What are the American Heart Association (AHA) guidelines for indications for Coronary Artery Bypass Grafting (CABG)?

AHA Guidelines on Indications for CABG

CABG is definitively indicated for patients with left main coronary artery disease, left main equivalent disease (≥70% stenosis of proximal LAD and proximal left circumflex), and three-vessel disease, with the strongest survival benefit in those with reduced left ventricular ejection fraction (<0.50). 1

Class I Indications (Strongest Recommendations)

Left Main and Left Main Equivalent Disease

• Perform CABG for any patient with significant left main coronary artery stenosis, regardless of symptom severity (asymptomatic, stable angina, or unstable angina/NSTEMI). 1
• Perform CABG for left main equivalent disease: ≥70% stenosis of both proximal LAD and proximal left circumflex artery. 1

Three-Vessel Disease

• CABG is mandatory for all patients with three-vessel disease, with amplified survival benefit when LVEF <0.50. 1, 2
• For diabetic patients with three-vessel disease, CABG is mandatory over both medical therapy and PCI, with substantially amplified mortality benefit. 2

Two-Vessel Disease with Proximal LAD Involvement

• Perform CABG when two-vessel disease includes significant proximal LAD stenosis AND either:
  • LVEF <0.50, OR
  • Demonstrable ischemia on noninvasive testing 1

One or Two-Vessel Disease with High-Risk Features

• CABG is indicated for 1- or 2-vessel CAD without proximal LAD stenosis when BOTH of the following are present:
  • Large area of viable myocardium
  • High-risk criteria on noninvasive testing 1

Refractory Symptoms

• Perform CABG for disabling angina despite maximal medical therapy when surgery can be performed with acceptable risk; obtain objective evidence of ischemia if angina is atypical. 1

Acute Coronary Syndromes Requiring Emergency/Urgent CABG

• Unstable angina/NSTEMI with left main or left main equivalent disease 1
• Ongoing ischemia not responsive to maximal medical therapy when revascularization is not optimal or possible 1
• STEMI with cardiogenic shock that can be performed within 18 hours of shock onset 1
• Life-threatening ventricular arrhythmias with ≥50% left main stenosis and/or triple-vessel disease 1, 2

Class IIa Indications (Reasonable to Perform)

Single-Vessel Proximal LAD Disease

• CABG is reasonable for isolated proximal LAD stenosis, becoming Class I if extensive ischemia is documented by noninvasive study and/or LVEF <0.50. 1

Unstable Angina/NSTEMI

• CABG is probably indicated for proximal LAD stenosis with 1- or 2-vessel disease in the setting of unstable angina/NSTEMI. 1

Moderate Ischemia Burden

• CABG may be useful for 1- or 2-vessel CAD without proximal LAD stenosis when:
  • Moderate area of viable myocardium present
  • Demonstrable ischemia on noninvasive testing 1

STEMI Scenarios

• CABG may be performed as primary reperfusion in STEMI when:
  • Suitable anatomy present
  • Patient not a candidate for or failed fibrinolysis/PCI
  • Within 6-12 hours of evolving STEMI 1

Class IIb Indications (May Be Considered)

• CABG may be considered for 1- or 2-vessel disease not involving proximal LAD when PCI is not optimal or possible AND there is a large area of viable myocardium with high-risk criteria on noninvasive testing (this becomes Class I). 1

Class III Indications (Not Recommended/Contraindicated)

Avoid CABG in These Scenarios:

• 1- or 2-vessel disease without proximal LAD stenosis when:

  • Only small area of viable myocardium, OR
  • No demonstrable ischemia on noninvasive testing, OR
  • Mild symptoms unlikely due to ischemia without adequate medical therapy trial 1

• Borderline stenoses (50-60% diameter) without demonstrable ischemia on noninvasive testing 1

• Insignificant coronary stenosis (<50% diameter reduction) 1

• Emergency CABG in hemodynamically stable patients with persistent angina but small area of myocardium at risk 1

• Emergency CABG with successful epicardial reperfusion but unsuccessful microvascular reperfusion 1

• PCI should not be performed (Class III contraindication) in patients with high SYNTAX scores (≥33) and three-vessel disease 2

Critical Timing Considerations

• CABG mortality is elevated for 3-7 days after MI; balance revascularization benefit against increased surgical risk during this window unless ongoing ischemia with hemodynamic compromise exists. 1, 2
• Beyond 7 days post-MI, standard revascularization criteria apply. 1

Essential Technical Recommendations

• The left internal mammary artery (LIMA) to LAD must be used in every CABG procedure with highest long-term patency rates exceeding 90% at 10 years. 1, 2, 3
• Withhold clopidogrel for 5 days before CABG when clinical circumstances permit. 1

Common Pitfalls to Avoid

• Do not defer CABG in asymptomatic or mildly symptomatic patients with three-vessel disease; survival benefit exists regardless of symptom severity. 2
• Do not withhold CABG in elderly patients based on age alone when surgical risk is acceptable. 2
• Do not assume PCI is equivalent to CABG for complex multivessel disease; CABG demonstrates lower risks of cardiac death, repeat revascularization, and MACCE compared with PCI in patients with triple-vessel disease and LV dysfunction. 4