Abstract 6095: Pioglitazone Improves Coronary Flow Velocity Reserve in Patients with Impaired Glucose Tolerance Independent of Glycemic Control
Recent study has shown that apolipoprotein CIII (apo CIII) increases expression of adhesion molecules in vascular endothelial cells and has proinflammatory effect on monocytes and predicts subsequent CAD. It has also been reported that in patients with diabetes mellitus, coronary flow velocity reserve (CFVR) is reduced without significant epicardial coronary artery stenosis because of impairment of coronary microcirculation. Peroxisome proliferators activated- receptor (PPAR)- gamma agonist, pioglitazone, has antiatherogenic and antiinflammatory effects in type 2 diabetic patients. However, its effect on coronary microcirculation and plasma apo CIII level in IGT patients was not elucidated. The aim of this study is to examine whether pioglitazone improves CFVR in IGT patients independent of glycemic control.
Methods: We studied 24 patients with IGT diagnosed by 75g-oral glucose tolerance test (OGTT) (male 11, female 13) without history of CAD. They were randomly assigned to pioglitazone (30mg/day) group or control group. Coronary flow velocity in the left anterior descending artery were recorded with transthoracic Doppler echocardiography at rest and during hyperemia induced by intravenous infusion of adenosine. CFVR was calculated as the ratio of hyperemic to basal mean diastolic velocity. Venous blood samples and CFVR were assessed at baseline and 6 months after treatment.
Results: Although there were no significant differences in fasting blood sugar, HbA1c and LDL-cholesterol, sigma IRI (sum of IRI during OGTT) and apo CIII decreased significantly after pioglitazone treatment (509.4±214.2 to 262.6±133.6 μIU/ml, p<0.005; 10.2±2.6 to 9.4±2.4 mg/dl, p<0.05). CFVR increased significantly (2.65±0.76 to 3.09±0.86, p<0.05) in pioglitazone group, but not (2.84±0.53 to 2.77±0.56, p=0.74) in the control group.
Conclusion; Pioglitazone improved coronary microcirculation independent of glycemic control through a decrease in apo CIII levels and improvement of hyperinsulinemia. This effect may be related to antiinflammatory mechanism of this drug.