OBJECTIVETo compare the angiogenesis in unstable and stable plaques and to investigate the potential role of neovessels in creating vulnerable sites for atherosclerotic plaques.

METHODSSpecimens of coronary arteries were obtained from 52 autopsy cases with acute coronary syndromes. Plaque morphology was studied by use of stained slides. 922 tissue blocks of late-stage lesions were classified into two groups: (1) unstable plaque (n = 153), the plaque was characterized by a large extracellular lipid core (more than 40% of the plaque area); (2) stable plaque (n = 769), lipid core less than 40% of the plaque area. Forty blocks were selected randomly from each group and serial sections were stained immunohistochemically with a polyclonal antibody against F VIII RAg. Computer-aided planimeter was used for quantitative analysis.

RESULTSIn unstable plaques, the occurrence of neovessels was more frequent and the neovessel density (number/mm(2)) was significantly increased as compared to that of stable plaques (frequency: 80.4% vs 66.6%, P < 0.01; shoulder: 22.16 +/- 19.96 vs 10.04 +/- 11.52, base: 21.68 +/- 20.44 vs 9.68 +/- 11.52, fibrous cap: 3.80 +/- 5.32 vs 1.48 +/- 2.28, P < 0.05). Most neovessels were located in the shoulder region and at the base of plaques.

CONCLUSIONSThese findings suggest that neovessels in coronary atherosclerotic plaques are closely associated with the decreased stabilization of the plaques.