Background
Evolving techniques and better understanding of coronary artery disease have changed outcomes for patients with severe coronary artery disease over the last two decades. The American College of Cardiology Foundation recently published an evidence-based reassessment of the role of coronary bypass surgery to guide clinical decision making.
Conclusions
CABG is associated with substantially less need for revascularization than is percutaneous coronary intervention (PCI) during the first year after intervention (less than 5% vs. nearly 25%). This advantage persists through year 5 (10% vs. 45%). Diabetics, in particular, have better survival after CABG as compared to PCI.
While PCI reduces angina, it has not been shown to improve survival or reduce MI in patients without recent acute coronary syndromes. Meta-analyses have not shown superior survival of bare metal stent over balloon angioplasty interventions. Similarly, drug eluting stents have not resulted in superior survival over bare metal stents.
Internal mammary artery grafts have a greater than 90% patency 10 years after CABG with only 1% demonstrating significant atherosclerotic stenosis.
Bilateral internal mammary artery grafts can improve cardiovascular outcomes but are associated with higher rates of sternal wound infections in obese and diabetic patients.
Up to 25% of saphenous vein grafts occlude in the first postoperative year, and annual occlusion rates thereafter are 1%-2% until year 5 and 4%-5% from years 5-10. After 10 years, half of saphenous vein grafts are patent, of which 50% demonstrate atherosclerosis.
Radial arteries are more muscular and prone to spasm unless used for left-sided lesions with more than 70% blockage.
On-pump CABG has better 1-year patency and equivalent neuropsychiatric outcomes with similar resource use when compared with off-pump procedures.
Inhalational anesthetics improve intracardiac blood flow and are associated with quicker extubation recovery times than is a narcotic-based regimen.
The left internal mammary artery should be used to bypass the left anterior descending unless there are contraindications, such as previous radiation injury or specific limitations to blood flow.
Because lower flow rates are associated with greater graft occlusion, arterial grafts should not be used for right coronary artery bypass unless there is a critical stenosis.
Coronary stenting should not be performed in patients who cannot adhere to or tolerate dual antiplatelet therapy (DAPT) because of the high risk of rethrombosis and related mortality: At least 30 days for bare metal stents and a year for drug eluting stents.
Aspirin, 100 to 325 mg a day, should be given throughout the perioperative period to improve outcomes with a minimal risk of bleeding. Postoperative aspirin, started within 6 hours of surgery, improves saphenous vein graft patency. Doses less than 100 mg, while efficacious for patients with coronary disease, are less efficacious for sustaining saphenous vein patency.
Thienopyridines such as clopidogrel and ticagrelor should be stopped preferably 5 days before CABG, but definitely 24 hours prior to surgery to avoid risk of hemorrhage. Prasugrel should be stopped at least 7 days preoperatively.
All patients should receive statin therapy perioperatively. Patients not on statin therapy have been shown to sustain higher rates of post-CABG cardiovascular complications.
Diabetic patients should receive postoperative continuous infusion insulin to keep blood glucose under 180 mg/dL. Targeting glucose levels under 140 mg/dL has uncertain value at the present time.
Perioperative beta-blocker administration reduces the incidence and impact of CABG-related atrial fibrillation. Acute and chronic beta-blocker administration favorably affects the reduction ofon reducing ischemia and mortality.
Epiaortic ultrasound is superior to palpation or transesophageal echo to detect location and severity of ascending aorta atherosclerosis that can pose a risk for perioperative stroke in CABG patients.
CABG should not be performed on patients with sustained ventricular tachycardia associated with myocardial scars but without evidence of current ischemia.
All patients should be considered for postoperative cardiac rehabilitation. A 3-month course of rehabilitation activities three times a week starting after the first month postoperatively can increase exercise tolerance by one-third.
Reference
2011 ACCF/AHA Guideline for Coronary Artery Bypass Graft Surgery: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines (Circulation 2011;124: e652-e735).