BACKGROUNDThe identification of vulnerable plaques before rupture is an important clinical goal. The purpose of the present study was to assess the difference in plaque composition among patients with acute coronary syndrome (ACS) and stable coronary artery disease (SCAD) by intravascular ultrasound virtual histologic analysis.

METHODSOne hundred and thirty-nine patients were divided into ACS group and SCAD group according to clinical presentation. A total of 229 de novo lesions with >50% stenosis in native coronary arteries with diameters >2.5 mm were studied with intravascular ultrasonography. Geometric and compositional data were obtained using intravascular ultrasound virtual histology software.

RESULTSThere were no significant differences in overall lesions for fibrous ((52.0+/-11.9)% vs (54.3+/-8.5)%, P>0.05), fibrolipidic ((12.3+/-10.1)% vs (13.8+/-9.5)%, P > 0.05), calcium ((14.0+/-9.1)% vs (19.3+/-13.1)%, P>0.05), or necrotic core ((22.0+/-11.1)% vs (19.7 +/- 5.4)%, P > 0.05) percentages in ACS and SCAD patients, respectively. There were also no significant differences in culprit lesions for fibrous ((46.4+/-12.0)% vs (53.6+/-8.8)%, P>0.05), fibrolipidic ((9.1+/-9.0)% vs (12.9+/-9.7)%, P>0.05), calcium ((16.6+/-9.7)% vs (21.8+/-26.3)%, P>0.05), or necrotic core ((28.0+/-12.6)% vs (20.6+/-5.2)%, P>0.05) percentages in ACS and SCAD patients, respectively. High density lipoprotein-cholesterol levels >1.04 mmol/L were associated with more fibrolipidic ((14.5+/-10.4)% vs (7.1+/-6.5)%, P<0.05) and less necrotic core ((20.6+/-9.7)% vs (27.9+/-12.6)%, P<0.05) percentages in the cohort with ACS.

CONCLUSIONSIn this study, coronary plaque composition assessed by intravascular ultrasound virtual histologic analysis was not significantly different between ACS and SCAD patients. The anatomic relationship of the specific plaque components to the lumen of the vessel was more important than the quantitative information of plaque composition for plaque stability.