What is the recommended management approach for patients with moderate mitral regurgitation undergoing off-pump Coronary Artery Bypass Grafting (CABG)?

Management of Moderate Mitral Regurgitation in Patients Undergoing Off-Pump CABG

Mitral valve surgery should be considered in patients with moderate mitral regurgitation undergoing CABG to improve symptoms. 1

Assessment and Classification

Moderate mitral regurgitation (MR) in patients undergoing coronary artery bypass grafting (CABG) requires careful evaluation to determine the optimal management approach. The etiology of MR in these patients is typically ischemic, resulting from:

• Local left ventricular remodeling
• Apical and posterior displacement of papillary muscles
• Excess valvular tenting
• Loss of systolic annular contraction

Evidence-Based Management Approach

For Patients with Moderate Ischemic MR:

1. When LVEF >30%:

   • Mitral valve repair should be considered at the time of CABG 1
   • This recommendation is supported by Class IIa, Level B evidence from the European Society of Cardiology/European Association for Cardio-Thoracic Surgery (ESC/EACTS) guidelines

2. When LVEF ≤30%:

   • Repair of moderate-to-severe mitral regurgitation should be considered in patients with a primary indication for CABG 1
   • This is also a Class IIa, Level B recommendation

Surgical Considerations:

• Preferred technique: Mitral valve repair with undersized rigid annuloplasty ring is often effective at relieving ischemic MR 1
• Timing: Concomitant procedure during CABG rather than staged intervention

Benefits of Combined Approach

Recent evidence shows that adding mitral valve repair to CABG in patients with moderate MR:

1. Provides better relief of mitral regurgitation:

   • 85% of CABG+MVr patients show reduction of 2 MR grades at 1 year versus only 14% with CABG alone 2
   • More durable correction of MR (11.2% residual moderate/severe MR at 2 years with combined procedure vs. 32.3% with CABG alone) 3

2. Improves functional status:

   • Both approaches lead to improvement in functional class, but combined procedure offers better symptom relief 2

Potential Risks and Considerations

The combined procedure does carry some additional risks:

• Increased perioperative morbidity 4
• Higher rates of neurologic events and supraventricular arrhythmias 3
• No significant difference in left ventricular reverse remodeling at 2 years 3
• Similar survival rates between CABG alone and combined procedure 2, 3

Decision Algorithm

1. Evaluate severity and mechanism of MR:

   • Confirm moderate MR using integrative echocardiographic approach
   • Assess if ischemic in etiology (Type IIIb dysfunction)

2. Assess LV function:

   • If LVEF >30%: Consider combined CABG + mitral valve repair
   • If LVEF ≤30%: Still consider repair, particularly with evidence of symptoms

3. Consider surgical expertise:

   • Outcomes of mitral valve repair depend on surgeon experience and center volume 1
   • Repair is preferable, but replacement should be considered with unfavorable morphology

4. For off-pump CABG specifically:

   • Off-pump CABG is reasonable to reduce perioperative bleeding and allogeneic blood transfusion (Class IIa, Level A) 1
   • When combined with mitral valve surgery, conversion to on-pump may be necessary

Follow-up Considerations

For patients who undergo CABG alone:

• Close monitoring for residual MR is essential
• Approximately 40% may have persistent moderate to severe MR 5
• Regular echocardiographic evaluation to assess MR progression and LV function

In conclusion, while both approaches (CABG alone or combined with mitral valve repair) are acceptable in certain clinical scenarios, current guidelines and evidence favor addressing moderate mitral regurgitation at the time of CABG, particularly when LVEF >30% and when performed by experienced surgical teams.