What are the indications for Coronary Artery Bypass Grafting (CABG) in patients with severe coronary artery disease?

Indications for Coronary Artery Bypass Grafting (CABG)

CABG is indicated for patients with hemodynamically significant coronary stenosis causing limiting angina despite optimized medical therapy, with the strongest survival benefit in left main disease, three-vessel disease (especially with diabetes or reduced ejection fraction ≤35-50%), and complex coronary anatomy (SYNTAX score >22). 1, 2

Primary Anatomic and Clinical Indications

Left Main Coronary Disease

• CABG is the definitive treatment for unprotected left main disease with >50% stenosis, particularly when anatomic complexity is present (SYNTAX score >22). 3
• PCI becomes acceptable only in low-complexity anatomy (SYNTAX ≤22) or prohibitive surgical risk. 2, 3

Three-Vessel Disease

• CABG is Class I indication for all patients with three-vessel disease, with amplified survival benefit when left ventricular ejection fraction is <0.50. 2
• In diabetic patients with three-vessel disease, CABG is mandatory over both medical therapy and PCI, showing 5-year MACCE of 18.7% for CABG versus 26.6% for PCI (P=0.005). 2, 3
• For non-diabetic patients with preserved ejection fraction, CABG remains preferred unless SYNTAX score ≤22 and complete revascularization is achievable with PCI. 2
• PCI is contraindicated (Class III) in three-vessel disease with high SYNTAX scores (≥33). 2

Multivessel Disease with Reduced Left Ventricular Function

• CABG is recommended in patients with severe LV systolic dysfunction (EF ≤35%) and coronary disease suitable for intervention, with presence of viable myocardium. 1
• Revascularization without evidence of myocardial viability is not recommended. 1

Two-Vessel Disease

• CABG should be considered when significant proximal left anterior descending artery involvement exists with reduced ejection fraction or extensive ischemia (>20% perfusion defect). 2

Acute Coronary Syndrome Indications

ST-Elevation Myocardial Infarction (STEMI)

• Emergency CABG is indicated for patients with cardiogenic shock when coronary anatomy is not amenable to PCI, independent of time delay from symptom onset. 1
• Primary PCI strategy is preferred over CABG when anatomy is suitable, but CABG becomes necessary for failed PCI with ongoing ischemia or hemodynamic compromise. 1, 4
• Avoid elective CABG within 3-7 days of acute MI unless ongoing ischemia with hemodynamic compromise exists, as surgical mortality is elevated during this window. 2

Non-ST-Elevation ACS (NSTE-ACS)

• Early invasive evaluation (<24 hours) with subsequent CABG is indicated in high-risk patients when multivessel disease is identified and anatomy favors surgical revascularization. 1
• CABG is preferred over PCI in NSTE-ACS patients with multivessel disease, diabetes, and higher coronary complexity. 4

Cardiogenic Shock

• Emergency invasive evaluation is indicated, with emergency CABG recommended when coronary anatomy is unsuitable for PCI. 1
• Routine revascularization of non-infarct-related arteries during primary PCI is not recommended; complete revascularization should be achieved with CABG if needed. 1

Symptom-Based Indications

Refractory Angina

• CABG is indicated for limiting angina (or angina equivalent) with insufficient response to optimized medical therapy in the presence of hemodynamically significant stenosis. 1
• The survival benefit exists regardless of symptom severity in three-vessel disease; do not defer CABG in asymptomatic or mildly symptomatic patients with high-risk anatomy. 2

Life-Threatening Ventricular Arrhythmias

• Emergency CABG is Class I indication for life-threatening ventricular arrhythmias in the presence of significant coronary disease. 2
• Primary PCI strategy is recommended in patients with resuscitated cardiac arrest and ECG consistent with STEMI. 1

Special Populations

Elderly Patients (Octogenarians)

• Age alone should not preclude CABG when surgical risk is acceptable, as the benefit-to-risk ratio remains favorable. 2
• CABG in octogenarians with multivessel disease provides superior long-term outcomes compared to medical therapy, with significant improvement in freedom from chest pain and functional class, though short-term morbidity is higher. 5

Patients with Malignancy

• The same cardiac indications apply regardless of cancer status; malignancy is not a contraindication to CABG. 6
• CABG is contraindicated only in patients with metastatic disease and life expectancy <6 months, or in hemodynamically stable patients with small area at risk. 6
• Complete revascularization should follow standard guidelines, with LIMA to LAD when feasible (75% utilization rate in cancer patients). 6

Patients with Liver Disease

• CABG can be performed in Child class A cirrhosis with acceptable risk (11% operative mortality, 80% one-year survival). 7
• Child class B has 18% operative mortality and 45% one-year survival; Child class C has 67% operative mortality and 16% one-year survival. 7
• For Child B or C cirrhosis with severe coronary disease, combined CABG-liver transplantation should be considered instead of CABG alone. 7
• In ischemic hepatopathy, if liver enzymes normalize and hepatic synthetic function recovers, CABG can be reconsidered based on standard cardiac indications. 7

Patients with Chronic Heart Failure

• In patients with chronic heart failure and systolic LV dysfunction (EF ≤35%), myocardial revascularization is recommended when viable myocardium is present. 1
• CABG is recommended as the first revascularization strategy choice in multivessel disease with acceptable surgical risk. 1

Redo CABG and Prior Revascularization

Early Graft Failure

• PCI is superior to re-operation in patients with early ischemia after CABG, with preferred target being the native vessel or ITA graft, not freshly occluded saphenous vein graft. 1
• For freshly occluded SVG with unsuitable native artery or multiple important graft occlusions, redo CABG is recommended rather than PCI. 1

Late Graft Failure

• Repeat revascularization is indicated in patients with extensive ischemia or severe symptoms despite medical therapy. 1
• PCI is recommended as first choice rather than redo CABG for late graft failure. 1
• IMA is the conduit of choice for redo CABG in patients in whom IMA was not used previously. 1

Failed PCI

• If repeat PCI fails to abort evolving significant MI, immediate CABG is indicated. 1
• When severe hemodynamic instability is present, IABP should be inserted prior to emergency revascularization. 1

Critical Technical Considerations

Mandatory Graft Selection

• Left internal mammary artery (LIMA) to left anterior descending artery (LAD) is mandatory in every CABG procedure, with highest long-term patency rates exceeding 90% at 10 years. 2
• Arterial grafts should be used preferentially, particularly in redo operations. 1

Timing Considerations

• Primary PCI-capable centers should deliver 24-hour/7-day service with primary PCI performed as fast as possible. 1
• For STEMI, reperfusion therapy is indicated in all patients with symptom onset <12 hours and persistent ST-elevation, with primary PCI strategy recommended over fibrinolysis. 1

Common Pitfalls to Avoid

• Do not perform PCI in patients with high SYNTAX scores (≥33) and three-vessel disease—this is contraindicated. 2
• Do not withhold CABG in elderly patients based on age alone when surgical risk is acceptable. 2
• Do not defer CABG in asymptomatic patients with three-vessel disease—survival benefit exists regardless of symptoms. 2
• Do not perform emergency CABG within 3-7 days of acute MI unless ongoing ischemia with hemodynamic compromise exists. 2
• Routine use of thrombus aspiration and IABP in cardiogenic shock is not recommended. 1