Prediction of Silent Ischemic Lesions after Carotid Artery Stenting Using Virtual Histology Intravascular Ultrasound

Abstract

Background: A major concern with carotid artery stenting (CAS) is the potential for cerebral embolism. The purpose of this study was to determine whether virtual histology intravascular ultrasound (VH-IVUS) can predict the risk of a silent ischemic lesion after CAS. Methods: We performed CAS in 45 patients with carotid stenosis. Before CAS, we assessed plaque characteristics by VH-IVUS. We also performed diffusion-weighted magnetic resonance imaging of the brain before and after CAS to detect newly appearing ipsilateral silent ischemic lesions (NISIL). Results: In the patient group that was positive for NISIL (P group: n = 18), the relative fibrofatty (FF) area identified by VH-IVUS in 5 cross-sections including the most stenotic lesion was significantly larger than that in areas of the NISIL-negative group (N group: n = 27; 32.7 ± 13.2 and 18.3 ± 9.8%, respectively; p < 0.001). The relative fibrous area was significantly lower in the P group than in the N group (59.2 ± 9.5 and 74.6 ± 9.1%, respectively; p < 0.001). There were no differences in the relative dense calcium and necrotic core areas between the P and N groups. From the analysis of receiver operating characteristic curves, most reliable cutoff values for predicting NISIL were a relative FF area of 30% in the most stenotic lesion. In multivariate logistic regression analysis, the relative FF area was an independent predictor of NISIL (p = 0.005). Conclusions: Quantitative tissue characterization of atherosclerotic lesions of carotid arteries using VH-IVUS was useful to predict NISIL after CAS. However, the positive predictive value determined by VH-IVUS was not superior to that determined by a noninvasive method.