What is the treatment for severe coronary artery disease using Coronary Artery Bypass Grafting (CABG)?

Coronary Artery Bypass Grafting (CABG) for Severe Coronary Artery Disease

CABG is the recommended treatment for patients with severe coronary artery disease involving significant left main coronary stenosis, three-vessel disease, or complex multivessel disease (SYNTAX score >22), as it provides superior survival benefits compared to percutaneous coronary intervention (PCI). 1

Indications for CABG

CABG is strongly indicated (Class I recommendation) in the following scenarios:

• Significant left main coronary artery stenosis (>50% diameter) 1
• Left main equivalent disease: significant (≥70%) stenosis of proximal LAD and proximal left circumflex artery 1
• Three-vessel coronary artery disease (with or without involvement of proximal LAD) 1
• Two-vessel disease with significant proximal LAD stenosis and either:
  • Left ventricular ejection fraction <50% or
  • Demonstrable ischemia on non-invasive testing 1

Patient-Specific Considerations

The decision between CABG and PCI should consider:

1. Coronary anatomy complexity:

   • SYNTAX score >22: CABG preferred 1
   • SYNTAX score ≤22: PCI may be considered 1

2. Comorbidities:

   • Diabetes mellitus: CABG provides superior outcomes, particularly when LIMA graft can be anastomosed to LAD 1
   • Left ventricular dysfunction (EF 35-50%): CABG is reasonable with viable myocardium 1

3. Urgency scenarios:

   • Cardiogenic shock: Emergency CABG if performed within 18 hours of shock onset 1
   • Life-threatening ventricular arrhythmias with ≥50% left main stenosis or triple-vessel disease 1

Technical Aspects of CABG

• Arterial grafts: The left internal mammary artery (LIMA) should be the primary conduit for LAD revascularization due to superior long-term patency 1
• Graft patency rates:
  • Left ITA: >91% at 1 year, 88% at 10-15 years
  • Saphenous vein grafts: >90% at 1 year, declining to 25-50% at 10-15 years 1

CABG vs. PCI Considerations

CABG offers several advantages over PCI:

• Mortality benefit: Superior survival in complex multivessel disease 1
• Reduced myocardial infarction: CABG provides better protection against future MIs 2
• Durability: Lower rates of repeat revascularization compared to PCI 3

However, CABG has higher perioperative stroke risk compared to PCI 4.

Special Scenarios

1. Unstable angina/non-ST elevation MI:

   • CABG recommended for significant left main disease or ongoing ischemia not responsive to maximal medical therapy 1

2. Previous CABG failure:

   • For early graft failure with severe symptoms, PCI is superior to redo CABG 1
   • For late graft failure, PCI is recommended as first choice rather than redo CABG 1

3. Hybrid procedures:

   • In selected high-risk patients, a hybrid approach combining LIMA-LAD bypass with PCI to other vessels may be considered to minimize invasiveness while preserving the survival benefit of LIMA-LAD grafting 5

Common Pitfalls

1. Delaying surgery in appropriate candidates: Patients with left main disease historically have poor outcomes with medical therapy alone 6

2. Inappropriate patient selection: CABG should not be performed in patients with:

   • Insignificant coronary stenosis (<50% diameter reduction)
   • No demonstrable ischemia on non-invasive testing
   • No viable myocardium in the region of intended revascularization 1

3. Medication management: If clinical circumstances permit, clopidogrel should be withheld for 5 days before CABG to reduce bleeding risk 1

CABG remains the gold standard for complex coronary artery disease, offering superior long-term outcomes in terms of survival and freedom from repeat revascularization, particularly in patients with diabetes, left main disease, or complex multivessel disease.