Symptomatic Carotid Atherosclerotic Disease: Correlations Between Plaque Composition and Ipsilateral Stroke Risk | Journal Scan

Study Questions:

Which components of carotid plaque morphology predict risk of a future ipsilateral ischemic stroke?

Methods:

Using two large atherosclerotic carotid plaque biobank studies from the United Kingdom and the Netherlands, the histologic characteristics of 1,640 carotid plaques from symptomatic patients undergoing carotid endarterectomy (CEA) for ≥50% stenosis between 1975 and 2012 were assessed. Each patient had an individualized stroke-risk score calculated (Carotid Stenosis Risk Prediction Model), which was then correlated with various histopathologic plaque features. Correlation was performed using bivariate linear regression. Comparison was also made based on the time between a symptomatic neurologic event and the surgical CEA as a predictor of stroke risk.

Results:

Higher 5-year predicted stroke risk (top vs. bottom quartile) was associated with a higher plaque thrombus (odds ratio [OR], 1.49; 95% confidence interval [CI], 1.11-1.89), degree of fibrous content (OR, 0.65; 95% CI, 0.49-9.87), higher macrophage infiltration (OR, 1.41; 95% CI, 1.05-1.90), higher microvessel density (OR, 1.49; 95% CI, 1.05-2.11), and higher overall plaque instability (OR, 1.40; 95% CI, 1.05-1.87). There was no association between higher predicted stroke risk and fibrous cap thickness, calcification, intraplaque hemorrhage, or lymphatic infiltration. In patients who underwent CEA within 30 days of their symptomatic event, increasing numbers of vulnerable plaque features were increasingly associated with higher quartile stroke-risk score (p = 0.002 for trend). The same association was not found for patients undergoing CEA more than 30 days since their last symptomatic neurologic event (p = 0.11 for trend).

Conclusions:

The authors concluded that increasing numbers of vulnerable plaque features are associated with increasing stroke-risk scores in patients undergoing CEA for symptomatic carotid atherosclerosis. The authors believe that this study provides a basis for plaque imaging studies to help correlate with stroke risk.

Perspective:

The authors used a validated stroke-risk score derived from the European Carotid Surgery Trial (ECST) and validated in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) to compare stroke-risk with various features of a vulnerable carotid plaque in patients undergoing CEA for symptomatic carotid stenosis. While the model used to stratify patients has reasonable predictive ability for stroke (c-statistic = 0.67), the comparison between plaque morphology and stroke risk is calculated based on a risk prediction score and not actual events. Still, this study highlights important aspects of a vulnerable plaque, analogous to vulnerable coronary artery plaques for acute coronary syndromes. The ability to predict the risk of stroke on the basis of plaque imaging studies still needs to be proven in a prospective study before it becomes widely adopted.

Clinical Topics: Acute Coronary Syndromes, Invasive Cardiovascular Angiography and Intervention, Vascular Medicine, Interventions and ACS, Interventions and Vascular Medicine

Keywords: Acute Coronary Syndrome, Biological Specimen Banks, Carotid Artery Diseases, Carotid Stenosis, Constriction, Pathologic, Coronary Vessels, Endarterectomy, Carotid, Great Britain, Macrophages, Microvessels, Netherlands, Plaque, Atherosclerotic, Risk, Thrombosis


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