What are the most common sites for coronary artery bypass grafting (CABG)?

Most Common Sites for Coronary Artery Bypass Grafting (CABG)

The most common sites for coronary artery bypass grafting are the left anterior descending (LAD) artery, followed by the left circumflex (LCx) artery, and the right coronary artery (RCA), with the left internal mammary artery (LIMA) to LAD being the most important graft due to its superior long-term patency and survival benefit. 1

Primary Target Vessels

• The LAD artery is the most critical target vessel in CABG, supplying the anterior wall and apex of the left ventricle, making it essential for cardiac function 1
• The left circumflex artery is typically the second most important vessel targeted in CABG, supplying the lateral wall of the left ventricle and sometimes part of the posterior wall 1
• The right coronary artery is the third major vessel commonly targeted, supplying the right ventricle and, in most cases, the inferior wall of the left ventricle 1
• Within the right coronary system, the posterior descending artery (PDA) is the most frequently targeted vessel (47.6%), followed by the right main coronary artery (29.1%) and the posterior branch of the left ventricle (PL) (23.3%) 2

Graft Selection by Target Location

• The left internal mammary artery (LIMA) to LAD bypass is considered the gold standard graft with the highest recommendation level in all major cardiac surgery guidelines 1
• For the right coronary artery system, the greater saphenous vein is the most commonly used conduit (92.3%), followed by the radial artery (5.5%) and internal mammary artery (1.9%) 2
• Arterial grafting to the RCA is typically recommended only when a critical stenosis (>90%) is present 1
• Bilateral internal mammary arteries (BIMA) provide survival benefit in younger patients with multivessel disease 3

Graft Patency by Location

• LIMA to LAD grafts have the highest long-term patency rates, exceeding 90% at 10 years 1
• Radial artery grafts show superior patency compared to saphenous vein grafts (89% vs 65-80% at 4-5 years) 1
• Saphenous vein grafts have declining patency over time (25-50% at 10-15 years), particularly when used for distal targets and severely diseased small vessels 3, 1
• Sequential grafting (connecting one graft to multiple coronary targets) in the right coronary system shows better flow characteristics and potentially better patency than single grafts 2

Anatomical Considerations

• Graft insertion sites are consistently located distal to typical acute thrombosis sites in all three major coronary arteries 4
• In the LAD, median graft insertion is at 72 mm from the origin, while median thrombosis sites are at 34 mm 4
• In the RCA, median graft insertion is at 91 mm, with median thrombosis sites at 42 mm 4
• In the LCx, median graft insertion is at 44 mm, with median thrombosis sites at 37 mm 4

Surgical Approaches

• Traditional CABG is performed via median sternotomy, which provides access to all coronary territories 3
• Minimally invasive direct coronary artery bypass (MIDCAB) is primarily limited to the LAD and diagonal branches through a left minithoracotomy 3
• Totally endoscopic coronary artery bypass (TECAB) can achieve complete revascularization in selected patients at specialized centers 3
• Off-pump CABG accounts for approximately 20% of CABG procedures in Western countries and the majority in Asia, potentially reducing morbidity related to cardiopulmonary bypass 5

Clinical Significance

• Complete revascularization addressing all three major coronary territories (when diseased) generally provides better long-term outcomes than incomplete revascularization 1
• Grafting all three major vessels is particularly important in patients with left main coronary artery disease 1
• The superior performance of CABG in high-risk patients may be attributed to targeting proximal coronary locations where thrombosis risk is clustered 4

Pitfalls and Caveats

• Endoscopic vein graft harvesting should be approached with caution as it has been associated with vein graft failure and adverse clinical outcomes 3
• Off-pump CABG requires significant technical expertise and may be associated with higher rates of incomplete revascularization and inferior graft patency in less experienced hands 6
• The rate of early vein graft failure is high (10-26% between 12-18 months) especially when used for distal targets and severely diseased small vessels 3
• While hybrid procedures combining MIDCAB with percutaneous intervention show promise, randomized trials are still lacking 3