Why is mitral valve repair preferred over open surgery for mitral valve replacement?

Why Mitral Valve Repair is Preferred Over Open Surgery for Mitral Valve Replacement

Mitral valve repair is strongly recommended over mitral valve replacement (MVR) because it has approximately half the operative mortality rate, better preserves left ventricular function, and avoids the risks associated with prosthetic valves. 1

Key Advantages of Mitral Valve Repair

Mitral valve repair offers several significant advantages over replacement:

1. Lower Mortality Risk

   • Operative mortality (30-day) for repair is approximately half that of MVR 1
   • This mortality benefit is consistently demonstrated across multiple clinical reports and STS database analyses

2. Better Preservation of Left Ventricular Function

   • Repair preserves the integrity of the mitral valve apparatus, which is essential for maintaining normal left ventricular shape and function 1
   • The mitral apparatus is an integral part of the left ventricle that aids in contraction and maintains efficient cardiac geometry

3. Avoidance of Prosthetic Valve Complications

   • No risk of thromboembolism or anticoagulant-induced hemorrhage (associated with mechanical valves) 1
   • No risk of structural deterioration (associated with bioprosthetic valves)
   • Eliminates the need for lifelong anticoagulation in patients without atrial fibrillation

4. Superior Long-Term Outcomes

   • For degenerative mitral disease with successful repair: 1, 2
     • Operative mortality <1%
     • Long-term survival equivalent to age-matched general population
     • Approximately 95% freedom from reoperation

     • 80% freedom from recurrent moderate or severe MR at 15-20 years

Clinical Evidence Supporting Repair

The 2014 AHA/ACC guidelines provide a Class I recommendation (Level of Evidence B) that mitral valve repair is preferred over MVR when surgical treatment is indicated for patients with chronic severe primary MR limited to the posterior leaflet 1. This recommendation extends to anterior leaflet or bileaflet involvement when a successful and durable repair can be accomplished.

Recent research confirms that among patients suitable for either surgical strategy, mitral valve repair shows better long-term survival compared to replacement, particularly in degenerative MR 3. This survival advantage is most pronounced in primary (degenerative) MR, while the benefit is less clear in secondary MR.

Surgical Considerations

The success of repair depends on several factors:

• Valve Morphology: Posterior leaflet disease is most amenable to repair with standardized techniques 1

• Surgical Expertise: Repair rates correlate with surgeon-specific mitral volumes 1

  • Hospitals performing >140 mitral operations per year had a 77% repair rate
  • Hospitals performing <36 mitral operations per year had only a 48% repair rate

• Complexity of Repair: More complex repairs (anterior leaflet or bileaflet) should be assigned to experienced mitral valve surgeons with established outcomes 1

Important Caveats

1. Quality of Repair Matters: A poor repair may be worse than a replacement. When in doubt about the durability of repair, MVR is preferable to a suboptimal repair 1

2. Volume-Outcome Relationship: The probability of successful mitral valve repair correlates with surgical experience and hospital volume 1

3. Repair Success Rates: Centers of excellence should achieve repair rates >95% for degenerative disease with mortality <1% 2

4. Secondary MR Considerations: The benefits of repair versus replacement are less clear in secondary (functional) MR, where repair may be associated with higher failure rates due to ongoing ventricular dysfunction 3, 4

Conclusion

For patients with mitral valve disease requiring intervention, repair offers significant advantages over replacement in terms of mortality, preservation of ventricular function, and avoidance of prosthesis-related complications. This is particularly true for primary (degenerative) MR, where the evidence strongly supports repair as the preferred approach when feasible with experienced surgeons.