See also separate articles Mitral Valve Disease, Mitral Stenosis and Mitral Regurgitation.

Surgery is the definitive management for both mitral stenosis and mitral regurgitation. The more severe the stenosis or regurgitation, the greater the benefit of surgical intervention. However, medical management is important in the treatment of co-existent ventricular failure or atrial fibrillation, the prevention of endocarditis with antibiotics, and anticoagulation where indicated.

Those patients who are not currently considered to warrant surgical intervention because of the mild degree of stenosis or regurgitation should be reviewed at regular intervals with repeat echocardiography to re-evaluate both the degree of stenosis and cardiac function.

National Institute for Health and Clinical Excellence (NICE) guidance supports the safety and efficacy of thoracoscopically assisted mitral valve surgery.¹

Mitral stenosis

Surgical options for the treatment of mitral stenosis are:²

• Balloon valvuloplasty (percutaneous balloon commissurotomy): the best results are obtained when the valve shows commissural fusion, is pliable, is not heavily calcified, and has little or no disease of the subvalvular apparatus:
  • Most cases are now performed by percutaneous balloon mitral valvotomy.³
  • Suitability is determined by valve morphology and the amount of mitral regurgitation present.²
  • If the valve is unfavourable for this procedure, open commissurotomy or mitral valve replacement is required.
  • Before balloon valvuloplasty, a transoesophageal echocardiogram is performed to look for the presence of clot in the left atrium or left atrial appendage. If thrombus is present, balloon valvuloplasty is abandoned, and the patient is begun on warfarin therapy for several months. A repeat transoesophageal echocardiogram is then performed and valvuloplasty can be performed if the thrombus has disappeared.²
  • Failure rates range from 1% to 15%. Major complications include haemopericardium, embolism and severe regurgitation. Operative mortality is 0.5-4%.⁴
  • 65% of patients are free of restenosis 10 years after the procedure.²
• Open-heart mitral valvotomy:
  • With recent emphasis on mitral valve conservation, this procedure is ideal for those patients thought not to be candidates for balloon valvuloplasty because of poor valve morphology.
  • When the valve can be conserved, it avoids the risks of prosthetic valves and also avoids the need for anticoagulation in patients in sinus rhythm.²
  • Long-term results are good with 96% survival and 92% free of valve-related complications at 15 years.⁴
• Valve replacement:
  • In cases in which rheumatic involvement of the valve precludes conservation, mitral valve replacement is performed.
  • The operative risk is 3% to 8% in the absence of pulmonary hypertension and other comorbidities.²

Indications for surgery

• The more advanced the patient's symptoms, the greater the survival advantage of surgical correction compared with medical therapy.²
• Therefore, surgery is indicated once more than mild symptoms are present, e.g. dyspnoea despite control of atrial fibrillation.
• Pulmonary hypertension (but when pulmonary hypertension has developed, surgical complications and mortality are increased).²
• Operation is required before atrial fibrillation becomes irreversible.
• Calculated valve area <1.5 cm² with signs of critical stenosis.
• Gradient of more than 10 mm Hg across valve.

Prognosis

• Patients who have surgical or percutaneous surgery for mitral stenosis have a greatly improved prognosis but life expectancy is still shortened, mainly because of complications of the mitral stenosis.⁵

Mitral regurgitation

Surgery is indicated in patients who have symptoms due to chronic mitral regurgitation but no contra-indications to surgery. The role of operative intervention for asymptomatic patients is controversial.⁴ There are three types of surgical correction for mitral regurgitation:³

• Mitral valve repair:
  • Advantages include the lowest operative mortality, preserved postoperative left ventricular (LV) function and excellent long-term results (re-operation is required in fewer than 10% of patients in experienced hands).³
  • Repair avoids the risks of a prosthetic valve, i.e. thromboembolism from mechanical valves and valve deterioration with bio-prosthetic valves.³
• Mitral valve replacement with chordal preservation:
  • In most cases when repair is impossible, it is possible to retain at least the posterior leaflet connections. This produces better outcomes than ablation of the entire apparatus.
  • Although this operation is better than a standard valve replacement with destruction of the valve apparatus, both procedures lead to the potential complications of prosthetic valves.³
• Mitral valve replacement with removal of the mitral apparatus:
  • Has the highest operative mortality and worst postoperative LV function.³
  • It should therefore be reserved for those patients for whom preservation of existing mitral apparatus is impossible.
  • Destruction of the mitral valve apparatus leads to as much as 25% reduction in ventricular function.³
• The main surgical treatment for functional mitral regurgitation (caused by changes in LV geometry due to impaired LV function) is restrictive annuloplasty.⁴

NICE currently recommends that the evidence for the safety and efficacy of percutaneous mitral valve leaflet repair or percutaneous mitral valve annuloplasty for mitral regurgitation is inadequate.^6,7

Indications for surgery

• Symptoms, especially dyspnoea.
• Severe mitral regurgitation confirmed by echocardiography and angiography.³
• Asymptomatic patients with LV dysfunction: surgery is necessary in order to prevent further and irreversible LV failure from developing.
• Severe mitral regurgitation with either atrial fibrillation or pulmonary hypertension needs prompt referral.
• Poor LV function may preclude surgery.
• Although advancing age is not a barrier to surgery for mitral regurgitation, there is an increased risk of surgery in the elderly and this may affect the decision as to whether to operate in some cases.³
• Operative intervention for ischaemic mitral regurgitation has a worse prognosis than non-ischaemic mitral regurgitation.

Recommendations for surgery in patients with mitral valve replacement who develop mitral regurgitation are the same as for other forms of non-ischaemic severe mitral regurgitation.⁸

Prognosis⁹

• Thromboembolism occurs at a rate of 1% to 3% per year for patients with mechanical valves who are on anticoagulation therapy.
• Operative mortality for isolated mitral valve repair surgery is 2%.
• Operative mortality for mitral valve replacement surgery is 4% mortality for patients younger than 50 years, and 17% for patients older than 80 years.

Mitral valve prolapse

See separate article Mitral Valve Prolapse.

Document references

1. Thoracoscopically-assisted mitral valve surgery, NICE Interventional Procedure Guideline (December 2007)
2. Carabello BA; Modern management of mitral stenosis.; Circulation. 2005 Jul 19;112(3):432-7.
3. Carabello BA; Indications for mitral valve surgery.; J Cardiovasc Surg (Torino). 2004 Oct;45(5):407-18. [abstract]
4. Vahanian A, Baumgartner H, Bax J, et al; Guidelines on the management of valvular heart disease: The Task Force on the Management of Valvular Heart Disease of the European Society of Cardiology. Eur Heart J. 2007 Jan;28(2):230-68. Epub 2007 Jan 26.
5. Dima C et al; Mitral Stenosis, Medscape, Nov 2010
6. Percutaneous mitral valve leaflet repair for mitral regurgitation, NICE Interventional Procedure Guideline (August 2009)
7. Percutaneous mitral valve annuloplasty, NICE Interventional Procedure Guideline (July 2010)
8. American College of Cardiology/American Heart Association, Guidelines for the Management of Patients with Valvular Heart Disease (2006)
9. Hanson I et al; Mitral Regurgitation, Medscape, May 2011