What is the treatment approach for mitral regurgitation?

Treatment Approach for 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, while secondary MR mandates guideline-directed medical therapy first. 1

Initial Diagnostic Classification

• Echocardiography is mandatory to distinguish primary from secondary MR, as this distinction completely determines the management pathway. 1
• Severe MR is defined by vena contracta ≥7 mm, EROA ≥0.4 cm² for primary MR, regurgitant fraction ≥50%, and regurgitant volume ≥60 mL/beat. 1
• For secondary MR, lower thresholds apply: EROA ≥0.3 cm² if the regurgitant orifice is elliptical, or EROA ≥0.2 cm² in some guidelines. 2
• Use cardiovascular magnetic resonance (CMR) when echocardiographic measurements are uncertain or ambiguous to quantify LV/RV function, chamber size, and MR severity. 2, 1
• Exercise echocardiography should be performed in patients with exercise-induced symptoms to detect dynamic worsening of MR, elevated pulmonary artery pressures, or failure of ventricular function to augment normally. 2, 1

Management of Primary (Degenerative) Mitral Regurgitation

Symptomatic Severe Primary MR

• Surgery is indicated for all symptomatic patients with severe primary MR regardless of left ventricular ejection fraction. 2, 1
• Mitral valve repair is strongly preferred over replacement when anatomically feasible, as it reduces mortality by approximately 70%. 1, 3
• Surgery must be performed at a heart valve center with high repair rates (≥80-90%) and low operative mortality (<1%). 1, 3

Asymptomatic Severe Primary MR

• Surgery is indicated when LVEF falls to ≤60% or LV end-systolic diameter reaches ≥40 mm, even without symptoms. 1
• Do not delay surgery once these thresholds are reached, as waiting leads to irreversible LV dysfunction and worse outcomes. 1
• Asymptomatic patients with severe MR require clinical and echocardiographic follow-up every 6-12 months. 2, 1
• Serum biomarkers (BNP/NT-proBNP) may help guide optimal timing of intervention in asymptomatic patients. 2, 1

Transcatheter Edge-to-Edge Repair (TEER) in Primary MR

• TEER is reserved only for high surgical risk patients with suitable valve morphology who have prohibitive surgical risk. 1
• Do not use TEER as first-line therapy for primary MR in surgical candidates, as surgery provides superior durability and outcomes. 1

Management of Secondary (Functional) Mitral Regurgitation

First-Line Medical Therapy

• Guideline-directed medical therapy (GDMT) is the mandatory first-line treatment for all patients with secondary MR before considering any intervention. 2, 1
• GDMT includes ACE inhibitors/ARBs, beta-blockers, and mineralocorticoid receptor antagonists titrated to maximally tolerated doses. 1
• Cardiac resynchronization therapy (CRT) should be implemented in patients who meet standard CRT criteria (LVEF ≤35%, QRS ≥130 ms, LBBB). 2, 1
• Diuretics are first-line for fluid overload manifestations such as lower extremity edema. 1
• Nitrates may be useful for acute dyspnea in patients with a large dynamic component of MR. 1

Surgical Intervention in Secondary MR

• Surgery is indicated when severe secondary MR is present and the patient is undergoing coronary artery bypass grafting (CABG) with LVEF >30%. 2, 1
• Surgery may be considered in patients with severe secondary MR and LVEF >30% who remain symptomatic despite optimal medical management (including CRT if indicated) and have low surgical risk. 2
• Mitral valve repair is preferred, but replacement should be considered in patients with unfavorable morphological characteristics. 2

Transcatheter Edge-to-Edge Repair (TEER) in Secondary MR

• TEER should be considered for patients with severe secondary MR, LVEF 20-50%, persistent NYHA class II-IV symptoms despite optimal medical therapy including CRT. 1
• Patients must have anatomy judged suitable for TEER and increased natriuretic peptide levels. 2
• Exclude patients with estimated PASP >70 mmHg, hemodynamic instability, moderate-severe RV dysfunction, or mitral valve orifice area <4.0 cm². 2

Multidisciplinary Heart Team Approach

• All intervention decisions must involve multidisciplinary team discussion by the heart team. 2, 1
• The heart team should consider valve morphology, MR etiology, patient comorbidities, surgical risk, frailty, organ system compromise, and procedure-specific impediments. 1
• Input from a cardiologist with experience managing heart failure and MR is essential for secondary MR decisions. 1

Surveillance Protocols

• Asymptomatic patients with severe MR: clinical and echocardiographic follow-up every 6-12 months. 2, 1
• Moderate MR: clinical evaluation every 6-12 months with annual echocardiography. 1
• Mild MR: monitoring every 3-5 years. 1

Critical Pitfalls to Avoid

• Do not delay surgery in asymptomatic primary MR once LVEF falls to ≤60% or LVESD reaches ≥40 mm. 1
• Do not proceed to intervention for secondary MR without first optimizing GDMT and considering CRT. 1
• Do not perform mitral valve replacement when repair is feasible. 1
• Do not use TEER as first-line therapy for primary MR in surgical candidates. 1
• In secondary MR, recognize that no survival benefit has been conclusively confirmed for reduction of MR independent of LV dysfunction, making medical optimization paramount. 2