Compositional analysis of angioscopic yellow plaques with intravascular ultrasound radiofrequency data.

BACKGROUND: To identify subclinical high-risk plaques is potentially important because those vulnerable plaques may have a greater likelihood of rupture and subsequent thrombosis. The aim of this study is to reveal the histology of angioscopic yellow plaques known as vulnerable plaques by intravascular ultrasound radiofrequency data analysis. METHODS: Thirty-one coronary plaques in 21 patients, which were non-culprit, de novo, angiographically non-obstructive (<50%) lesions, were analyzed with Virtual Histology - intravascular ultrasound (VH-IVUS) and coronary angioscopy. These plaques were prospectively divided into 4 groups (Grade 0 to 3) by the yellow color intensity and we compared plaque morphology, echogenicity and composition among their groups. RESULTS: Morphology and echogenicity evaluated by standard gray-scale IVUS were not significantly different among those groups. On analyzing plaque composition by VH-IVUS, mean percentage of necrotic core was significantly larger in yellow plaque (Grade 2 and 3) than white plaque (Grade 0). CONCLUSIONS: Angioscopic yellow plaque included a larger amount of necrotic core analyzed by VH-IVUS than white plaque.