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Internal Medicine
Cardiology
Cardiothoracic Surgery

Mitral Regurgitation

High EvidenceUpdated: 2025-12-22

On This Page

Red Flags

  • Acute severe MR (acute pulmonary oedema)
  • Cardiogenic shock
  • Papillary muscle rupture post-MI
  • Endocarditis with valve destruction
Overview

Mitral Regurgitation

1. Topic Overview

Summary

Mitral regurgitation (MR) is the most common valvular heart disease worldwide. It is classified as primary (organic valve disease) or secondary (functional, due to LV or LA dysfunction). Degenerative disease (myxomatous degeneration/mitral valve prolapse) is the leading cause in developed countries. Management depends on aetiology, severity, symptoms, and LV function. Surgical repair remains the gold standard for primary MR, while optimisation of heart failure therapy is first-line for secondary MR, with transcatheter edge-to-edge repair (MitraClip) emerging as an option for selected patients.

Key Facts

  • Definition: Backward flow from LV to LA during systole due to incompetent mitral valve
  • Types: Primary (valve abnormality) vs Secondary (functional/ischaemic)
  • Prevalence: Most common valve disease; 2% moderate/severe over 65
  • Common Cause: Degenerative (MVP) in developed countries; rheumatic in developing
  • Severe Criteria: EROA over 40 mm², regurgitant volume over 60 mL
  • Treatment: Repair preferred over replacement for primary MR
2. Epidemiology

Prevalence

PopulationPrevalence
General population1.7% any MR
Over 65 years10% any MR; 2% moderate/severe
Post-MI20-50% (any degree)

Causes

Primary MR:

  • Degenerative/myxomatous (MVP) - most common in developed countries
  • Rheumatic heart disease
  • Infective endocarditis
  • Congenital (cleft mitral valve)

Secondary MR:

  • Ischaemic (papillary muscle dysfunction, LV remodeling)
  • Dilated cardiomyopathy (annular dilation)
  • HCM
3. Pathophysiology

Acute vs Chronic MR

FeatureAcute MRChronic MR
LA sizeNormalDilated
LA pressureMarkedly elevatedModestly elevated
PresentationPulmonary oedema, shockGradual dyspnoea, AF
LVNormal sizeDilated (volume overload)
UrgencyEmergencyElective intervention

Compensatory Mechanisms

  1. LA Dilation: Accommodates regurgitant volume
  2. LV Dilation: Eccentric hypertrophy
  3. Increased Compliance: Reduces LA pressure
  4. Eventually Decompensates: EF falls, symptoms develop
4. Clinical Presentation

Symptoms

Signs

Auscultation:

Other:

Exertional dyspnoea (most common)
Common presentation.
Orthopnoea and PND
Common presentation.
Fatigue
Common presentation.
Palpitations (AF common)
Common presentation.
Ankle swelling (right heart failure, late)
Common presentation.
5. Investigations

Echocardiography

Severity Assessment:

ParameterMildModerateSevere
Vena contracta (mm)Under 33-6.9≥7
EROA (mm²)Under 2020-39≥40
Regurgitant volume (mL)Under 3030-59≥60

Additional Assessment:

  • LV size and function (LVESD, EF)
  • LA size
  • Pulmonary artery pressure
  • Mechanism (primary vs secondary)
6. Management

Primary MR

Symptomatic:

  • Surgery indicated (Class I)
  • Repair preferred over replacement

Asymptomatic Severe:

  • Surgery if: LVEF 60-69%, LVESD over 40 mm, AF, pulmonary hypertension

Surgical Options:

  • Repair: Gold standard; lower mortality, better LV function preservation
  • Replacement: If repair not feasible

Secondary MR

First Line:

  • Optimise GDMT (as per HFrEF)
  • CRT if indicated

Transcatheter Edge-to-Edge Repair (MitraClip):

  • For symptomatic severe secondary MR despite optimal GDMT
  • COAPT trial positive; careful patient selection
7. Prognosis
  • Asymptomatic severe MR: 10-year survival ~60% without surgery
  • Post-repair: Excellent outcomes, 80-90% 10-year survival
  • Secondary MR: Prognosis driven by underlying cardiomyopathy
8. Patient/Layperson Explanation

What is Mitral Regurgitation?

Mitral regurgitation means your mitral valve doesn't close properly. This allows blood to leak backwards into your heart's upper chamber when it should be pumping forward.

What causes it?

Common causes include:

  • Wear and tear of the valve (degenerative disease)
  • Heart attacks affecting the muscles supporting the valve
  • Infection of the valve (endocarditis)
  • Stretching of the valve ring if the heart enlarges

How is it treated?

Mild leaks often need just monitoring. For severe leaks causing symptoms:

  • Valve repair (preferred) or replacement surgery
  • Newer catheter-based clips (MitraClip) for some patients
9. References

  1. Vahanian A, et al. 2021 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J. 2022;43(7):561-632. PMID: 34453165

  2. Stone GW, et al. Transcatheter Mitral-Valve Repair in Patients with Heart Failure (COAPT). N Engl J Med. 2018;379(24):2307-2318. PMID: 30280640

Medical Disclaimer: MedVellum content is for educational purposes and clinical reference.

Last updated: 2025-12-22

At a Glance

EvidenceHigh
Last Updated2025-12-22

Red Flags

  • Acute severe MR (acute pulmonary oedema)
  • Cardiogenic shock
  • Papillary muscle rupture post-MI
  • Endocarditis with valve destruction

Clinical Pearls

  • **Medical Disclaimer**: MedVellum content is for educational purposes and clinical reference.

Guidelines

  • NICE Guidelines
  • BTS Guidelines
  • RCUK Guidelines