What is the treatment approach for a patient with severe mitral regurgitation?

Treatment Approach for Severe Mitral Regurgitation

The treatment of severe mitral regurgitation fundamentally depends on whether it is primary (degenerative) or secondary (functional), with primary MR requiring surgical mitral valve repair as the preferred definitive treatment, while secondary MR mandates optimization of guideline-directed medical therapy first, followed by consideration of intervention only in carefully selected patients. 1, 2

Initial Classification and Assessment

Perform transthoracic echocardiography immediately to classify whether the MR is primary or secondary, as this fundamentally determines your entire management strategy. 2, 3

• Assess left ventricular ejection fraction, left ventricular end-systolic dimension, left atrial size, and pulmonary artery systolic pressure 1, 4
• Quantify MR severity using integrated parameters: vena contracta ≥7 mm, effective regurgitant orifice area (EROA) ≥0.4 cm² for primary MR (≥0.2 cm² for secondary MR), regurgitant volume ≥60 mL/beat for primary MR (≥30 mL for secondary MR), and regurgitant fraction ≥50% 1
• Evaluate valve morphology to determine suitability for repair versus replacement 1
• Consider exercise echocardiography when symptoms are exercise-induced to assess for dynamic worsening of MR 2, 5

Management of Primary (Degenerative) Mitral Regurgitation

Symptomatic Patients

Refer immediately to an experienced surgical center for mitral valve repair, as surgery is indicated for all symptomatic patients with severe primary MR. 1, 2

• Mitral valve repair is strongly preferred over replacement when technically feasible, as repair improves outcomes and reduces mortality by approximately 70% compared to medical therapy alone 1, 6
• The best outcomes occur in centers with operative mortality <1% and repair rates ≥80-90% 6

Asymptomatic Patients

Surgery is reasonable for asymptomatic patients with severe primary MR when any of the following are present: 1, 3

• LVEF ≤60% 1
• LV end-systolic dimension ≥40 mm 1
• New-onset atrial fibrillation 1, 3
• Pulmonary artery systolic pressure >50 mmHg 1

Early referral to experienced surgical centers is reasonable even in asymptomatic patients when repair success rate is >95% with <1% mortality risk, as intervention before the onset of left ventricular dysfunction optimizes outcomes. 3, 6

Medical Therapy for Primary MR

While surgery is definitive treatment, medical therapy may be used as a bridge or in patients who decline/are not candidates for surgery: 7

• Beta-blockers appear to lessen MR severity, prevent deterioration of left ventricular function, and improve survival in asymptomatic patients with moderate to severe primary MR 7
• ACE inhibitors or angiotensin receptor blockers reduce MR severity, especially in asymptomatic patients 7
• Caution: In patients with mitral valve prolapse or hypertrophic cardiomyopathy, vasodilators can paradoxically increase MR severity 7
• Diuretics for symptomatic fluid overload 2

Management of Secondary (Functional) Mitral Regurgitation

First-Line Medical Optimization

Optimize guideline-directed medical therapy as the mandatory first step before considering any intervention, as secondary MR severity is dynamic and changes with loading conditions, blood pressure, volume status, and heart rate. 1, 2, 3

• Diuretics as first-line therapy for fluid overload manifestations 2
• ACE inhibitors or angiotensin receptor blockers for heart failure symptoms 2, 7
• Beta-blockers for heart failure and rate control 3
• Aldosterone antagonists if heart failure symptoms persist 2
• Nitrates for acute dyspnea when there is a large dynamic component to MR 2

Reassess MR severity after optimized medical treatment before deciding on intervention, as many patients will have significant reduction in MR severity. 1, 2, 3

Cardiac Resynchronization Therapy

Consider cardiac resynchronization therapy in appropriate candidates (LVEF ≤35%, QRS ≥120 ms, sinus rhythm), as it may reduce MR severity through increased closing force and resynchronization of papillary muscles. 2, 3

Surgical Intervention for Secondary MR

Surgery (repair or replacement) is indicated in the following scenarios: 1, 2

• Patients with severe secondary MR undergoing coronary artery bypass grafting with LVEF >30% 1, 2
• Patients who remain symptomatic despite optimal medical therapy (including CRT if indicated) with LVEF >30% and low surgical risk 1

Mitral valve repair is preferred, but replacement should be considered in patients with unfavorable morphological characteristics. 1

Transcatheter Edge-to-Edge Repair (TEER)

Percutaneous mitral clip procedure may be considered in patients with symptomatic severe secondary MR who are inoperable or at high surgical risk, avoiding futility. 1, 2

• The COAPT trial demonstrated benefit in carefully selected patients with proportionate secondary MR 1
• Pre-procedural assessment requires coaptation length ≥2 mm and coaptation depth <11 mm 1
• Flail gap should be <10 mm and flail/prolapse width <15 mm for primary MR 1

Surveillance Protocol

For patients not undergoing immediate intervention: 2, 3, 5

• Severe MR: Clinical evaluation every 6 months with annual echocardiography 2, 3
• Moderate MR: Clinical evaluation every 6-12 months with annual echocardiography 2, 5
• Monitor for progression of MR severity, development of symptoms, changes in left ventricular size or function, and pulmonary artery pressure 5

Critical Pitfalls to Avoid

Do not delay surgical intervention in primary MR until symptoms become severe or left ventricular dysfunction occurs, as this leads to irreversible myocardial damage and worse outcomes. 3, 6

Failing to recognize the dynamic nature of secondary MR can lead to inappropriate management decisions—always reassess after medical optimization before considering intervention. 1, 3

Over 50% of patients with severe primary MR who meet guideline criteria for surgery do not receive appropriate treatment, often because MR is not addressed by the treating physician—ensure systematic evaluation and referral. 8

In secondary MR, intervention without addressing the underlying heart failure with optimal medical therapy leads to unacceptably high morbidity and mortality. 1