OBJECTIVETo observe pathohistological features of vulnerable plaques in coronary arteries.

METHODSAutopsy coronary samples from 67 patients died of acute coronary syndrome (ACS) and 60 patients of non-cardiac death from 1992 to 2006 in Beijing Hospital were examined. Morphological features of vulnerable plaques of ACS cases were evaluated in terms of thrombus, ratio of lipid core, the minimal thickness of fibrous cap and the density of inflammatory infiltration.

RESULTS(1) There are 305 plaques in ACS group and the incidence of big lipid core is 153 (50.16%), thin fibrous cap is 187(61.31%), inflammatory infiltration is 263 (86.23%), neovasculature conformation is 217 (71.15%), severe stenosis is 26 (8.52%), calcification is 238 (78.03%), superficial calcified nodule is 26 (8.52%), fissured plaque is 12 (3.93%), endothelial denudation is 3 (0.98%) and intraplaque hemorrhage is 54 (17.70%), which are significantly higher than control samples except endothelial denudation (P < 0.01). (2) The incidence of vulnerable plaques in ACS group is significantly higher than in the control group (89.51% vs. 21.98%, P < 0.01). There are 4.07 sections of vulnerable plaques with high density of inflammatory infiltration out of 4.55 sections reviewed in ACS patients, while there are 0.85 sections of vulnerable plaques with mild inflammatory infiltration out of 3.87 sections reviewed in the control cases.

CONCLUSIONSFormation of vulnerable plaque was an important pathological factor for the development of ACS. The major morphological characteristics of vulnerable plaque are big lipid core, thin fibrous cap, inflammatory infiltration, neovascularization, severe stenosis, plaque rupture, and endothelial denudation suggesting inflammation performed an important role in the formation of vulnerable plaque.