OBJECTIVESTo analyze the relationship between oxidized low density lipoprotein (oxLDL), angiogenesis and stabilization of atherosclerotic plaques in human coronary arteries; and to investigate the role of oxLDL in creating vulnerable sites in atherosclerotic plaques.

METHODSSamples of coronary arteries were obtained at autopsies of 42 patients with acute coronary syndrome. Eighty randomly selected blocks were studied by immunohistochemistry using antibodies against oxLDL and endothelial cells (factor VIII). Computer-aided planimeter was used for quantitative analysis.

RESULTSIn unstable plaques, percentage of immunoreactive areas for oxLDL was significantly higher than that in stable plaques. Most of the oxLDL were located in shoulder region of these plaques, as compared to the fibrous cap and basal regions. The details of distribution of oxLDL were as follows: shoulder region (20.43 +/- 3.12 for unstable plaques and 17.65 +/- 4.22 for stable plaques), fibrous cap (4.77 +/- 2.03 for unstable plaque and 2.80 +/- 0.22 for stable plaques) and basal region (5.65 +/- 1.65 for unstable plaques and 3.22 +/- 1.02 for unstable plaques). OxLDL was also a main component in the lipid core. In the shoulder region, there was a significant positive correlation between neovascularization and oxLDL (r = 0.8247, P = 0.000).

CONCLUSIONSThe amount of oxLDL is significantly higher in unstable atherosclerotic plaques, especially over the shoulder region. OxLDL in coronary atherosclerotic plaques is thus an important factor in determining stabilization of the plaques. OxLDL may induce influx of inflammatory cells which subsequently leads to decreased plaque stabilization.