Mitral Regurgitation

Introduction

  • Mitral regurgitation can be categorized into acute and chronic and into primary (due to the mitral valve apparatus) and secondary (due to LA/LV disease)
  • Acute mitral regurgitation is a surgical emergency
  • Primary MR should be intervened upon when symptomatic or impaired LV systolic function
  • Secondary MR is primary treated by managing the heart failure but emerging therapies may be considered

Acute Mitral Regurgitation

  • Acute MR is a life threatening disease that causes acute pressure and volume overload of the left atrium and ventricle leading to pulmonary congestion and poor cardiac output
  • Causes include leaflet destruction from endocarditis, papillary muscle rupture post myocardial infarction, and spontaneous chordal rupture in myxomatous mitral valves
  • First line test for diagnosis is generally by transthoracic echocardiography though transesophageal is often done, either up front  if patient is unwell and pretest probability is high, or as a followup for preoperative planning
  • Acute MR requires surgery and mitral valve repair is preferred.
  • Medical therapy can be used to stabilize patients which focuses on afterload reduction with easy to titrate medications such as nitrates and intra-aortic balloon pump

Chronic Mitral Regurgitation

Types of Mitral Regurgitation:

  • Primary: mitral regurgitation due to an pathologic problem with the mitral valve apparatus (leaflets, papillary muscle, chordae tendonae, and annulus)
  • Secondary: functional mitral regurgitation due to diseases of the ventricle and/or atria

Causes

  • Most common cause of primary MR is degenerative (myxomatous) mitral valve leading to mitral valve prolapse (MVP) and/or flail. Other causes include mitral annular calcification, rheumatic heart disease, coronary artery disease (papillary muscle rupture), endocarditis and collagen vascular diseases.

Stages of Valve Disease

  • Stage A – Risk Factors
  • Stage B – Progressive valve dysfunction
  • Stage C – Severe asymptomatic disease
    (C2 – severe asymptomatic with LV dysfunction)
  • Stage D – Severe symptomatic disease
Stages of Chronic Primary MR

History & Physical

History

  • Most patients are asymptomatic in the mild-moderate stages. Once severe, symptoms and signs occur due to secondary change of enlargement and reduced function of LV, pulmonary hypertension and atrial fibrillation
  • Exertional dyspnea, fatigue and weakness are the most common symptoms (due to poor cardiac output and pulmonary hypertension)
  • At late stages patients will develop symptoms of pulmonary congestion and edema

Physical exam

  • Palpation: displaced apical impulse
  • Auscultation: holosystolic murmur heard best over the apex and radiates to the axilla (posterolateral directed MR) or LV base/next (anteromedial directed MR) and if MVP may here a midsystolic click
    • Minimal respiratory variation (as compared to right sided lesions)
    • Louder with increased venous return (passive leg raise) or increased arterial pressure (squat or isometric hand grip) and later MVP click
    • Quieter with decreased venous return (Valsalva) and earlier MVP click
  • Crackles due to pulmonary edema
  • Note: in acute MR may not here murmur

Investigations

  • ECG: left atrial enlargment (p-mitrale), atrial fibrillation

  • Chest Xray: cardiomegaly and enlarged left atrium

  • Echocardiography: Transthoracic echocardiography is the first line test to confirm diagnosis and severity of MR

    • Important to pay attention to cause of MR as the management will be different (TEE may be needed to confirm cause)

    • Other parameters to look at are LV size and function (indications for intervention), left atrial size and pulmonary hypertension

Mangement

Asymptomatic MR

  • In asymptomatic MR, serial monitoring with echo is indicated. Timing of follow-up interval is based on severity of MR.
  • Asymptomatic severe MR (stage C) should have followup echo every 6-12 months to monitor LV function/size and pulmonary pressure

Symptomatic severe MR 

Medical Management

Valve Intervention

  • Primary Mitral Regurgitation Indications for Intervention:
    • Severe MR + symptoms (Class 1)
    • Severe MR + systolic dysfunction (EF≤60% or End Systolic Diameter ≥40mm) (Class 1)
    • See graphic for Class 2 indications
    • MV repair preferred over replacement when possible
    • Note: no longer a low end cutoff for EF
  • Secondary Mitral Regurgitation Indications for Intervention
    • Area of ongoing research, should be aware that in certain situations trans-catheter edge to edge repair (ie. MitraClip) or mitral valve surgery can be considered
    • Patients should be managed by a HF specialist
Primary MR
Secondary MR

Authors

  • Primary Author: Dr. Atul Jaidka (MD, FRCPC, Cardiology Fellow)
  • Reviewer: 
  • Last Updated: June 17, 2021
  • Comments or questions please email feedback@cardioguide.ca
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