PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
Mitral stenosis occurs when there is obstruction to flow through the mitral valve separating the left atrium and left ventricle of the heart.
- The obstruction occurs due to a structural abnormality of the valve. Mitral stenosis increases left atrial and pulmonary arterial pressure (especially in tachycardia).
- Pulmonary hypertension can lead to right ventricular dilation and tricuspid regurgitation. Right ventricular failure results in raised jugular venous pressure, liver congestion, ascites and peripheral oedema. Left ventricular function and cardiac output can be normal in isolated mitral stenosis.
Mitral stenosis may be associated with other heart valve lesions - eg tricuspid regurgitation. 
Causes of mitral stenosis include:
- Rheumatic fever (the most common cause).
- Degenerative calcification (can occur in the elderly).
- Congenital mitral stenosis (secondary to parachute mitral valve or Lutembacher's syndrome).
- Inborn errors of metabolism (eg, Hurler-Scheie syndrome, Anderson-Fabry disease).
- Systemic lupus erythematosus.
- Rheumatoid arthritis.
- Carcinoid syndrome.
- Infective endocarditis with large vegetations.
- Amyloid deposition in the mitral valve.
Patients with mitral stenosis may feel asymptomatic for years and then present with a gradual decrease in activity.
- Breathlessness: progressive breathlessness is the main symptom. This can include shortness of breath on exertion, orthopnoea and paroxysmal nocturnal dyspnoea. Pulmonary oedema can be triggered by the onset of atrial fibrillation.
- Atrial fibrillation: palpitations due to atrial fibrillation may be the presenting feature.
- Systemic emboli: are a rarer presentation. Stroke, renal failure and myocardial infarction can occur.
- Haemoptysis: this may occur secondary to rupture of the bronchial veins due to raised left atrial pressure.
- During pregnancy: the increase in blood volume may make a previously asymptomatic woman develop symptoms.
- Malar flush on the cheeks.
- Raised jugular venous pressure.
- Laterally displaced apex beat.
- Right ventricular heave.
- Loud first heart sound with an opening snap in early diastole.
- A mid-late diastolic murmur, best heard, with the patient in the left lateral position, with the bell of the stethoscope (see separate article Heart Auscultation).
- Atrial fibrillation.
- Signs of right ventricular failure including hepatomegaly, ascites and peripheral oedema.
- CXR: may show left atrial enlargement and interstitial oedema (Kerley A and B lines) if severe. Mitral valve calcification may be seen. There may be prominent pulmonary vessels with redistribution of pulmonary vasculature to the upper lobes.
- ECG: may reveal atrial fibrillation, left atrial enlargement and right ventricular hypertrophy. (See separate article ECG A Methodical Approach.)
- Is the main method used to assess the severity and consequences of mitral stenosis, as well as the extent of anatomical lesions.
- Echocardiography also evaluates pulmonary artery pressures, associated mitral regurgitation, concomitant valve disease, and left atrial size.
- Due to the frequent association of mitral stenosis with other valve diseases, a comprehensive evaluation of the tricuspid and aortic valves is essential.
- Transthoracic echocardiography (TTE) usually provides sufficient information for routine management.
- Trans-oesophageal echocardiography (TOE) should be performed to exclude left atrial thrombus before percutaneous mitral commissurotomy (PMC) or after an embolic episode, or if TTE provides insufficient information.
- Asymptomatic patients with clinically significant mitral stenosis, who have not undergone intervention, should be followed up yearly by means of clinical and echocardiographic examinations and at longer intervals (2 to 3 years) in cases of less severe stenosis.
- PMC is the treatment of choice when treatment is indicated, except for patients with suboptimum valve morphology, (even these patients are sometimes treated with PMC if surgery is not feasible or if surgical risk is prohibitive).
- Commissurotomy (valvulotomy) involves making one or more incisions at the edges of the commissure formed between the valves in order to relieve the constriction.
- Diuretics or long-acting nitrates can be used to alleviate dyspnoea. Beta-blockers or heart-rate regulating calcium-channel blockers can improve exercise tolerance.
- Anticoagulant therapy is indicated in patients with either permanent or paroxysmal atrial fibrillation. In patients with sinus rhythm, anticoagulation is indicated when there has been prior embolism, or a thrombus is present in the left atrium.
- Symptomatic patients with severe mitral stenosis or those with pulmonary hypertension should be considered for PMC.
- Contra-indications to PMC include mitral valve area >1.5 cm², left atrial thrombus, greater than mild mitral regurgitation, severe or bicommissural calcification, absence of commissural fusion, severe concomitant aortic valve disease, severe combined tricuspid stenosis and regurgitation, and concomitant coronary artery disease requiring bypass surgery.
- When PMC is not successful and symptoms persist, surgery should be considered early unless there are definite contra-indications.
- Major complications include procedural mortality (0.5-4%), haemopericardium (0.5-10%), embolism (0.5-5%), and severe regurgitation (2-10%).
- Event-free survival after PMC ranges from 30-70% after 10-20 years. When functional deterioration occurs, it is late and mainly related to re-stenosis. Successful PMC also reduces embolic risk.
- Closed mitral commissurotomy is still performed in developing countries, but otherwise has largely been replaced by open mitral commissurotomy using cardiopulmonary bypass, which is also now seldom performed. In series from experienced centres, mostly including young patients, long-term results are good with ten-year survival rates of 81-90%.
- Surgical valve replacement should be considered for patients who are not candidates for percutaneous intervention. Surgery for mitral stenosis is currently mostly valve replacement as a result of increasingly elderly presentation and unfavourable valve characteristics for valve repair.
- Pulmonary hypertension
- Dilated left atrium
- Atrial fibrillation
- Thromboembolic events
- Right heart failure
- Infective endocarditis
- The reported five-year survival rate of patients with symptomatic mitral stenosis who refuse valvotomy is only 44%.
- For patients with no symptoms or minimal symptoms, survival is greater than 80% at ten years.
- When limiting symptoms occur, ten-year survival is less than 15% in patients with untreated mitral stenosis.
- When severe pulmonary hypertension develops, mean survival is less than three years.
- Most patients with severe untreated mitral stenosis die as a result of progressive heart failure but others may die from systemic embolism or pulmonary embolism, or infection.
- The prognosis is much improved in patients who undergo surgical or percutaneous relief of valve obstruction. However, life expectancy is still shortened compared with that expected for age, largely because of the complications of mitral stenosis.
- Primary and secondary prevention of rheumatic fever.
- Prevention of endocarditis.
Further reading & references
- Dima C et al; Mitral Stenosis, Medscape, May 2012
- Carabello BA; Modern management of mitral stenosis.; Circulation. 2005 Jul 19;112(3):432-7.
- Management of Valvular Heart Disease, European Society of Cardiology (2012)
- Chandrashekhar Y, Westaby S, Narula J; Mitral stenosis. Lancet. 2009 Oct 10;374(9697):1271-83. Epub 2009 Sep 9.
- Maganti K, Rigolin VH, Sarano ME, et al; Valvular heart disease: diagnosis and management. Mayo Clin Proc. 2010 May;85(5):483-500.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Michelle Wright
Dr Colin Tidy
Dr Hayley Willacy