Multimodality imaging of attenuated plaque using grayscale and virtual histology intravascular ultrasound and optical coherent tomography.

BACKGROUND: Although attenuated plaque is a marker for plaque vulnerability, the quantification and its implication have not been known. METHODS: Multimodality pre-procedural imaging using grayscale intravascular ultrasound (IVUS), virtual histology-IVUS (VH-IVUS), and optical coherence tomography (OCT) were performed in 115 coronary lesions with diameter stenosis (DS) >30% and plaque burden ≥50% and compared the diagnostic accuracies for detecting thin-cap fibroatheromas (TCFA). RESULTS: A maximal arc of attenuation (40 MHz IVUS) ≥29.0° was the cutoff for predicting VH-TCFA (sensitivity 74%, specificity 66%); and OCT-TCFA (sensitivity 89%, specificity 64%), while a maximal arc attenuation ≥29.0° (20MHz IVUS) showed a poor sensitivity for predicting TCFA. Compared to the lesions with an arc of attenuation <30° as a rough cutoff value, the lesions with a maximum arc of attenuation ≥30° (40 MHz) were associated with more severe (smaller angiographic minimum lumen diameter and greater DS, smaller IVUS-MLA and a larger plaque burden) and had more unstable lesion characteristics: (1) larger remodeling index and more plaque ruptures (grayscale IVUS); (2) greater %necrotic core and more VH-TCFAs (VH-IVUS); and (3) more lipid, macrophages, cholesterol crystals, and microchannels; thinner fibrous caps; and more OCT-TCFAs, OCT-detected plaque ruptures, and red and white thrombi (OCT). Among 58 patients treated with stent implantation, postintervention peak CK-MB was higher in patients with the maximal attenuation ≥30° compared to those without (median 2.7 ng/ml [IQR 0.9-18.7 ng/ml] vs. median 0.9 ng/ml [IQR 0.7-2.1 ng/ml], P = 0.012). CONCLUSION: Attenuated plaque with a maximal attenuation ≥30° vs. <30° (40 MHz, but not 20 MHz IVUS) were more likely to be associated with unstable lesion morphology that may contribute to the immediate poststenting CK-MB elevation. © 2016 Wiley Periodicals, Inc.