Mitral valve stenosis — sometimes called mitral stenosis — is a narrowing of the heart's mitral valve. This abnormal valve doesn't open properly, blocking blood flow into the main pumping chamber of your heart (left ventricle). Mitral valve stenosis can make you tired and short of breath, among other problems.

The main cause of mitral valve stenosis is an infection called rheumatic fever, which is related to strep infections. Rheumatic fever — now rare in the United States, but still common in developing countries — can scar the mitral valve. Left untreated, mitral valve stenosis can lead to serious heart complications.


In mitral valve stenosis, pressure that builds up in the heart is then sent back to the lungs, resulting in fluid buildup (congestion) and shortness of breath.

The condition usually progresses slowly over time. You may feel fine with mitral valve stenosis, or you may have mild symptoms for decades. Symptoms of mitral valve stenosis typically appear between the ages of 15 and 40, but they can occur at any age — even during childhood.

Signs and symptoms of mitral valve stenosis include:

  • Shortness of breath, especially with activity or when you lie down
  • Fatigue, especially during increased activity
  • Swollen feet or legs
  • Sensations of a rapid, fluttering heartbeat (palpitations)
  • Chest discomfort or chest pain
  • Coughing up blood
  • Dizziness or fainting
  • Heart murmur
  • Fluid buildup in the lungs
  • Irregular heart rhythms (arrhythmias)

Mitral valve stenosis symptoms may appear or worsen anytime your heart rate increases, such as during exercise. Or they may be triggered by pregnancy or other things that cause stress on the body, such as an infection.

When to see a doctor

Call your doctor for an immediate appointment if you have fatigue or shortness of breath during physical activity, heart palpitations or chest pain.

If you have been diagnosed with mitral valve stenosis but haven't had symptoms, ask your doctor about how often you should have follow-up evaluations.


Causes of mitral valve stenosis include:

  • Rheumatic fever. A complication of strep throat, rheumatic fever can damage the mitral valve. Rheumatic fever is the most common cause of mitral valve stenosis. It can damage the mitral valve by causing the flaps to thicken or fuse. Signs and symptoms of mitral valve stenosis might not show up for years.
  • Calcium deposits. As you age, calcium deposits can build up around the mitral valve (annulus), which can occasionally cause mitral valve stenosis.
  • Radiation therapy. Treatment for certain types of cancer that requires radiation to your chest area can sometimes cause the mitral valve to thicken and harden.
  • Other causes. In rare cases, babies are born with a narrowed mitral valve (congenital defect) that causes problems over time. Some autoimmune diseases, such as lupus, also may rarely cause mitral valve stenosis.

How the heart works

The heart, the center of your circulatory system, consists of four chambers. The two upper chambers (atria) receive blood. The two lower chambers (ventricles) pump blood.

Four heart valves open and close to let blood flow in only one direction through your heart. The mitral valve — which lies between the two chambers on the left side of your heart — comprises two flaps of tissue called leaflets.

The mitral valve opens when blood flows from the left atrium to the left ventricle. Then the flaps close to prevent the blood that has just passed into the left ventricle from flowing backward. A defective heart valve fails to either open or close fully.

Risk factors

Mitral valve stenosis isn't as common as it once was because the most common cause, rheumatic fever, is rare in the United States. However, rheumatic fever remains a problem in developing nations.

Risk factors for mitral valve stenosis include untreated strep infections and a history of rheumatic fever.

Older adults are at increased risk of mitral valve stenosis. As you age, calcium deposits can build up around the mitral valve, which may lead to mitral valve stenosis.

Rarely, people who receive radiation therapy to the chest area for certain types of cancer may develop mitral valve stenosis.


Like other heart valve problems, mitral valve stenosis can strain your heart and decrease blood flow. Untreated, mitral valve stenosis can lead to complications such as:

  • High blood pressure in the lung arteries (pulmonary hypertension). Increased pressure in the arteries that carry blood from your heart to your lungs (pulmonary arteries) causes your heart to work harder.
  • Heart failure. A narrowed mitral valve interferes with blood flow. As a result, pressure may increase in your lungs, leading to fluid buildup. The fluid buildup strains the right side of the heart, leading to right heart failure.
  • Fluid in the lungs (pulmonary edema). In this condition, blood and fluid back up into your lungs. Pulmonary edema can cause shortness of breath and may cause you to cough up blood-tinged mucus.
  • Heart enlargement. The pressure buildup of mitral valve stenosis results in enlargement of your heart's upper left chamber (atrium).
  • Atrial fibrillation. The stretching and enlargement of your heart's left atrium may lead to this heart rhythm problem in which the upper chambers of your heart beat chaotically and too quickly.
  • Blood clots. Untreated atrial fibrillation can cause blood clots to form in the upper left chamber of your heart. Blood clots from your heart can break loose and travel to other parts of your body, causing serious problems, such as a stroke if a clot blocks a blood vessel in your brain.


The best way to prevent mitral valve stenosis is to prevent its most common cause, rheumatic fever. You can do this by making sure you and your children see your doctor for sore throats. Untreated strep throat infections can develop into rheumatic fever. Fortunately, strep throat is usually easily treated with antibiotics.

Mitral valve stenosis care at Mayo Clinic

May 15, 2021
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