Which coronary artery should be grafted first in a patient who has just received one coronary artery bypass graft?

The LAD Should Be Grafted First with the Left Internal Mammary Artery (LIMA)

When performing coronary artery bypass grafting, the left anterior descending (LAD) artery should be grafted first using the left internal mammary artery (LIMA) when bypass of the LAD is indicated. This is a Class I recommendation with strong evidence supporting superior long-term outcomes 1.

Rationale for LAD-First Strategy

The LAD supplies the largest territory of viable myocardium, and its revascularization provides the greatest survival benefit. The LIMA-to-LAD graft demonstrates exceptional long-term patency (>90% at 10 years) compared to saphenous vein grafts (only 50-60% patent at 10 years) 1. This translates directly into:

• Improved survival - The LIMA-LAD graft reduces mortality, recurrent infarction, and need for repeat revascularization 1
• Superior patency - Only 4% of internal mammary arteries develop atherosclerosis, and merely 1% develop hemodynamically significant stenoses 1
• Resistance to atherosclerosis - The continuous internal elastic lamina prevents smooth muscle cell migration and prostacyclin release inhibits platelet aggregation 1

Sequential Grafting Strategy After LAD

After securing the LIMA-to-LAD graft, the second most important target vessel should be grafted next:

For the Second Graft:

Use a radial artery rather than saphenous vein graft for the second most important non-LAD vessel (typically the left circumflex or right coronary artery when critically stenosed >90%) 2, 3. This Class I recommendation is based on:

• Improved long-term patency (86-96% at 1 year, 89% at 4-5 years) 4
• Reduced adverse cardiac events at 5 and 10 years 2
• Improved survival compared to saphenous vein grafts 2

Key technical considerations for radial artery use:

• Target vessels must have severe stenoses (>70% for left-sided arteries, >90% for right-sided arteries) 1
• Assess palmar arch completeness before harvesting 2, 3
• Avoid in patients with chronic kidney disease likely to progress to hemodialysis 2, 3
• Use calcium channel blockers for the first postoperative year to prevent spasm 2, 3

Alternative for Second Graft:

If radial artery is unavailable or unsuitable, the right internal mammary artery (RIMA) is reasonable for grafting the left circumflex or right coronary artery when critically stenosed 1. The RIMA shows excellent patency (96% at 4-5 years) 4.

Common Pitfalls to Avoid

1. Do NOT use arterial grafts for right coronary artery with <90% stenosis - This is a Class III (Harm) recommendation due to competitive flow causing graft failure 1

2. Avoid saphenous vein grafts when arterial conduits are available - SVGs have declining patency: 10-25% occlude within 1 year, and 50-60% are occluded by 10 years 1

3. Do NOT harvest radial artery after transradial catheterization - This compromises graft quality 2, 3

4. Avoid bilateral radial artery procedures - Preserve one radial artery for potential future use 2, 3

Priority Sequence Summary

1. First graft: LIMA to LAD (Class I, Level B)
2. Second graft: Radial artery to second most important vessel (Class I, Level B)
3. Third graft: RIMA or additional radial artery if available and patient is appropriate candidate (Class IIa, Level B)
4. Saphenous vein grafts: Only when arterial conduits exhausted or unsuitable

This hierarchical approach maximizes long-term graft patency, reduces mortality, and minimizes need for repeat revascularization—the outcomes that matter most for patient survival and quality of life.