Carotid artery stenosis is a narrowing of one or both of the carotid arteries, which supply blood to your brain. These arteries can be narrowed and damaged by plaque buildup (atherosclerosis). This plaque may limit blood flow to the brain. If this plaque breaks open, it may form a blood clot. Or pieces of the plaque may break off. A piece of plaque or a blood clot could move to the brain and cause a stroke.

There are two main ways to reduce the risk of stroke:

• Take medicines and have a heart-healthy lifestyle. This is sometimes called medical therapy.
• Have a carotid artery procedure such as carotid surgery (endarterectomy) or carotid stenting to remove the plaque or widen the artery.

Having a procedure does not take the place of medicines and a healthy lifestyle. If you decide to have a procedure, it's still important to take your medicines and have healthy habits to reduce your stroke risk as much as possible.

Taking medicines and having a heart-healthy lifestyle are important for anyone who has narrowing in a carotid artery. These steps help control the conditions that increase your risk of stroke.

Medicines that can help reduce the risk of stroke include:

• Aspirin or other medicine to prevent blood clots.
• Blood pressure medicines. These help prevent the damage to blood vessels that can cause plaque to build up.
• Statins and other medicines to lower cholesterol.

Healthy habits that can help reduce the risk of stroke include:

• Not smoking.
• Eating heart-healthy foods.
• Being active. Your doctor can tell you what amount and type of activity is right for you.
• Staying at a healthy weight or losing weight if you need to.
• Managing other health problems, such as diabetes.

In people with carotid artery stenosis who take medicine and have healthy habits, about 1 out of 100 will have a stroke each year, and about 99 will not.^{footnote 6}

Your stroke risk may be higher based on things like your age and health. Your doctor can help you understand your risk of stroke.

Two procedures that can help reduce the risk of stroke are carotid endarterectomy and carotid artery stenting. Endarterectomy is more common than stenting.

Carotid endarterectomy (say "kuh-RAW-tid en-dar-tuh-REK-tuh-mee") is surgery to remove plaque buildup from a carotid artery. During this procedure, a surgeon:

• Makes a cut in the neck just below the jaw.
• Opens the carotid artery and carefully removes the plaque.
• Closes the artery and skin incisions with stitches and sometimes a patch.

Carotid artery stenting is also called carotid angioplasty. During this procedure, a doctor:

• Threads a tube through an artery in the groin or arm and passes it up to the carotid artery.
• Inflates a tiny balloon to enlarge the narrowed portion of the artery.
• Places a small, expandable tube called a stent to keep the artery open.

A carotid procedure may lower the risk of stroke from about 2% per year to 1% per year.^{footnote 2footnote 3}

Overall, endarterectomy and stenting seem to work about equally well to help prevent stroke.^{footnote 5}

It is not clear that a procedure will reduce stroke risk more than medicines and lifestyle changes alone. Studies are being done to compare current medical therapy with endarterectomy and stenting.

Having a carotid artery procedure may help prevent a stroke in the long term. But in the short term, it increases the risk of stroke and death.

The risk of problems is highest shortly after the procedure is done. The risk decreases over time. In the first 30 days after a procedure, up to about 3 in 100 people have a stroke or die. That means about 97 out of 100 people do not have a stroke or die.^{footnote 5}

Endarterectomy and stenting have similar rates of risk. But carotid stenting is linked with a higher risk of stroke in people older than 70.^{footnote 5}

Other risks of carotid endarterectomy include:

• Infection.
• Nerve damage that could cause serious problems, like trouble swallowing.
• The artery could narrow again.

Other risks of carotid artery stenting include:

• Infection.
• Bleeding or damage to the blood vessel at the catheter insertion site.
• Narrowing of the stent or artery again.

Your chance of having a problem can depend on things like your age and your overall health. Your doctor can help you understand your risk of problems from a procedure. It is also important to find a surgeon and a hospital that are experienced in doing the procedure and have a low rate of serious problems.^{footnote 1footnote 4}

Your doctor may recommend tests such as a carotid angiogram, a carotid ultrasound, or a magnetic resonance angiogram (MRA). These tests can help your doctor:

• Measure the amount of narrowing in your carotid arteries. This is usually described as a percentage. For example, if plaque is blocking half of the artery, the doctor may say the artery is 50% narrowed. If plaque is blocking three-quarters of the artery, the doctor may say the artery is 75% narrowed.
• Check to see how well blood flows through the area that is narrowed by plaque.
• Find out where the narrowing is located. Some of these tests can check the carotid arteries as well as the blood vessels above and below the neck.

A doctor may suggest a procedure if it seems likely that the benefits of a procedure will outweigh the risks. To decide if this is the case, a doctor will check several things, including:^{footnote 1}

• The amount of narrowing in your carotid artery. A procedure may be an option if you have severe narrowing. This may mean narrowing of more than 70%. A procedure is not an option if you have narrowing of less than 50%.
• The location of the narrowing in the artery.
• Your health. A procedure may be an option if you do not have other serious health problems. Having a serious health problem increases your risk of problems from a procedure.
• Your age and life expectancy. A procedure does not reduce your risk of stroke right away. You need to be likely to live for at least 3 to 5 more years to get a reduction in stroke risk.

A doctor may give you the option of having a procedure, but this is not a clear-cut decision. It is also not one you have to make in a hurry. You can take time to weigh your choices and decide what feels right for you. How you feel about the risks and benefits is just as important as the medical facts.