The influence of carotid plaque morphology on the development of cerebral symptoms

Background: Large randomized trials such as the European Carotid Surgery Trial (ECST) and North American Symptomatic Carotid Endarterectomy Trial (NASCET) have defined a role for carotid endarterectomy in symptomatic patients with severe carotid artery stenosis. Data from the same trials also shows that a subgroup of patients with less severe stenosis with a higher risk of stroke might benefit form carotid endarterectomy. In recent years, it has become apparent that besides the degree of stenosis, the morphology of the plaque itself plays a significant role in its potential for development: of symptoms, and noninvasive methods of assessing plaque morphology are currently being developed. This paper reviews the literature regarding the relationship between carotid plaque morphology and the potential for development of clinical symptoms. Methods: A Medline search and a meta-analysis of the literature was carried out. Intraplaque hemorrhage and plaque ulceration were both found to be associated with a higher risk of stroke development (p = 0.001 and 0.0001, respectively). Intraluminal thrombus was not found to be associated with an increased risk of symptom development in the data analyzed. A possible explanation for this incongruous finding is discussed. In addition, the paper also discusses the role of noninvasive plaque characterization as a method of identifying unstable plaques in the future. Conclusion: Certain characteristics of plaque morphology correlate with a higher risk of development: of symptoms and better noninvasive identification of plaque characterization will lead to better patient selection and may be especially useful identifying patients with lower degrees of stenosis but with potentially unstable plaques who might: benefit from carotid endarterectomy but do not qualify for surgery using currently accepted criteria.