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Mitral Regurgitation

BASICS

Description

  • Failure of mitral valve (MV) closure leading to backflow into the left atrium (LA)
  • Can be acute or chronic, primary, secondary (functional), or mixed
  • Leads to LA/LV enlargement, pulmonary hypertension, AF, heart failure, sudden death

Primary MR: structural valve abnormality
Secondary MR: dilated LV causes papillary muscle displacement
Mixed MR: features of both

EPIDEMIOLOGY

  • Most common valvular disease in U.S.
  • Moderate to severe MR: 2.5 million (2000)
  • Expected to double by 2030

Prevalence (by echo): - Mild: 19–40% - Moderate: 1.9% - Severe: 0.2%

Etiology breakdown: - Degenerative: 60–70% - Ischemic: 20% - Endocarditis/rheumatic: 2–5%

ETIOLOGY AND PATHOPHYSIOLOGY

Acute MR: - Leaflet perforation: endocarditis, trauma - Chordae rupture: spontaneous or infectious - Papillary muscle rupture: acute MI

Chronic MR: - Primary: MVP, annular calcification, RHD, lupus, anorectic drugs - Secondary: - Ischemic: CAD/MI - Nonischemic: cardiomyopathy, AF, RV pacing

Acute MR: no compensation β†’ low CO, cardiogenic shock
Chronic MR: LV/LA compensation β†’ remodeling, dysfunction, AF

RISK FACTORS

  • Age, hypertension, RHD, endocarditis, drugs, radiation

PREVENTION

  • Manage CAD risk factors
  • RHD prophylaxis with antibiotics (post-strep)
  • No routine dental prophylaxis anymore

ASSOCIATED CONDITIONS

  • Marfan syndrome (with MVP + MR)

DIAGNOSIS

History

  • Acute: dyspnea, orthopnea, PND
  • Chronic: exertional dyspnea, fatigue, AF

Physical Exam

  • Acute MR:
  • Thready pulse, rales, S3/S4
  • Early/holosystolic murmur
  • Chronic MR:
  • Brisk arterial pulse, S3 gallop, thrill at apex
  • Murmur: holosystolic at apex radiating to axilla
  • Signs of right HF in late stages

Differential Diagnosis

  • AS, TR, VSD β€” distinguished by murmur site, radiation, timing

Initial Tests

  • CXR:
  • Acute: pulmonary edema
  • Chronic: LA/LV enlargement
  • ECG: AF, P mitrale, LVH, Q waves
  • TTE: key for severity, mechanism, remodeling
  • Biomarkers: BNP as needed

Advanced Testing

  • TEE: detailed valve anatomy
  • CMR: ventricular volumes, function
  • Stress tests, cath, coronary angio as indicated

Severe MR Parameters: - LA/LV dilation - Central jet >50% of LA - ERO β‰₯0.4 cmΒ², regurgitant volume β‰₯60 mL

TREATMENT

Medication

  • Acute severe MR: vasodilators (nitroprusside, nicardipine) to stabilize
  • Chronic MR:
  • Asymptomatic/normal EF: no medical therapy proven
  • Symptomatic/dysfunction:
    • Diuretics, Ξ²-blockers, ACE-I/ARB/ARNI, aldosterone antagonists

Secondary MR (with LV dysfunction): same as HF therapy

Surgery/Procedures

Acute MR

  • Emergency MV repair/replacement for rupture

Chronic Severe MR

  • Primary MR:
  • Surgery if symptomatic and EF >30%
  • Asymptomatic: surgery if EF 30–60% or ESD β‰₯40 mm
  • MV repair > replacement if feasible

  • Consider TEER for inoperable symptomatic patients

  • Secondary MR:

  • If undergoing CABG/AVR
  • TEER if NYHA III/IV with criteria:
    • LVEF 20–50%, LVESD ≀7 cm, PASP ≀70 mmHg
  • CRT in eligible symptomatic patients

Geriatric Considerations

  • 75 y: prefer medical therapy, repair > replacement

ADMISSION CONSIDERATIONS

  • Acute MR: stabilize ABCs, urgent surgical consult

ONGOING CARE

Follow-Up Recommendations

  • Mild MR: annual eval + TTE q3–5y
  • Moderate MR: annual eval + TTE q1–2y
  • Severe MR: eval + TTE q6–12mo
  • Use strain imaging, biomarkers for monitoring
  • Consider stress testing if uncertain exercise capacity

Patient Education

  • Avoid trauma in athletes post-MV repair
  • Exercise okay if normal EF, sinus rhythm, no PH
  • AF or anticoagulation β†’ avoid contact sports

PROGNOSIS

  • Acute severe MR:
  • Surgery: 50% mortality
  • Medical therapy: 95% 2-week mortality
  • Chronic MR:
  • Asymptomatic severe: 10%/yr progression
  • Symptomatic severe: 8-year survival 33% w/o surgery

PREGNANCY CONSIDERATIONS

  • NYHA III/IV β†’ high maternal/fetal risk

COMPLICATIONS

  • AF, CHF, pulmonary edema, endocarditis, sudden death

ICD-10

  • I34.0: Nonrheumatic mitral insufficiency
  • I05.1: Rheumatic mitral insufficiency
  • Q23.3: Congenital mitral insufficiency

Clinical Pearls

  • Mild to moderate MR: monitor q3–5y (mild), q1–2y (moderate)
  • Severe primary MR: usually needs MV repair
  • Surgery decision: based on EF, symptoms, and structure