Mitral Stenosis

Overview

Mitral stenosis causes an obstruction to blood flow from the left atrium to left ventricle usually as a result of rheumatic heart disease. The stenosis results in increased pressure in the left atrium, pulmonary vasculature and right side of heart. Mitral valve disease is a frequent cause of heart failure and death.

Aetiology and Risk Factors

Aetiology

• Rheumatic fever leading to rheumatic heart disease (95% of cases)
• Congenital mitral stenosis
• Degenerative mitral-annular and leaflet calcification
• Systemic lupus erythematosus or antiphospholipid syndrome
• Left-atrial myxoma or large thrombus mimicking MS
• Rarely, carcinoid disease or infiltrative disorders

Pathophysiology

Narrowing of the mitral valve obstructs left-ventricular filling during diastole.Left-atrial pressure rises to maintain forward blood flow.Elevated left-atrial pressure causes:

• Left-atrial enlargement
• Pulmonary venous congestion
• Pulmonary oedema

Left-atrial enlargement predisposes to atrial fibrillation and thrombus formation.Chronic pulmonary venous hypertension causes pulmonary arterial hypertension.Progressive pulmonary hypertension may produce:

• Right-ventricular hypertrophy and failure
• Functional tricuspid regurgitation
• Peripheral oedema

Tachycardia shortens diastole, reducing filling time and markedly worsening symptoms.Left-ventricular systolic function is usually preserved unless another cardiac disorder is present.

Clinical Manifestation

• Exertional dyspnoea
• Decreased excercise tolerance
• Haemoptysis
• Chest pain
• Fatigue
• History of rheumatic fever
• Malar flush
• Signs of right-sided heart failure
  • ascites
  • raised JVP
  • peripheral oedema
• Thromboembolic event “Stroke”
• Hoarseness (recurrent laryngeal nerve compressed)
• Dysphagia (esophagus compressed)

Cardiovascular Examination

• Malar flush
• Pulse
  • Weak pulse due to reduced strove volume
  • Atrial fibrillation
• Left parasternal heave (from right ventricular hypertrophy)
• Auscultation – Mitral valve (Apex – left 5th intercostal space mid-clavicular)
  • Pre systolic murmur precedes S1, a result of increase blood flow from atrial contraction
  • Opening snap of the mitral valve following S2 (closure of the aortic and pulmonic valves) is the opening of the stenotic mitral valve (SNAP)
  • Long murmur during Diastole (longer in chronic mitral stenosis)
  • Low-pitched diastolic rumble that is most prominent at the apex.

Diagnosis

Diagnosis

• Transthoracic echocardiography—first-line
• Transoesophageal echocardiography

Investigations

• ECG
  • Atrial fibrillation
  • Left atrial enlargement – P mitrale
  • Right ventricular hypertrophy – Right axis deviation
• Chest X-ray
  • Straight or convex L heart border
  • Double shadow of LA behind RA
  • Splaying of carina
  • Dilated upper lobe veins
  • Prominent pulmonary conus
  • Pulmonary haemosiderosis
• Trans-thoracic echocardiography
• Transoesophageal echocardiography
• Cardiac catherization

Symptoms and signs similar to mitral stenosis

• left atrial myxoma
• prosthetic valve obstruction
• Cor tratriatum

Treatment

Mild or asymptomatic disease

• Regular clinical and echocardiographic surveillance.
• Treat hypertension and other cardiovascular risk factors.

Symptomatic medical treatment

Medical treatment reduces symptoms but does not relieve the valve obstruction.

• Diuretics: reduce pulmonary and peripheral congestion.
• Heart-rate control: increases diastolic filling time:
  • Beta blocker
  • Diltiazem or verapamil where appropriate
  • Digoxin may assist ventricular-rate control in atrial fibrillation
• Treat precipitating factors such as infection, anaemia or hyperthyroidism.

Anticoagulation

A vitamin K antagonist such as warfarin is indicated in rheumatic MS with:

• Atrial fibrillation
• Previous systemic embolism
• Left-atrial thrombus

Direct oral anticoagulants are not recommended as substitutes for warfarin in patients with atrial fibrillation and clinically significant rheumatic MS.

Percutaneous mitral balloon commissurotomy

Preferred intervention for symptomatic severe rheumatic MS when:

• Mitral valve area is ≤1.5 cm².
• Valve anatomy is suitable.
• There is no left-atrial thrombus.
• There is no more than mild mitral regurgitation.

It may also be considered in selected asymptomatic patients with pulmonary hypertension, very severe MS, high embolic risk or planned pregnancy.

Contraindications to balloon commissurotomy

Left-atrial thrombus

More than mild mitral regurgitation

Severe or bicommissural calcification

Absence of commissural fusion

Significant associated valve or coronary disease requiring surgery

Unfavourable valve or subvalvular anatomy.

Surgery

Mitral-valve repair, open commissurotomy or replacement is considered when:

• The patient is symptomatic with severe MS but unsuitable for balloon commissurotomy.
• Balloon commissurotomy has failed.
• Significant mitral regurgitation is also present.
• The valve is severely calcified.
• Other cardiac surgery is required.

A mechanical valve requires lifelong anticoagulation; a bioprosthetic valve has limited durability but usually avoids lifelong anticoagulation unless another indication exists.

Complications and Prognosis

Complications

• Atrial Fibrillation
• Stroke
• Warfarin-induced haemorrhage
• Systemic Embolism – due to thrombus formation in the right atrium
• Infective endocarditis
• Functional tricuspid reguritation

Prognosis

• Rheumatic MS often has a long asymptomatic period before symptoms develop.
• Prognosis worsens substantially after the development of:
  • Atrial fibrillation
  • Pulmonary hypertension
  • Recurrent pulmonary oedema
  • Right-sided heart failure
  • Systemic embolisation
• Successful balloon commissurotomy or surgery can markedly improve symptoms and haemodynamics.
• Restenosis may occur over time, particularly with unfavourable anatomy or ongoing rheumatic disease.

References

1. Praz F, Borger MA, Lanz J, et al. 2025 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J. 2025;46(44):4635–4736. doi:10.1093/eurheartj/ehaf194.
2. Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA guideline for the management of patients with valvular heart disease. Circulation. 2021;143(5)–e227. doi:10.1161/CIR.0000000000000923.
3. Vahanian A, Beyersdorf F, Praz F, et al. 2021 ESC/EACTS guidelines for the management of valvular heart disease. Eur Heart J. 2022;43(7):561–632. doi:10.1093/eurheartj/ehab395.
4. Chandrashekhar Y, Westaby S, Narula J. Mitral stenosis. Lancet. 2009;374(9697):1271–1283. doi:10.1016/S0140-6736(09)60994-6.
5. Karthikeyan G, Connolly SJ, Ntsekhe M, et al. Rivaroxaban in rheumatic heart disease-associated atrial fibrillation. N Engl J Med. 2022;387(11):978–988. doi:10.1056/NEJMoa2209051.