What is the recommended antithrombotic regimen for a patient with atrial fibrillation (AF) post coronary artery bypass grafting (CABG): antiplatelet therapy alone or direct oral anticoagulant (DOAC) alone?

Antithrombotic Management for AF Post-CABG

For patients with atrial fibrillation after CABG, oral anticoagulation (DOAC preferred) alone should be used beyond 12 months post-surgery, not antiplatelet therapy alone. 1

Time-Based Algorithm Post-CABG

First 12 Months Post-CABG

• Continue aspirin (<100 mg/day) plus oral anticoagulation (dual therapy) for the first 12 months after CABG surgery in AF patients requiring anticoagulation for stroke prevention 1
• The American College of Cardiology specifically recommends clopidogrel (not aspirin) plus oral anticoagulation during this period, with clopidogrel continued for 12 months 2
• A DOAC is strongly preferred over warfarin to reduce bleeding risk while maintaining efficacy 1

Beyond 12 Months Post-CABG

• Discontinue all antiplatelet therapy and continue oral anticoagulation monotherapy based on the patient's CHA₂DS₂-VASc score 1, 2
• This transition is critical: real-world data from 2,564 CABG patients with AF showed that OAC alone was associated with superior net clinical benefit compared to antiplatelet therapy alone (43% lower risk of MACCE, adjusted HR 1.43 for PI alone vs OAC alone) 3
• Antiplatelet monotherapy in AF patients post-CABG is explicitly not recommended as it fails to prevent stroke and increases mortality 1, 3

Critical Evidence Supporting OAC Over Antiplatelet Therapy

The SWEDEHEART registry study provides the strongest real-world evidence: among AF patients post-CABG, those treated with antiplatelet therapy alone had significantly higher rates of stroke and myocardial infarction compared to OAC alone, while combination therapy (OAC + antiplatelet) increased bleeding without additional benefit 3

Antiplatelet therapy alone is explicitly contraindicated in AF patients for stroke prevention, regardless of CABG status 1

Bleeding Risk Considerations

• Assess bleeding risk using HAS-BLED score; patients with scores ≥3 require more frequent monitoring but should still receive OAC, not antiplatelet therapy 2
• For high bleeding risk patients, consider shortening dual therapy to 6-9 months before transitioning to OAC monotherapy, but never substitute antiplatelet monotherapy for OAC 2
• Proton pump inhibitors should be prescribed for all patients on combination antithrombotic therapy 4

Common Pitfalls to Avoid

Do not continue antiplatelet therapy beyond 12 months in stable post-CABG AF patients on oral anticoagulation - this increases bleeding risk without reducing ischemic events 1, 2

Do not use antiplatelet monotherapy as a substitute for OAC in AF patients - this is associated with 50% higher stroke risk and increased all-cause mortality 3, 5

Do not base anticoagulation decisions on perceived rhythm control success - the CHA₂DS₂-VASc score determines long-term anticoagulation need, not surgical success 1, 2

DOAC Selection and Dosing

• Use standard DOAC dosing unless specific dose-reduction criteria are met (renal function, age, weight) 1
• Apixaban, rivaroxaban, or dabigatran are all acceptable; choice should be based on renal function, drug interactions, and patient preference 6
• If warfarin is used, target INR 2.0-3.0 1