Aug. 17, 2011 -- Two noninvasive imaging tests may help determine which people with a narrowing of arteries in the neck will need surgery to reduce their future risk of stroke, a study suggests.
A narrowing of the carotid arteries in the neck is known as asymptomatic carotid stenosis (ACS). "Asymptomatic" means the patient does not experience any symptoms.
Carotid arteries in the neck deliver blood to the brain. They typically become narrowed when plaques build up in the inner lining of the arteries.
There is some uncertainty within the medical community on how to best identify people with ACS who are at high risk for stroke and need surgery or stenting to open their carotid arteries as opposed to treatment with medication.
In a two-year study of 435 people with severe ACS, researchers used ultrasound to assess the quality and composition of the plaque in the carotid arteries and a Doppler ultrasound test to look for the presence of tiny blood clots or particles called microemboli that may break off from the arteries and travel to the brain, causing stroke.
During the study, 10 people had strokes and 20 people had transient ischemic attacks or mini-strokes.
People with fatty plaque in their carotid artery were more than six times more likely to have a stroke than those people without this type of plaque. Plaques that are rich in fat are considered more dangerous.
People with both fatty plaque and signs of microemboli were more than 10 times more likely to have a stroke than those without these two markers, the study shows.
According to the new study, the risk of future stroke is 8% per year for people who test positive on both screening tests. By contrast, future risk of stroke is lower than 1% per year for those with negative results on both imaging tests. The findings held regardless of other stroke risk factors such as high blood pressure, diabetes, smoking, and vascular disease.
"Most patients will stay asymptomatic [without symptoms] and not suffer a stroke, but it's hard to identify the patients who are at highest risk and should undergo surgery," says study researcher Raffi Topakian, MD, a neurologist at Academic Teaching Hospital Wagner-Jauregg in Linz, Austria. "If you are at high risk for future stroke, medication is not enough for you."