February 18, 2014
News Review From Harvard Medical School -- Carotid Artery Test Not Recommended for All
Most adults don't need to have a test for narrowed arteries in the neck, an expert group says. The draft advice comes from the U.S. Preventive Services Task Force. This independent group of experts issues advice on preventive care and testing. Doctors, the government and insurance companies usually follow its advice. The new report focuses on carotid artery stenosis. The carotid arteries supply the brain with blood. They can become narrow inside because of a buildup of fatty deposits. Carotid artery stenosis increases the risk of stroke. But the task force said that screening all adults with ultrasound would not be worthwhile. Narrowed carotid arteries are not common. But some tests could show "false positive" results. This is when a test result looks suspicious but the problem is not really there. Such results might lead to more tests and even surgeries that were not needed. The task force advice applies only people with no extra risk of stroke. It does not apply to people who have had a stroke, mini-stroke or symptoms that resemble stroke. HealthDay News wrote about the task force report February 17.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
Having a narrowed carotid artery is one of the factors that increase the risk of stroke. Doctors call it carotid artery stenosis. The carotid arteries are the blood vessels in the neck that supply oxygen-rich blood to the brain. If the narrowed artery suddenly becomes blocked, a stroke is likely to happen. Strokes also can occur if blood pressure gets too low to allow enough blood to feed the brain.
To reduce the risk of stroke, you would think it is always helpful to find a narrowed carotid artery and then open it with surgery. That's the reason the U.S. Preventive Services Task Force once again has looked at this question: Should all adults have a screening test to look for carotid artery stenosis, even if they feel fine?
The last time the task force addressed this question, the answer was no. That was in 2007. Now the task force has taken another look at the benefits vs. risks of screening for carotid artery stenosis in the general adult population.
The task force recruits experts with different specialties. This reduces the risk of bias, which can happen when just one specialty group issues guidelines. The updated advice is now posted for public comment. And once again, the task force recommends against routine screening.
Here are some of the reasons:
- Only a small number of strokes are directly related to a carotid artery narrowing of 70% or greater. (Doctors consider surgery to open the artery if the narrowing is 70% or greater.)
- Less than 1% of the general population has carotid artery stenosis of 70% or greater.
- Some people with this degree of narrowing have symptoms. For those without symptoms, there is only a small improvement in stroke risk for people who get surgery instead of just taking medicine.
- The procedure to open the artery carries a risk of stroke, heart attack and death during and right after the surgery. In hospitals that do many procedures to open carotid arteries, the risk is lower. But it varies from state to state, and hospital to hospital.
Most doctors use U.S. Preventive Services Task Force guidelines to help make decisions for their patients. Insurance companies, especially Medicare, follow task force advice for determining whether to cover costs.
What Changes Can I Make Now?
The test used most often to look for carotid artery stenosis is an ultrasound. The test itself is harmless. It uses radio waves to see if there is any narrowing of the carotid artery. There is no radiation. Based on the images, the doctor can estimate the amount of narrowing.
The task force guidelines do not recommend routine screening of all adults. But an important question that this group did not address is: Which adults should have an ultrasound test to look for carotid artery stenosis?
There is widespread agreement that a person with symptoms of a stroke, even if they last only a few minutes, should have carotid artery ultrasound. If you don't have any symptoms, your doctor might order a carotid ultrasound test for other reasons. They include:
- Your doctor listens with a stethoscope to your neck and hears a whooshing sound called a bruit. This sound is almost always produced by a narrowed artery.
- You have had a heart attack or have known coronary artery disease or other artery disease.
- You have multiple risk factors that increase your risk of stroke, such as:
- A family history of heart attack or stroke before age 55 for a man or 60 for a woman
- High blood pressure
- High LDL cholesterol, especially if HDL cholesterol is low
Most strokes happen in people with a buildup of fatty deposits in the arteries of the neck and inside the brain. This is true even for strokes not directly related to significant carotid artery stenosis. So the primary way to prevent a stroke is to prevent the fatty deposits from getting into the artery walls.
You can help prevent these fatty deposits with the same steps that also reduce your risk of heart disease and heart attack:
- Don't smoke. Quitting reduces your heart attack risk within weeks.
- Stick to a heart-healthy diet, such as a Mediterranean-style diet.
- Maintain a healthy weight to help prevent diabetes.
- Stay physically active and exercise regularly.
- Keep your blood pressure under control.
Work to keep your LDL cholesterol and triglyceride levels down and HDL cholesterol up. Diet and exercise are the first steps. Your doctor may prescribe medicines if needed.
What Can I Expect Looking to the Future?
You can expect the task force to make its draft guidelines formal. As before, they will recommend against routine carotid artery ultrasound screening.