Mitral Regurgitation- Causes, Symptoms, Diagnosis, Treatment and Ongoing care

Basics

Description

  • Disorder of mitral valve (MV) closure, either structural or functional, resulting in a backflow of part 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
    • Structural versus functional (e.g., ischemic)
      • Functional: “Mitral valve is structurally normal, and disease results from valve deformation caused by ventricular remodelling.”
      • MV structures include not only the mitral annulus, MV leaflets, chordae tendineae, and papillary muscles but also the posterior LA wall and the LV wall.
  • System(s) affected: Cardiac; Pulmonary

Epidemiology

Moderate to severe MR affects 2.5 million people in the US (2000 data), making it the most frequent valvular disease, and this number 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%

Risk Factors

  • Age
  • Hypertension
  • Rheumatic heart disease
  • Endocarditis
  • Anorectic drugs

General Prevention

  • Risk factor modification for coronary artery disease (CAD)/myocardial infarction (MI)
  • Antibiotic prophylaxis for poststreptococcal rheumatic heart disease
  • Endocarditis prophylaxis for mitral regurgitation no longer recommended

Pathophysiology

  • Acute MR: Acute damage to MV leads to sudden LA and LV volume overload and increased LV preload. Sudden rise in LV volume load without compensatory LV remodelling results in impaired forward cardiac output and possible shock.
  • Chronic MR: LV eccentric hypertrophy compensates for the increased regurgitant volume to maintain forward cardiac output and reduce symptoms of pulmonary congestion. However, continuous LV remodelling may result in LV dysfunction.
  • Ischemic MR:
    • Papillary muscle rupture or ischemia during acute MI.
    • Functional MR due to incomplete coaptation of valve leaflets or restricted valve movement resulting from ischemia

Etiology

  • Acute MR:
    • Flail leaflet: Myxomatous disease, infective endocarditis, or trauma
    • Ruptured chordae tendineae: Trauma, spontaneous rupture, infective endocarditis, or rheumatic fever
    • Ruptured or displacement of papillary muscle: Acute MI, severe myocardial ischemia, or trauma
  • Chronic MR:
    • Structural
      • Degenerative: mitral annular calcification, mitral valve prolapse (MVP)
      • Infective endocarditis
      • Rheumatic heart disease
      • Anorectic drugs
      • Congenital
    • Functional
      • CAD/MI
      • Hypertrophic cardiomyopathy

Commonly Associated Conditions

MVP with MR common in Marfan syndrome

Mitral valve, Heart murmur, risk factor modification, coronary artery disease, valvular disease, myocardial infarction, heart failure,

Diagnosis

History

  • Associated conditions: Rheumatic heart disease, prior MI, connective tissue disorder
  • Acute MR:
    • Sudden onset of dyspnea
    • Orthopnea/paroxysmal nocturnal dyspnea
    • Cardiogenic shock
  • Chronic MR:
    • Exertional dyspnea
    • Fatigue
    • Palpitation: Paroxysmal or persistent AF

Physical Exam

  • Acute MR:
    • Rapid and thready pulse
    • 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
    • Loud P2 (if pulmonary hypertension)
    • S3 gallop
    • Holosystolic murmur at apex that radiates to axilla
    • Ankle edema, jugular venous distension, ascites if development of right-sided heart failure

Diagnostic Tests & Interpretation

Lab

  • CXR:
    • Acute MR: Pulmonary edema with 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
      • LV hypertrophy
      • Q waves from prior MI
      • Atrial fibrillation

Initial lab tests

  • Cardiac enzymes and brain natriuretic peptide, if appropriate
  • See workup for MI, CAD, and congestive heart failure (CHF)

Imaging

Initial approach

Transthoracic echocardiogram (TTE)

  • Indications for TTE:
    • Baseline evaluation of LV function, right ventricular and LA size, pulmonary artery pressure, and severity of MR (2)[C]
    • Delineation of mechanism of MR (2)[B]
    • Surveillance of asymptomatic moderate–severe LV function (ejection fraction and end-systolic dimension) (2)[C]
    • Evaluate MV apparatus and LV size and function after a change in signs or symptoms in a patient with MR (2)[C].
    • Evaluate after MV repair or replacement (2)[C].
  • 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 & Special Considerations

  • Intervals for follow-up TTE: See “Follow-up” below.
  • Transesophageal echocardiogram (TEE):
    • Intraoperatively to define severity/cause of MR and/or LV function
    • Nondiagnostic TTE
    • Evaluation of prosthetic heart valves
  • Exercise Doppler echo:
    • Assess exercise tolerance and the effects of exercise on pulmonary artery pressure in asymptomatic patients with severe MR (2)[C].
  • Cardiovascular magnetic resonance:
    • When regurgitant severity is indeterminant on echocardiography, especially in patients with LV dysfunction

Diagnostic Procedures/Surgery

  • Cardiac catheterization:
    • Hemodynamic measurements (2)[C]
      • Pulmonary pressure is discordant to the severity of MR as assessed by noninvasive testing
    • Left ventriculography and hemodynamic measurement (2)[C]
      • Noninvasive tests are inconclusive regarding severity of MR
      • Regurgitant severity is discordant between clinical and noninvasive findings
    • Coronary angiography (2)[C]
      • Prior to MV surgery in patients at risk for CAD

Pathological Findings

Quantification of severe MR involves assessment of:

  • Structural parameters:
    • LA size: Usually dilated, unless acute
    • LV size: Usually dilated, unless acute
    • Leaflets: Abnormal
  • Doppler parameters
  • Quantitative parameter

Differential Diagnosis

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  • Aortic stenosis (AS): Usually midsystolic but can be long, difficult to distinguish from holosystolic, heard at apex, and radiated to the carotid arteries (unlike MR)
  • Tricuspid regurgitation: Also 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 (not axilla and has thrill)

Treatment

Acute severe MR:

  • Medical therapy has a limited role and is aimed primarily to stabilize hemodynamics preoperatively (2).
  • Urgent surgical consultation

Medication

Chronic MR:

  • Structural
    • Asymptomatic: No proven long-term medical therapy
    • Symptomatic:
      • Diuretics
      • Chronic vasodilator therapy for nonsurgical candidates.
  • Functional:
    • LV dysfunction or symptomatic: ACEI, β-blockers (particularly carvedilol and long-actingmetoprolol)

Surgery/Other Procedures

  • Isolated MV surgery is not indicated for patients with mild to moderate MR (2)[C].
  • Acute severe MR secondary to acute MI:
    • Acute rupture of papillary muscle: Emergency MV repair or 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 at an experienced center is recommended over MV replacement in most circumstances
      • Survival rate: 80–94% versus 40–60% at 5–10 years
      • 10-year rate of stroke: 10% (repair) versus 12% (bioprosthetic-valve replacement) versus 23 %(mechanical-valve replacement) (3)
      • Risk of endocarditis: 1.5% at 15 years versus 0.3–1.2% per year (3)
      • Overall rates of reoperation are similar (3).
    • Indications for MV surgery in chronic severe MR (2)
      • Symptomatic: Absence of severe LV dysfunction (ejection fraction [EF] >30% and end-systolic dimension [ESD] <55 mm); NYHA functional class III-IV; severe LV dysfunction (EF <30% and/or ESD >55 mm). Surgery is indicated only if repair is highly likely to be successful.
      • Asymptomatic: Mild to moderate LV dysfunction (EF 30–60% or ESD ≥40 mm); preserved LV function (EF >60% and ESD <40 mm): MV repair in experienced surgical centers is reasonable if chance of successful repair without residual MR is >90%; preserved LV function and new onset atrial fibrillation; preserved LV function and pulmonary hypertension (PASP >50 mm Hg at rest or PASP >60 mm Hg with exercise)
  • Nonischemic functional severe MR: In selected patients may consider:
    • Cardiac resynchronization therapy
    • Percutaneous mitral annuloplasty

Geriatric Considerations

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

In-Patient Considerations

Initial Stabilization

Acute MR:

  • Stabilize ABCs.
  • IV, O2, and monitoring
  • Nitroprusside (+ dobutamine and/or aortic balloon counterpulsation if hypotensive) (3)[C]
  • Treat underlying causes (e.g., MI).
  • Treat acute pulmonary edema.
    • Lasix
    • Morphine
  • 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
  • Moderate MR: Annual clinical evaluation and echocardiography to assess LV function
  • Severe MR: Clinical evaluation and echocardiography every 6–12 months
  • Consider serial CXRs and ECGs.
  • Consider stress test if exercise capacity is in question.

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
  • Atrial fibrillation and anticoagulation: No contact sports

Prognosis

  • Acute severe MR: Mortality risk with surgery, 50%; mortality risk with medical therapy alone, 75% in 1st 24 hours; 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
    • MV repair versus replacement

Pregnancy Considerations

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

Complications

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

References

1. Enriquez-Sarano M, Akins CW, Vahanian A. Mitral regurgitation. Lancet. 2009;373:1382–94.

2. Bonow RO, et al, American College of Cardiology/American Heart Association Task Force et al. 2008 Focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valcular heart disease. Circulation 2008;118:e523–661.

3. Foster E et al. Clinical practice. Mitral regurgitation due to degenerative mitral-valve disease. N Engl J Med. 2010;363:156–65.

Codes

ICD9

  • 394.1 Rheumatic mitral insufficiency
  • 424.0 Mitral valve disorders
  • 746.6 Congenital mitral insufficiency

Snomed

  • 48724000 mitral valve regurgitation (disorder)
  • 29928006 congenital insufficiency of mitral valve (disorder)
  • 31085000 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 mitral valve repair.
  • Endocarditis prophylaxis not recommended

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