What is the treatment approach for mitral regurgitation?

Treatment of Mitral Regurgitation

The treatment of mitral regurgitation fundamentally depends on whether it is primary (degenerative) or secondary (functional), with primary MR requiring surgical intervention when severe and symptomatic or when specific ventricular parameters are met, while secondary MR mandates optimization of guideline-directed medical therapy as the cornerstone before considering any interventional approach. 1, 2

Initial Classification: The Critical First Step

• Echocardiography is mandatory to distinguish primary from secondary MR, as this classification completely determines the management pathway. 1, 2
• Severe primary MR is defined by EROA ≥0.4 cm², regurgitant volume ≥60 mL/beat, regurgitant fraction ≥50%, and vena contracta ≥7 mm. 1, 2
• Severe secondary MR uses lower thresholds: EROA ≥0.2-0.3 cm² (particularly if elliptical orifice) and regurgitant volume ≥30 mL. 3, 1
• Exercise echocardiography should be performed when symptoms occur with exertion to unmask dynamic worsening of MR. 1, 4

Management of Primary (Degenerative) MR

Surgical Indications - The Gold Standard

Surgery is indicated for all symptomatic patients with severe primary MR regardless of left ventricular function. 1, 2

For asymptomatic patients with severe primary MR, surgery is indicated when:

• LVEF ≤60% and/or LV end-systolic diameter ≥40 mm 1, 2
• New-onset atrial fibrillation develops 1
• Pulmonary artery systolic pressure >50 mmHg 1

Critical Technical Considerations

• Mitral valve repair is strongly preferred over replacement when anatomically feasible, reducing mortality by approximately 70%. 2, 5
• Surgery should be performed at high-volume centers with repair rates ≥80-90% and operative mortality <1%. 2, 5
• Transcatheter edge-to-edge repair (TEER) is reserved exclusively for high surgical risk patients with prohibitive operative risk and suitable valve morphology. 2

Medical Therapy Role in Primary MR

• Diuretics are first-line for fluid overload manifestations such as lower extremity edema. 1, 2
• Beta-blockers may lessen MR severity, prevent LV function deterioration, and improve survival in asymptomatic patients with moderate-to-severe primary MR. 6
• ACE inhibitors/ARBs can reduce MR severity, especially in asymptomatic patients, but must be avoided in hypertrophic cardiomyopathy or mitral valve prolapse as vasodilators can paradoxically worsen MR. 6

Management of Secondary (Functional) MR

Guideline-Directed Medical Therapy: The Mandatory Foundation

Optimization of guideline-directed medical therapy (GDMT) is the absolute first-line treatment before any interventional consideration. 3, 1, 2

GDMT includes:

• ACE inhibitors/ARBs or ARNI 1, 2
• Beta-blockers 1, 2
• Mineralocorticoid receptor antagonists 1, 2
• Diuretics for volume management 1, 2
• Nitrates for acute dyspnea with large dynamic MR component 1, 2

Cardiac Resynchronization Therapy

• CRT should be implemented in patients meeting guideline-directed criteria, as it may reduce MR severity through increased closing force and resynchronization of papillary muscles. 1, 2
• MR severity must be reassessed after GDMT and CRT optimization before considering further intervention. 3

Interventional Approaches for Secondary MR

Transcatheter edge-to-edge repair (TEER) should be considered when:

• Severe secondary MR persists despite optimal medical therapy 3, 2
• LVEF 20-50% 2
• NYHA class II-IV symptoms persist 2
• Patient has been evaluated by a multidisciplinary heart team 3, 2

Surgery is indicated when:

• Severe secondary MR is present in patients undergoing coronary artery bypass grafting with LVEF >30% 3, 1, 2
• Patients remain symptomatic despite optimal medical therapy (including CRT if indicated) with low surgical risk 3

Critical caveat: No survival benefit has been conclusively demonstrated for mitral valve intervention in secondary MR outside of concomitant CABG, making patient selection paramount. 3

Surveillance Strategy

Severe MR

• Clinical and echocardiographic follow-up every 6-12 months for asymptomatic patients 1, 4, 2
• Serum biomarkers (BNP) may guide optimal intervention timing 1, 2

Moderate MR

• Clinical evaluation every 6-12 months with annual echocardiography 1, 4

Mild MR

• Monitor every 3-5 years 1, 4
• No specific medical therapy indicated for isolated mild MR with normal LV function 4

Multidisciplinary Heart Team Approach

All intervention decisions must involve multidisciplinary team discussion. 1, 2

The heart team must evaluate:

• Valve morphology and MR etiology 1, 2
• Patient comorbidities and surgical risk (STS-PROM score) 1
• Frailty and organ system compromise 1
• Procedure-specific impediments 1

Critical Pitfalls to Avoid

• Do not delay surgery in asymptomatic primary MR once LVEF falls to ≤60% or LVESD reaches ≥40 mm—irreversible LV dysfunction develops beyond these thresholds. 2
• Do not proceed to intervention for secondary MR without first optimizing GDMT and considering CRT. 2
• Do not perform mitral valve replacement when repair is technically feasible. 2
• Do not use TEER as first-line therapy for primary MR in surgical candidates—surgery remains superior. 2
• Recognize that over 50% of patients with severe primary MR who meet surgical criteria do not receive appropriate treatment, often because MR is not adequately addressed by the treating physician. 7