How should I surgically repair the mitral valve in an adult with primary (organic) mitral regurgitation (MR) who is symptomatic or has left ventricular ejection fraction (EF) ≤60% or left ventricular end‑systolic dimension (LVESD) ≥40 mm and no contraindications?

Surgical Mitral Valve Repair for Primary Mitral Regurgitation

Mitral valve repair is the strongly preferred surgical technique over replacement for adults with symptomatic primary MR or those with LVEF ≤60%/LVESD ≥40mm, and should be performed at experienced centers with >95% repair rates and <1% mortality. 1

Repair vs. Replacement: The Evidence is Clear

Mitral valve repair must be prioritized over replacement whenever a durable repair is achievable because repair provides superior long-term survival, freedom from valve-related complications, and better preservation of left ventricular function. 1, 2

Specific Anatomic Considerations:

• Posterior leaflet disease alone: Repair is mandatory and should achieve >95% success rates with 90% freedom from reoperation at 15 years. 1, 2 Replacement should not be performed for isolated posterior leaflet disease affecting less than half the leaflet unless repair has been attempted and failed. 1

• Anterior leaflet or bileaflet disease: Repair remains strongly preferred when a successful and durable repair can be accomplished, though this requires greater surgical expertise. 1 Freedom from reoperation is approximately 80% at 15-20 years for complex repairs, which still exceeds replacement outcomes. 1

Critical Surgical Principles

The Repair Technique Must Address:

1. Leaflet prolapse correction through:

   • Leaflet resection (French correction approach with extensive resection and rigid annuloplasty) 3
   • Artificial chordae placement (American correction approach with minimal resection and flexible annuloplasty) 3, 4
   • Both techniques produce durable results when principles are followed correctly 3

2. Annular dilatation correction with annuloplasty ring placement (choice between rigid vs. flexible remains surgeon-dependent but both are effective) 3, 4

3. Subvalvular apparatus preservation is mandatory - this reduces early mortality significantly (3.6% vs 13.3% when not preserved, even in reoperative cases) 5

When Replacement Becomes Necessary

If repair is not feasible, mitral valve replacement with complete preservation of the subvalvular apparatus (both anterior and posterior) is the required approach. 1 This preservation is critical for maintaining left ventricular function and reducing operative mortality. 5

Replacement may be necessary in:

• Extensive calcification or annular calcification 1
• Failed repair attempts (though this should be rare at experienced centers) 1
• Rheumatic disease with extensive leaflet thickening/calcification 6

The Center of Excellence Requirement

Complex repairs and all asymptomatic patients must be referred to experienced mitral valve centers where: 1, 7, 2

• Repair rates exceed 95% for all valve pathologies 1, 2
• Operative mortality is <1% 1
• Surgeons perform >140 mitral operations annually (hospital-level volume correlates with 77% repair rate vs 48% at low-volume centers) 1

The evidence shows that even among low-volume centers, >25% outperform median high-volume centers, so actual surgeon-specific outcomes matter more than volume alone. 1

Surgical Timing Based on Your Patient's Parameters

For your patient with symptomatic primary MR OR LVEF ≤60% OR LVESD ≥40mm:

• Surgery is indicated (Class I recommendation) if symptomatic with LVEF >30% 1
• Surgery is indicated (Class I recommendation) if asymptomatic but LVEF ≤60% and/or LVESD ≥40mm 1
• Even with LVESD ≥40mm, significant spherical mid-to-apical LV remodeling has already occurred that standard echocardiographic measurements underestimate 8
• Post-repair, expect LVEF to decrease by approximately 7% (from 61% to 54% in studies), which is why operating before severe LV dysfunction develops is critical 8

Critical Pitfalls to Avoid

Do not delay surgery once LVEF ≤60% or LVESD ≥40mm - even mild symptoms before referral cause irreversible cardiac structural changes, and repair rates drop from 96% in asymptomatic patients to 85% in symptomatic patients. 9

Do not send complex repairs to low-volume surgeons - predictable complex repairs require experienced centers with established high repair rates and low mortality. 1, 7

Do not accept significant residual MR at surgery completion - ensuring no patient leaves the operating room with significant persistent MR is essential for durable results. 3

Do not remove the subvalvular apparatus during replacement - if replacement becomes necessary, preservation of both anterior and posterior subvalvular structures reduces mortality from 13.3% to 3.6%. 5

Minimally Invasive Approaches

Partial sternotomy or mini-thoracotomy (video-assisted with or without robotics) are increasingly performed in 20-30% of centers with comparable results to conventional surgery, though this requires specific expertise. 2

Transcatheter Options (MitraClip)

For your surgical candidate, transcatheter edge-to-edge repair is not appropriate - it should only be considered for patients at prohibitive surgical risk with favorable anatomy. 1, 7 The MitraClip has only 75% procedural success, 55% one-year freedom from death/surgery/moderate MR, and 20% require reintervention within one year. 1