When is a coronary artery bypass grafting (CABG) procedure performed after a stress test?

Coronary Artery Bypass Grafting (CABG) Following Stress Test

CABG is recommended following a stress test when there is evidence of significant myocardial ischemia with high-risk coronary anatomy that would benefit from surgical revascularization rather than medical therapy or percutaneous intervention. 1

Indications for CABG After Stress Test

• Large ischemic burden on stress testing: When stress testing reveals evidence of extensive myocardial ischemia, especially involving multiple coronary territories, CABG may be indicated to improve survival and quality of life 1

• Left main coronary artery disease: CABG is indicated when stress testing followed by coronary angiography reveals ≥50% stenosis in the left main coronary artery 1

• Multivessel disease: CABG is appropriate for patients with three-vessel disease (≥70% stenosis in all three main vessels) identified after stress testing prompted coronary angiography 1

• Failed medical therapy: Patients with stable chest pain despite optimal guideline-directed medical therapy who demonstrate significant ischemia on stress testing may benefit from CABG 1

• High-risk findings: Stress testing that reveals multiple regional wall motion abnormalities or diffuse ischemic changes in multiple territories may justify proceeding to diagnostic angiography and subsequent CABG 1

Clinical Decision Pathway

1. Initial stress test identifies high-risk features: When a stress test demonstrates significant ischemia, coronary angiography is typically the next step 1

2. Coronary angiography confirms surgical disease: CABG is indicated when angiography reveals:

   • Left main disease
   • Three-vessel disease
   • Complex two-vessel disease with proximal LAD involvement
   • Diffuse disease not amenable to PCI 1

3. Pre-operative risk assessment: For patients undergoing non-cardiac surgery with poor functional capacity (<4 METs) and elevated perioperative risk, abnormal stress test results may lead to coronary angiography and CABG before proceeding with the originally planned surgery 1

Special Populations

• Diabetic patients: Patients with diabetes and evidence of multivessel disease on stress testing often benefit more from CABG than PCI 1

• Reduced left ventricular function: Patients with reduced ejection fraction and evidence of viable myocardium on stress imaging may have mortality benefit from CABG 1

• Previous revascularization: For patients with prior CABG who develop recurrent symptoms, stress testing may identify graft failure or progression of native disease requiring repeat CABG 2, 3

Common Pitfalls

• Overreliance on anatomic findings alone: Decision for CABG should incorporate both anatomic severity of disease and functional significance (ischemic burden) 1

• Failure to consider patient preferences: The decision pathway should include discussion of risks, benefits, and alternatives to CABG 1

• Inadequate medical therapy trial: Some patients with positive stress tests may achieve symptom control with optimized medical therapy before proceeding to CABG 1

• Routine stress testing after CABG: Routine stress testing in asymptomatic post-CABG patients is generally not recommended and should be reserved for those with specific clinical indications 4, 2

• Ignoring comorbidities: The decision for CABG after stress testing should consider overall surgical risk and life expectancy 1