What is heart bypass surgery, also known as coronary artery bypass grafting (CABG), for an adult patient with a history of angina or heart attacks and severe coronary artery disease?

What is Heart Bypass Surgery (CABG)?

Coronary artery bypass grafting (CABG) is an open-heart surgical procedure that creates new routes for blood flow around severely blocked coronary arteries by grafting healthy blood vessels (typically the left internal mammary artery to the left anterior descending artery, plus saphenous vein grafts or radial artery grafts to other diseased vessels) to restore oxygen delivery to heart muscle that would otherwise die from ischemia. 1

The Basic Surgical Technique

The surgeon harvests blood vessels from elsewhere in your body—most critically the left internal mammary artery (LIMA) from inside your chest wall, and typically saphenous veins from your leg or radial artery from your forearm—then attaches these grafts to bypass the blockages in your coronary arteries. 1, 2

The Mandatory Technical Standard

• The LIMA must be grafted to the left anterior descending (LAD) artery in every CABG procedure—this is non-negotiable because LIMA-to-LAD grafts maintain patency rates exceeding 90% at 10 years, far superior to any other conduit. 1, 2
• Additional diseased vessels (typically the right coronary artery and left circumflex branches) receive saphenous vein grafts or radial artery grafts, with radial artery showing superior patency (89% vs 65-80% at 4-5 years compared to saphenous vein). 2

Two Main Surgical Approaches

Traditional on-pump CABG: The heart is stopped, and a cardiopulmonary bypass machine temporarily takes over the function of your heart and lungs during the operation. 3

Off-pump CABG (OPCAB): The surgery is performed on a beating heart without the bypass machine, using specialized stabilization devices to immobilize the specific area being grafted while the rest of the heart continues beating. 3, 4 This approach now accounts for approximately 20% of procedures in Western countries and 60% in Japan, though outcomes remain comparable to on-pump surgery. 3, 4

Who Needs This Surgery?

The Strongest Indications (Where CABG Saves Lives)

You need CABG if you have left main coronary artery disease with >50% blockage—this is a Class I indication because the left main supplies blood to most of the left ventricle, and its blockage carries extremely high mortality risk without surgical intervention. 3, 1, 2

You need CABG if you have three-vessel disease (blockages in all three major coronary arteries), particularly if you're diabetic or have reduced heart pump function (ejection fraction <50%)—the survival benefit is substantial and proven across multiple large trials. 1, 2, 5, 6

You need CABG if you have two-vessel disease involving the proximal LAD with either reduced ejection fraction (<50%) or extensive ischemia on stress testing—this anatomic pattern carries high risk that CABG specifically addresses. 2, 5

When Anatomy Complexity Matters

• If your coronary disease is complex (SYNTAX score >22), CABG is mandatory over stenting because PCI in complex anatomy results in significantly higher rates of death, heart attack, and need for repeat procedures at 5 years. 2, 5, 6
• If your coronary disease is less complex (SYNTAX score ≤22) and you're at high surgical risk, PCI becomes an acceptable alternative, though CABG still provides better long-term outcomes. 2, 6

Emergency Situations Requiring Immediate CABG

You need emergency CABG if you develop cardiogenic shock within 18 hours of a heart attack and your coronary anatomy isn't suitable for stenting—time is critical, and surgery is your only survival option. 3, 2, 5

You need emergency CABG if you experience life-threatening ventricular arrhythmias in the presence of three-vessel disease or left main disease—the arrhythmias are ischemia-driven and will continue until revascularization is achieved. 3, 2, 5

You need emergency CABG if a stenting procedure fails and you have ongoing ischemia with hemodynamic compromise—this is a surgical emergency requiring immediate sternotomy. 3, 2

The Critical Timing Window

Avoid elective CABG within 3-7 days of an acute heart attack unless you have ongoing ischemia with hemodynamic instability—surgical mortality is significantly elevated during this window because the heart muscle is inflamed and friable. 3, 2, 5 Beyond 7 days, standard indications apply. 3

What Happens During Recovery?

Immediate Postoperative Period

• You'll spend 1-2 days in the intensive care unit with continuous cardiac monitoring, mechanical ventilation initially, chest tubes draining fluid from around your heart and lungs, and multiple intravenous lines. 3
• The most critical early complications include bleeding (requiring potential reoperation), perioperative heart attack (occurring in a small percentage despite revascularization), stroke (risk 1-3% depending on your preoperative risk factors), and atrial fibrillation (occurring in 25-40% of patients). 3, 7

Hospital Stay and Beyond

• Total hospital stay typically ranges 5-7 days for uncomplicated cases. 3
• Up to 14% of CABG patients return to the emergency department within 30 days with postoperative complications including sternal wound infections, pneumonia, graft failure, pericardial effusion, or hemodynamic instability. 7

Long-Term Outcomes: What the Evidence Shows

CABG provides superior long-term survival compared to stenting in patients with multivessel disease—the adjusted hazard ratio for death after CABG relative to stenting is 0.64 for three-vessel disease with proximal LAD involvement, meaning a 36% reduction in mortality risk. 8

The major trade-off is that stroke risk is higher with CABG (1-3%) compared to PCI, while repeat revascularization rates are dramatically higher after PCI (27.3% vs 4.6% at 3 years). 3, 6, 8

Special Consideration for Diabetic Patients

If you have diabetes and multivessel coronary disease, CABG is mandatory over stenting regardless of anatomic complexity—5-year major adverse cardiac events occur in 18.7% after CABG versus 26.6% after PCI, with improved long-term survival. 2, 6

Common Pitfalls to Avoid

Don't assume age alone disqualifies you from CABG—when surgical risk is acceptable, the benefit-to-risk ratio remains favorable even in elderly patients, and age-based discrimination leads to undertreatment of viable candidates. 1, 2, 5

Don't proceed with CABG if you're taking clopidogrel—this antiplatelet medication must be withheld for 5 days before surgery when clinical circumstances permit to reduce bleeding complications. 3, 2

Don't accept single-vessel CABG without proximal LAD involvement unless you have refractory symptoms and aren't a PCI candidate—this is a Class III (harm) recommendation because the risk-benefit ratio doesn't favor surgery in this anatomic pattern. 3, 2

The Bottom Line on Graft Durability

Your LIMA-to-LAD graft will likely remain patent for decades (>90% at 10 years), but saphenous vein grafts deteriorate over time with only 50-60% remaining patent at 10 years due to progressive atherosclerosis. 3, 9 This is why arterial grafts (LIMA, radial artery) are increasingly preferred when technically feasible. 3, 9

If you need repeat revascularization years after CABG, PCI of your native coronary vessels (using the old grafts as conduits to reach the target) is now preferred over attempting to stent diseased saphenous vein grafts, which carry high complication rates. 1, 9