Mitral Stenosis

Reviewed 06/2017
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Subject: Mitral Stenosis

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BASICS

DESCRIPTION

  • The mitral valve apparatus is made up of anterior and posterior leaflets which are attached to the anterolateral and posteromedial papillary muscles via the chordae.

  • Mitral stenosis (MS) is a narrowing of the valve area causing obstruction of the left ventricular inflow, resulting in increased left atrial pressures and consequent elevation of pulmonary venous and atrial pressures.

  • Normal valve orifice 4 to 6 cm2; symptoms typically seen when orifice is ≪2.5 cm21.

  • Staging of the disease is used to guide appropriate treatment regimen. Stages vary from A (with risk factors), B (hemodynamic obstruction), C (severe but no symptoms), to D (symptomatic) 1.

  • The most common etiology for MS is rheumatic heart disease (RHD), and MS is the most common valvular disease secondary to RHD.

  • Other etiologies will be discussed below.

EPIDEMIOLOGY

  • Globally, the prevalence of RHD is 15.6 million every year. Approximately 282,500 new cases are reported and 233,000 deaths have been attributed to RHD 2.

  • Predominant age: Symptoms primarily occur in 3rd to 4th decades; predominant sex: female > male (2:3)

Incidence

Incidence of rheumatic disease in the continental United States remains very low. Annual incidence of acute rheumatic fever in the continental United States is 0.04 to 0.06 cases per 1,000 children. However, global burden remains significant 3

ETIOLOGY AND PATHOPHYSIOLOGY

  • Narrowing of the valve orifice leads to obstruction of blood flow between LA and LV. This impairs LV filling during diastole and causes increased LA pressure. Increased LA pressure is transmitted passively (“back pressure”) to the pulmonary circulation causing pulmonary hypertension and pulmonary congestion over time.

  • Chronic LA pressure overload results in atrial dilation and fibrosis and may cause Afib.

  • Rheumatic fever: most common etiology (see “Risk Factors”)

  • Aging (extension of mitral annular calcification)

  • Rare causes: congenital (associated with mucopolysaccharidoses), autoimmune: systemic lupus erythematosus (SLE); rheumatoid arthritis; malignant carcinoid; Whipple disease; methysergide therapy; and other acquired pathologies such as LA myxoma, LA thrombus, endomyocardial fibrosis

RISK FACTORS

  • Rheumatic fever is the greatest risk factor.

    • ▪ 30-40% of rheumatic fever patients eventually develop MS, presenting 20 years after diagnosis of rheumatic fever.
    • ▪ Acute rheumatic fever occurs 2 to 3 weeks after an episode of untreated pharyngitis caused by rheumatogenic Group A streptococci (GAS) organism in a genetically susceptible host.
    • ▪ Recurrent infections can accelerate the progression of the disease.
    • ▪ Low socioeconomic status (i.e., crowded conditions) favors the spread of streptococcal infection.
  • Aging (increasing valvular calcification)

  • Chest irradiation (increasing tissue fibrosis)

GENERAL PREVENTION

  • Prompt recognition and treatment of GAS infection; recognition of cardinal signs and symptoms of acute rheumatic fever via Jones criteria

  • Ultrasound-based screening has been shown to increase diagnosis of RHD in asymptomatic patients residing in areas of high prevalence.

COMMONLY ASSOCIATED CONDITIONS

  • Afib (30-40% of symptomatic patients)

  • Associated valve lesions due to chronic inflammation (aortic stenosis, aortic insufficiency)

  • Pulmonary HTN and right heart failure

  • Systemic embolism, stroke, pulmonary embolism (10%)

  • Infection, including infectious endocarditis (1-5%)

  • Chronic rheumatic myocarditis

DIAGNOSIS

HISTORY

  • History of rheumatic fever

  • Severity depends on valve area; most early cases will be asymptomatic.

  • Mean age of symptom onset in rheumatic valvular disease is in the late 30s to 40s. Latent period 20 to 40 years after infection. Rapid progression can be seen in some high prevalence areas.

  • Presenting features usually include dyspnea on exertion, decreased exercise tolerance, chest pain, embolic events, palpitations, hoarseness, hemoptysis, fatigue, paroxysmal nocturnal dyspnea, Afib, and embolic events.

  • In advanced disease, symptoms of pulmonary HTN and right heart failure predominate: jugular venous distention, hepatomegaly, ascites, and peripheral edema

  • Other presentations: hemoptysis (due to increased collateralization between pulmonary and bronchial circulation causing intraparenchymal hemorrhage), hoarseness (compression of recurrent laryngeal nerve by enlarged pulmonary artery or LA), dysphagia (compression of bronchi), chronic cough (due to LA compressing the bronchi) and infective endocarditis. Not infrequently, symptoms are first noted in pregnancy.

PHYSICAL EXAM

  • Elevated jugular venous pressure, left parasternal heave. Apical impulse may be displaced, diastolic thrill in the left lateral decubitus position

  • Auscultation

    • ▪ Classic murmur: accentuated S1, opening snap, apical early decrescendo diastolic rumble with presystolic accentuation (presystolic accentuation of murmur is lost with AF). Murmur is low pitch and best heard at the apex in the left lateral decubitus position.
    • ▪ Murmur is accentuated with exercise and decreased with rest and Valsalva.
      • * With mobile, noncalcified valve, murmur persists throughout diastole and S1, and the opening snap remains loud.
      • * With increasing severity of MS, murmur often is difficult to hear. S1 and the opening snap may be soft to absent.
      • * A shorter S2 to O2 interval indicates more severe MS.
      • * Further evaluation is required while looking for concomitant murmurs.
  • If pulmonary HTN is present, increased P2, highpitched decrescendo diastolic murmur of pulmonic insufficiency is heard (Graham Steell murmur); may have signs of right heart failure

  • May also find associated aortic or tricuspid murmurs due to involvement from RHD

DIAGNOSTIC TESTS & INTERPRETATION

Initial Tests (lab, imaging)

  • ECG 4,5[C]

    • ▪ LA enlargement (manifested by broad, notched P waves in lead II [P mitrale], with P wave duration >0.12 sec with a negative terminal deflection of the P wave in lead V1)
    • ▪ Afib is a common finding.
    • ▪ Right ventricular hypertrophy (RVH), right axis deviation, and an R-to-S ratio greater than 1 in in V1 are possible.
  • Chest radiograph 4,5[C]

    • ▪ LA enlargement, straightening of the left heart border, a “double density,” in the cardiac silhouette, and elevation of the left main stem bronchus
    • ▪ Prominent pulmonary arteries at the hilum with rapid tapering, RVH, and edema pattern with Kerley A and B lines (late presentation)
  • Transthoracic echo (TTE) recommended in all patients with signs and symptoms of MS 1[B]

    • ▪ Used for diagnosis of MS
      • * Assess doming of the valve, mitral orifice size, and commissural fusion.
      • * Extent of involvement based on degree of commissural fusion, calcification, and subvalvular fibrosis
    • ▪ Assess for concomitant valvulopathies.
  • TEE should be performed if TTE images are nondiagnostic or if being considered for a percutaneous mitral balloon commissurotomy (PMBC) to exclude thrombus in left atrium and evaluate severity of MR 1[B].

  • Exercise stress testing can also be considered in patients with MS who have a discrepancy in their symptoms and signs and resting Echo findings 1[C].

  • Cardiac catheterization indications 1,5[C]

    • ▪ Class I recommendation
      • * When echo is inconclusive
      • * Discrepancy between echo, symptoms, and severity
    • ▪ Class II recommendation
      • * Assess cause of severe pulmonary HTN that is out of proportion to echo results.
    • ▪ Class III recommendation: satisfactory result of echo
Follow-Up Tests & Special Considerations
  • If valve area >1.5 cm2 and mean pressure gradient ≪5 mm Hg, clinical f/u in 3 to 5 years is recommended.

  • Otherwise, f/u is usually symptom based. Symptomatic patients with severe MS need further evaluation for interventional/surgical treatment.

  • Holter monitor placement in order to r/o paroxysmal Afib.

Diagnostic Procedures/Other

  • Exercise testing is recommended for those with clinical discrepancy.

  • Wilkin's score evaluates valvular anatomy from a TTE in order to see if patient is a candidate for surgery.

Test Interpretation

  • Rheumatic fever-induced pathologic changes: leaflet thickening, leaflet calcification, commissural fusion, chordal shortening

  • MV area defined 1

    • ▪ Normal: 4 to 6 cm2, progressive MS: >1.5 cm2, severe MS: ≪1.5 cm2, very severe: ≪1.0 cm2

TREATMENT

GENERAL MEASURES

  • Treatment is dependent on severity of stenosis and symptoms.

  • Patients who have a valvular area >1.5 cm2 and no symptoms can be managed medically.

  • MS is generally progressive, and medical therapy only delays the need for definitive therapy. It entails (i) treatment to prevent recurrence of rheumatic fever, (ii) treatments aimed at improving dyspnea and exercise tolerance, (iii) controlling the ventricular rate whether in sinus rhythm or Afib, (iv) and anticoagulation for prevention of thromboembolic events.

MEDICATION

First Line

  • Antibiotic prophylaxis against rheumatic fever and/or carditis is recommended for patients with history of rheumatic fever 1[C].

  • Secondary prophylaxis is dependent on many factors: number of previous attacks, time since previous infection, risk for getting GAS, age of patient, and absence or presence of cardiac involvement 6.

    • ▪ Penicillin V (PCN) PO or penicillin G IM: IM is more effective than PO.
    • ▪ If allergic to PCN, can use sulfadiazine and macrolides alternatively
    • ▪ Duration of rheumatic fever prophylaxis is variable: 6
      • * Rheumatic fever without carditis: Take for 5 years or until age 21 years, whichever is longer.
      • * Rheumatic fever with carditis but no residual heart disease: Take for 10 years or well into adulthood, whichever is longer.
      • * Rheumatic fever with carditis plus residual heart disease: Take for 10 years or until 40 years old, whichever is longer.
  • Antibiotic prophylaxis against infective endocarditis is not routinely recommended, unless there are other indications 1[B].

  • Diuretics for congestive symptoms 1[A]

  • β-Blockers or nondihydropyridine calcium channel blockers used for controlling heart rate both in SR and AF to allow adequate diastolic filling and decrease LA diastolic pressure tachycardia or exertional symptoms 1

  • Consider cardioversion, especially in patients with mild MS and recent dx of Afib (≪6 months).

  • Use of anticoagulation 1[B]

    • ▪ Class I recommendations
      • * MS and Afib or history of Afib, MS and prior embolic event, or MS and LA thrombus
    • ▪ Class IIB recommendations
      • * Patients with enlarged LA and spontaneous contrast on echo
  • Warfarin is the only accepted modality for anticoagulation in patients with rheumatic mitral valve disease (international normalized ratio) range 2 to 3.

  • Heparin in the acute Afib setting

  • The new oral anticoagulants (factor Xa inhibitor and direct thrombin inhibitor) are not approved for use in Afib that is secondary to MS.

Second Line

One can also consider amiodarone or digitalis if β-blockers and CCBs are not proven beneficial 2[C]. 

SURGERY/OTHER PROCEDURES

  • Surgical techniques include balloon valvotomy, open mitral commissurotomy, or closed mitral commissurotomy and mitral valve replacement.

  • Patients with severe MS and symptoms consistent with NYHA class III to IV are candidates for surgery.

  • Any patient with a valve area >1.5 cm2, LA thrombus, moderate MR, severe bicommissural calcifications, severe aortic valve disease, moderate TR or TS, concomitant coronary artery disease are not candidates for PMBC.

  • PMBC is recommended for those with severe MS symptoms and favorable valve morphology 1[A], in asymptomatic patient with very severe MS and favorable valve anatomy in the absence of symptoms 1[C], and in patients with suboptimal valvular anatomy, with a high risk for surgery 1[C].

  • Balloon valvotomy: symptomatic patients with NYHA class II, III, or IV symptoms with valves that look favorable and with favorable comorbidities 1[A]

  • MV surgery: when MS is severe with severe symptoms (NYHA class III to IV) who are not high-risk surgical candidates and balloon valvotomy is contra-indicated or failed PMBC 1[B]

  • Consider patient age, bleeding risk, and other comorbidities prior to deciding if patient should have a prosthetic versus mechanical valve.

Pregnancy Considerations

  • Volume expansion during pregnancy can exacerbate heart failure symptoms. Patients with known severe MS, prepregnancy discussions should be pursued with a cardiologist.

  • Pregnant patients can safely use β-blockers. Despite some concerns of teratogenic affects with diuretics, furosemide has been used in symptomatic MS patients during pregnancy with minimal adverse effects.

  • Coumadin is considered relatively safe in the 2nd and 3rd trimesters if anticoagulation is required. However, unfractionated heparin is preferred prior to labor and delivery.

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

  • Counsel patients with MS that is usually slowly progressive but can have sudden onset of Afib, which could become rapidly fatal. Call 911 for marked worsening of symptoms.

  • Echocardiographic surveillance in asymptomatic patients in any degree of MS: very severe (≪1.0 cm2) MS: yearly, severe (≤1.5 cm2) MS: every 1 to 2 years, mild or moderate MS: every 3 to 5 years

  • Follow-up will depend on the severity of the MS and the patient's symptoms.

    • ▪ Asymptomatic patients: annual history and examination
    • ▪ Symptomatic patients are followed closely based on clinical response to adjust therapy and plan-definitive treatment 1[C].

DIET

Salt restriction for pulmonary congestion 

PROGNOSIS

Natural history 
  • Asymptomatic latent period after rheumatic fever for 10 to 30 years. 10-year survival for asymptomatic or minimally symptomatic patients is 80%.

  • 10-year survival after onset of debilitating symptoms is only 0-15%.

  • Mean survival with significant pulmonary HTN is ≪3 years.

  • Commissurotomy is an effective means of reducing stenosis but is not curative. Restenosis sometimes occurs and can be early (≪5 years) or late (>20 years).

COMPLICATIONS

Left and right heart failure, Afib and systemic embolization, pulmonary HTN, hepatic congestion, and bacterial endocarditis 

REFERENCES

Nishimura  RA, Otto  CM, Bonow  RO, et al. 2014 AHA/ACC guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Thorac Cardiovasc Surg.  2014;148(1):e1–e132.  [View Abstract]
Carapetis  JR, Steer  AC, Mulholland  EK, et al. The global burden of group A streptococcal diseases. Lancet Infect Dis.  2005;5(11):685–694.  [View Abstract]
Maganti  K, Rigolin  VH, Sarano  ME, et al. Valvular heart disease: diagnosis and management. Mayo Clin Proc.  2010;85(5):483–500.  [View Abstract]
Anderson  JL, Halperin  JL, Albert  NM, et al. Management of patients with atrial fibrillation (compilation of 2006 ACCF/AHA/ESC and 2011 ACCF/AHA/HRS recommendations): a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol.  2013;61(18):1935–1944.  [View Abstract]
Manyemba  J, Mayosi  BM. Penicillin for secondary prevention of rheumatic fever. Cochrane Database Syst Rev.  2002;(3):CD002227.  [View Abstract]
Dajani  A, Taubert  K, Ferrieri  P, et al. Treatment of acute streptococcal pharyngitis and prevention of rheumatic fever: a statement for health professionals. Pediatrics.  1995;96(4 Pt 1):758–764.  [View Abstract]

CODES

ICD10

  • I05.0 Rheumatic mitral stenosis

  • I05.8 Other rheumatic mitral valve diseases

  • I34.2 Nonrheumatic mitral (valve) stenosis

  • I05.2 Rheumatic mitral stenosis with insufficiency

  • Q23.2 Congenital mitral stenosis

  • I05.1 Rheumatic mitral insufficiency

ICD9

  • 394.0 Mitral stenosis

  • 424.0 Mitral valve disorders

  • 394.1 Rheumatic mitral insufficiency

  • 394.2 Mitral stenosis with insufficiency

  • 746.5 Congenital mitral stenosis

SNOMED

  • 79619009 Mitral valve stenosis (disorder)

  • 86466006 Rheumatic mitral stenosis (disorder)

  • 194727002 Non-rheumatic mitral valve stenosis

  • 194726006 Mitral stenosis with insufficiency (disorder)

  • 82458004 Congenital stenosis of mitral valve (disorder)

CLINICAL PEARLS

  • Asymptomatic patients may be followed clinically with yearly exams for development of symptoms with periodic echo to evaluate valve area.

  • Once symptoms of MS develop, initiate appropriate medical therapy but advise patient that for most, surgical therapy will be needed to prolong survival. Almost all cases of MV stenosis progress in severity over time.

  • MS often presents during the intrapartum period. For patients with known severe MS, intervention should be pursued prior to pregnancy. Pregnancy in a patient with severe MS has a high rate of both maternal and fetal complications, including death.

 
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