Is there a role for surgery to replace the mitral valve in patients with functional mitral regurgitation (MR)?

Role of Mitral Valve Replacement in Functional Mitral Regurgitation

Mitral valve replacement should be considered in patients with severe functional mitral regurgitation who remain symptomatic despite optimal medical therapy, have unfavorable valve morphology for repair, and have LVEF >30%, particularly when concomitant CABG is indicated.

Understanding Functional Mitral Regurgitation

Functional mitral regurgitation (MR) differs fundamentally from primary MR:

• Results from left ventricular dysfunction and remodeling rather than primary valve pathology
• Characterized by tethering of mitral leaflets due to papillary muscle displacement
• Often associated with coronary artery disease or dilated cardiomyopathy
• More challenging to treat as the underlying problem is ventricular rather than valvular

Treatment Algorithm for Functional MR

Step 1: Optimize Medical Therapy

• All patients with functional MR should first receive guideline-directed medical therapy for heart failure 1
• This includes ACE inhibitors/ARBs, beta-blockers, and aldosterone antagonists
• Consider cardiac resynchronization therapy (CRT) if indicated

Step 2: Surgical Intervention Decision Points

Strong indications for surgical intervention:

• Severe functional MR in patients undergoing CABG with LVEF >30% (Class I, Level C) 1
• Severe functional MR with LVEF >30% in patients who remain symptomatic despite optimal medical management (including CRT if indicated) and have low surgical risk 1

When to consider mitral valve replacement over repair:

• Patients with unfavorable morphological characteristics for repair 1
• Severe tethering of mitral leaflets
• Extensive annular calcification
• Previous failed repair

Repair vs. Replacement in Functional MR

While mitral valve repair is generally preferred for primary MR, the evidence for functional MR is different:

• Chordal-sparing mitral valve replacement may be preferable to downsized annuloplasty repair for severely symptomatic patients with severe ischemic MR 1
• Repair patients experience significantly higher rates of recurrent moderate or severe MR with more heart failure events and cardiovascular readmissions during follow-up 1

Surgical Considerations

Technical aspects:

• Preservation of the subvalvular apparatus is critical during valve replacement to maintain left ventricular function 2
• Chordal-sparing techniques should be employed whenever possible
• The decision between repair and replacement should be made by an experienced surgeon in consultation with a multidisciplinary team 1

Factors influencing surgical approach:

• Specific pathoanatomic findings
• Degree of leaflet tethering
• Extent of ventricular remodeling
• Presence of coronary artery disease and/or atrial fibrillation 1

Special Considerations

Surgical expertise:

• Outcomes are highly dependent on surgeon experience and center volume 1
• Referral to high-volume centers is recommended for complex cases

Contraindications to surgery:

• LVEF ≤30% with limited viability
• Severe right ventricular dysfunction
• Severe pulmonary hypertension not responsive to vasodilator therapy
• Multiple comorbidities with high surgical risk

Alternative Options for High-Risk Patients

For patients with prohibitive surgical risk:

• Transcatheter edge-to-edge repair may be considered for severely symptomatic patients (NYHA class III-IV) with favorable anatomy 1, 3
• Percutaneous mitral valve repair has shown reduction in 1-year mortality, 2-year mortality, and cardiovascular mortality compared to optimal medical therapy alone in high-risk patients 3

Conclusion

The decision for mitral valve replacement in functional MR should be based on symptom status, left ventricular function, surgical risk, and valve morphology. While repair is generally preferred when feasible, replacement may offer more durable results in patients with unfavorable valve characteristics for repair, particularly in the setting of ischemic MR.