Atherosclerotic plaque composition assessed by virtual histology intravascular ultrasound and cerebral embolization after carotid stenting

Abstract

Plaque composition, as determined by VH-IVUS, only weakly correlates with the degree of cerebral embolization after carotid stenting. Specifically, there is a trend for larger dense calcium volume in patients with distal embolization. Of note, the proportion of necrotic core, which has traditionally been considered the main component of a vulnerable or unstable plaque, is not definitely associated with subclinical cerebral embolization after CAS when a filter device for embolic protection is used. The role of VH-IVUS in evaluating plaque composition during CAS remains unestablished and warrants further investigation.

Intracranial-Derived Atherosclerosis Assessment: An In Vitro Comparison between Virtual Histology by Intravascular Ultrasonography, 7T MRI, and Histopathologic Findings

“…[18][19][20] The relative lack of identification of necrotic core can be partly explained by the different definitions used in histologic analysis and VH-IVUS. 21 In histologic analysis, the necrotic core is defined by areas with lipid-rich cellular debris and lack of extracellular matrix 22,23 ; VH-IVUS relies on the presence of calcification to detect the necrotic core.…”

Risk Factors for Cerebral Embolization After Carotid Artery Stenting With Embolic Protection

“…[9][10][11] New cerebral ischemic lesions after CAS with embolic protection have been found in up to 70% of patients. [16][17][18][19] About 30% of these lesions occur in the cerebral hemisphere contralateral to the target lesion. 19 Although in a small randomized trial of CAS the incidence of new MRI lesions was not significantly different in patients with and without cerebral protection, 20 a meta-analysis comprising >1300 patients revealed a significantly lower incidence (33%) in protected patients as compared with unprotected patients (45%).…”

“…We, however, excluded patients from CAS if severe circular calcification was present. Others determined the composition of atherosclerotic plaques of the carotid artery by virtual histological intravascular ultrasound 24 and also found no correlation between calcified lesions and the degree of cerebral embolization, whereas plaque burden, necrotic core, fibro-fatty, and fibrous volumes showed a positive correlation. In another study 25 fibro-lipid plaques as compared with calcified plaques assessed by ultrasound and multislice computer tomography were associated with significantly higher numbers of new ischemic lesions.…”

Discussion

“…However, your findings last year on plaque morphology 3 and now this year on stent design have not confirmed conventional wisdom from observational studies and have failed to provide positive technical guidance.…”