Objective: coronary plaque composition cannot be assessed accurately using gray-scale intravascular ultrasound (IVUS). Using virtual histology IVUS (VH-IVUS), a comparison of coronary plaque composition between acute coronary syndromes (ACS) and stable angina pectoris (SAP) was performed.
Methods: pre-intervention IVUS of de novo culprit and target lesions was performed in 47 patients (25 with ACS and 22 with SAP). Using VH-IVUS, plaque was characterized as fibrotic, fibro-fatty, dense calcium, and necrotic core. VH-IVUS-derived thin-cap fibro-atheroma (VH-TCFA) was defined as necrotic core >10% of plaque area without overlying fibrous tissue in a plaque burden >40%. Lesions were classified into 3 groups: ruptured, VH-TCFA, and non–VH-TCFA plaque. Unstable lesions were defined as either VH-TCFA or ruptured plaque.
Results: compared with patients with SAP, those with ACS had significantly more unstable lesions. Planar VH-IVUS analysis at minimum lumen site shown that necrotic core and dense calcium by percentages and absolute quantities areas are significantly greater in ACS group compared with SAP group. Volumetric analysis over a 10-mm-long segment centered at the minimum luminal site showed that the percentage of necrotic core was significantly greater and that the percentage of fibrotic plaque was significantly smaller in patients with ACS.. VH-TCFA were more frequently observed in ACS patients than in SAP patients (p = 0.006).
Conclusions: culprit lesions in patients with ACS were more unstable and had greater amounts of necrotic core and smaller amounts of fibro-fatty plaque compared with target lesions in patients with SAP.
Keywords: intravascular ultrasound, coronary plaque, plaque components.