Heart Bypass Surgery (Coronary Artery Bypass Grafting - CABG)

What Is It?

Why Is It Done?

• Medications and lifestyle changes no longer control angina
• There is significant obstruction of the left main coronary artery
• There is three-vessel disease (all three major coronary arteries blocked)
• There is two-vessel disease with significant involvement of the proximal left anterior descending (LAD) artery
• The left ventricular ejection fraction is reduced (EF <35%)
• The patient has diabetes mellitus with multivessel coronary disease - in this group, CABG is superior to stenting (PCI) for preventing death, heart attack, and repeat procedures
• The patient cannot take dual-antiplatelet therapy (required after stenting)

The Graft Conduits (Bypass Vessels)

Types of CABG

1. On-Pump CABG (Traditional)

• The heart is stopped and the patient is placed on a cardiopulmonary bypass (CPB) machine (heart-lung machine), which oxygenates and circulates blood during surgery.
• Provides a still, bloodless field for precise sewing.
• Associated with some risk of neurological complications from the bypass circuit.

2. Off-Pump CABG (Beating Heart Surgery)

• Surgery is performed on the beating heart without CPB.
• Reduces some complications related to the bypass circuit.
• A 2024 meta-analysis (PMID 38626442) found comparable overall outcomes between on-pump and off-pump techniques, with some advantages in specific patient subgroups.

3. Minimally Invasive CABG

• Performed through a small thoracotomy (a limited chest opening) rather than a full sternotomy.
• Can shorten recovery time and reduce morbidity in suitable patients.
• Total endoscopic approaches are also available in specialized centers.

The Surgical Steps (Overview)

1. Anesthesia and monitoring lines are placed.
2. The surgeon makes a median sternotomy (splitting the breastbone) to access the heart.
3. The graft vessel is harvested (LIMA is taken off the chest wall; saphenous vein is taken from the leg).
4. For on-pump surgery, the patient is connected to the heart-lung bypass machine and the heart is stopped with a cold cardioplegia solution.
5. The graft is sewn (anastomosed) to the coronary artery beyond the blockage, and the other end is attached to the aorta (or left as the LIMA pedicle).
6. The heart is restarted, the bypass machine is disconnected.
7. The chest is closed with sternal wires and sutures.

Outcomes

• Mortality: Less than 1% in low-risk patients with normal heart function, operated by an experienced team. Rises significantly with age >80, poor heart function, and multiple comorbidities.
• Angina relief: Abolished or greatly reduced in approximately 90% of patients after complete revascularization.
• Survival benefit: Proven in left main disease, three-vessel disease, reduced ejection fraction, and diabetics with multivessel disease.
• Graft failure: Saphenous vein grafts occlude in 10-20% within the first year; arterial grafts last considerably longer. Risk factor control (especially cholesterol management) improves graft patency.
• Cardiac rehabilitation post-CABG, including in elderly patients, improves recovery and outcomes - supported by a 2025 systematic review (PMID 41299466).

CABG vs. Stenting (PCI)

• Left main coronary artery disease
• Three-vessel disease with complex anatomy (high SYNTAX score)
• Diabetics with multivessel disease
• Patients with poor LV function
• Patients who cannot tolerate prolonged antiplatelet therapy
• Recurrent in-stent restenosis

Risks and Complications

• Bleeding and the need for transfusion
• Stroke (especially in older patients or those with aortic disease)
• Atrial fibrillation (very common post-operatively, usually temporary)
• Wound infection (superficial or deep sternal wound infection)
• Kidney injury
• Delirium - occurs in 3-35% of patients after CABG
• Graft occlusion and recurrence of symptoms over time
• Heart attack perioperatively (Type 5 MI)

Recovery

• Hospital stay: typically 5-7 days
• Return to light activity: 4-6 weeks
• Full recovery: 2-3 months
• Cardiac rehabilitation is strongly recommended and has been shown to improve outcomes, including in elderly patients