Indications for CABG (Coronary Artery Bypass Grafting)

A. Indications Based on Anatomy (Survival Benefit)

1. Left Main Coronary Artery (LMS) Disease

• Significant stenosis of the left main coronary artery ("left main stem disease") carries the worst prognosis without surgery
• CABG is strongly preferred over PCI for left main disease associated with high-complexity CAD
• Even for low-complexity left main disease, CABG remains the gold standard

2. Three-Vessel Disease (Triple Vessel Disease)

• Stenosis of all three major epicardial coronary arteries
• Survival benefit is proven, especially when LV function is impaired (EF <50%)
• CABG is clearly preferred over PCI in this group

3. Two-Vessel Disease with Proximal LAD Involvement

• Two-vessel disease that includes the proximal left anterior descending (LAD) artery
• Particularly when associated with impaired LV function (EF <50%) or diabetes
• Internal mammary artery (IMA) to LAD provides better patency and survival than saphenous vein

4. Multivessel Disease with Diabetes Mellitus

• Among diabetics with multivessel CAD, CABG + optimal medical therapy is superior to PCI (including drug-eluting stents) in preventing death, MI, and repeat revascularization
• CABG with a left IMA conduit is specifically preferred over PCI in diabetics with LAD involvement
• Benefits are especially pronounced in insulin-sensitizing vs. insulin-providing strategy patients

5. Multivessel Disease with Impaired LV Function (EF <35-50%)

• Patients with hibernating myocardium (viable but chronically ischemic segments) benefit from revascularization - CABG can restore contractile function and improve survival
• Detected by PET, cardiac MRI, thallium-201 scanning, or low-dose dobutamine echocardiography

B. Indications Based on Symptoms

6. Symptomatic Angina Not Controlled by Medical Therapy

• The ideal candidate has troublesome or disabling angina that is inadequately controlled by or not tolerated with medical therapy
• Should have severe stenoses of two or three epicardial arteries with objective evidence of myocardial ischemia
• CABG abolishes or greatly reduces angina in ~90% of patients after complete revascularization

7. Lifestyle-Limiting Angina Despite Guideline-Directed Medical Therapy

• Patients who wish to lead a more active life but are severely limited by angina are candidates for revascularization (CABG preferred over PCI in complex anatomy)

C. Special Situations

8. Survivors of Sudden Cardiac Death / Sustained VT from Obstructive CAD

• Survival may be improved by CABG in these patients when the arrhythmia is caused by ischemia

9. Previous CABG with Multiple Saphenous Vein Graft Stenoses

• Especially when a graft supplying the LAD is stenosed; redo CABG may improve survival

10. Recurrent Stenosis After PCI with High-Risk Criteria on Noninvasive Testing

• Patients with in-stent restenosis or disease progression who are high-risk on stress testing

11. Concomitant Cardiac Surgery

• Patients undergoing other cardiac surgery (valve repair/replacement, repair of structural defects) who also have significant CAD should have simultaneous CABG

12. Acute MI (Emergency/Urgent Situations)

• Failed PCI or coronary anatomy not amenable to PCI in the setting of acute STEMI/NSTEMI
• Mechanical complications of MI (VSD, acute MR) requiring surgical repair

D. Factors Favoring CABG Over PCI

E. Contraindications / High-Risk Factors for CABG

• Severe LV dysfunction
• Advanced age (≥80 years)
• Significant comorbidities (renal failure, COPD, peripheral vascular disease)
• Lack of experienced surgical team
• No viable myocardium to revascularize

Key Points on Graft Choice

• Internal mammary artery (IMA) to LAD is the gold standard - better long-term patency, improved survival vs. saphenous vein
• Radial artery also preferred over saphenous vein for additional grafts
• Saphenous vein graft occlusion rates: 10-20% in the first year, ~2%/year at 5-7 years, ~4%/year thereafter

Sources: Harrison's Principles of Internal Medicine 22E (2025), p. 2147-2148 - Bailey and Love's Short Practice of Surgery 28th Ed., p. 968