> Table of Contents > Mitral Stenosis
Mitral Stenosis
Zeeshan Hussain, MD
Nirmanmoh Bhatia, MD
Marcus F. Stoddard, MD
image BASICS
DESCRIPTION
  • Mitral stenosis (MS) presents as resistance to diastolic filling of the left ventricle (LV) due to narrowing of mitral valve (MV) orifice.
  • Normal valve orifice 4 to 6 cm2; symptoms typically seen when orifice is <2.5 cm2.
  • Hemodynamic consequences are due to passive transmission of left atrial (LA) pressure to the pulmonary circulation; may coexist with mitral regurgitation and aortic valvulopathies
  • Stages vary from A (with risk factors), B (hemodynamically obstruction), C (severe but no symptoms), to D (symptomatic) (1)
EPIDEMIOLOGY
  • Most common acquired valvular disease secondary to rheumatic heart disease (60% of cases)
  • Predominant age: Symptoms primarily occur in 4th to 7th decades.
  • Predominant sex: female > male (2:1)
Incidence
Decreased incidence of MS is seen in the United States because of decreased incidence of rheumatic fever (primarily shift in prevalence away from rheumatogenic strains of group A streptococci [GAS] and also treatment of GAS infection). However, global burden remains significant (2).
ETIOLOGY AND PATHOPHYSIOLOGY
  • Obstruction between LA and LV impairs LV filling during diastole and leads to increased LA pressure.
  • Increased LA pressure is transmitted passively (“back pressure”) to the pulmonary circulation; over time, pulmonary hypertension (HTN) results.
  • Over time, LA pressure overload can dilate the chamber and interrupt the cardiac conduction system, resulting in atrial fibrillation.
  • Pulmonary HTN can also cause increased collateralization between pulmonary and bronchial circulation, resulting in intraparenchymal hemorrhage with hemoptysis.
  • Rheumatic fever: most common (see “Risk Factors”)
  • Aging (extension of mitral annular calcification)
  • Rare causes
    • Congenital (associated with mucopolysaccharidoses)
    • Autoimmune: systemic lupus erythematosus (SLE), rheumatoid arthritis
    • Malignant carcinoid
    • Other acquired: 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 an average of 20 years after diagnosis of rheumatic fever.
    • Acute rheumatic fever occurs 2 to 3 weeks after episode of untreated GAS pharyngitis caused by rheumatogenic organism in a genetically susceptible host.
    • 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
  • Modified Jones criteria for acute rheumatic fever: Diagnosis requires evidence of streptococcal infection plus two major criteria or one major plus two minor criteria.

Evidence of streptococcal infection

Antistreptolysin O titer or positive throat culture

Major criteria

Carditis, polyarthritis, Sydenham chorea, erythema marginatum, subcutaneous nodules

Minor criteria

Migratory arthralgias, fever, acute phase reactants (elevated erythrocyte sedimentation rate [ESR], leukocytosis), prolonged PR interval on ECG

COMMONLY ASSOCIATED CONDITIONS
  • Atrial fibrillation (30-40% of symptomatic patients)
  • Associated valve lesions due to chronic inflammation (aortic stenosis, aortic insufficiency)
  • Pulmonary congestion and pulmonary HTN
  • Right heart failure
  • Systemic embolism, pulmonary embolism (10%)
  • Infection, including infectious endocarditis (1-5%)
image DIAGNOSIS
PHYSICAL EXAM
  • Reduced peripheral pulses
  • Auscultation
    • Classic murmur: accentuated S1, opening snap, apical early decrescendo diastolic rumble with presystolic accentuation
    • Murmur variability seen in severe stenosis
      • With mobile, noncalcified valve, murmur persists throughout diastole and S1, and the opening snap remains loud.
      • With a heavily calcified valve, murmur often is difficult to hear. S1 and the opening snap may be soft to absent.
      • In contrast to tricuspid stenosis, the intensity of the murmur from MS increases with inspiration and a prominent a wave in jugular venous pulse.
  • If HTN is present: Right ventricle (RV) lift, increased P2, high-pitched decrescendo diastolic murmur of pulmonic insufficiency (Graham Steell murmur) may have signs of right heart failure.
  • May also find associated aortic or, less commonly, tricuspid murmurs due to aortic or tricuspid valve involvement from rheumatic heart disease
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 a negative terminal deflection of the P wave in lead V1)
    • Atrial fibrillation is common.
    • Right ventricular hypertrophy (RVH), right axis deviation, and a large R wave in V1 are possible.
  • Chest radiograph (4,5)[C]
    • LA enlargement, straightening of the left heart border, a “double density,” and elevation of the left main stem bronchus
    • Prominent pulmonary arteries at the hilum with rapid tapering, RVH
    • Pulmonary edema pattern with Kerley B lines (late presentation)
  • ECG indications (1)[B],(5)[C]
    • Class I
      • Diagnosis of MS
      • Assess severity.
      • Reassess after change in symptoms.
      • Exercise Doppler for discrepancies between symptoms and echo findings.
      • During evaluation for commissurotomy
      • TEE when transthoracic echo nondiagnostic, to exclude thrombus in left atrium or to evaluate severity of MR (1)[B]
    • Class II
      • Reassess asymptomatic patients.
      • 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
    • Class III
      • Satisfactory result of transthoracic echo
  • ECG findings
    • MV anterior leaflet doming, immobility of the posterior leaflet
    • Echo can demonstrate alternative causes of MS if not rheumatic.
    • MV area defined (1)
      • Normal: 4 to 6 cm2
      • Progressive MS: >1.5 cm2
      • Severe MS: <1.5 cm2
      • Very severe: <1.0 cm2
  • Cardiac catheterization indications (1,5)[C]
    • Class I recommendations
      • When echo is inconclusive
      • Discrepancy between echo and symptoms
      • Discrepancy between echo and valve area
    • Class II recommendations
      • To assess response of LA and pulmonary artery pressures to exercise when symptoms and echo findings do not match
      • Assess cause of severe HTN out of proportion to echo results.
    • Class III recommendations: satisfactory result of echo
Follow-Up Tests & Special Considerations
  • If valve area >1.5 cm2 and mean pressure gradient <5 mm Hg, then no further initial workup is needed.
  • If valve area is <1.5 cm2, then do further workup prior to surgical correction.
P.679

Diagnostic Procedures/Other
Exercise or dobutamine stress test (1,5)[C].
  • When symptoms are severe but echo findings are mild
  • To determine if surgery is needed
Test Interpretation
Rheumatic fever-induced pathologic changes: leaflet thickening, leaflet calcification, commissural fusion, chordal shortening
image TREATMENT
GENERAL MEASURES
  • Exercise
    • Patients with mild MS are usually asymptomatic even with strenuous exercise.
    • Usually recommend low-level aerobic exercise, limited by symptoms of dyspnea (5)[C]
  • Counsel patients that MS usually is slowly progressive but can have sudden onset of atrial fibrillation, which could become rapidly fatal. Call 911 for marked worsening of symptoms.
  • Atrial fibrillation accompanying MS impairs LV filling, especially with a rapid ventricular response.
    • Rate control with &bgr;-blockers or calcium channel blockers (1)[C]
    • Cardioversion for medical failure or if patient is unstable (6)[B]
    • If the atrial fibrillation has been present for >24 to 48 hours, then anticoagulate for 3 weeks then cardiovert, or alternatively, heparinize, perform TEE, and if no atrial thrombus, then cardiovert (6)[B].
    • After cardioversion, patient needs long-term anticoagulation.
    • These patients can critically decompensate due to loss of atrial contractility, causing an inability to fill the LV.
MEDICATION
First Line
  • Because MS is a mechanical anomaly, medical management is always considered adjunctive to interventional management when the latter is indicated.
  • Antibiotic prophylaxis against rheumatic fever and/or carditis is recommended for patients with history of rheumatic fever (1)[C].
    • Penicillin V PO or penicillin G IM: IM is more effective than PO (7)[A].
    • Sulfadiazine
    • Macrolides: Take antibiotic continuously to prevent recurrence of rheumatic fever or carditis.
    • Duration of rheumatic fever prophylaxis
      • 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 (1)[B].
  • &bgr;-Blockers or calcium channel blockers for tachycardia or exertional symptoms (1)[B]
  • Diuretics for congestive symptoms (5)[C]
  • Digitalis for atrial fibrillation if LV or RV dysfunction (5)[C]
  • Anticoagulation (1)[B]
    • Class I recommendations
      • MS and atrial fibrillation or history of atrial fibrillation
      • MS and prior embolic event
      • MS and LA thrombus
    • Class IIB recommendations
      • Asymptomatic MS but with severe MS and LA dimension >54 mm by echo
      • Severe MS, enlarged LA and spontaneous contrast on echo
  • Warfarin (international normalized ratio) range 2 to 3
  • Heparin in the acute atrial fibrillation setting
  • The new oral anticoagulants (factor Xa inhibitor and direct thrombin inhibitor) are not approved for use in atrial fibrillation that is secondary to MS.
Second Line
Amiodarone for rate control if &bgr;-blockers or calcium channel blockers cannot be used (5)[C]
SURGERY/OTHER PROCEDURES
  • 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 and balloon valvotomy is contraindicated due to unfavorable anatomy (1)[B],(8)[C]
Pregnancy Considerations
Volume expansion during pregnancy can exacerbate heart failure symptoms. Hence, MS often presents during the intrapartum period. For patients with known severe MS, intervention should be pursued before pregnancy. Such patients have a high rate of both maternal and fetal complications, including death. Percutaneous balloon valvotomy can be performed in symptomatic pregnant patients.
image ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
  • Ascertain the valve gradient and pulmonary arterial pressure with ECG.
  • Follow-up will depend on the severity of the MS and the patient's symptoms.
    • Asymptomatic patients: annual history and examination; follow-up serial echocardiography based on the severity of MS
    • Symptomatic patients are reviewed according to individual therapy, symptoms, and signs; ECG to evaluate for changes (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 symptoms is 50-60%.
  • Symptoms typically become debilitating 10 years after onset.
  • 10-Year survival after onset of debilitating symptoms is only 0-15%.
  • Mean survival with significant HTN is <3 years.
  • The severity of MS progresses over time in almost all patients. There are no known definitive medical therapies, apart from prevention of recurrent rheumatic fever, that alter its natural history. When symptoms develop, balloon valvotomy, open mitral commissurotomy, or closed mitral commissurotomy provides effective means of reducing stenosis but is not curative. Restenosis sometimes occurs and can be early (<5 years) or late (>20 years).
  • Appropriate medical treatment can delay necessity for surgery, and surgical treatment substantially prolongs survival in patients with severe MS.
REFERENCES
1. 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.
2. Ray S. Changing epidemiology and natural history of valvular heart disease. Clin Med (Lond). 2010;10(2):168-171.
3. Ramakrishna CD, Khadar SA, George R, et al. The age-specific clinical and anatomical profile of mitral stenosis. Singapore Med J. 2009;50(7):680-685.
4. Maganti K, Rigolin VH, Sarano ME, et al. Valvular heart disease: diagnosis and management. Mayo Clin Proc. 2010;85(5):483-500.
5. Bruce CJ, Nishimura RA. Newer advances in the diagnosis and treatment of mitral stenosis. Curr Probl Cardiol. 1998;23(3):125-192.
6. 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.
7. Manyemba J, Mayosi BM. Penicillin for secondary prevention of rheumatic fever. Cochrane Database Syst Rev. 2002;(3):CD002227.
8. Zakkar M, Amirak E, Chan KM, et al. Rheumatic mitral valve disease: current surgical status. Prog Cardiovasc Dis. 2009;51(6):478-481.
Additional Reading
&NA;
  • Chandrashekhar Y, Westaby S, Narula J. Mitral stenosis. Lancet. 2009;374(9697):1271-1283.
  • Guérios EE, Bueno R, Nercolini D, et al. Mitral stenosis and percutaneous mitral valvuloplasty (part 1). J Invasive Cardiol. 2005;17(7):382-386.
Codes
&NA;
ICD10
  • I05.0 Rheumatic mitral stenosis
  • I05.8 Other rheumatic mitral valve diseases
  • I34.2 Nonrheumatic mitral (valve) stenosis
Clinical Pearls
&NA;
  • 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.