Is clopidogrel (Plavix) necessary after Coronary Artery Bypass Grafting (CABG)?

Clopidogrel After CABG: Evidence-Based Recommendations

Clopidogrel is NOT routinely necessary after CABG surgery for most patients—aspirin alone (75-162 mg daily) started within 6-48 hours postoperatively and continued indefinitely is the standard of care. 1, 2

Standard Post-CABG Antiplatelet Therapy

All patients undergoing CABG should receive aspirin monotherapy unless specific high-risk conditions exist. 1, 3

• Aspirin should be initiated within 6 hours postoperatively at doses of 100-325 mg daily and continued indefinitely 1, 2
• Starting aspirin within 48 hours reduces mortality, myocardial infarction, stroke, renal failure, and bowel infarction 1, 3
• The benefit on saphenous vein graft patency is lost if aspirin is delayed beyond 48 hours after surgery 1, 3
• Soluble aspirin may be preferred over enteric-coated formulations for optimal platelet inhibition 1, 2

When Clopidogrel IS Indicated After CABG

Add clopidogrel 75 mg daily to aspirin only in these specific high-risk scenarios: 4, 3

1. Recent Acute Coronary Syndrome (ACS)

• If CABG was performed for unstable angina or myocardial infarction, resume clopidogrel postoperatively to complete a full 12-month course of dual antiplatelet therapy from the time of ACS presentation 1, 4, 5
• The benefit in ACS patients occurs primarily before surgery, but continuation after CABG reduces recurrent ischemic events 1, 5

2. Recent Coronary Stenting

• Drug-eluting stent placed <12 months before CABG: Continue dual antiplatelet therapy for at least 12 months total from stent placement 1, 3
• Bare metal stent placed <1 month before CABG: Continue dual antiplatelet therapy for at least 1 month total from stent placement 1, 3
• If the stented vessel was successfully bypassed, clopidogrel may be discontinued earlier based on individual assessment 5

3. Stable Ischemic Heart Disease (Selected Cases)

• Dual antiplatelet therapy for 12 months after CABG may be reasonable to improve vein graft patency in selected patients at greater risk of graft occlusion and at low bleeding risk 4, 3
• This is a weaker recommendation (Class IIa) and should be reserved for complex grafting procedures or prior history of graft failure 3

Evidence Against Routine Clopidogrel Use

The evidence does NOT support routine dual antiplatelet therapy after CABG in stable patients: 6, 7

• Subgroup analyses from large ACS trials showed no clear clinical benefit of clopidogrel plus aspirin after CABG compared to aspirin alone 1, 6
• A 3,014-patient observational study found clopidogrel use was associated with statistically insignificant higher graft failure and similar 5-year outcomes compared to aspirin alone 7
• There is a consistent trend toward increased major and minor bleeding with dual antiplatelet therapy 6, 7

Timing Considerations

If clopidogrel was given before CABG, specific timing rules apply: 1, 4

• Clopidogrel should be discontinued at least 5 days before elective CABG to reduce bleeding risk 1, 4
• Prasugrel requires 7 days discontinuation, ticagrelor requires 3 days 1, 4
• Clopidogrel given within 5 days of CABG increases major bleeding by 50% and transfusion requirements by 70% 1, 3
• For high-risk patients with refractory ischemia or severe left main disease, early surgery without discontinuing clopidogrel may be necessary despite bleeding risk 5

Aspirin-Intolerant Patients

For patients who cannot take aspirin: 1, 2

• Clopidogrel 75 mg daily is a reasonable alternative as monotherapy 1, 2
• Ticlopidine is another option but offers no advantage over clopidogrel and requires white blood cell monitoring due to neutropenia risk 1

Critical Pitfalls to Avoid

• Do not delay aspirin beyond 48 hours postoperatively—this eliminates the graft patency benefit 1, 3
• Do not routinely add clopidogrel to aspirin in stable CABG patients—this increases bleeding without proven clinical benefit 6, 7
• Do not use warfarin or dipyridamole—they add nothing to aspirin's effect on graft patency and may increase bleeding 1
• Do not forget to restart clopidogrel after CABG in ACS patients—discontinuation increases risk of recurrent ischemic events 5

Practical Algorithm

1. Start aspirin 75-162 mg within 6-24 hours post-CABG in all patients 2, 3
2. Assess for high-risk features:
   • Recent ACS (within 12 months)? → Add clopidogrel for 12 months total 4, 5
   • Recent stent (DES <12 months, BMS <1 month)? → Add clopidogrel per stent guidelines 3
   • Complex grafting or prior graft failure AND low bleeding risk? → Consider clopidogrel for 12 months 4, 3
3. If none of the above apply: aspirin monotherapy indefinitely 1, 2