Use of LIMA in Coronary Artery Bypass Grafting

Introduction to LIMA and LAD

• The Left Internal Mammary Artery (LIMA) is the gold standard conduit for bypassing the Left Anterior Descending (LAD) artery during coronary artery bypass grafting (CABG) due to its superior long-term patency and improved patient survival compared to other conduits 1, 2
• The LAD artery is a major coronary artery that supplies blood to the anterior wall of the left ventricle 1
• Significant stenosis in the LAD, especially in the proximal segment, is a primary indication for revascularization 1

Clinical Importance of LIMA-to-LAD Grafting

• LIMA grafting to the LAD is a Class I recommendation (Level of Evidence: B) in coronary artery bypass surgery 2
• The use of LIMA for LAD bypass significantly reduces mortality, recurrent myocardial infarction, rehospitalization for cardiac events, and the need for repeat revascularization 1
• The American College of Cardiology/American Heart Association measures the percentage of eligible patients who receive an IMA graft (preferably LIMA) when bypass of the LAD is indicated 3

Special Considerations

• In patients with diabetes and multivessel disease including hemodynamically significant LAD disease, CABG with LIMA-to-LAD is preferred over percutaneous coronary intervention (PCI) 1, 4
• When the LIMA is unavailable or unsuitable, the RIMA is the recommended alternative for LAD bypass 2, 5
• For patients with complex 3-vessel coronary artery disease (especially with SYNTAX score >22), CABG with LIMA-to-LAD is preferred over PCI 6, 7
• In patients with left main disease, the evidence supporting CABG with LIMA-to-LAD is particularly strong 1, 8

Anatomical Location and Surgical Relevance of the Left Internal Mammary Artery

Anatomical Course and Relationship to the Heart

• The Left Internal Mammary Artery (LIMA) is located in the anterior mediastinum, anterior to the pericardium and heart itself, making it readily accessible during median sternotomy for cardiac surgery, as noted by the American College of Cardiology 9, 10

Surgical Relevance and Access

• The LIMA is harvested as a pedicled graft or as a skeletonized graft, then brought down to reach the heart surface, with its proximity to the left anterior descending (LAD) artery making it the ideal conduit for LAD revascularization, as reported in Circulation 9
• Significant proximal left subclavian stenosis is a contraindication to LIMA use, as it would compromise flow through the graft, according to the American College of Cardiology 10

Use of Left Internal Mammary Artery in Coronary Artery Bypass Grafting

Indications and Conduits

• For redo CABG procedures, the European Heart Journal recommends LIMA as the conduit of choice in patients in whom the LIMA was not used previously 11