Malondialdehyde-modified low-density lipoprotein is a useful marker to identify patients with vulnerable plaque.

BACKGROUND: The association between elevated malondialdehyde-modified low-density lipoprotein (MDA-LDL) and plaque instability in patients with coronary artery disease (CAD) is suspected but not established. The aim of the present study was therefore to investigate the association between serum MDA-LDL and plaque characteristics on angioscopy. METHODS AND RESULTS: A total of 37 consecutive patients with CAD and single-vessel disease who underwent pre-interventional angioscopy, were studied. Using angioscopy at the target lesions, the presence of yellow plaque and complex plaque was examined. Moreover, we evaluated the yellow intensity, which has been shown to have an inverse correlation with the fibrous-cap thickness of the plaques, with quantitative colorimetry to identify a thin-cap atheroma. Serum MDA-LDL in patients with thin-cap atheroma diagnosed on quantitative colorimetry was significantly higher than in patients without thin-cap atheroma (P<0.0009). Univariate logistic regression indicated that serum MDA-LDL was a predictor for thin-cap atheroma (odds ratio [OR], 1.48; 95% confidence interval [CI]: 1.10-1.97; P=0.003) and for complex plaque (OR, 1.22; 95% CI: 1.00-1.48; P=0.046). On multivariate logistic regression serum MDA-LDL was the only independent predictor for thin-cap atheroma (OR, 1.48; 95% CI: 1.10-1.97; P=0.011). CONCLUSIONS: Using angioscopy and quantitative colorimetry, elevated MDA-LDL was confirmed to be associated with thin-cap atheroma in CAD patients.

Tea catechin consumption reduces circulating oxidized low-density lipoprotein.

It has been reported that green tea consumption reduces the risk of coronary artery disease and cardiac events. Catechin is a major constituent of Japanese green tea and an antioxidant. Lipids and oxidization of low-density lipoprotein cholesterol (LDL-C) play important roles in atherosclerosis. Therefore, we evaluated the effect of catechin intake on the lipid profile and plasma oxidized LDL. The study population consisted of 40 healthy adult volunteers (10 men, 30 women). Catechin was extracted from green tea leaves. The subjects were randomly divided into two groups, a catechin group (n = 29) and a control group (n = 11). In the catechin group, catechin (500 mg: equivalent to 6 or 7 cups of green tea) was administered orally. Venous blood samples were obtained before eating a meal at the start and after 4 weeks without any lifestyle modification. Plasma oxidized LDL assay was performed with a sandwich-type enzyme immunoassay using anti-oxidized phosphatidylcholine monoclonal antibody. The baseline lipid profiles and tea consumptions were similar between the two groups. Plasma oxidized LDL was significantly decreased after catechin administration (from 9.56 +/- 9.2 to 7.76 +/- 7.7 U/mL, P = 0.005), while plasma LDL-C, triglyceride, and HDL-C concentrations did not change. Catechin decreased the plasma oxidized LDL concentration without significant change in plasma LDL concentration. The mechanism of the beneficial effects of green tea on coronary artery disease might result from a decrease in plasma oxidized LDL.