What medications should be stopped before Coronary Artery Bypass Grafting (CABG) surgery and why?

Medications to Stop Before CABG and Why

P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor) must be discontinued before elective CABG to prevent life-threatening surgical bleeding, while aspirin should be continued and most anticoagulants require specific timing for discontinuation or transition to unfractionated heparin.

P2Y12 Inhibitor Antiplatelet Agents (Primary Bleeding Risk)

These medications cause the most significant bleeding complications during CABG because they irreversibly inhibit platelet function for the entire lifespan of the platelet (7-10 days), making surgical hemostasis extremely difficult 1.

Specific Timing Requirements:

• Clopidogrel: Discontinue at least 5 days before surgery 1, 2

  • Patients undergoing CABG within 5 days of last dose have significantly higher rates of reoperation for bleeding and major hemorrhage compared to those with >5 days washout 3
  • The 5-day period allows for dissipation of the antiplatelet effect as new platelets are generated 1

• Prasugrel: Discontinue at least 7 days before surgery 1, 2, 4

  • FDA labeling explicitly warns against starting prasugrel in patients likely to undergo urgent CABG 4
  • CABG-related major bleeding occurs in 14.1% of prasugrel patients vs 4.5% on clopidogrel, with risk persisting up to 7 days from last dose 4
  • For patients receiving prasugrel within 3 days of CABG, bleeding rates reach 26.7% compared to 5.0% with clopidogrel 4

• Ticagrelor: Discontinue at least 7 days before surgery 1, 2

  • Despite having a shorter half-life than clopidogrel, requires 7-day washout due to potent antiplatelet effects 1

Critical Exception: These discontinuation recommendations apply only when surgery can be safely delayed; in emergency situations where the benefit of immediate revascularization outweighs bleeding risk, surgery should proceed despite antiplatelet therapy 1

Aspirin: CONTINUE Perioperatively

• Aspirin should be continued through surgery at 100-325 mg daily 1, 2
• Low-dose aspirin reduces perioperative myocardial infarction, acute renal injury, and mortality without significantly increasing bleeding risk 5
• This represents a critical distinction from P2Y12 inhibitors—aspirin's benefits outweigh its modest bleeding risk in the CABG setting 6, 5

Anticoagulant Medications

Low Molecular Weight Heparins:

• Enoxaparin: Discontinue 12-24 hours before CABG 1, 2
  • Transition to unfractionated heparin (UFH) per institutional practice 1
  • The longer half-life and sustained binding to vascular wall make timing critical 7

Other Anticoagulants:

• Fondaparinux: Discontinue 24 hours before CABG 1, 2

  • Transition to UFH per institutional practice 1

• Bivalirudin: Discontinue 3 hours before CABG 1, 2

  • Transition to UFH per institutional practice 1
  • Shorter discontinuation time reflects its direct thrombin inhibition with predictable pharmacokinetics 7

• Unfractionated Heparin: CONTINUE until surgery 1, 8

  • UFH is preferred because it can be stopped immediately when needed during the procedure 8
  • Particularly important for patients with intra-aortic balloon pumps who require continuous anticoagulation 8

GP IIb/IIIa Inhibitors

• Eptifibatide or Tirofiban: Discontinue 4 hours before CABG 1, 2

  • These agents have fast off-rates from the GPIIb/IIIa receptor, allowing relatively short discontinuation times 7

• Abciximab: Discontinue at least 12 hours before surgery 2

  • Longer discontinuation time required due to irreversible binding to platelets 7

Rationale for These Recommendations

The fundamental issue is surgical bleeding risk versus thrombotic risk. P2Y12 inhibitors cause irreversible platelet dysfunction that cannot be overcome during surgery, leading to:

• Increased reoperation rates for bleeding 3
• Greater blood product transfusion requirements (mean 2.4-2.9 units PRBC with clopidogrel vs 1.4 units without) 9
• Higher mortality when surgery occurs too soon after drug administration 3, 5

Common Pitfall: Platelet transfusions are less effective if given within 6 hours of P2Y12 inhibitor loading dose or 4 hours of maintenance dose, because circulating drug will inhibit transfused platelets 4. This makes preoperative discontinuation far more effective than attempting to reverse effects intraoperatively.

Special Considerations

• For patients with recent coronary stents or acute coronary syndrome, premature discontinuation of antiplatelet therapy increases risk of stent thrombosis and recurrent MI 4, 5
• The decision to delay surgery must balance bleeding risk against ischemic risk on a case-by-case basis 1
• Point-of-care platelet function testing can identify patients at highest bleeding risk, though these tests have limitations 6