Oxidatively modified low density lipoprotein (OxLDL) plays an important role in the development of atherosclerosis as its uptake by macrophages and smooth muscle cells leads to formation of foam cells which is a critical step in the evolution of the pathological state.^1,2 Circulating OxLDL concentrations may therefore reflect the state of pathological atherosclerosis, and be a possible biochemical risk marker for coronary artery disease (CAD). Numerous efforts have been directed at detecting OxLDL concentrations in the circulation for this reason, but technical difficulties have hampered detection of minute amounts of OxLDL. To overcome these limitations, we focused on circulating malondialdehyde modified LDL (MDA-LDL), a chemical modification thought to reflect naturally occurring oxidation of LDL,^3,4 and developed a sensitive immunoassay of circulating MDA-LDL concentrations. The diagnostic performance of MDA-LDL in CAD was compared against known lipid markers. This comparison revealed, for the first time, that MDA-LDL is superior, thus suggesting that MDA-LDL may be a promising tool for the biochemical detection of CAD.

METHODS

Consenting patients with CAD defined as having greater than 75% stenosis in one or more arteries on coronary angiography were enrolled, as were normal control subjects which included patients with normal coronary angiograms, and subjects who were admitted for regular health examinations and had: (1) no history of CAD; (2) normal renal function; (3) normal ECG and chest x ray.

Blood was drawn under fasting conditions and centrifuged within four hours. Stabilising reagent containing sucrose and EDTA was added and samples were stored at −20°C until the time of …