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 ). If this plaque breaks open, it may form a blood clot, which could move to the brain and cause a stroke .

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

• Take medicines and make healthy lifestyle changes, such as being more active. 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 making healthy lifestyle changes 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:

• 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.

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 1}

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

There are two procedures that can help reduce the risk of stroke: 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.

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 2 , footnote 3} It might take up to 5 years to get this decrease in stroke risk. ^{footnote 4}

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 serious problems is highest shortly after the procedure is done. The risk decreases over time. In the first 30 days after a procedure, the risk of stroke or death may be about 3%. That means there is a 97% chance that these things may not happen. ^{footnote 5}

Endarterectomy and stenting have similar rates of risk. ^{footnote 5} But endarterectomy is usually safer than stenting for people older than 70. For people in this age group, the risk of stroke or death from stenting is too high. ^{footnote 5}

Other risks of carotid endarterectomy include:

• Infection.
• Breathing problems.
• Nerve damage that could cause serious problems, like trouble swallowing.

Other risks of carotid artery stenting include:

• Infection.
• Bleeding or damage to the blood vessel at the catheter insertion site.

Your chance of having a serious problem depends on things like your age and your overall health. Your doctor can help you understand your risk of problems from a procedure. It is important that your risk is less than 3%. 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 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.
• Find out what kind of plaque is narrowing the artery. But no test can tell for sure which plaques are likely to cause a blood clot to form and cause a stroke.

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:

• 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 60% to 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 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.