A new study shows that a simple ultrasound test may help to identify people at high risk of stroke who have a condition called asymptomatic carotid stenosis, a narrowing of the carotid artery found in the neck, in which few or no symptoms are present. The research is published in the August 17, 2011, online issue of Neurology®, the medical journal of the American Academy of Neurology.
"There is debate over how to best treat people with asymptomatic carotid stenosis. A procedure called carotid endarterectomy can reduce the risk of stroke, but there are risks and costs involved with the surgery. Identifying people with asymptomatic carotid stenosis who are at higher risk of stroke would help determine whether carotid endarterectomy is needed," said study author Raffi Topakian, MD, of the Academic Teaching Hospital Wagner-Jauregg in Linz, Austria.
The surgery removes the plaque buildup in the carotid artery, which is the main artery from the heart to the brain.
For the study, 435 people with asymptomatic carotid stenosis were followed for two years. They underwent ultrasound of the carotid artery and of blood vessels in the brain to determine whether two markers for high risk of stroke were present. The markers were signs of blood clots passing into the brain, and a type of carotid plaque called echolucent plaque, which has a higher fat content than other plaque.
Of the participants, 164 people had echolucent plaque, or 38 percent, and 73 people, or 17 percent, had at least one sign of a blood clot. Six percent, or 27 people, had both markers. During the study, 10 people had strokes and 20 people had transient ischemic attacks, or mini-strokes.
The study found that people with the echolucent plaque in their carotid artery were more than six times more likely to have a stroke than those people without the plaque. People who had the plaque and signs of blood clots were more than 10 times more likely to have a stroke than those without both markers. The results remained the same regardless of high blood pressure, diabetes, smoking and vascular disease.
"With further study, our results may lead to a simple, clinically applicable method for predicting future stroke in people with asymptomatic carotid stenosis and help to determine the best way to treat people with the disorder, such as selecting patients with asymptomatic carotid stenosis for carotid endarterectomy," said Topakian. "This method identifies a high risk group with an annual stroke risk of about nine percent and a low risk group with an annual risk of less than one percent.
In an accompanying editorial, Lars Marquardt, MD, DPhil, of the University of Erlangen-Nuremberg in Germany noted that the overall risk of stroke among people with asymptomatic carotid stenosis is relatively low and has decreased in recent years due to better management through cholesterol and high blood pressure drugs. He also said that incorporating screening for plaque and blood clots in people with no symptoms may be difficult and costly.
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