Subclavian Steal Syndrome

What is subclavian steal syndrome?

Subclavian steal syndrome is a condition where an artery takes or “steals” blood that’s supposed to go to your brain. Instead, that blood goes to your arm. This happens because of a narrowing or blockage in your subclavian artery (usually the left one) that normally sends blood to your arm on that side.

As this blockage gets worse, blood moves through the subclavian artery with less pressure. Stronger pressure from nearby arteries makes your blood flow backward in a vertebral artery that branches off the subclavian artery. This makes the blood available for your subclavian artery to take.

It’s like your spouse taking food off your plate when they’re sitting next to you (within easy reach of your plate). The food that was supposed to go into your mouth ends up going into their mouth. And you’re still hungry.

A variation of subclavian steal syndrome, coronary steal syndrome, sends blood to your arm instead of your heart muscle, typically causing heart attack-like symptoms. This only happens to some people who’ve had certain types of coronary artery bypass surgery. Both of these syndromes happen because of atherosclerosis (plaque buildup) or other causes of narrowing in your subclavian artery.

How common is subclavian steal syndrome?

Researchers don’t know exactly how many people have subclavian steal syndrome. But they estimate that .6% to 6.4% of people have it. About 18% of people with peripheral artery disease also have subclavian steal syndrome. 

The condition is more common among people assigned male at birth (AMAB) and in people older than 55. 

Today’s advanced imaging identifies the condition in more people without symptoms than in the past.

What are the symptoms of subclavian steal syndrome?

Subclavian steal syndrome symptoms are more likely to happen when you exercise your arm or turn your head suddenly to the side. Symptoms may include:

• Blurry vision.
• Dizziness.
• Pain, numbness, tingling or tiredness in your arm.
• Fainting.
• Hearing loss.
• Vertigo.
• Clumsy muscle movement (ataxia).

Most people don’t have symptoms because their brains are getting enough blood from other arteries that are healthy. In these cases, they don’t need treatment.

What causes subclavian steal syndrome?

Causes of subclavian steal syndrome include:

• Atherosclerosis (plaque buildup in your artery, which is the most common cause).
• Arteriovenous malformations.
• Aortic dissection.
• Takayasu’s arteritis.
• Fibromuscular dysplasia.

These causes are similar to causes of subclavian artery stenosis.

What are the risk factors for subclavian steal syndrome?

Risk factors for subclavian steal syndrome include having:

• Surgery to fix coarctation of the aorta.
• Issues present at birth that affect your aortic arch or certain blood vessels.
• Compression of the subclavian artery (common in some athletes).
• An extra rib called a cervical rib.

What are the complications of subclavian steal syndrome?

If subclavian steal syndrome makes you faint, that can lead to falls and injuries. Also, you may have a hard time doing things that require you to exercise your affected arm.

How is subclavian steal syndrome diagnosed?

Diagnosis of subclavian steal syndrome starts with a physical exam. A healthcare provider will pay special attention to the pulses in each arm and wrist. They’ll also check the carotid arteries on both sides of your neck, as well as your subclavian arteries for a bruit, or “whooshing” sound. If they hear this sound through their stethoscope, you may have a blockage in that artery.

What are the signs of steal syndrome?

If you have subclavian steal syndrome, a healthcare provider will find a different blood pressure in each of your arms. Your blood pressure in one arm could be at least 15 millimeters of mercury (mmHg) higher than the other.

A provider may also notice a difference in your radial pulses (in your wrists) if they check them at the same time. The side with subclavian steal syndrome may have a weaker, slower pulse.

What tests will be done to diagnose subclavian steal syndrome?

A healthcare provider will start with an ultrasound of your subclavian artery. Next, they may use:

• MRA (magnetic resonance angiogram).
• CT (computed tomography) angiogram.
• Digital subtraction angiogram (a technique that lets a provider see blood vessels better by taking other body parts out of the image).

These tests can help healthcare providers assign a grade to describe subclavian steal syndrome as mild or severe. They use Grade I, II or III, with Grade III being the most severe. Tests also help them decide on treatment.

What is the treatment for subclavian steal syndrome?

If you have symptoms, subclavian steal syndrome treatment may mean surgery to improve blood flow in your subclavian artery. Depending on your situation, this could be open surgery or endovascular surgery. Until you have surgery, you should avoid exercising your affected arm too much.

If you’re not a candidate for surgery, your provider may prescribe anticoagulants or antiplatelets.

If you have mild symptoms, they may get better over time. Your provider may prescribe medicines to lower your blood pressure and cholesterol.

People without symptoms don’t need treatment. But if you have narrowing in your subclavian artery, there’s a good chance you have it in other arteries, too. This is because plaque buildup (atherosclerosis) usually happens in arteries throughout your body.

So, you may need treatment for plaque buildup. You may need to stop smoking and manage high blood pressure and high cholesterol. These and other steps can prevent a future heart attack or stroke.

Specific medicines/procedures used

You may need one or more of these procedures:

• Surgery to connect your subclavian artery to another artery (like your carotid) to use as a bypass route.
• Angioplasty and stenting.
• Atherectomy.
• Endarterectomy.

Complications of the treatment

Risks vary by procedure. They may include:

• Your subclavian artery getting narrow again.
• Blood clots, which can cause a stroke.
• Injury to a nerve or blood vessel.
• Issues with healing.

How long does it take to recover from this treatment?

It can take a few days or a week or more to recover from a procedure that treats subclavian steal syndrome. Recovery from surgery usually takes the longest.

Can subclavian steal syndrome be prevented?

Some causes of subclavian steal syndrome are beyond your control. But you may be able to prevent subclavian steal syndrome by preventing plaque buildup, which is its most common cause.

How can I lower my risk?

You can lower your risk of plaque buildup — and subclavian steal syndrome — by making changes to your daily life, like:

• Staying at a weight that’s healthy for you.
• Getting physical activity for 30 minutes per day on most days.
• Avoiding tobacco products.
• Eating heart-healthy foods (those with low saturated fat and trans fat).
• Managing high cholesterol, high blood pressure and diabetes.

What can I expect if I have subclavian steal syndrome?

More than 95% of people who get surgical treatment for subclavian steal syndrome don’t need a repeat procedure. The prognosis (outlook) for them is good.

Is subclavian steal syndrome life-threatening?

No, but it’s a warning sign that means you have atherosclerosis. Plaque buildup in your arteries puts you at risk for future issues, like your heart or brain not getting enough oxygen. These can lead to a heart attack or stroke.

How do I take care of myself?​

If you have subclavian steal syndrome, follow your healthcare provider’s recommendations for taking medicine or having a procedure. It’s also important to manage high blood pressure, high cholesterol and diabetes (if you have them) and to avoid using tobacco products.

When should I see my healthcare provider?

You should have regular checkups with your healthcare provider after treatment, especially if your symptoms come back. They may want to repeat imaging tests if they think your subclavian artery is narrow again. Checkups may be a month, six months and 12 months after treatment. Then you can see your provider once a year.

What questions should I ask my doctor?

You may want to ask your healthcare provider:

• How soon do I need treatment?
• Which treatment is best for me?
• What’s your success rate in treating people for this?

A note from Cleveland Clinic

Having a condition with the word “steal” in it can make you wonder what’s going on inside your body. But subclavian steal syndrome is a treatable issue, and many people don’t even need those treatments. The bigger takeaway is that this means you have plaque buildup. Your body is telling you that it’s time to start or ramp up heart-healthy habits. Ask your provider what changes you can make to improve your health. Even small changes you start today can add up.