Indications for CABG and Required Workup
Patients would benefit from Coronary Artery Bypass Grafting (CABG) when they have significant coronary artery disease that meets specific anatomical and clinical criteria, particularly when survival benefit is demonstrated over other treatment options. 1
Primary Indications for CABG
Class I Recommendations (Strong Indications)
- Significant left main coronary artery stenosis (>50% diameter) 2, 1
- Left main equivalent disease: ≥70% stenosis of both proximal LAD and proximal left circumflex artery 2, 1
- Three-vessel coronary artery disease (especially with LVEF <50%) 2, 1
- Two-vessel disease with significant proximal LAD stenosis AND either:
- Ejection fraction <50% OR
- Demonstrable ischemia on noninvasive testing 2
- Unstable angina/NSTEMI with significant left main or left main equivalent disease 2
- Disabling angina despite maximal medical therapy when surgery can be performed with acceptable risk 2
Class IIa Recommendations (Reasonable Indications)
- Proximal LAD stenosis with 1-vessel disease (becomes Class I if extensive ischemia is documented or LVEF <50%) 2
- Two-vessel disease with severe/extensive myocardial ischemia or vessels supplying large area of viable myocardium 2
- Mild-moderate LV dysfunction (EF 35-50%) with multivessel CAD or proximal LAD stenosis when viable myocardium is present 2
- Complex 3-vessel CAD (SYNTAX score >22) 2, 3
- Multivessel CAD with diabetes mellitus, particularly if LIMA graft can be anastomosed to LAD 2, 3
Required Workup Before CABG
1. Coronary Anatomy Assessment
- Coronary angiography: Essential to determine:
- Location and severity of stenoses (≥50% left main or ≥70% non-left main) 2
- Number of vessels involved
- Suitability for grafting
- SYNTAX score calculation to assess complexity of coronary disease 2, 3
2. Left Ventricular Function Assessment
- Echocardiography or cardiac MRI to determine:
- Left ventricular ejection fraction (LVEF)
- Regional wall motion abnormalities
- Presence of valvular disease
3. Viability Assessment (when LV dysfunction present)
- Stress testing with imaging (stress echo, nuclear imaging, or cardiac MRI) to:
4. Risk Stratification
- Cardiac risk assessment using validated tools (STS score, EuroSCORE)
- Evaluation of comorbidities that may increase surgical risk:
- Renal function
- Pulmonary function
- Peripheral vascular disease
- Cerebrovascular disease
- Diabetes status
5. Additional Testing
- Carotid duplex ultrasonography for patients with history of cerebrovascular disease or carotid bruits
- Pulmonary function tests for patients with significant pulmonary disease
- Complete blood count, coagulation profile, and comprehensive metabolic panel
- Medication review with particular attention to antiplatelet and anticoagulant medications
Special Considerations
- Timing after MI: CABG mortality is elevated 3-7 days after MI; benefit must be balanced against increased risk 2
- Diabetes: CABG generally preferred over PCI in diabetic patients with multivessel disease 2, 3
- Heart team approach: Complex cases should involve collaborative decision-making between cardiologists, cardiac surgeons, and other specialists 3
- Long-term survival benefit: Studies show CABG provides extended survival advantage over medical therapy alone in patients with ischemic cardiomyopathy 4, 5
Contraindications for CABG
- 1 or 2-vessel disease without proximal LAD involvement, especially with small area of viable myocardium or no demonstrable ischemia 2, 1
- Borderline coronary stenoses (50-60% diameter) outside left main without demonstrable ischemia 2, 1
- Insignificant coronary stenosis (<50% diameter reduction) 2, 1
By following this structured approach to patient evaluation and selection, you can identify those who would benefit most from CABG and ensure appropriate preoperative workup is completed.