Mitral Regurgitation

Yongkasem Vorasettakarnkij, MD, MSc Reviewed 06/2017
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Subject: Mitral Regurgitation

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BASICS

DESCRIPTION

  • Disorder of mitral valve (MV) closure, either primary or secondary (functional), resulting in a backflow of the left ventricular (LV) stroke volume into the left atrium (LA); uncompensated, this leads to LV and LA enlargement, elevated pulmonary pressures, atrial fibrillation, heart failure, and sudden cardiac death

  • Types of mitral regurgitation (MR):

    • ▪ Acute versus chronic
    • ▪ Primary versus secondary (functional)
      • * Primary: MV structures include not only the mitral annulus, MV leaflets, chordae tendineae, and papillary muscles but also posterior LA wall and LV wall.
      • * Secondary: No valvular abnormalities are found. The abnormal and dilated LV causes papillary muscle displacement, resulting in leaflet tethering with annular dilatation that prevents coaptation.
  • System(s) affected: cardiac; pulmonary

EPIDEMIOLOGY

Moderate to severe MR affects 2.5 million people in the United States (2000 data). It is the most common valvular disease, and its prevalence is expected to double by 2030 1

Prevalence

  • By severity on echocardiography:

    • ▪ Mild MR: 19% (up to 40% if trivial jets included)
    • ▪ Moderate MR: 1.9%
    • ▪ Severe MR: 0.2%
  • By category 1

    • ▪ Degenerative (myxomatous disease, annular calcification): 60-70%
    • ▪ Ischemic: 20%
    • ▪ Endocarditis: 2-5%
    • ▪ Rheumatic: 2-5%

ETIOLOGY AND PATHOPHYSIOLOGY

  • Acute MR: acute damage to MV leads to sudden LA and LV volume overload. Sudden rise in LV volume load without compensatory LV remodeling results in impaired forward cardiac output and possible cardiogenic shock.

  • Chronic MR: LV eccentric hypertrophy compensates for increased regurgitant volume to maintain forward cardiac output and alleviate pulmonary congestion. However, ongoing LV remodeling can result in LV dysfunction. Simultaneously, LA compensatory dilatation for the larger regurgitant volume predisposes patients to develop atrial fibrillation (AF).

  • Ischemic MR: papillary muscle rupture, ischemia during acute myocardial infarction (MI), and incomplete coaptation of valve leaflets or restricted valve movement resulting from ischemia

  • Acute MR

    • ▪ Flail leaflet: myxomatous disease, infective endocarditis, or trauma
    • ▪ Ruptured chordae tendineae: trauma, spontaneous rupture, infective endocarditis, or rheumatic fever
    • ▪ Ruptured or displaced papillary muscle: acute MI, severe myocardial ischemia, or trauma
  • Chronic MR

    • ▪ Primary
      • * Degenerative: mitral annular calcification, mitral valve prolapse (MVP)
      • * Infective endocarditis
      • * Rheumatic heart disease (RHD)
      • * Inflammatory diseases: lupus, eosinophilic endocardial disease
      • * Anorectic drugs
      • * Congenital (cleft leaflet)
    • ▪ Secondary (functional)
      • * Ischemic: coronary artery disease (CAD)/MI
      • * Nonischemic: cardiomyopathy, LV dysfunction from any cause, hypertrophic cardiomyopathy

RISK FACTORS

Age, hypertension, RHD, endocarditis, anorectic drugs 

GENERAL PREVENTION

  • Risk factor modification for CAD

  • Antibiotic prophylaxis for poststreptococcal RHD

  • Endocarditis prophylaxis for MR is no longer recommended.

COMMONLY ASSOCIATED CONDITIONS

MVP with MR common in Marfan syndrome 

DIAGNOSIS

HISTORY

  • Associated conditions: RHD, prior MI, connective tissue disorder

  • Acute MR

    • ▪ Sudden onset of dyspnea
    • ▪ Orthopnea, paroxysmal nocturnal dyspnea
    • ▪ Chronic MR
      • * Exertional dyspnea
      • * Fatigue
      • * Palpitation: paroxysmal/persistent AF

PHYSICAL EXAM

  • Acute MR

    • ▪ Rapid and thready pulses
    • ▪ Sign of poor tissue perfusion with peripheral vasoconstriction
    • ▪ Hyperdynamic precordium without apical displacement
    • ▪ S3 and S4 (if in sinus rhythm)
    • ▪ Systolic murmur at left sternal border and base
      • * Early, middle, or holosystolic murmur
      • * Often soft, low-pitched decrescendo murmur
    • ▪ Rales
  • Chronic MR

    • ▪ Brisk upstroke of arterial pulse
    • ▪ Leftward displaced LV apical impulse
    • ▪ Systolic thrill at the apex (suggests severe MR)
    • ▪ Soft S1 and widely split S2, S3 gallop
    • ▪ Loud P2 (if pulmonary hypertension)
    • ▪ Holosystolic murmur at apex that radiates to axilla
    • ▪ Ankle edema, jugular venous distension, and ascites, if development of right-sided heart failure

DIFFERENTIAL DIAGNOSIS

  • Aortic stenosis (AS): usually midsystolic but can be long; difficult to distinguish from holosystolic, at apical area, and radiating to the carotid arteries (unlike MR)

  • Tricuspid regurgitation: holosystolic but at left lower sternal border; does not radiate to axilla or increase in intensity with inspiration (unlike MR)

  • Ventricular septal defect (VSD): harsh holosystolic murmur at lower left sternal border but radiates to right sternal border (not axilla)

DIAGNOSTIC TESTS & INTERPRETATION

  • Chest x-ray (CXR)

    • ▪ Acute MR: pulmonary edema, normal heart size
    • ▪ Chronic MR: LA and LV enlargement
  • ECG

    • ▪ Acute MR
      • * Varies depending on etiologies (e.g., acute MI)
    • ▪ Chronic MR
      • * P mitrale from LA enlargement, AF
      • * LV hypertrophy
      • * Q waves from prior MI

Initial Tests (lab, imaging)

  • Cardiac enzymes and brain natriuretic peptide (BNP), if appropriate

  • Transthoracic echocardiogram (TTE)

    • ▪ Indications for TTE 2
      • * Baseline evaluation of LV size and function, right ventricular function and LA size, pulmonary artery pressure, and severity of MR
      • * Delineation of mechanism of MR
      • * Surveillance of asymptomatic moderate to severe LV dysfunction (ejection fraction [EF] and end-systolic dimension [ESD])
      • * Evaluate MV apparatus and LV size and function after a change in signs/symptoms in a patient with MR.
      • * Evaluate after MV repair or replacement.
    • ▪ Findings in acute MR
      • * Evidence of etiology: flail leaflet or infective vegetations
      • * Normal LA and LV size
    • ▪ Findings in chronic MR
      • * Evidence of degenerative, rheumatic, ischemic, congenital, and other causes
      • * Enlarged LA and LV
Follow-Up Tests & Special Considerations
  • Intervals for follow up TTE: See “Follow-Up Recommendations.”

  • Cardiovascular magnetic resonance (CMR):

    • ▪ TTE results are not satisfactory to assess LV and RV volumes, function, or MR severity 2[C].
  • Transesophageal echocardiogram (TEE)

    • ▪ Intraoperatively to define the anatomic basis of MR and to guide repair 2[C]
    • ▪ Nondiagnostic information about severity, mechanism of MR, and/or status of LV function from noninvasive imaging 2[C]
  • Exercise hemodynamics with either doppler echo or cardiac catheterization 2[C]

    • ▪ Discrepancy between symptoms and the severity of MR from resting TTE in symptomatic patients with chronic primary MR
  • Exercise treadmill testing 2[C]

    • ▪ To establish symptom status and exercise tolerance in asymptomatic patients with chronic primary MR.
  • Noninvasive imaging (stress nuclear/position emission tomography, CMR, stress echocardiography), cardiac CT angiography, or cardiac catheterization, including coronary angiography

    • ▪ To establish etiology of chronic secondary MR and/or to assess myocardial viability 2[C]

Diagnostic Procedures/Other

Cardiac catheterization 2 
  • Left ventriculography and hemodynamic measurement

    • ▪ Noninvasive tests are inconclusive regarding severity of MR, LV function, or the need for surgery.
  • Coronary angiography: prior to MV surgery in patients at risk for CAD

Test Interpretation

Quantification of severe MR requires integration of the following: 
  • Structural parameters

    • ▪ LA size: dilated, unless acute
    • ▪ LV size: dilated, unless acute
    • ▪ Leaflets: abnormal
    • ▪ Doppler parameters
    • ▪ Quantitative parameter

TREATMENT

MEDICATION

  • Acute, severe MR

    • ▪ Medical therapy has a limited role and is aimed primarily to stabilize hemodynamics preoperatively.
    • ▪ Vasodilators (nitroprusside, nicardipine): to improve hemodynamic compensation but is often limited by systemic hypotension 2
  • Chronic MR

    • ▪ Primary
      • * Asymptomatic: no proven long-term medical therapy
      • * Symptomatic: diuretics, β-blockers (carvedilol, metoprolol), angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs), and possibly aldosterone antagonists as indicated in standard therapy for heart failure 2[C]
    • ▪ Secondary: LV dysfunction or symptomatic (stages B-D)
      • * ACEIs or ARBs, β-blockers, and/or aldosterone antagonists as indicated in standard therapy for heart failure 2[C]

SURGERY/OTHER PROCEDURES

  • Isolated MV surgery is not indicated for patients with mild to moderate MR.

  • Acute, severe MR secondary to acute MI

    • ▪ Acute rupture of papillary muscle: emergency MV repair/replacement
    • ▪ Papillary muscle displacement
      • * Aggressive medical stabilization and intra-aortic balloon pump
      • * Valve surgery usually required in addition to revascularization.
  • Chronic severe MR

    • ▪ MV repair in an experienced center is recommended over MV replacement in most circumstances 3:
      • * Survival rate: early and overall mortality were lower after MV repair than after MV replacement
      • * 10-year rate of stroke: 10% (repair) versus 12% (bioprosthetic valve replacement) versus 23% (mechanical valve replacement)
      • * Risk of endocarditis: 1.5% at 15 years versus 0.3-1.2% per year
      • * Overall rates of reoperation are similar.
    • ▪ Severe primary MR 2
      • * MV surgery
        • ▪ Symptomatic patients (stage D)
          • □ Absence of severe LV dysfunction (EF ≥ 30%) 2[B]
          • □ Severe LV dysfunction (EF ≪30%) 2[C]
        • ▪ Asymptomatic patients
          • □ Mild to moderate LV dysfunction (EF 30-60% and/or ESD ≥40 mm, stage C2) 2[B]
          • □ MV repair is reasonable for asymptomatic patients (stage C1) with preserved LV function (EF >60% and ESD ≪40 mm):
            • The likelihood of successful repair without residual MR is >95% and expected mortality ≪1% when performed at a heart valve center of excellence 2[C].
            • Nonrheumatic MR with new onset AF or resting pulmonary hypertension (pulmonary artery systolic pressure [PASP] >50 mm Hg) and the likelihood of a successful and durable repair is high 2[C].
      • * Transcatheter MV repair:
        • ▪ May be considered for severely symptomatic patients (NYHA class III/IV) despite optimal GDMT for HF, who have a reasonable life expectancy but a prohibitive surgical risk because of severe comorbidities 2[C]
    • ▪ Severe secondary MR 2
      • * MV surgery
        • ▪ Undergoing coronary artery bypass graft (CABG) or aortic valve replacement (AVR) 2[C]
        • ▪ Persistent symptom (NYHA class III-IV) despite optimal GDMT for HF 2[C]
      • * Cardiac resynchronization therapy with biventricular pacing is recommended for symptomatic patients (stage B-D) who meet the indications for device therapy 2[C].

Geriatric Considerations

  • Medical therapy alone for patients >75 years of age with MR is preferred, owing to increased operative mortality and decreased survival (compared with those with AS), especially with preexisting CAD or need for MV replacement.

  • MV repair is preferable than MV replacement.

ADMISSION, INPATIENT, AND NURSING CONSIDERATIONS

Acute MR: Stabilize ABCs (airway, breathing, circulation). Initiate IV, O2, and monitoring. Nitroprusside (+dobutamine and/or aortic balloon counterpulsation if hypotensive). Treat underlying causes (e.g., MI). Treat acute pulmonary edema with furosemide and morphine. Obtain urgent surgical consultation. 

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Chronic MR: asymptomatic 
  • Mild MR with normal LV size and function and no pulmonary hypertension: Annual clinical evaluation to assess symptom progression and TTE every 3 to 5 years to assess MR severity, LV size and function.

  • Moderate MR: annual clinical evaluation and TTE every 1 to 2 years

  • Severe MR: clinical evaluation and TTE every 6 to 12 months

  • Consider serial CXRs and ECGs, and consider stress test if exercise capacity is doubtful.

PATIENT EDUCATION

  • Exercise after MV repair: Avoid sports with risk for bodily contact or trauma. Low-intensity competitive sports are allowed.

  • Competitive athletes with MR

    • ▪ Asymptomatic with normal LV size and function, normal pulmonary artery pressures, and sinus rhythm: no restrictions
    • ▪ Mildly symptomatic and those with LV dilatation: Activities with low to moderate dynamic and static cardiac demand allowed
  • AF and anticoagulation: no contact sports

PROGNOSIS

  • Acute, severe MR: Mortality risk with surgery is 50%; mortality risk with medical therapy alone is 75% in first 24 hours and 95% at 2 weeks.

  • Chronic MR: asymptomatic severe MR with normal LVEF: 10% yearly rate of progression to symptoms and subnormal resting LVEF. Symptomatic severe MR: 8-year survival rate, 33% without surgery; mortality rate, 5% yearly

Pregnancy Considerations

MR with NYHA functional class III-IV at high risk for maternal and/or fetal risk 

COMPLICATIONS

Acute pulmonary edema, CHF, AF, bleeding risk with anticoagulation, endocarditis, sudden cardiac death 

REFERENCES

Enriquez-Sarano  M, Akins  CW, Vahanian  A. Mitral regurgitation. Lancet.  2009;373(9672):1382–1394.  [View Abstract]
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. Circulation.  2014;129(23):e521–e643.  [View Abstract]
Foster  E. Clinical practice. Mitral regurgitation due to degenerative mitral-valve disease. N Engl J Med.  2010;363(2):156–165.  [View Abstract]

ADDITIONAL READING

  • Acker MA, Parides MK, Perrault LP, et al. Mitral-valve repair versus replacement for severe ischemic mitral regurgitation. N Engl J Med.  2014;370(1):23–32.

  • Feldman T, Young A. Percutaneous approaches to valve repair for mitral regurgitation. J Am Coll Cardiol.  2014;63(20):2057–2068.

  • Vahanian A, Alfieri O, Andreotti F, et al. Guidelines on the management of valvular heart disease (version 2012). Eur Heart J.  2012;33(19):2451–2496.

  • Yancy CW, Jessup M, Bozkurt B, et al. 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. Circulation.  2013;128(16):e240–e327.

CODES

ICD10

  • I34.0 Nonrheumatic mitral (valve) insufficiency

  • I05.1 Rheumatic mitral insufficiency

  • Q23.3 Congenital mitral insufficiency

ICD9

  • 424.0 Mitral valve disorders

  • 394.1 Rheumatic mitral insufficiency

  • 746.6 Congenital mitral insufficiency

SNOMED

  • 48724000 Mitral valve regurgitation (disorder)

  • 31085000 Rheumatic mitral regurgitation (disorder)

  • 29928006 Congenital insufficiency of mitral valve (disorder)

  • 373116009 Acute mitral regurgitation

  • 194978002 Non-rheumatic mitral regurgitation (disorder)

CLINICAL PEARLS

  • Follow-up for mild to moderate MR: serial exam and/or echo unless LV structural changes

  • Severe MR is usually managed with MV repair.

  • Endocarditis prophylaxis is not recommended.

 
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