Mitral Valve Disease

What the mitral valve does

The heart has four valves that keep blood flowing one way. The mitral valve has two flaps (leaflets) held by thin cords (chordae tendineae) attached to muscles inside the left ventricle. When the left atrium contracts, the valve opens to let oxygen-rich blood from the lungs into the left ventricle. When the ventricle squeezes to pump blood to the body, the valve snaps shut so blood does not flow backward.

When the valve leaks or narrows, pressure builds up in the left atrium and lungs, the heart works harder, and over time the chambers enlarge.

Types of mitral valve disease

Each type has its own page: mitral valve regurgitation, mitral valve stenosis and mitral valve prolapse.

Primary vs secondary mitral regurgitation

• Primary (degenerative): the valve itself is damaged, most often by prolapse or a torn chord.
• Secondary (functional): the valve is normal, but the heart muscle around it is enlarged or scarred, often after a heart attack or in cardiomyopathy, pulling the leaflets apart. Treatment focuses on the heart muscle first.

Symptoms

Many people have no symptoms for years. When they occur, they include:

• shortness of breath, first on exertion, later when lying flat or at night
• tiredness and reduced exercise tolerance
• heart palpitations or an irregular pulse from atrial fibrillation
• swollen ankles and feet
• a cough, sometimes with blood-streaked sputum in severe mitral stenosis
• dizziness or fainting

Mitral stenosis symptoms often surface or worsen during pregnancy, exercise, infection or atrial fibrillation, when the heart beats faster.

Mitral valve prolapse can be linked to palpitations, chest discomfort and anxiety-like symptoms, though whether prolapse itself causes these is debated.

Causes and risk factors

• Age-related degeneration of the valve and calcium in the ring that supports it
• Mitral valve prolapse, sometimes inherited, and connective tissue disorders such as Marfan syndrome
• Rheumatic fever after untreated strep throat, the main cause of mitral stenosis worldwide; valve damage shows up 10 to 20 or more years later
• Heart attack damaging the muscles that support the valve; a sudden rupture causes acute severe leakage
• Heart enlargement from cardiomyopathy or long-standing atrial fibrillation
• Endocarditis, an infection that can destroy valve tissue
• Radiation to the chest and some medicines (older appetite suppressants such as fenfluramine, ergot-derived drugs)
• Congenital valve abnormalities

Diagnosis

1. Listening with a stethoscope: most mitral valve disease is first suspected because of a murmur or click.
2. Echocardiogram: an ultrasound of the heart that shows the valve's structure, how much it leaks or how narrow it is, chamber size and pumping function. It is the key test.
3. Transesophageal echo (TEE): a probe passed into the food pipe under sedation gives detailed images, used before repair or to look for clots or infection.
4. Electrocardiogram (ECG) to check rhythm, especially for atrial fibrillation.
5. Chest X-ray for heart size and fluid in the lungs.
6. Exercise testing to check true fitness and symptoms.
7. Cardiac MRI and catheterization in selected cases, to measure pressures, leak severity or coronary artery disease before surgery.

Disease is graded as mild, moderate or severe, and staged from A (at risk) to D (severe with symptoms) in US guidelines.

Treatment

Monitoring

Mild disease without symptoms needs repeat echocardiograms, typically every 3 to 5 years for mild disease and every 6 to 12 months for severe disease, to catch changes before the heart is damaged.

Medicines

Medicines do not fix the valve but manage its effects:

• Diuretics for fluid buildup and breathlessness
• Beta-blockers or other rate-control drugs for atrial fibrillation and to slow the heart in mitral stenosis
• Blood thinners (anticoagulants) for atrial fibrillation; in moderate to severe rheumatic mitral stenosis with atrial fibrillation, warfarin is used rather than newer anticoagulants
• Heart failure medicines for secondary mitral regurgitation
• Antibiotic prevention of rheumatic fever recurrence for people with rheumatic valve disease

Procedures

• Mitral valve repair: the preferred surgery for primary mitral regurgitation, especially prolapse. Surgeons reshape the leaflets, replace torn chords and place a ring to support the valve. It preserves heart function and avoids lifelong anticoagulation for a mechanical valve.
• Mitral valve replacement: with a mechanical valve, which lasts decades but requires lifelong warfarin, or a tissue valve, which needs no long-term warfarin but wears out after about 10 to 20 years.
• Transcatheter edge-to-edge repair (TEER): a clip delivered through a vein in the leg grips the leaflets together. It is used for people with severe symptoms who are too high-risk for surgery, and in selected secondary regurgitation.
• Balloon mitral valvotomy: a balloon passed through a vein widens a narrowed rheumatic valve, often avoiding surgery.
• Transcatheter mitral valve replacement is available in some centers for selected patients.

Complications

• Atrial fibrillation and stroke from blood clots in the enlarged left atrium
• Heart failure
• Pulmonary hypertension: raised pressure in the lung arteries
• Endocarditis
• Sudden death is rare, mostly linked to severe prolapse with specific high-risk features

Living with mitral valve disease

• Keep follow-up echocardiograms even if you feel well.
• Report new breathlessness, palpitations or swelling promptly.
• Keep teeth and gums healthy and see a dentist regularly, since mouth bacteria are a common cause of endocarditis. Antibiotics before dental work are recommended only for people with replacement valves, previous endocarditis or certain other high-risk conditions.
• Stay active; ask your cardiologist about very intense or competitive exercise if your disease is severe.
• Plan pregnancy with your cardiologist, especially with mitral stenosis.

Frequently asked questions

What is mitral valve disease?

It is any condition that stops the mitral valve working properly. The valve may leak (regurgitation), become narrowed (stenosis) or bulge backward when closing (prolapse). These make the heart work harder and can cause breathlessness, tiredness, palpitations and atrial fibrillation as the disease progresses.

What are the first symptoms of mitral valve disease?

Often there are none, and a doctor finds a murmur. Early symptoms are usually breathlessness or tiredness during exercise, then palpitations. Later, people may be breathless lying down, wake up short of breath at night, and develop swollen ankles.

Is mitral valve disease serious?

It ranges from harmless to serious. Mild prolapse or a small leak may never cause problems. Severe regurgitation or stenosis can lead to heart failure, atrial fibrillation and stroke if untreated. Regular echocardiograms allow treatment before permanent heart damage occurs.

Can a mitral valve be repaired without open-heart surgery?

Sometimes. A catheter-based clip (transcatheter edge-to-edge repair) can reduce leakage for people at high surgical risk, and a balloon can widen a narrowed rheumatic valve. Many repairs are also done through small incisions with minimally invasive or robotic surgery.

How long can you live with mitral valve disease?

Many people with mild disease have a normal life expectancy. With severe disease, timely repair or replacement restores near-normal survival for most, especially if surgery happens before the heart enlarges or weakens. Outlook is worse when severe disease is left untreated.