Understanding Mitral Valve Stenosis

What is Mitral Valve Stenosis?

Mitral valve stenosis is a heart condition where the mitral valve, which controls blood flow between the left atrium and left ventricle of your heart, becomes narrowed or tightened. This narrowing restricts the normal flow of blood through the heart, making it harder for your heart to pump blood effectively to the rest of your body.

The mitral valve normally opens wide during diastole (when the heart relaxes) to allow blood to flow from the left atrium into the left ventricle. When stenosis occurs, this opening becomes smaller, creating a bottleneck that forces the heart to work harder to maintain adequate blood flow.

Understanding the Causes

Rheumatic Heart Disease is the primary cause of mitral valve stenosis. This condition develops as a complication of rheumatic fever, which can occur after untreated or inadequately treated strep throat infections. The rheumatic process causes inflammation that leads to scarring and fusion of the valve leaflets, gradually narrowing the valve opening over time.

In high-income countries, there is typically a long latent phase lasting decades between the initial rheumatic illness and the development of significant valve stenosis. However, in low- to middle-income countries, this progression can happen much more quickly, likely due to recurrent episodes of carditis.

Non-rheumatic causes are less common but can include calcific degeneration of the mitral valve, particularly in older patients with kidney disease, where calcium deposits accumulate around the valve ring (mitral annular calcification).

Recognizing the Stages and Progression

Healthcare providers classify mitral stenosis into four distinct stages:

Stage A (At Risk) represents patients who may be at risk of developing mitral stenosis but currently have normal valve function and no symptoms.

Stage B (Progressive Stenosis) involves mild valve narrowing with some structural changes visible on heart imaging, but patients typically remain without symptoms.

Stage C (Asymptomatic Severe Stenosis) occurs when the valve area becomes significantly narrowed (≤1.5 cm²) with evidence of increased pressure in the lungs, but patients have not yet developed symptoms.

Stage D (Symptomatic Severe Stenosis) represents the most advanced stage, where severe valve narrowing causes symptoms that significantly impact daily life.

The progression from mild stenosis to severe disease is typically slow, with the valve area decreasing by approximately 0.1 cm² per year on average. However, this rate varies considerably between individuals.

Common Symptoms to Watch For

Many people with mild to moderate mitral stenosis experience no symptoms for years. However, as the condition progresses, several symptoms may develop:

Shortness of breath is often the first and most common symptom, initially occurring only during physical activity but potentially progressing to occur even at rest. This happens because the narrowed valve causes blood to back up in the lungs.

Fatigue and reduced exercise tolerance develop as the heart struggles to pump adequate blood to meet the body's demands during physical activity.

Chest discomfort or pain may occur, particularly during exertion.

Palpitations or irregular heartbeats are common, as mitral stenosis often leads to atrial fibrillation, a type of irregular heart rhythm.

Coughing, sometimes with pink-tinged sputum, can occur due to fluid backing up in the lungs.

Swelling in the legs, ankles, or feet may develop in more advanced cases as the heart's pumping efficiency decreases.

Symptoms can worsen rapidly during periods of increased demand on the heart, such as during pregnancy, with fever, anemia, hyperthyroidism, or when atrial fibrillation develops.

Diagnosis and Testing

Echocardiography (heart ultrasound) is the primary diagnostic tool for mitral stenosis. This non-invasive test allows doctors to visualize the valve structure, measure the valve opening area, and assess the impact on heart function. The characteristic appearance includes diastolic doming of the mitral valve leaflets and commissural fusion.

Transesophageal echocardiography (TEE) may be recommended if balloon valvuloplasty is being considered, as it provides more detailed images of the valve and can detect blood clots in the left atrium.

Exercise testing might be performed in some patients to assess how the valve stenosis affects heart function during physical activity and to help guide treatment decisions.

Cardiac catheterization is rarely needed in the modern era but may be considered when there are discrepancies between symptoms and echocardiographic findings, or when other heart conditions need to be evaluated simultaneously.

Treatment Approaches

Medical Management

For patients with mitral stenosis and atrial fibrillation, anticoagulation therapy with warfarin is essential to prevent stroke and other blood clot complications. These patients have a significantly higher risk of forming dangerous blood clots.

Heart rate control can be beneficial for patients experiencing rapid heart rates, whether they have atrial fibrillation or normal rhythm with symptomatic tachycardia. Medications such as beta-blockers, calcium channel blockers, or ivabradine can help by lengthening the time available for the heart to fill with blood during each heartbeat.

However, it's important to understand that medical therapy treats symptoms and complications but does not fix the underlying valve problem.

Interventional Procedures

Percutaneous Mitral Balloon Commissurotomy (PMBC), also known as balloon valvuloplasty, is often the first-line treatment for suitable patients with symptomatic severe mitral stenosis. During this minimally invasive procedure, a thin tube (catheter) with a balloon at the tip is inserted through a blood vessel and guided to the heart. The balloon is then inflated to stretch open the fused valve leaflets, increasing the valve opening.

This procedure is particularly effective for patients with flexible valve leaflets and minimal calcium deposits. The success of balloon valvuloplasty depends significantly on the valve's anatomy and the degree of calcification present.

Surgical options may be necessary when balloon valvuloplasty is not suitable or has not been successful. Surgical mitral commissurotomy involves surgically separating the fused valve leaflets, while mitral valve replacement may be required in cases with severely damaged or heavily calcified valves.

Factors Influencing Treatment Choice

The decision between different treatment approaches depends on several factors including the valve's anatomy, the degree of calcium deposits, the presence of other valve problems, overall heart function, and the patient's age and general health status.

Patients with pliable valve leaflets, minimal calcium deposits, and no significant mitral regurgitation are typically excellent candidates for balloon valvuloplasty. Those with heavily calcified, rigid valves or significant associated mitral regurgitation may require surgical intervention.

Living with Mitral Stenosis

Regular follow-up care is essential for all patients with mitral stenosis. Even those without symptoms require periodic echocardiograms to monitor disease progression. The frequency of follow-up depends on the severity of stenosis, with more severe cases requiring more frequent monitoring.

Lifestyle modifications can help manage symptoms and improve quality of life. These may include limiting salt intake if fluid retention is a problem, maintaining appropriate physical activity levels as recommended by your healthcare provider, and avoiding tobacco use.

Prevention of rheumatic fever recurrence is crucial for patients whose mitral stenosis resulted from rheumatic heart disease. This may involve long-term antibiotic therapy and prompt treatment of strep throat infections.

Pregnancy considerations are important for women of childbearing age. Pregnancy increases the workload on the heart and can worsen symptoms. Women with severe mitral stenosis should discuss pregnancy planning with their cardiologist, as balloon valvuloplasty can be safely performed during pregnancy if needed.

Complications and When to Seek Help

Atrial fibrillation is a common complication that can significantly worsen symptoms and increase stroke risk. This irregular heart rhythm requires prompt medical attention and ongoing management.

Blood clots and stroke are serious risks, particularly for patients with atrial fibrillation or very enlarged left atria. Proper anticoagulation therapy can significantly reduce these risks.

Pulmonary hypertension (high pressure in the lung blood vessels) can develop as blood backs up from the narrowed mitral valve, potentially leading to right heart failure if left untreated.

You should seek immediate medical attention if you experience sudden worsening of shortness of breath, chest pain, fainting, or signs of stroke such as sudden weakness, speech difficulties, or facial drooping.

Outlook and Prognosis

The outlook for patients with mitral stenosis has improved dramatically with modern treatment approaches. Many patients who undergo successful balloon valvuloplasty or surgery can expect significant symptom improvement and return to normal or near-normal activity levels.

The timing of intervention is crucial - procedures performed before irreversible heart damage occurs generally yield the best long-term results. This is why regular monitoring and following your healthcare provider's recommendations are so important.

Long-term outcomes depend on factors such as the success of the procedure, the degree of heart damage present before treatment, the development of other heart rhythm problems, and adherence to follow-up care and medications.

Working with Your Healthcare Team

Managing mitral stenosis effectively requires collaboration between you and your healthcare team, which may include your primary care physician, cardiologist, and possibly a cardiac surgeon. Don't hesitate to ask questions about your condition, treatment options, and what to expect.

Keep track of your symptoms, including when they occur and what might trigger them. This information helps your healthcare providers make the best treatment decisions for your specific situation.

Understanding your condition empowers you to participate actively in your care and make informed decisions about your treatment. With proper management, many people with mitral stenosis lead full, active lives.

August 2025

Prepared by Professor Eric Lim for PEACHealth with background research and drafting assistance by LLM.