Can mitral valve repair unmask or worsen pre-existing aortic regurgitation?

Mitral Valve Repair Can Unmask or Worsen Pre-existing Aortic Regurgitation

Yes, mitral valve repair can unmask or worsen pre-existing aortic regurgitation due to hemodynamic changes that occur after correcting mitral valve pathology.

Mechanism of Unmasking Aortic Regurgitation After Mitral Valve Repair

The relationship between mitral and aortic valve function is complex and interdependent due to their anatomical proximity and shared hemodynamic environment. When mitral valve repair is performed, several mechanisms can lead to unmasking or worsening of aortic regurgitation:

1. Hemodynamic Changes:

   • After mitral valve repair, left ventricular loading conditions change significantly
   • Improved forward flow through the mitral valve increases the volume and pressure load on the aortic valve
   • This increased hemodynamic stress can expose pre-existing aortic valve weakness

2. Structural Considerations:

   • Mitral annular sutures placed during repair can potentially affect the adjacent aortic valve, as noted in guidelines 1
   • The guidelines specifically state: "Assessment of LV function and examination of the aortic valve and adjacent structures should always be performed with transesophageal echocardiography after MV surgery"

3. Left Ventricular Remodeling:

   • Correction of mitral regurgitation leads to increased afterload on the left ventricle
   • This altered loading pattern can change ventricular geometry and affect aortic valve function

Clinical Implications and Management

Pre-operative Assessment

• Comprehensive evaluation of both valves is essential before mitral valve surgery
• Intraoperative transesophageal echocardiography (TEE) should be used to assess the severity and mechanism of both mitral and aortic valve pathology 1
• Even mild aortic regurgitation should be carefully documented before mitral valve surgery

Intraoperative Considerations

• After mitral valve repair and weaning from cardiopulmonary bypass, TEE should specifically evaluate:
  • Residual mitral regurgitation
  • New or worsened aortic regurgitation
  • Left ventricular function
  • Representative loading conditions may need to be created with volume or vasopressors to fully assess valve function 1

Decision-Making for Concomitant Valve Surgery

When both valves show pathology, the decision-making process becomes more complex:

1. For severe aortic regurgitation with mitral disease:

   • Guidelines recommend addressing both valves 1
   • "If AR requiring surgery is associated with severe MR, then both should be operated on"

2. For moderate aortic regurgitation with mitral disease:

   • The decision should consider:
     • Etiology of aortic regurgitation
     • Patient age
     • Disease progression
     • Possibility of valve repair 1

3. For mild aortic regurgitation with mitral disease:

   • Careful monitoring is typically recommended rather than intervention on the aortic valve
   • However, post-repair assessment is crucial as the "mild" AR may worsen after mitral repair

Evidence on Outcomes

Research has shown that unaddressed valve disease can have significant implications:

• A study by Barreiro et al. 2 demonstrated that in patients with severe aortic regurgitation, the presence of mitral regurgitation was associated with decreased survival

• Concomitant mitral valve repair during aortic valve replacement was associated with better survival (hazard ratio 0.29)

• Conversely, Seeburger et al. 3 found that new or worsened mitral regurgitation occurs in approximately 8.4% of patients after surgical aortic valve replacement, highlighting the bidirectional relationship between these valves

Practical Approach to Prevent Complications

1. Pre-operative Planning:

   • Thorough echocardiographic assessment of both valves
   • Consider stress echocardiography to unmask dynamic valve changes 1

2. Intraoperative Management:

   • Comprehensive TEE before and after repair
   • Assessment under various loading conditions
   • Be prepared to address unexpected aortic regurgitation if it appears significant after mitral repair

3. Post-operative Surveillance:

   • Close follow-up echocardiography at 1,6, and 12 months
   • Monitor for progressive aortic regurgitation
   • Early intervention if significant progression occurs

Conclusion

The interrelationship between mitral and aortic valves is complex. Mitral valve repair can indeed unmask or worsen pre-existing aortic regurgitation through altered hemodynamics and ventricular remodeling. Comprehensive pre-operative, intraoperative, and post-operative assessment is essential to identify and manage this potential complication.