Coronary artery bypass grafting indications

🫀 The Bypass Blueprint

• Key Indications:
  • Left main stenosis (>50%)
  • 3-vessel disease (esp. with ↓ LVEF)
  • 2-vessel disease + proximal LAD stenosis (esp. in diabetics)
  • Refractory angina despite max medical therapy
  • Failed PCI

⭐ CABG provides a survival benefit over PCI in patients with multivessel disease, particularly those with diabetes or complex coronary anatomy.

🗺️ Diagnosis - Mapping the Pipes

• Invasive Coronary Angiography: Gold standard for defining coronary anatomy and stenosis severity.
  • Significant Stenosis: ≥70% reduction in luminal diameter.
  • Left Main (LM) Stenosis: Significant at ≥50%.
• Physiologic Assessment:
  • Fractional Flow Reserve (FFR): An FFR ≤0.80 across a stenosis indicates ischemia and warrants revascularization.

⭐ A "widow-maker" lesion refers to significant stenosis of the left main coronary artery, which supplies a large portion of the left ventricle.

⚔️ Management - The Great Debate

The choice between Coronary Artery Bypass Grafting (CABG) and Percutaneous Coronary Intervention (PCI) depends on disease complexity and patient comorbidities. CABG is favored for extensive disease due to proven survival benefits in high-risk groups.

• Key CABG Indications (Survival Benefit over PCI):
  • Significant Left Main coronary artery stenosis (>50%).
  • Three-vessel disease, particularly with:
    • Diabetes Mellitus (DM).
    • Impaired Left Ventricular Ejection Fraction (LVEF < 40%).
  • Two-vessel disease involving a significant proximal Left Anterior Descending (LAD) stenosis.
  • Complex, diffuse disease not anatomically suitable for stenting.

⭐ The SYNTAX trial established CABG's superiority over PCI for complex three-vessel or left main disease, demonstrating lower long-term rates of Major Adverse Cardiac and Cerebrovascular Events (MACCE) and need for repeat revascularization.

🚑 Complications - Post-Op Pitfalls

• Bleeding: Re-explore if >200 mL/hr for 2-4 hrs.
• Infection: Mediastinitis (fever, sternal instability, drainage).
• Graft Failure: Perioperative MI (new ECG changes, ↑troponins).
• Neuro: Stroke, cognitive decline ("pump head").
• Renal: Acute Kidney Injury (AKI).

⭐ Atrial fibrillation is the most common complication (~30%), typically on post-op day 2-3. Manage with rate/rhythm control & anticoagulation.

⚡ Biggest Takeaways

• CABG is indicated for significant left main coronary artery stenosis (>50%).
• Three-vessel disease shows a survival benefit with CABG, especially with diabetes mellitus or LV dysfunction (EF <50%).
• Two-vessel disease involving the proximal LAD and one other major artery.
• Disabling angina refractory to maximal medical therapy and not amenable to PCI.
• Failed PCI with ongoing ischemia or hemodynamic instability.
• Post-MI mechanical complications like ventricular septal rupture or papillary muscle rupture.