sham rats. LV remodeling, assessed through the 2 weeks increase in end-diastolic volume, increased between rats with limited, moderate and large MI (+72 ± 25, +109 ± 56, +190 ± 69 μl, respectively, P = 0.007). This 3-groups classification allowed predicting 44% of the 2 weeks increase in end-diastolic volume, and additional 34% were predicted by heart rate at 48 h. The acipimox-enhanced FDG gated-PET technique provides efficient characterization and prediction of early remodeling in the rat infarct model.

Topics: Animals; Diastole; Disease Models, Animal; Fluorodeoxyglucose F18; Hypolipidemic Agents; Male; Myocardial Infarction; Myocardium; Positron-Emission Tomography; Predictive Value of Tests; Pyrazines; Radiopharmaceuticals; Rats; Rats, Wistar; Time Factors; Ventricular Function, Left; Ventricular Remodeling

Recently, the euglycemic hyperinsulinemic clamp technique was shown to give excellent image quality during metabolic steady-state conditions. Acipimox is a new potent nicotinic acid derivative that rapidly reduces serum free fatty acid (FFA) levels by inhibiting lipolysis in peripheral tissue.. To compare the effects of acipimox administration and insulin clamp on [18F]fluorodeoxyglucose ([18F]FDG) uptake and myocardial glucose utilization, five nondiabetic and seven type II diabetic patients who had had previous myocardial infarctions were studied twice: once during a clamp study and once after the administration of acipimox (2 x 250 mg orally). All patients also underwent resting SPECT perfusion imaging prior to PET scans.. The patients tolerated acipimox well. Although fasting plasma glucose levels were higher in diabetic patients (9.2 +/- 3.4 versus 5.5 +/- 0.3 mM, p = 0.03), they were decreased both during clamping and after acipimox; during imaging, no significant differences between the groups and approaches were detected. By visual analysis, the image quality and myocardial [18F]FDG uptake patterns were similar during clamping and after acipimox. Compared with the relative [18F]FDG uptake values obtained during clamping, acipimox yielded similar results in normal, mismatch and scar segments (r = 0.88, p = 0.0001). Similar rMGU values were also obtained during both approaches.. Thus, PET imaging with [18F]FDG after the administration of acipimox is a simple and feasible method for clinical viability studies both in nondiabetic and diabetic patients. It results in excellent image quality and gives rMGU levels similar to the insulin clamp technique.

Topics: Adult; Aged; Coronary Angiography; Deoxyglucose; Diabetes Mellitus, Type 2; Echocardiography; Female; Fluorodeoxyglucose F18; Glucose; Glucose Clamp Technique; Heart; Humans; Male; Middle Aged; Myocardial Infarction; Myocardium; Nicotinic Acids; Pyrazines; Radionuclide Ventriculography; Tomography, Emission-Computed