EFFECT OF NICOTINIC-ACID ON EXOGENOUS MYOCARDIAL GLUCOSE-UTILIZATION

Clinical assessment of myocardial glucose uptake with F-18-fluorodeoxyglucose (F-18-FDG) and PET requires the control of circulating substrates to achieve acceptable image quality. Methods: To determine the efficacy of the hypolipemic effect of oral niacin upon myocardial F-18-FDG uptake, five volunteers were studied with F-18-FDG and PET in the fasting state, with and without treatment with niacin. Levels of glucose, fatty acids, insulin and catecholamines were measured at baseline and before and after F-18-FDG administration by programmed infusion. Results: No significant changes in glucose or insulin levels occurred with niacin. A significant decrease in fatty acid levels with niacin treatment was associated with a two- to three-fold increase in myocardial glucose utilization rates relative to the fasting state. Furthermore, regional variation in tracer distribution with greater uptake in the lateral wall than the septum or anterior wall in the fasting studies was not present after niacin treatment. Conclusion: As determined by programmed infusion of F-18-FDG and PET imaging, niacin treatment in normal volunteers was associated With an increase in exogenous glucose utilization by the heart and a decrease in the cardiac regional variation of F-18-FDG. Further studies are needed to compare the relative value of niacin therapy and oral glucose loading for determination of myocardial exogenous glucose utilization rates.