ABSTRACT
OBJECTIVES: We used virtual histology-intravascular ultrasound (VH-IVUS) to investigate the characteristics of culprit lesions in acute coronary syndromes (ACS). BACKGROUND: Autopsy studies of patients who died of ACS have shown that culprit atheromatous plaques almost always contain a large lipid-necrotic core covered by a ruptured thin fibrous cap. There are no studies of sufficient size that have assessed the in vivo characterization of plaques responsible for ACS. METHODS: Patients undergoing angiography for stable ischemic heart disease and ACS (with and without ST-segment elevation) were enrolled in a prospective study. Lesions in patients with stable angina were classified as stable and those in patients with ACS as culprit or nonculprit. RESULTS: The study included 189 patients: VH-IVUS was used to assess 253 lesions (73 stable, 82 nonculprit, and 98 culprit lesions). The thin-cap fibroatheroma phenotype (VH-TCFA) was more frequent among lesions in patients with ACS (55.1% in culprit lesions, 36.6% in nonculprit lesions and 14.4% in stable lesions; P = .007). The arc of the VH-TCFA exposed to the vessel lumen was significantly greater in culprit lesions than in nonculprit lesions (122.28° ± 58 vs 89.46° ± 52; respectively; P = .007). Multivariate analysis showed that VH-TCFA (OR 2.1; P = .033), calcified nodules (OR 2.1; P = .046), positive remodeling (OR 3.5; P < .001) and necrotic core volume (OR 1.02;P = .009) were independently associated with a clinically identified culprit lesion. CONCLUSIONS: Plaque phenotype, rather than the proportion of each tissue, appears to be associated with plaque instability. VH-TCFA, particularly subtype IV, is associated with lesions responsible for ACS.
