Acipimox does not augment thallium-201 redistribution in the fasting state

Background. Recently oral glucose loading and a thallium-glucose insulin in fusion have been used to augment myocardial uptake of thallium-201 (Tl-201) , Acipimox is a nicotinic-acid derivative that reduces serum free fatty aci d (FEA) levels and enhances myocardial glucose uptake, This study was perfo rmed to assess the effects of acipimox on Tl-201 redistribution. Methods, Fourteen patients with coronary artery disease underwent 2 success ive Tl-201 perfusion studies. Stress was performed by adenosine coupled wit h ergometer exercise. Patients received either 500 mg of acipimox or placeb o immediately after stress, and images mere acquired. Redistribution imagin g was carried out after 4 hours. Patients returned after 7 to 14 days for a repeat stress protocol, receiving the alternate test article. Both studies were carried out under identical conditions with identical medication with the patient in the fasting state. Image analysis was conducted quantitativ ely with polar plots and by using segmental uptake as a percentage of maxim al counts with a 9-segment model. Results. There mere no significant differences between the acipimox and pla cebo arms of the study of hemodynamic parameters. On polar plot analysis, t here were no differences between acipimox and placebo for mean values of st ress defect extent (97 +/- 16.1 vs 96.5 +/- 18.8 pixels), defect severity ( 532.2 +/- 120 vs 537 +/- 133.9 standard deviations [SDs]), for defect rever sibility (61.7 +/- 18 vs 55.4 +/- 15.3 SDs), and percentage reversibility ( 21.2% +/- 5.5% vs 19.2% +/- 5.8%), respectively. Similarly, on segmental up take analysis there was no significant difference between the acipimox and placebo arms with regard to the proportion of segments classified as normal , fixed defect, reversible defect, or reverse redistribution, Conclusion. Although acipimox has been shown to augment myocardial glucose uptake and myocardial glucose uptake has been shown to improve cellular upt ake of Tl-201, in the fasting state acipimox does not enhance the redistrib ution after stress. This mag be because serum insulin levels are not increa sed by acipimox, and insulin is instrumental in enhancing the joint transpo rt of glucose and Tl-201 into myocytes.