Mitral Valve Stenosis: Symptoms, Causes, Diagnosis, and Treatment Explained
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
TL;DR: Mitral valve stenosis (mitral stenosis) is a narrowing of the valve between the two left heart chambers, which reduces or blocks blood flow into the left ventricle, the heart's main pumping chamber. It most often follows rheumatic fever, a complication of untreated strep throat, but can also result from age-related calcium buildup, chest radiation, rare congenital defects, or autoimmune disease. It usually worsens slowly, with symptoms like shortness of breath, fatigue, swollen legs, irregular heartbeats (including atrial fibrillation), dizziness, chest pain, or coughing up blood; some people have no symptoms at all. If untreated, it can lead to blood clots, stroke, pulmonary hypertension, and right-sided heart failure. Treatment ranges from regular checkups and medication (diuretics, blood thinners, heart-rate medicines) to balloon valvuloplasty or valve repair/replacement surgery, depending on severity.
Quick Answer: Mitral valve stenosis is a heart condition in which the mitral valve, the valve between the two left heart chambers, becomes narrowed, so less blood flows into the left ventricle, the heart's main pumping chamber. It usually worsens slowly and can stay silent for years; the first clues are often shortness of breath with activity or when lying down, fatigue, a pounding or irregular heartbeat, and swollen feet or legs. The most common cause is rheumatic fever after untreated strep throat, though calcium buildup with aging, chest radiation, and rarely congenital or autoimmune causes also occur. Diagnosis rests on an exam, stethoscope findings (a heart murmur), and imaging, especially an echocardiogram, which also grades the disease from Stage A (at risk) through Stage D (symptomatic severe). Treatment may be simple regular checkups and medicine, or balloon valvuloplasty or valve repair/replacement surgery, depending on how severe the disease is and whether it's getting worse [1] [2].
What Is Mitral Valve Stenosis?
Mitral valve stenosis, sometimes called mitral stenosis, is a narrowing of the valve between the two left heart chambers. The narrowed valve reduces or blocks blood flow into the lower left heart chamber [1].
That lower left chamber is the heart's main pumping chamber. It is called the left ventricle [1].
When the valve can't open properly, it blocks blood flow coming into the left ventricle. The heart must then work harder to force blood through the smaller valve opening [1].
Mitral valve stenosis can make you tired and short of breath. Other symptoms may include irregular heartbeats, dizziness, chest pain, or coughing up blood. Some people don't notice any symptoms at all [1].
To understand the condition, it helps to know how the heart's valves work. A typical heart has two upper and two lower chambers. The upper chambers, the right and left atria, receive incoming blood. The lower, more muscular chambers, the right and left ventricles, pump blood out of the heart [1].
The heart valves are gates at the chamber openings. They keep blood flowing in the right direction. Each valve has flaps, called leaflets, that open and close once during each heartbeat. If a valve doesn't open or close properly, less blood may flow through the heart to the body [1].
"Mitral valve stenosis is a condition in which the heart's mitral valve is narrowed. The valve doesn't open properly, blocking blood flow coming into the left ventricle, the main pumping chamber of the heart." [1]
How Does a Narrowed Mitral Valve Affect Blood Flow?
In mitral valve stenosis, the valve opening narrows. The heart now must work harder to force blood through the smaller valve opening. Blood flow between the upper left and lower left heart chambers may decrease [1].
Think of the mitral valve as a doorway between the left atrium (upper chamber) and the left ventricle (lower chamber). When that doorway narrows, blood backs up, pressure rises, and the heart works harder, setting the stage for every complication described below [1].
What Are the Symptoms?
Mitral valve stenosis usually worsens slowly. You may not have any symptoms, or you may have mild ones for many years. Symptoms can occur at any age, even during childhood [1].
Symptoms include [1]:
Shortness of breath, especially with activity or when you lie down
Fatigue, especially during increased activity
Swollen feet or legs
Pounding, skipping, or otherwise irregular heartbeats, called arrhythmias
Dizziness or fainting
Fluid buildup in the lungs
Chest discomfort or chest pain
Coughing up blood
Mitral valve stenosis symptoms may appear or get worse when the heart rate increases, such as during exercise. Anything that puts stress on the body, including pregnancy or infections, may trigger symptoms [1].
When to see a doctor
Make an appointment with your healthcare professional right away if you have chest pain, a fast, fluttering, or pounding heartbeat, or shortness of breath during activity. Your healthcare professional may tell you to see a doctor trained in heart diseases, called a cardiologist [1].
If you have been diagnosed with mitral valve stenosis but haven't had symptoms, ask your healthcare team how often to have follow-up exams [1].
What Causes Mitral Valve Stenosis?
The most common cause is rheumatic fever, a complication of strep throat. Rheumatic fever is now rare in the United States [1].
When rheumatic fever damages the mitral valve, the condition is called rheumatic mitral valve disease. Symptoms may not be seen until years to decades after the rheumatic fever [1].
Other causes include [1]:
Cause | What happens | Notes |
Rheumatic fever | Complication of strep throat damages the valve (rheumatic mitral valve disease) | Most common cause; symptoms can appear years to decades later |
Calcium deposits (aging) | Calcium builds up around the valve, narrowing the structures that support the flaps (mitral annular calcification, or MAC) | Severe MAC can cause symptoms; difficult to treat even with surgery; often accompanies aortic valve problems |
Radiation therapy | Chest-area radiation thickens and hardens the valve | Damage typically appears 20 to 30 years after radiation |
Congenital heart defect | Some babies are born with a narrowed mitral valve | Rare |
Other conditions | Lupus and other autoimmune conditions | Rare |
What Raises Your Risk?
Risk factors for mitral valve stenosis include [1]:
Risk factor | Details |
Untreated strep infections | A history of untreated strep throat or rheumatic fever increases risk; rheumatic fever is rare in the United States but still a problem in developing nations |
Aging | Older adults are at increased risk of calcium buildup around the mitral valve |
Radiation therapy | Chest-area radiation for certain cancers rarely leads to stenosis 20 to 30 years later |
Illicit drug use | MDMA (molly, ecstasy) increases the risk of mitral valve disease |
Certain medicines | Ergot alkaloids in some migraine medicines (e.g., ergotamine) may rarely cause valve scarring; older weight-loss medicines with fenfluramine or dexfenfluramine (fen-phen, no longer sold in the U.S.) are linked to valve disease |
Can Mitral Valve Stenosis Be Prevented?
Rheumatic fever is the most common cause of mitral valve stenosis. So the best way to prevent the condition is to prevent rheumatic fever [1].
You can do this by making sure you and your children see a healthcare professional for sore throats. Untreated strep throat infections can develop into rheumatic fever. Strep throat is usually easily treated with antibiotics [1].
What Complications Can Occur If It's Not Treated?
Untreated mitral valve stenosis can lead to serious heart complications [1]:
Complication | How it develops | Why it matters |
Irregular heartbeats (arrhythmias) | The narrowed valve may cause atrial fibrillation (AFib), a common complication whose risk increases with age and more-severe stenosis | AFib is a gateway to the next complication |
Blood clots and stroke | AFib can cause blood clots to form in the heart; a clot that travels to the brain can cause a stroke | One of the most dangerous consequences |
Pulmonary hypertension | The narrowed valve slows or blocks blood flow, raising pressure in the lung arteries and forcing the heart to work harder to pump blood through the lungs | Feeds right-sided strain |
Right-sided heart failure | High lung-artery pressure strains the right side of the heart until the muscle weakens and fails | The end-stage consequence of the chain above |
Emergency guidance: Seek care right away for chest pain, a fast, fluttering, or pounding heartbeat, or shortness of breath during activity [1].
How Is Mitral Valve Stenosis Diagnosed?
To diagnose mitral valve stenosis, your healthcare professional examines you and asks questions about your symptoms and medical history. You also may be asked about your family's medical history [2].
The healthcare professional listens to your heart and lungs with a stethoscope. Mitral valve stenosis often causes an irregular heart sound due to the narrowed opening. This sound is called a heart murmur. The condition also can cause fluid buildup in the lungs [2].
Which tests confirm the diagnosis?
If you have symptoms, imaging tests examine the heart. Some tests confirm mitral stenosis and help find the cause; results help decide treatment [2].
Test | What it does |
Echocardiogram | Sound waves create images of the beating heart; confirms mitral stenosis, shows poor blood flow and valve changes, and determines severity. Very severe stenosis: yearly echocardiogram; less severe: about every 3 to 5 years |
Electrocardiogram (ECG/EKG) | Quick, painless test showing how the heart is beating; sticky sensor patches on the chest, sometimes arms and legs, connected to a computer |
Chest X-ray | Shows the condition of the heart and lungs; can reveal an enlarged heart, a sign of certain valve disease |
Exercise stress test | Treadmill or stationary bike while heart activity is checked; shows how the heart responds to activity; medicines that mimic exercise are used if you can't exercise |
Cardiac CT | Combines X-ray images for a detailed view of the heart and valves; commonly used for stenosis not caused by rheumatic fever |
Cardiac MRI | Magnetic fields and radio waves create detailed images; may determine severity |
Cardiac catheterization | A catheter guided through a groin or wrist vessel to the heart; dye highlights arteries on X-ray; used only when other tests can't diagnose or determine severity |
How is the disease staged?
After testing confirms heart valve disease, your healthcare professional may tell you the stage of disease. Staging helps determine the most appropriate treatment. The stage depends on symptoms, disease severity, valve structure, and blood flow through the heart and lungs [2].
Stage | Name | What it means |
A | At risk | Risk factors for heart valve disease are present |
B | Progressive | Valve disease is mild or moderate; no symptoms |
C | Asymptomatic severe | Disease is severe, but there are no symptoms |
D | Symptomatic severe | Disease is severe and is causing symptoms |
How Is Mitral Valve Stenosis Treated?
Treatment may include medicine, mitral valve repair or replacement surgery, or open-heart surgery. If you have mild to moderate mitral valve stenosis with no symptoms, you might not need immediate treatment. Instead, regular health checkups watch for worsening. A doctor trained in heart disease, called a cardiologist, typically provides care [2].
Medications
Medicines are used to reduce the symptoms of mitral valve stenosis [2]:
Diuretics (water pills) reduce fluid buildup in the lungs or other areas of the body.
Blood thinners (anticoagulants) help prevent blood clots if you have atrial fibrillation (AFib).
Beta blockers, calcium channel blockers, or other heart medicines slow the heart rate.
Antiarrhythmics treat irregular heartbeats.
Antibiotics prevent a return of rheumatic fever if that's what damaged the valve.
Balloon valvuloplasty
Balloon valvuloplasty repairs a mitral valve with a narrowed opening. It is also called mitral balloon valvotomy, percutaneous mitral balloon commissurotomy, or percutaneous transvenous mitral commissurotomy [2].
The doctor inserts a balloon-tipped catheter into an artery, usually in the groin, and guides it to the mitral valve. The balloon is inflated, widening the valve opening, then deflated. The catheter and balloon are removed [2].
Valvuloplasty might be done even if you don't have symptoms. But not everyone with mitral valve stenosis is a candidate for the treatment, so ask your healthcare professional if it's an option for you [2].
Open-heart surgery to repair the valve
If a catheter procedure isn't an option, an open-heart surgery called open valvotomy may be done. It is also called surgical commissurotomy. It removes calcium deposits and other scar tissue blocking the mitral valve opening [2].
The heart must be stopped to prevent bleeding during this surgery, and a heart-lung machine temporarily takes over the heart's job. The procedure may need to be repeated if mitral valve stenosis returns [2].
Mitral valve replacement
If the mitral valve can't be repaired, the damaged valve is replaced with a mechanical one or a valve made from cow, pig, or human heart tissue. A valve made from animal or human tissue is called a biological tissue valve [2].
Valve type | Long-term consideration |
Biological tissue valve (cow, pig, or human tissue) | Breaks down over time and may need to be replaced |
Mechanical valve | Requires lifelong blood thinners to prevent blood clots |
You and your healthcare professional should talk about the benefits and risks of each type of valve to choose the best option [2].
What is the outlook after treatment?
The outlook for people who have a catheter treatment or surgery for mitral stenosis is generally good. However, older age, poor health, and heavy calcium buildup on or around the valves increase the risk of surgery complications. Long-term pulmonary hypertension may worsen the outlook after valve surgery [2].
How Can Lifestyle Changes Support Treatment?
If you have mitral valve stenosis, these steps help keep your heart healthy [2]:
Eat nutritious foods. A variety of fruits and vegetables, low-fat or fat-free dairy products, poultry, fish, and whole grains. Avoid saturated and trans fat. Use less salt and sugar [2].
Keep a healthy weight. Losing weight can help control blood pressure and lower complication risk [2].
Don't smoke or use tobacco. Smoking is a major risk factor for heart disease [2].
Limit alcohol. Up to one drink a day for women and up to two drinks a day for men [2].
Ask about exercise. How long and hard you can exercise may depend on disease severity. People with severe mitral stenosis should not do competitive sports [2].
Get regular health checkups. You should have an echocardiogram at least every year. If you frequently feel your heart pounding or beating fast, get medical help. Fast heart rhythms that aren't treated can quickly get worse in people with mitral valve stenosis [2].
Manage stress through relaxation activities, meditation, physical activity, and time with family and friends [2].
Get good sleep. Poor sleep may increase the risk of heart disease and other chronic conditions. Adults should aim for 7 to 9 hours of sleep daily, going to bed and waking at the same time every day [2].
Pregnancy
If you have mitral valve stenosis and want to become pregnant, talk with a healthcare professional first. Pregnancy causes the heart to work harder. How a heart with mitral valve stenosis handles the extra work depends on how narrow the valve is and how well the heart pumps. Your care team should closely check you during pregnancy, and you can discuss which medicines are safe and whether valve treatment is needed before pregnancy [2].
How Should You Prepare for the Appointment?
If you have mitral valve stenosis, you may see a doctor trained in heart diseases, called a cardiologist [2].
Before your appointment [2]:
Write down your symptoms and when they started.
List important medical information, including other health conditions and any family history of heart disease.
List all the medicines you take, including over-the-counter ones, with dosages.
Take someone with you to the appointment, if possible, to help you remember the information.
Write down questions to ask.
Questions for the first appointment include: What is the likely cause of my symptoms? Are there other possible causes? What tests do I need? Should I see a specialist? [2]
Questions for the cardiologist include: What is my diagnosis? What treatment do you recommend? What are the possible side effects of the medicines? What will my recovery be like? How will you check my health over time? What is my risk of long-term complications? Do I need to change my exercise routine? What diet and lifestyle changes should I make? How can I best manage my other health conditions together? [2]
What to expect from your doctor: Be prepared to answer questions such as what your symptoms are and when they began; whether they always occur or come and go; whether you have rapid, fluttering, or pounding heartbeats; whether you have coughed up blood; whether exercise makes symptoms worse; whether family members have heart valve disease; whether you've had rheumatic fever; whether you're being treated for other conditions; your smoking, alcohol, and caffeine habits; and whether you're planning to become pregnant [2].
In the meantime: Find out whether family members have heart disease, since the symptoms of mitral valve stenosis are similar to other heart conditions that can run in families. If exercise makes your symptoms worse, do not exercise until you see your healthcare professional [2].
Conclusion and Next Steps
Mitral valve stenosis is a mechanical problem with a slow build: the valve between the two left heart chambers narrows, the heart works harder to push blood through a smaller opening, and over years that extra effort can reshape the rhythm of the heart and the pressure in the lungs. The condition's most important feature is that it can stay silent. You may have no symptoms, or only mild ones, for many years. That is why the warning signs deserve attention the moment they appear: shortness of breath with activity or when lying down, fatigue, swollen feet or legs, a pounding or irregular heartbeat, dizziness, chest pain, or coughing up blood.
The most common cause, rheumatic fever after untreated strep throat, is a reminder that prevention starts early: get sore throats treated. And the good news for anyone diagnosed is that treatment is well established. Mild cases may need nothing more than regular checkups. Medicines can control fluid, rhythm, and heart rate. And when the valve itself needs fixing, balloon valvuloplasty, surgical repair, or replacement offer generally good outcomes, with the mechanical-versus-biological valve choice and the monitoring schedule tailored to you.
Call to action: If you experience chest pain, a fast or fluttering heartbeat, or shortness of breath during activity, make an appointment with your healthcare professional right away, and ask whether a cardiology referral and an echocardiogram are appropriate. If you've already been diagnosed, keep your echocardiogram schedule (yearly for severe disease, every 3 to 5 years for milder cases), treat any fast heart rhythms promptly, and talk to your care team before becoming pregnant. If you have a history of untreated strep infections or rheumatic fever, mention it at your next checkup, since it changes how your heart health should be monitored.
Frequently Asked Questions
What is mitral valve stenosis?
Mitral valve stenosis (mitral stenosis) is a narrowing of the valve between the two left heart chambers. The narrowed valve reduces or blocks blood flow into the left ventricle, the heart's main pumping chamber [1].
What does the mitral valve do?
It is one of four heart valves that keep blood flowing in the right direction. Each valve has flaps called leaflets that open and close once during each heartbeat. The mitral valve sits between the left atrium (upper chamber, which receives incoming blood) and the left ventricle (lower chamber, which pumps blood out) [1].
What causes mitral valve stenosis?
The most common cause is rheumatic fever, a complication of strep throat. Other causes include age-related calcium deposits around the valve (mitral annular calcification), chest radiation therapy 20 to 30 years earlier, rare congenital defects, and rarely autoimmune conditions such as lupus [1].
Is mitral valve stenosis linked to strep throat?
Yes. Untreated strep throat infections can develop into rheumatic fever, which can damage the mitral valve, sometimes called rheumatic mitral valve disease. Symptoms may not appear until years to decades later. Preventing rheumatic fever by treating strep throat with antibiotics is the best prevention [1].
What are the symptoms?
Shortness of breath (especially with activity or lying down), fatigue during increased activity, swollen feet or legs, pounding or irregular heartbeats (arrhythmias), dizziness or fainting, fluid buildup in the lungs, chest discomfort or pain, and coughing up blood. Symptoms can appear or worsen when the heart rate increases, and stressors such as pregnancy or infections may trigger them [1].
Can you have mitral valve stenosis with no symptoms?
Yes. The condition usually worsens slowly; you may not have symptoms, or may have mild ones, for many years. Some people never notice symptoms. That's why follow-up exams matter after diagnosis [1].
At what age does it appear?
Symptoms can occur at any age, even during childhood. But the condition usually worsens slowly, so many people develop symptoms in adulthood, years after the original valve damage [1].
When should I see a doctor urgently?
Make an appointment right away for chest pain, a fast, fluttering, or pounding heartbeat, or shortness of breath during activity. You may be referred to a cardiologist, a doctor trained in heart diseases [1].
What complications can occur if it's not treated?
Untreated mitral valve stenosis can cause atrial fibrillation (AFib), blood clots that can travel to the brain and cause a stroke, pulmonary hypertension (high blood pressure in the lung arteries), and right-sided heart failure [1].
How is it diagnosed?
With a physical exam, a medical and family history, and a stethoscope check. Mitral stenosis often causes a heart murmur, an irregular heart sound from the narrowed opening. Imaging tests such as an echocardiogram confirm the diagnosis and find the cause; ECG/EKG, chest X-ray, stress tests, cardiac CT, cardiac MRI, and cardiac catheterization may also be used [2].
What is the staging system for mitral valve stenosis?
Stage A: At risk (risk factors present). Stage B: Progressive (mild or moderate disease, no symptoms). Stage C: Asymptomatic severe (severe disease, no symptoms). Stage D: Symptomatic severe (severe disease causing symptoms). Staging helps determine the most appropriate treatment [2].
How often do I need an echocardiogram?
If you have very severe mitral stenosis, you should get an echocardiogram every year. Those with less severe disease need one about every 3 to 5 years [2].
Do I need surgery for mitral valve stenosis?
Not always. Mild to moderate disease with no symptoms may need only regular checkups. When intervention is needed, options include balloon valvuloplasty (widening the valve with a balloon catheter), open-heart valve repair (open valvotomy), or valve replacement with a mechanical or biological valve. The choice depends on severity, valve anatomy, and whether you're a candidate for catheter treatment [2].
What medicines treat mitral valve stenosis?
Medicines reduce symptoms: diuretics (water pills) for fluid buildup; blood thinners to prevent clots with AFib; beta blockers, calcium channel blockers, or other heart medicines to slow the heart rate; antiarrhythmics for irregular heartbeats; and antibiotics to prevent a return of rheumatic fever [2].
What is the difference between a mechanical and biological valve?
A biological tissue valve (made from cow, pig, or human heart tissue) breaks down over time and may need replacement. A mechanical valve requires lifelong blood thinners to prevent blood clots. You and your healthcare team should discuss the benefits and risks of each [2].
Is the outlook good after treatment?
The outlook after catheter treatment or surgery is generally good. Older age, poor health, and heavy calcium buildup on or around the valves increase the risk of surgery complications, and long-term pulmonary hypertension may worsen the outlook [2].
Can I exercise with mitral valve stenosis?
Ask your healthcare team, as it depends on disease severity. People with severe mitral stenosis should not do competitive sports. If exercise makes your symptoms worse, do not exercise until you see your healthcare professional [2].
Is pregnancy safe with mitral valve stenosis?
Talk with a healthcare professional before becoming pregnant. Pregnancy makes the heart work harder, and how it copes depends on how narrow the valve is and how well the heart pumps. You'll be closely monitored during pregnancy, and your team can discuss safe medicines and whether valve treatment is needed first [2].
How can I protect my heart day to day?
Eat nutritious foods with less salt, sugar, and saturated or trans fat; maintain a healthy weight; don't smoke; limit alcohol; manage stress; get 7 to 9 hours of sleep on a consistent schedule; and keep regular checkups, including at least a yearly echocardiogram for those diagnosed [2].
Sources
Medical Disclaimer
For education only; this article is not medical advice. Always consult a qualified healthcare professional for diagnosis and treatment decisions.
Comments