Does treating atrial fibrillation (afib) improve mitral regurgitation (MR)?

Treating Atrial Fibrillation Can Improve Mitral Regurgitation

Yes, treating atrial fibrillation can significantly improve mitral regurgitation, particularly when the MR is secondary to atrial functional changes or tachycardia-induced cardiomyopathy. 1, 2

Relationship Between Atrial Fibrillation and Mitral Regurgitation

Atrial fibrillation and mitral regurgitation have a bidirectional relationship that can be characterized as:

1. AF as a cause of MR ("atrial functional MR"):

   • AF causes left atrial enlargement and mitral annular dilation
   • Irregular ventricular response disrupts normal mitral valve function
   • Loss of coordinated atrial contraction affects valve dynamics 2

2. AF worsening pre-existing MR:

   • AF is listed as a prognostic factor for primary MR in guidelines 1
   • Rapid ventricular rates can exacerbate functional MR
   • AF can lead to tachycardia-induced cardiomyopathy with secondary MR 1

Evidence Supporting Improvement of MR with AF Treatment

Rhythm Control Benefits

• Restoration of sinus rhythm significantly reduces MR severity:

  • In patients who maintained sinus rhythm after AF ablation, MR improved from moderate to mild levels (mean severity 2.3 to 1.0, p<0.0001) 3
  • Patients with successful rhythm control showed favorable reverse remodeling of the mitral apparatus geometry:
    • Reduced annular size (35±4 mm to 33±3 mm, p<0.002)
    • Decreased tenting area (175±56 mm² to 137±37 mm², p<0.003) 3

• Mechanism of improvement:

  • Reverse remodeling of the left atrium
  • Restoration of coordinated atrial contraction
  • Normalization of ventricular rate and regularity 2

Type of MR Matters

• Secondary (functional) MR responds better to AF treatment:

  • Patients with secondary MR had lower AF recurrence rates after catheter ablation (32.6%) compared to those with primary MR (56.6%, p<0.02) 4
  • Secondary MR due to atrial enlargement or tachycardia-induced cardiomyopathy is more likely to improve with rhythm control 2, 3

• Ablation strategy considerations:

  • Recent evidence from the EARNEST-PVI trial shows that patients with MR benefit more from extensive ablation beyond pulmonary vein isolation alone 5

Clinical Implications and Management Algorithm

1. Assess MR type and severity in AF patients:

   • Determine if MR is primary (organic valve disease) or secondary (functional)
   • Evaluate for atrial functional MR specifically related to AF

2. For patients with AF and secondary/functional MR:

   • Prioritize rhythm control strategies
   • Consider catheter ablation, particularly with extensive ablation approach for persistent AF with MR 5
   • Rate control alone may be insufficient as irregular rhythm contributes to MR 1

3. For patients with AF and primary MR:

   • AF is considered a risk factor for disease progression 1
   • Recent onset of AF is an indication for mitral valve surgery if repair is likely 1
   • Rhythm control may still provide partial improvement but less dramatic than in functional MR 4

4. Monitor for improvement:

   • Reassess MR severity after successful rhythm control
   • Allow adequate time (6+ months) for reverse remodeling to occur 3

Caveats and Pitfalls

• Not all MR will improve with AF treatment:

  • Primary MR due to organic valve disease will have limited improvement
  • Long-standing AF with permanent structural changes may have less reversibility
  • Severe ventricular remodeling may prevent complete recovery

• Anticoagulation considerations:

  • Patients with AF and moderate-to-severe MR have higher bleeding risk on DOACs compared to those with mild-to-moderate MR (3.92% vs 1.18%) 6
  • Careful monitoring is required when anticoagulating these patients

• Timing matters:

  • Earlier intervention for AF may prevent irreversible structural changes
  • Guidelines recognize that recent-onset AF with MR may warrant more aggressive intervention 1

In conclusion, treating atrial fibrillation can significantly improve mitral regurgitation, especially when the MR is functional or atrial in nature. The greatest benefits are seen when sinus rhythm is successfully restored and maintained, allowing for reverse remodeling of the atria and mitral apparatus.