Enhanced Susceptibility to Oxidation and Diminished Vitamin E Content of LDL from Patients with Stable Coronary Artery Disease

Abstract

AbstractBackground: Convincing evidence points to oxidative modification of LDL as an important trigger in a complex chain of events leading to atherosclerosis. We investigated the occurrence of enhanced susceptibility of LDL to oxidation and decreased vitamin E concentration in LDL as additional risk factors promoting atherosclerosis among patients with established coronary artery disease (CAD).Methods: We examined 132 patients with angiographically confirmed CAD and compared them with 111 healthy control individuals. We measured conjugated diene production to assess susceptibility of LDL to copper-mediated oxidation. Vitamin E content of LDL was measured by HPLC.Results: The mean lag time of LDL oxidation and LDL α-tocopherol/LDL-cholesterol ratio were lower in the patients with CAD (55 ± 14 min and 2.4 ± 1.0 mmol/mmol) than in the controls (63 ± 13 min and 2.9 ± 1.1 mmol/mmol; P <0.0001 and <0.001, respectively). Multiple stepwise regression analysis demonstrated the lag time (odds ratio, 1.96; 95% confidence interval, 1.34–2.87; P <0.0001) and concentration of vitamin E in LDL (odds ratio, 1.65; 95% confidence interval, 1.16–2.33; P <0.005) as independent determinants of CAD. Significant inverse Spearman rank correlations were found between lag time (r = −0.285; P <0.001) or concentration of vitamin E in LDL (r = −0.197; P <0.002) and severity of CAD. Lag times were not significantly correlated with serum C-reactive protein or ferritin.Conclusions: Our data suggest that a short LDL oxidation lag time and a low concentration of vitamin E in LDL might be independent coronary risk factors for stable CAD in Iranian people.