What antiplatelet therapy can be given to a patient who has undergone Coronary Artery Bypass Grafting (CABG) and is allergic to Acetylsalicylic Acid (ASA), can they take Clopidogrel?

Antiplatelet Therapy for CABG Patients with ASA Allergy

Yes, clopidogrel 75 mg daily is the recommended alternative antiplatelet therapy for patients who have undergone CABG and are allergic to or intolerant of aspirin. 1

Primary Recommendation

• Clopidogrel 75 mg daily should be initiated and continued indefinitely in CABG patients who cannot take aspirin due to allergy or intolerance 1
• This is a Class IIa recommendation (reasonable alternative) with Level of Evidence C from the ACC/AHA CABG guidelines 1
• The recommendation applies equally to patients undergoing CABG as part of secondary prevention after coronary artery disease 1

Timing of Initiation

• If clopidogrel was not started preoperatively, it should be initiated within 6 hours postoperatively (similar timing to aspirin) and continued indefinitely 1
• For patients who received clopidogrel preoperatively for acute coronary syndrome, restart clopidogrel after surgery when hemostasis is assured to prevent recurrent acute ischemic events 2
• The goal is to minimize the gap in antiplatelet coverage while ensuring adequate hemostasis 2

Evidence Supporting Clopidogrel Use

• While aspirin significantly improves saphenous vein graft (SVG) patency rates particularly during the first postoperative year, clopidogrel serves as an effective alternative when aspirin cannot be used 1
• A subset analysis from the CURE trial demonstrated that clopidogrel reduced cardiovascular death, MI, and stroke compared with placebo in CABG patients 1
• Recent comparative data shows that clopidogrel monotherapy after CABG produces similar outcomes to aspirin regarding all-cause mortality, major adverse events, and graft patency over 4 years of follow-up 3
• Clopidogrel is associated with fewer adverse effects than ticlopidine (another alternative), with severe leukopenia occurring very rarely 1

Important Caveats and Considerations

Why Not Ticlopidine?

• Although ticlopidine is efficacious at inhibiting platelet aggregation and offers an alternative in truly aspirin-allergic patients, it may be associated with potentially life-threatening neutropenia, requiring repetitive white blood cell count monitoring 1
• Clopidogrel is preferred over ticlopidine due to its superior safety profile 1

Graft Patency Considerations

• Arterial graft patency rates are high even without antiplatelet therapy, so the primary benefit of antiplatelet agents is on SVG patency and prevention of cardiovascular events 1
• New graft occlusion rates with clopidogrel monotherapy (1.2% of distal anastomoses) are comparable to aspirin (1.6%) at 5-year follow-up angiography 3

Advantages of Clopidogrel Over Aspirin

• Significantly fewer patients on clopidogrel required changes in antiplatelet regimen (2.2%) compared to aspirin (22.8%) due to intolerance or other issues 3
• Clopidogrel produces less gastrointestinal bleeding than aspirin (2.0% vs 2.7%) in patients with atherosclerotic disease 4

Statin Therapy Must Also Be Addressed

• All patients undergoing CABG should receive statin therapy unless contraindicated (Class I, Level of Evidence A) 1
• Target LDL cholesterol to less than 100 mg/dL with at least 30% reduction, or less than 70 mg/dL in very high-risk patients 1
• This is equally important as antiplatelet therapy for secondary prevention 1

What NOT to Do

• Do not use dipyridamole or warfarin as alternatives - they add nothing to graft patency and warfarin increases bleeding risk compared to antiplatelet agents 1
• Do not withhold antiplatelet therapy - the benefits for mortality, MI, stroke, renal failure, and bowel infarction reduction when given within 48 hours after CABG are substantial 1
• Avoid dual antiplatelet therapy (aspirin plus clopidogrel) in stable post-CABG patients unless there was recent stent placement or acute coronary syndrome, as this significantly increases bleeding risk without proportional long-term benefit 4