Aortic Valve Stenosis: Should I Have Surgery?

Decision point

You may want to have a say in this decision, or you may simply want to follow your doctor's recommendation. Either way, this information will help you understand what your choices are so that you can talk to your doctor about them.

Aortic Valve Stenosis: Should I Have Surgery?

Get the facts

Your options

  • Have surgery to replace your aortic valve.
  • Don't have surgery.

Key points to remember

  • Replacing the aortic valve can fix the valve when you have aortic valve stenosis. Surgery may help you live longer, feel better, and have a better quality of life.
  • Whether replacement is right for you is based on many things. These include your overall health, how severe your stenosis is, whether you have symptoms, how well blood is flowing through the valve, and how well your heart is pumping blood.
  • If you have severe stenosis but are otherwise healthy, surgery has a high rate of success and a low risk of causing other problems. The risks of not replacing the valve are likely greater than the risks of surgery.
  • If you have severe stenosis, especially if you also have symptoms, your life may be much shorter if you don't have the valve replaced. People who have symptoms of aortic valve stenosis have a high risk of sudden death.
  • If you have mild or moderate stenosis, the risks of valve replacement surgery may outweigh the benefits. Your doctor may suggest that you wait until the stenosis gets worse.
FAQs

What is aortic valve stenosis?

Aortic valve stenosis is a narrowing of the aortic valve. The aortic valve allows blood to flow from the heart's lower left chamber (ventricle) into the aorta and to the body. Stenosis prevents the valve from opening properly, forcing the heart to work harder to pump blood through the valve. This causes pressure to build up in the left ventricle and thickens the heart muscle.

Your heart can make up for aortic valve stenosis and the extra pressure for a long time. But at some point, it won't be able to keep up the extra effort of pumping blood through the narrowed valve. This can lead to heart failure.

What are the symptoms of aortic valve stenosis?

Aortic valve stenosis gets worse slowly. For many years you may not feel any symptoms. But at some point, the valve will become so narrow that symptoms occur. Symptoms are often brought on by exercise, when the heart has to work harder. Symptoms include:

  • Chest pain or pressure (angina). You may have a heavy, tight feeling in your chest.
  • Feeling dizzy or faint.
  • Feeling tired and being short of breath.
  • A feeling that your heart is pounding, racing, or beating unevenly (palpitations).

What are the treatment options for aortic valve stenosis?

There are a few ways that doctors can treat aortic valve stenosis. But a surgery or procedure is the only treatment that will fix the valve.

Surgery. The most common surgery is valve replacement. This is typically an open-heart surgery. Surgery to repair the valve is not common.

Transcatheter valve replacement. A newer, less invasive way to replace an aortic valve is called transcatheter aortic valve replacement. This procedure is only available for a person who cannot have surgery or for a person who has a high risk of serious problems from surgery. It is a procedure that uses catheters in blood vessels to replace the aortic valve with a specially designed artificial valve. This procedure is available in a small number of hospitals. And it is not right for everyone.

Balloon valvuloplasty. A procedure called balloon valvuloplasty is another treatment option. But it does not fix the valve problem. And it is not right for everyone. Balloon valvuloplasty is a less invasive procedure that makes the valve opening bigger. It may be an option for some children, teens, or young adults in their 20s. If a person who is too sick to have their aortic valve replaced right away, valvuloplasty may be used as a short-term fix until they can have the valve replaced.

Medicine. Your doctor may prescribe medicines to prevent or treat complications. Medicine cannot fix the valve.

Healthy lifestyle. Your doctor will probably recommend some lifestyle changes to keep your heart healthy. These include eating heart-healthy foods, being active, staying at a healthy weight, and not smoking.

Why is it important to wait for stenosis to get worse before having surgery?

Timing is important. If you have valve surgery too soon, you face the risks of surgery before you need to. And you may also increase the chance that you will need another new valve in the future. This chance depends on the type of valve you get. But if you wait too long to have surgery, your heart may become damaged, leading to heart failure.

Your doctor will check many things to see if your disease is bad enough to recommend surgery. These things include how severe your stenosis is, whether you have symptoms, how well blood is flowing through the valve, and how well your heart is pumping blood.

If you do not have severe stenosis yet, the risks of surgery may outweigh the benefits. Your doctor will likely recommend that you wait to have your valve replaced.

What are the benefits of surgery?

Replacing your valve can help you have a more normal life span, help you feel better, and improve your quality of life.

You will likely feel better after your valve is replaced, because blood will flow normally through the artificial valve.

If you have severe stenosis but don't have your valve replaced, you may die suddenly or develop heart failure. Replacing the valve can lower these risks.

What are the risks of surgery?

Valve replacement surgery has a high rate of success and a low risk of causing other problems if you are otherwise healthy.

In people who do not have left ventricular heart failure, the risk of death from surgery ranges from 2% to 5%.1 That means that out of 100 people who have the surgery, 2 to 5 people will die and 95 to 98 people will live.

The risk is lower for people who have the surgery when they are younger than 70. Out of 100 of these people, 1 will die and 99 will live. The risk of death is higher in people who have left ventricular heart failure and other signs that their heart is not working well.1

Even if valve replacement surgery is a success, you may have problems after surgery, such as:

  • An increased risk of blood clots. These can break off and cause a stroke or heart attack. To reduce the risk of blood clots, you will take a blood-thinning medicine.
  • A need for another replacement valve. This will depend on the type of valve you get and how long you live after you have the surgery.
  • Incomplete relief from symptoms. Some types of valves do not have openings as wide as a normal valve for a person your size. This can limit how well the valve works to relieve your symptoms.
  • A valve that fails. There is a small chance that the valve will not work. Your doctor will need to check from time to time to make sure that your valve is working.

After you have the new valve, you'll need to take antibiotics to prevent an infection of the valve anytime you have certain other procedures, such as dental work or another surgery.

Heart surgery, such as valve surgery, also can cause an irregular heartbeat (atrial fibrillation). This can cause clots to form and increases your risk of stroke.

If you are older, should you still have surgery?

Most people who have severe aortic valve stenosis are older than 65. But your age shouldn't stop you from having valve replacement surgery.

There are other health problems that may increase the risks of surgery, though. These include coronary artery disease, heart failure, advanced cancer, and brain problems because of a stroke. If you have other serious health problems, it's important to think about whether surgery will improve your quality of life and your chances of living a longer life.

Why might your doctor recommend valve replacement surgery?

Your doctor may advise you to have valve replacement if:

  • You have severe stenosis.
  • You have symptoms of stenosis.
  • There may be other reasons that your doctor recommends replacing the valve. Talk with your doctor about the benefits and risks for you.

Compare your options

Compare

What is usually involved?









What are the benefits?









What are the risks and side effects?









Have surgery to replace your aortic valve Have surgery to replace your aortic valve
  • The surgery can take 2 to 5 hours. You will stay in the hospital 4 to 5 days after surgery. You will have a big scar on your chest from the incision.
  • It can take several weeks to recover.
  • Valve replacement is a treatment that will fix the valve.
  • You may feel better and live longer.
  • Valve replacement surgery has a high rate of success and a low risk of causing other problems, if you are otherwise healthy.
  • All surgery has risks, including the risks of anesthesia and bleeding.
  • The risk of dying from this surgery ranges from 1% to 5%. This means that out of 100 people who have the surgery, 1 to 5 people will die and 95 to 99 people will live.1
  • You may not be healthy enough to have surgery.
  • If the valve fails or wears out, you may need another surgery to replace the artificial valve.
Do not have surgery Do not have surgery
  • You may take medicines to treat complications.
  • You can make lifestyle changes to help keep your heart healthy.
  • If you don't have severe stenosis, you will likely wait until the stenosis gets worse before you consider having surgery.
  • You avoid the risks of surgery.
  • If you don't have severe stenosis, you avoid having surgery too soon and maybe needing another valve replacement later.
  • If you wait too long to have surgery, your heart may become damaged, leading to heart failure.
  • Medicines can treat complications, but they won't fix the valve.
  • If you have severe stenosis and don't have surgery, your life may be much shorter.

Personal stories about aortic valve replacement surgery

These stories are based on information gathered from health professionals and consumers. They may be helpful as you make important health decisions.

A few days ago, I began to notice how out of breath I am just walking up a few stairs in my house. I've also been having some chest pain. I visited my doctor and found that I have a severely narrowed aortic valve. Apparently I have had it for years, but it's just now become bad enough that I'm having symptoms. My doctor said I should have my valve replaced. I don't want to develop permanent heart damage from this.

Maria Theresa, age 67

My doctor heard a heart murmur during a routine physical examination. I had an echocardiogram and found out that I have mild aortic stenosis. I feel fine. I don't have any chest pain or shortness of breath. My doctor said it could be many years before I have symptoms, if at all. So we agreed that I would have an echo every 3 years to keep an eye on it. And I will make sure to report any symptoms.

Maddie, age 40

I have moderate aortic stenosis. It was discovered during some tests I had for coronary artery disease. I'm scheduled to have coronary bypass surgery. My cardiologist suggested that I have a new aortic valve put in at the same time I have the bypass surgery. That way I only have to have one open-heart operation.

Ralph, age 58

I've known for years that I have aortic stenosis. I'm now in the severe stage as far as the width of the valve opening. I don't have any symptoms. But my doctor says my heart isn't pumping blood as well as it should be. My doctor said that replacing the valve could help me live longer, so I am going to have the surgery.

Fred, age 70

What matters most to you?

Your personal feelings are just as important as the medical facts. Think about what matters most to you in this decision, and show how you feel about the following statements.

Reasons to have surgery to replace your aortic valve

Reasons not to have surgery

I have symptoms of aortic valve stenosis.

I don't have symptoms.

More important
Equally important
More important

I don't have symptoms yet, but I have severe stenosis.

I don't have severe stenosis.

More important
Equally important
More important

Surgery is my chance to live a longer life.

I have other health problems, and I don't think this surgery will help me live longer.

More important
Equally important
More important

For me, the benefits of valve replacement outweigh the risks of the surgery.

I don't want to have surgery of any kind.

More important
Equally important
More important

My other important reasons:

My other important reasons:

More important
Equally important
More important

Where are you leaning now?

Now that you've thought about the facts and your feelings, you may have a general idea of where you stand on this decision. Show which way you are leaning right now.

Having surgery

NOT having surgery

Leaning toward
Undecided
Leaning toward

What else do you need to make your decision?

Check the facts

1.

If you have severe aortic valve stenosis, what is a treatment to fix your aortic valve?

  • Taking medicineSorry, that's wrong. Aortic valve replacement is a treatment to fix aortic valve stenosis.
  • Replacing the aortic valveYou're right. Aortic valve replacement is a treatment to fix aortic valve stenosis.
  • I'm not sureIt may help to go back and read "Get the Facts." Aortic valve replacement is a treatment to fix aortic valve stenosis.
2.

If you have severe aortic valve stenosis, but have no other health problems, which treatment carries greater risks?

  • Having valve replacement surgerySorry, that's wrong. If you have severe stenosis, the risks of not replacing the valve are greater than the risks of surgery, if you have no other health problems.
  • Not having valve replacement surgeryYou're right. If you have severe stenosis, the risks of not replacing the valve are greater than the risks of surgery, if you have no other health problems.
  • I'm not sureIt might help to go back and read "Get the Facts." If you have severe stenosis, the risks of not replacing the valve are greater than the risks of surgery.
3.

If you do not have severe aortic valve stenosis, what might your doctor suggest?

  • Go ahead and replace the aortic valveSorry, that's not right. If you do not have severe stenosis, your doctor may suggest that you wait until the stenosis gets worse to have surgery.
  • Wait to replace the aortic valveYou are right. If you do not have severe stenosis, your doctor may suggest that you wait until the stenosis gets worse to have surgery.
  • I'm not sureIt may help to go back and read "Get the Facts." If you do not have severe stenosis, your doctor may suggest that you wait until the stenosis gets worse to have surgery.

Decide what's next

1.

Do you understand the options available to you?

2.

Are you clear about which benefits and side effects matter most to you?

3.

Do you have enough support and advice from others to make a choice?

Certainty

1.

How sure do you feel right now about your decision?

Not sure at all
Somewhat sure
Very sure

Your Summary

Here's a record of your answers. You can use it to talk with your doctor or loved ones about your decision.

Your decision 

Next steps

Which way you're leaning

How sure you are

Your comments

Your knowledge of the facts 

Key concepts that you understood

Key concepts that may need review

Getting ready to act 

Patient choices

Credits and References

Credits
AuthorHealthwise Staff
Primary Medical ReviewerRakesh K. Pai, MD, FACC - Cardiology, Electrophysiology
Specialist Medical ReviewerDavid C. Stuesse, MD - Cardiac and Thoracic Surgery

References
Citations
  1. Otto CM, Bonow RO (2012). Valvular heart disease. In RO Bonow et al., eds., Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine, 9th ed., vol. 2, pp. 1468–1539. Philadelphia: Saunders.
You may want to have a say in this decision, or you may simply want to follow your doctor's recommendation. Either way, this information will help you understand what your choices are so that you can talk to your doctor about them.

Aortic Valve Stenosis: Should I Have Surgery?

Here's a record of your answers. You can use it to talk with your doctor or loved ones about your decision.
  1. Get the facts
  2. Compare your options
  3. What matters most to you?
  4. Where are you leaning now?
  5. What else do you need to make your decision?

1. Get the Facts

Your options

  • Have surgery to replace your aortic valve.
  • Don't have surgery.

Key points to remember

  • Replacing the aortic valve can fix the valve when you have aortic valve stenosis. Surgery may help you live longer, feel better, and have a better quality of life.
  • Whether replacement is right for you is based on many things. These include your overall health, how severe your stenosis is, whether you have symptoms, how well blood is flowing through the valve, and how well your heart is pumping blood.
  • If you have severe stenosis but are otherwise healthy, surgery has a high rate of success and a low risk of causing other problems. The risks of not replacing the valve are likely greater than the risks of surgery.
  • If you have severe stenosis, especially if you also have symptoms, your life may be much shorter if you don't have the valve replaced. People who have symptoms of aortic valve stenosis have a high risk of sudden death.
  • If you have mild or moderate stenosis, the risks of valve replacement surgery may outweigh the benefits. Your doctor may suggest that you wait until the stenosis gets worse.
FAQs

What is aortic valve stenosis?

Aortic valve stenosis is a narrowing of the aortic valve . The aortic valve allows blood to flow from the heart's lower left chamber (ventricle) into the aorta and to the body. Stenosis prevents the valve from opening properly, forcing the heart to work harder to pump blood through the valve. This causes pressure to build up in the left ventricle and thickens the heart muscle.

Your heart can make up for aortic valve stenosis and the extra pressure for a long time. But at some point, it won't be able to keep up the extra effort of pumping blood through the narrowed valve. This can lead to heart failure.

What are the symptoms of aortic valve stenosis?

Aortic valve stenosis gets worse slowly. For many years you may not feel any symptoms. But at some point, the valve will become so narrow that symptoms occur. Symptoms are often brought on by exercise, when the heart has to work harder. Symptoms include:

  • Chest pain or pressure (angina). You may have a heavy, tight feeling in your chest.
  • Feeling dizzy or faint.
  • Feeling tired and being short of breath.
  • A feeling that your heart is pounding, racing, or beating unevenly (palpitations).

What are the treatment options for aortic valve stenosis?

There are a few ways that doctors can treat aortic valve stenosis. But a surgery or procedure is the only treatment that will fix the valve.

Surgery. The most common surgery is valve replacement. This is typically an open-heart surgery. Surgery to repair the valve is not common.

Transcatheter valve replacement. A newer, less invasive way to replace an aortic valve is called transcatheter aortic valve replacement. This procedure is only available for a person who cannot have surgery or for a person who has a high risk of serious problems from surgery. It is a procedure that uses catheters in blood vessels to replace the aortic valve with a specially designed artificial valve. This procedure is available in a small number of hospitals. And it is not right for everyone.

Balloon valvuloplasty. A procedure called balloon valvuloplasty is another treatment option. But it does not fix the valve problem. And it is not right for everyone. Balloon valvuloplasty is a less invasive procedure that makes the valve opening bigger. It may be an option for some children, teens, or young adults in their 20s. If a person who is too sick to have their aortic valve replaced right away, valvuloplasty may be used as a short-term fix until they can have the valve replaced.

Medicine. Your doctor may prescribe medicines to prevent or treat complications. Medicine cannot fix the valve.

Healthy lifestyle. Your doctor will probably recommend some lifestyle changes to keep your heart healthy. These include eating heart-healthy foods, being active, staying at a healthy weight, and not smoking.

Why is it important to wait for stenosis to get worse before having surgery?

Timing is important. If you have valve surgery too soon, you face the risks of surgery before you need to. And you may also increase the chance that you will need another new valve in the future. This chance depends on the type of valve you get. But if you wait too long to have surgery, your heart may become damaged, leading to heart failure.

Your doctor will check many things to see if your disease is bad enough to recommend surgery. These things include how severe your stenosis is, whether you have symptoms, how well blood is flowing through the valve, and how well your heart is pumping blood.

If you do not have severe stenosis yet, the risks of surgery may outweigh the benefits. Your doctor will likely recommend that you wait to have your valve replaced.

What are the benefits of surgery?

Replacing your valve can help you have a more normal life span, help you feel better, and improve your quality of life.

You will likely feel better after your valve is replaced, because blood will flow normally through the artificial valve.

If you have severe stenosis but don't have your valve replaced, you may die suddenly or develop heart failure. Replacing the valve can lower these risks.

What are the risks of surgery?

Valve replacement surgery has a high rate of success and a low risk of causing other problems if you are otherwise healthy.

In people who do not have left ventricular heart failure, the risk of death from surgery ranges from 2% to 5%.1 That means that out of 100 people who have the surgery, 2 to 5 people will die and 95 to 98 people will live.

The risk is lower for people who have the surgery when they are younger than 70. Out of 100 of these people, 1 will die and 99 will live. The risk of death is higher in people who have left ventricular heart failure and other signs that their heart is not working well.1

Even if valve replacement surgery is a success, you may have problems after surgery, such as:

  • An increased risk of blood clots. These can break off and cause a stroke or heart attack. To reduce the risk of blood clots, you will take a blood-thinning medicine.
  • A need for another replacement valve. This will depend on the type of valve you get and how long you live after you have the surgery.
  • Incomplete relief from symptoms. Some types of valves do not have openings as wide as a normal valve for a person your size. This can limit how well the valve works to relieve your symptoms.
  • A valve that fails. There is a small chance that the valve will not work. Your doctor will need to check from time to time to make sure that your valve is working.

After you have the new valve, you'll need to take antibiotics to prevent an infection of the valve anytime you have certain other procedures, such as dental work or another surgery.

Heart surgery, such as valve surgery, also can cause an irregular heartbeat (atrial fibrillation). This can cause clots to form and increases your risk of stroke.

If you are older, should you still have surgery?

Most people who have severe aortic valve stenosis are older than 65. But your age shouldn't stop you from having valve replacement surgery.

There are other health problems that may increase the risks of surgery, though. These include coronary artery disease, heart failure, advanced cancer, and brain problems because of a stroke. If you have other serious health problems, it's important to think about whether surgery will improve your quality of life and your chances of living a longer life.

Why might your doctor recommend valve replacement surgery?

Your doctor may advise you to have valve replacement if:

  • You have severe stenosis.
  • You have symptoms of stenosis.
  • There may be other reasons that your doctor recommends replacing the valve. Talk with your doctor about the benefits and risks for you.

2. Compare your options

  Have surgery to replace your aortic valve Do not have surgery
What is usually involved?
  • The surgery can take 2 to 5 hours. You will stay in the hospital 4 to 5 days after surgery. You will have a big scar on your chest from the incision.
  • It can take several weeks to recover.
  • You may take medicines to treat complications.
  • You can make lifestyle changes to help keep your heart healthy.
  • If you don't have severe stenosis, you will likely wait until the stenosis gets worse before you consider having surgery.
What are the benefits?
  • Valve replacement is a treatment that will fix the valve.
  • You may feel better and live longer.
  • Valve replacement surgery has a high rate of success and a low risk of causing other problems, if you are otherwise healthy.
  • You avoid the risks of surgery.
  • If you don't have severe stenosis, you avoid having surgery too soon and maybe needing another valve replacement later.
What are the risks and side effects?
  • All surgery has risks, including the risks of anesthesia and bleeding.
  • The risk of dying from this surgery ranges from 1% to 5%. This means that out of 100 people who have the surgery, 1 to 5 people will die and 95 to 99 people will live.1
  • You may not be healthy enough to have surgery.
  • If the valve fails or wears out, you may need another surgery to replace the artificial valve.
  • If you wait too long to have surgery, your heart may become damaged, leading to heart failure.
  • Medicines can treat complications, but they won't fix the valve.
  • If you have severe stenosis and don't have surgery, your life may be much shorter.

Personal stories

Are you interested in what others decided to do? Many people have faced this decision. These personal stories may help you decide.

Personal stories about aortic valve replacement surgery

These stories are based on information gathered from health professionals and consumers. They may be helpful as you make important health decisions.

"A few days ago, I began to notice how out of breath I am just walking up a few stairs in my house. I've also been having some chest pain. I visited my doctor and found that I have a severely narrowed aortic valve. Apparently I have had it for years, but it's just now become bad enough that I'm having symptoms. My doctor said I should have my valve replaced. I don't want to develop permanent heart damage from this."

— Maria Theresa, age 67

"My doctor heard a heart murmur during a routine physical examination. I had an echocardiogram and found out that I have mild aortic stenosis. I feel fine. I don't have any chest pain or shortness of breath. My doctor said it could be many years before I have symptoms, if at all. So we agreed that I would have an echo every 3 years to keep an eye on it. And I will make sure to report any symptoms."

— Maddie, age 40

"I have moderate aortic stenosis. It was discovered during some tests I had for coronary artery disease. I'm scheduled to have coronary bypass surgery. My cardiologist suggested that I have a new aortic valve put in at the same time I have the bypass surgery. That way I only have to have one open-heart operation."

— Ralph, age 58

"I've known for years that I have aortic stenosis. I'm now in the severe stage as far as the width of the valve opening. I don't have any symptoms. But my doctor says my heart isn't pumping blood as well as it should be. My doctor said that replacing the valve could help me live longer, so I am going to have the surgery."

— Fred, age 70

3. What matters most to you?

Your personal feelings are just as important as the medical facts. Think about what matters most to you in this decision, and show how you feel about the following statements.

Reasons to have surgery to replace your aortic valve

Reasons not to have surgery

I have symptoms of aortic valve stenosis.

I don't have symptoms.

       
More important
Equally important
More important

I don't have symptoms yet, but I have severe stenosis.

I don't have severe stenosis.

       
More important
Equally important
More important

Surgery is my chance to live a longer life.

I have other health problems, and I don't think this surgery will help me live longer.

       
More important
Equally important
More important

For me, the benefits of valve replacement outweigh the risks of the surgery.

I don't want to have surgery of any kind.

       
More important
Equally important
More important

My other important reasons:

My other important reasons:

  
       
More important
Equally important
More important

4. Where are you leaning now?

Now that you've thought about the facts and your feelings, you may have a general idea of where you stand on this decision. Show which way you are leaning right now.

Having surgery

NOT having surgery

       
Leaning toward
Undecided
Leaning toward

5. What else do you need to make your decision?

Check the facts

1. If you have severe aortic valve stenosis, what is a treatment to fix your aortic valve?

  • Taking medicine
  • Replacing the aortic valve
  • I'm not sure
You're right. Aortic valve replacement is a treatment to fix aortic valve stenosis.

2. If you have severe aortic valve stenosis, but have no other health problems, which treatment carries greater risks?

  • Having valve replacement surgery
  • Not having valve replacement surgery
  • I'm not sure
You're right. If you have severe stenosis, the risks of not replacing the valve are greater than the risks of surgery, if you have no other health problems.

3. If you do not have severe aortic valve stenosis, what might your doctor suggest?

  • Go ahead and replace the aortic valve
  • Wait to replace the aortic valve
  • I'm not sure
You are right. If you do not have severe stenosis, your doctor may suggest that you wait until the stenosis gets worse to have surgery.

Decide what's next

1. Do you understand the options available to you?

2. Are you clear about which benefits and side effects matter most to you?

3. Do you have enough support and advice from others to make a choice?

Certainty

1. How sure do you feel right now about your decision?

     
Not sure at all
Somewhat sure
Very sure

2. Check what you need to do before you make this decision.

  • I'm ready to take action.
  • I want to discuss the options with others.
  • I want to learn more about my options.
 
Credits
ByHealthwise Staff
Primary Medical ReviewerRakesh K. Pai, MD, FACC - Cardiology, Electrophysiology
Specialist Medical ReviewerDavid C. Stuesse, MD - Cardiac and Thoracic Surgery

References
Citations
  1. Otto CM, Bonow RO (2012). Valvular heart disease. In RO Bonow et al., eds., Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine, 9th ed., vol. 2, pp. 1468–1539. Philadelphia: Saunders.

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