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Mitral Regurgitation

Chronic Mitral Regurgitation

  • Myxomatous degeneration of the mitral valve leaflets and chordae
    • Abnormal accumulation of proteoglycans
  • Most common cause in developed countries is MVP
    • Rheumatic HD, Annulus dilation from LV dilation, endocarditis, CAD or MI causing papillary muscle ischemia
  • LV systolic dysfunction is MCC of Chronic Secondary MR

Exam

  • Atrial fibrillation is common
  • Severe Dyspnea, fatigue, HF due to decreased CO and increased
  • Chronic severe MR can cause left atrial dilation which can lead to Afib (palpitations)

Murmur

  • Constant intensity, holosystolic murmur at the apex
    • Radiates to the axilla
  • S1 is soft or absent and S2 is widely split
  • S3 is common if severe
    • A third heart sound may arise from volume overload, displaced apical impulse
  • Mid-systolic clock followed by a mid-late systolic murmur
  • Progresses to a severe MR with sole holosystolic murmur w/o a click

Diagnosis: TTE

  • LVEF is often normal or increased
  • Increased left ventricular compliance in chronic MR, dilated LA
  • Central regurgitation jet in secondary MR, Eccentric in RHD due to leaflet dysfunction
  • Stage D or Stage C with:
    • LVEF: <60%
    • Symptoms
    • LV enlargement with LV end systolic diameter ≥40mm
    • PAH with PAP >50mmHg
    • New onset Atrial Fibrillation

F/U

  • Severe + No symptoms: Echo 6-12 months

Treatment

  • Trends in diagnosis and management
  • Less than severe MR guidelines
  • Significant: ACEIs/ARBs and Diuretics (Afterload reducers)
    • ± Beta blockers
    • Nitroprusside
    • IABP if needed
  • Percutaneous Valve Repair > Replacement in Stage C and D
    • Reconstruction: Valve repair ± annuloplasty with an annuloplasty ring
      • Especially likely to be done with MVP, ruptured chordae, flail leaflets, endocarditis, and annular dilation
    • Mitral Valve reconstruction whenever possible, ½ the morbidity and better outcomes than replacement
      • Replacements need replaced after 15 years, also require lifelong anticoagulation
    • More likely to be done in MR due to Rheumatic fever
  • Mitral Clip (TEER)
    • Class 2a recommendation
    • Transcatheter “edge-to-edge” percutaneous MV repair
    • Clip is placed across two leaflets in their mid-part, creating a double orifice mitral valve
    • For severe disease + high surgical risk
  • Severe
    • Regurgitant orifice area 0.4cm or greater, regurgitant volume of 60mL or greater or a vena contracta of 0.7cm or greater
    • Primary (Degenerative): mid-systolic click, late mitral regurgitation, and anterior prolapse
      • LVEF >60% + Asymptomatic: Echo q6-12 months
      • LVEF >60% + Asymptomatic + LVESD >40, PASP >50, or New-onset atrial fibrillation: Surgical Repair
      • LVEF >60% + Symptomatic: Surgical Repair >> Replacement when possible
      • LVEF 30-60%: Surgical Repair >> Replacement when possible
  • Class 1 indications for Repair: LVEF 30-60% and/or an LV End-systolic diameter of ≥40mm
    • Undergoing other cardiac procedure
  • Surgical MV repair unless Class III or IV and high surgical risk: TEER if anatomy is favorable and life expectancy is >1 year
    • Replacement otherwise
      • LVEF <30%: Medical Optimization (surgery on case-by-case basis), typically irreversible damage
    • GDMT as 1st line therapy (reverses remodeling) for Secondary MR (Class I)

Acute Mitral Regurgitation

  • Increased LVEDP, increased LA pressure with acute pulmonary edema and congestive heart failure
  • Normal left ventricular compliance, increased LA pressure
  • Causes:
    • Native:
      • Flail leaflet (endocarditis, MVP, trauma)
      • Papillary muscle ischemia or rupture (MI, Trauma)
      • Chordae Tendineae rupture (Endocarditis, Acute RF, trauma, spontaneous)
    • Prosthetic:
      • Tissue valve leaflet rupture
      • Mechanical valve closure problem (thrombosis)
      • Paravalvular regurgitation due to infection

Symptoms

  • Acute-onset pulmonary edema
  • Blowing decrescendo murmur at the apex with axillary radiation
  • Severe Dyspnea

Murmur Character

  • Early decrescendo systolic murmur best heard at the apical impulse/apex

Diagnosis: TEE

  • Hyperactive LV with normal to high ejection fraction and a normal sized LA
  • Large left sided V waves on wedge pressure tracing

Management

  • Afterload reduction and diuresis
  • Intra-aortic balloon pump may be helpful, unlike in severe AR
  • Urgent surgery is often required
    • Other Causes:
      • Mild-Moderate MR: Mitral Annular Calcification, older adults with fibrous annulus degeneration
      • Infective Endocarditis (fever, embolic findings)