Exercise-induced increase in lipid peroxidation in patients with chronic heart failure: relation to exercise intolerance.

BACKGROUND: Little is known about the relationship between exercise intolerance and lipid peroxidation in chronic heart failure (CHF) patients. This study was designed to investigate the relationship between exercise-induced plasma malondialdehyde (MDA) changes in CHF patients and to determine whether there is any association between plasma MDA levels and exercise capacity assessed by cardiopulmonary exercise testing. METHODS: Cardiopulmonary exercise testing was applied to 31 CHF patients (16 ischemic, 15 idiopathic) and controls. Rest and peak exercise blood samples were analyzed for MDA. RESULTS: Patients with CHF had elevation of plasma MDA levels during exercise compared with controls (p < 0.001 vs. p = 0.588). MDA change remained significant both in ischemic and idiopathic cardiomyopathy groups (p < 0.05 and p < 0.01, respectively). Delta MDA (peak exercise MDA - rest MDA) showed significant inverse correlation with peak oxygen consumption in patients with CHF. CONCLUSION: Lipid peroxidation is increased in patients with CHF during exercise regardless of etiology, and this increase is inversely related to oxygen consumption.

Plasma homocysteine concentration in patients with poor or good coronary collaterals.

BACKGROUND: Elevated plasma homocysteine (Hcy) concentrations are associated with an increased risk of vascular disease. Hcy is known to inhibit endothelial cell proliferation in vitro. The purpose of the present study was to investigate the role of plasma Hcy concentrations on development of collateral circulation in single-vessel chronic total occlusion. METHODS AND RESULTS: Collateral status was determined by Rentrop's classification. Of 817 patients, 56 cases of pure single-vessel chronic total occlusion were studied. Plasma Hcy concentrations in patients with single-vessel total coronary occlusion were higher compared with controls (17.3 +/-12.6 micromol/L vs 10.9+/-4.9 micromol/L, p=0.015). There was no significant difference in plasma Hcy concentrations of the good and poor collateral groups (17.2+/-13.7 micromol/L vs 15.3+/-9.3 micromol/L, p=0.834). Plasma Hcy concentrations in individual Rentrop subclasses 0, 1, 2 and 3 were as follows: 15.9 +/-9.1, 16.3+/-12.4, 17.1+/-14.1 and 20.1+/-13.5 micromol/L (p=0.893). There was a positive linear correlation between Rentrop subclass and angina pectoris duration (r=0.41, p=0.003). Angina pectoris duration was the only independent variable affecting the development of coronary collaterals in the present study (odds ratio [confidence interval]: 1.85 [1.12-2.91], p=0.014). CONCLUSION: Patients with single-vessel chronic total occlusion had higher plasma Hcy concentrations than controls, but similar Hcy concentrations when compared according to the presence of poor or good coronary collaterals. There is a lack of association between plasma Hcy concentration and coronary collateral status in the current study.

Increased secretion of insulin during oral glucose tolerance test can be a predictor of stent restenosis in nondiabetic patients.

Insulin is known to stimulate proliferation and migration of vascular smooth muscle cells. As the predominant mechanism of restenosis after stent implantation is neointimal tissue proliferation, one can expect a relationship between hyperinsulinemia and restenosis in these patients. The aim of this study was to determine whether hyperinsulinemia during oral glucose tolerance test is a predictor of the development of restenosis after stent implantation in nondiabetic patients. We prospectively studied 52 nondiabetic patients with effort angina who underwent elective stent implantation for single-vessel coronary artery disease. In order to increase the statistical power of the study, numerous exclusion criteria were applied. All patients were subjected to a 75 g oral glucose tolerance test a day before the stent implantation and underwent follow-up angiography 6 months later. Plasma insulin levels in fasting (6.77 +/- 1.57 vs. 5.36 +/- 1.35 micro U/ml; P = 0.005), at 30 min (102.48 +/- 10.6 vs. 47.74 +/- 12.75 micro U/ml; P = 0.001), 1 hr after (120.23 +/- 14.1 vs. 63.08 +/- 12.62 micro /ml; P = 0.001), 2 hr after (63.58 +/- 8.64 vs. 34.88 +/- 6.82 micro /ml; P = 0.001), and 3 hr after (25.71 +/- 5.65 vs. 23.02 +/- 4.61 micro /ml; P = 0.04) loading were significantly higher in patients with stent restenosis than in patients without stent restenosis. Insulin area and insulin area/glucose area were also significantly higher in patients with stent restenosis than in patients without (219.5 +/- 23.8 vs. 118.9 +/- 21.8, P = 0.001, and 0.62 +/- 0.09 vs. 0.33 +/- 0.06, P = 0.001, respectively). By multiple logistic regression analysis, insulin area during oral glucose tolerance test was found to be an independent predictor of stent restenosis (OR = 1.12; 95% CI = 1.01-1.25; P = 0.031). In conclusion, nondiabetic patients with hyperinsulinemia during oral glucose tolerance test have a high risk for restenosis after stent implantation, and performing this simple test before intervention may be useful for the prediction of stent restenosis.