What is the first-line anticoagulant following Coronary Artery Bypass Grafting (CABG)?

First-Line Anticoagulants Following CABG

Aspirin (100-325 mg daily) is the first-line anticoagulant therapy following CABG and should be initiated within 6 hours postoperatively if not started preoperatively, then continued indefinitely to improve saphenous vein graft patency and reduce mortality. 1

Preoperative Antiplatelet Management

• For patients already on antiplatelet therapy before CABG:
  • Aspirin (100-325 mg daily) should be continued through the perioperative period 2
  • Clopidogrel and ticagrelor should be discontinued at least 5 days before elective CABG 2
  • Prasugrel should be discontinued at least 7 days before elective CABG 2
  • For urgent CABG, P2Y12 inhibitors should be discontinued for at least 24 hours to reduce major bleeding complications 2

Postoperative Antiplatelet Protocol

Immediate Post-CABG Period

• Aspirin should be initiated within 6 hours after surgery if not given preoperatively 1
• Non-enteric coated formulations are preferred for more reliable platelet inhibition 1
• Dosing options:
  • 81 mg daily (commonly used in practice) 1
  • 100-325 mg daily (ACC/AHA recommendation) 2, 1

Long-term Management

• Continue aspirin indefinitely at 75-162 mg daily 1
• For patients intolerant or allergic to aspirin, clopidogrel 75 mg daily is a reasonable alternative 2

Evidence Supporting Aspirin as First-Line Therapy

Aspirin significantly improves saphenous vein graft patency rates, particularly during the first postoperative year 2. Early initiation of aspirin therapy (within 6 hours) has been shown to:

• Reduce early vein graft occlusion rates (1.6% with aspirin vs. 6.2% with placebo) 3
• Provide continued protection against graft occlusion up to 1 year after CABG 3
• Reduce rates of mortality, MI, stroke, renal failure, and bowel infarction 1

Importantly, the benefit of postoperative aspirin on SVG patency is lost when it is initiated more than 48 hours after surgery 2, 1.

Special Clinical Scenarios

Patients with Recent ACS Prior to CABG

• For patients with ACS within 12 months prior to CABG:
  • Continue aspirin (81-100 mg daily) 2
  • Consider continuing clopidogrel for up to 12 months after ACS 2, 1

Patients with Prior PCI and Stents

• If CABG is performed within 12 months of PCI:
  • Continue SAPT (preferably aspirin) until 1 year post-PCI 2
  • After 12 months post-PCI, aspirin alone is sufficient 2

Dual Antiplatelet Therapy Considerations

While aspirin monotherapy is the standard first-line approach, DAPT may be considered in specific situations:

• Some evidence suggests DAPT (aspirin plus clopidogrel) may be associated with fewer 30-day adverse outcomes compared to aspirin alone 4
• DAPT may have significant protective effects in patients undergoing off-pump CABG 5
• However, evidence for routine DAPT in stable CAD patients after CABG is insufficient for a strong recommendation 1, 5

Practical Considerations and Pitfalls

• Timing is critical: Delaying aspirin initiation beyond 48 hours postoperatively results in lost benefit on graft patency 1
• Dosing frequency: Some evidence suggests twice-daily aspirin dosing may be more effective than once-daily dosing at suppressing serum thromboxane B2 formation after CABG 6
• Dose optimization: Low-dose aspirin (81 mg) within 24 hours of CABG has been associated with decreased early postoperative mortality compared to higher doses (325 mg) 7
• Avoid unnecessary anticoagulation: In patients with NSTE-ACS, anticoagulant therapy should be discontinued after CABG unless there is a compelling reason to continue such therapy 2

By following these evidence-based recommendations for antiplatelet therapy after CABG, clinicians can optimize graft patency and reduce mortality while minimizing bleeding complications.