Objective: Risk assessment based on plaque vulnerability would be valuable in the management of asymptomatic carotid stenosis. The purpose of this study was to compare plaque morphology in symptomatic and asymptomatic patients with significant extracranial carotid artery stenosis using MDCT angiography.
Materials and methods: We identified 31 patients with greater than 60% carotid artery stenosis on MDCT angiography using the criteria of the North American Symptomatic Carotid Endarterectomy Trial Collaborators. We analyzed plaque density by blinded review in Hounsfield units in the atherosclerotic plaques of 15 symptomatic and 21 asymptomatic stenotic vessels for classification as soft, intermediate, or calcified. Data were analyzed using multiple logistic regression.
Results: Even with age, traditional cardiovascular risk factors, and treatment taken into account, we found that calcified plaques were 21 times less likely to be symptomatic than noncalcified plaques (95% confidence interval for odds ratio, 0.003, 0.749; p = 0.030). No significant predictive value was found between soft (p = 0.23) or intermediate (p = 0.18) plaque morphology for the occurrence of symptoms.
Conclusion: MDCT angiography may help risk-stratify patients with asymptomatic carotid artery stenosis. Extracranial carotid artery calcified plaques causing stenosis are significantly less likely to be symptomatic and thus may be more stable than noncalcified plaques. This finding may have implications for the interpretation of calcification of atherosclerotic plaque in other vascular beds.