What is the role of mitral clipping in patients with ischemic mitral regurgitation and normal ejection fraction (EF)?

Role of Mitral Clipping in Patients with Ischemic Mitral Regurgitation and Normal EF

Mitral clipping is a therapeutic option for high-surgical-risk or inoperable patients with severe ischemic mitral regurgitation and normal ejection fraction who remain symptomatic despite optimal guideline-directed medical therapy. 1

Patient Selection Criteria

Appropriate patient selection is critical for successful outcomes with mitral clipping in ischemic mitral regurgitation:

• Severity of MR: Moderate-to-severe or severe mitral regurgitation (EROA ≥20 mm² and regurgitant volume ≥30 ml for secondary MR) 1
• Symptoms: NYHA functional class II, III, or ambulatory IV despite optimal medical therapy 1
• Surgical Risk: High surgical risk (logistic EuroSCORE >18% or STS score >10%) 2
• Valve Morphology: Favorable anatomy for clipping procedure 1

Favorable Anatomical Features

• Coaptation length ≥2 mm
• Coaptation depth <11 mm
• Pathology preferably in segments A2/P2
• Mitral valve opening area ≥4 cm²
• Mean pressure gradient at rest ≤4 mmHg 1

Unfavorable Anatomical Features

• Significant calcification at the site of grasping
• Short (<8 mm) and very restrictive posterior leaflets
• Flail gap >10 mm
• Flail width >15 mm
• Severe mitral annular calcification
• Rheumatic mitral valve disease
• Mitral valve clefts
• Commissural MR 1

Procedural Considerations

The mitral clipping procedure requires:

• Comprehensive pre-procedural echocardiographic assessment
• Transesophageal echocardiography guidance during the procedure
• Experienced operators in centers with high procedural volume 1, 3

The procedure involves:

1. Transseptal puncture (superior-posterior position 3.5-4 cm above leaflets)
2. Advancement of the clip-delivery system to the mitral valve
3. Positioning of the clip above the regurgitant area
4. Grasping of anterior and posterior leaflets
5. Clip closure 1

Clinical Outcomes

Mitral clipping in high-risk patients with ischemic MR and normal EF has shown:

• High technical success rates (96%) 2
• Low 30-day mortality (3.2%) 2
• Low stroke risk (1.1% at 30 days) 2
• Significant improvement in NYHA functional class 4
• Reduction in MR severity by 1-3 grades in most patients 4

Important Considerations and Pitfalls

1. Residual MR: Residual MR after clip placement is a significant risk factor for adverse outcomes at one year (OR 7.4) 5. Optimal correction of MR should be achieved during the procedure.

2. Risk of Mitral Stenosis: Placement of multiple clips may lead to elevated transmitral gradients and symptomatic mitral stenosis in some patients (reported in 2.4% of cases), potentially requiring surgical correction 6.

3. Patient Selection: Careful patient selection is crucial. Patients with unfavorable valve morphology may have suboptimal outcomes.

4. Medical Therapy Optimization: Guideline-directed medical therapy should be optimized before considering mitral clipping, including:

   • ACE inhibitors/ARBs
   • Beta-blockers
   • Mineralocorticoid receptor antagonists
   • SGLT2 inhibitors
   • Sacubitril/valsartan 1, 3

5. Heart Team Approach: Decision-making should involve a multidisciplinary heart team to determine the most appropriate intervention 1, 3.

Comparison with Surgical Options

For patients with normal EF and ischemic MR who are surgical candidates:

• Mitral valve repair is generally preferred over replacement when feasible 7
• Surgery is indicated in patients with severe MR undergoing CABG 1
• Surgery should be considered in symptomatic patients with severe MR and evidence of viability 1

However, for high-surgical-risk patients, mitral clipping provides a less invasive alternative with favorable outcomes compared to medical therapy alone 2, 4.

Follow-up Recommendations

After mitral clipping procedure:

• Regular echocardiographic assessment (every 6-12 months)
• Continued optimization of medical therapy
• Monitoring for recurrent MR or progression of heart failure 3

In conclusion, mitral clipping represents an important therapeutic option for patients with ischemic mitral regurgitation and normal ejection fraction who are at high surgical risk and remain symptomatic despite optimal medical therapy. Careful patient selection based on clinical and anatomical criteria is essential for achieving optimal outcomes.