Small Dense LDL Particles in Relation to LDL Oxidation in Normolipidemic CAD Patients

Aims: Lipid and lipoprotein cholesterol levels are not predictive of coronary artery disease (CAD) risk in all the subjects. The heterogeneity of lipoprotein particles plays an important role in this respect. This fact needs to be studied in normolipidemic CAD patients. The aim of the present study was to evaluate the role of small dense LDL particles in relation to LDL oxidation in normolipidemic coronary artery disease patients. Methods and Results: One hundred and twenty eight CAD patients and 200 age and sex matched normal individuals were studied. Subjects were screened for various biochemical investigations such as lipid profile, serum apoB, LDL apoB carbonyl content, MDA-LDL levels. Log (TG/HDL-C) ratio was taken as an index of LDL particle size. In the present study, lipid levels could not discriminate well between patients and normal subjects. However normolipidemic CAD patients had increased positive values of log (TG/HDL-C) as compared to controls indicating the predominance of small dense LDL particles. This was further supported from the raised serum apoB levels. LDL apoB carbonyl content (LDL protein oxidation) and MDA-LDL levels (LDL lipid peroxidation) were raised in normolipidemic CAD patients as compared to normal subjects. Conclusions: Assessment of LDL particle size and LDL oxidation status might be more predictive of CAD risk even in subjects with normal lipid and lipoprotein cholesterol levels.