How long should Plavix (clopidogrel) be continued after coronary artery bypass grafting (CABG)?

Duration of Clopidogrel (Plavix) After CABG

In patients with stable ischemic heart disease, treatment with clopidogrel for 12 months after CABG may be reasonable to improve vein graft patency, according to the 2016 ACC/AHA guidelines. 1

Recommendations Based on Clinical Scenario

Patients with Stable Ischemic Heart Disease (SIHD)

• Duration: 12 months of clopidogrel therapy after CABG may be reasonable (Class IIb, Level of Evidence B-NR) 1
• Purpose: To improve vein graft patency
• Aspirin: Should be initiated within 6 hours postoperatively and continued indefinitely at 81-325 mg daily 1

Patients with Acute Coronary Syndrome (ACS)

• Duration: P2Y12 inhibitor therapy should be resumed after CABG to complete a full 12 months of therapy after ACS (Class I, Level of Evidence C-LD) 1
• Timing: Reinstitute P2Y12 inhibitor as soon as possible after CABG 1
• Preference: Ticagrelor or prasugrel preferred over clopidogrel if no contraindications exist 1

Evidence Supporting These Recommendations

The recommendation for 12 months of clopidogrel after CABG is based on evidence that dual antiplatelet therapy (DAPT) improves vein graft patency. The 2016 ACC/AHA guidelines specifically state that "in patients with SIHD, treatment with DAPT (with clopidogrel initiated early postoperatively) for 12 months after CABG may be reasonable to improve vein graft patency" 1.

Several studies support this recommendation:

• Sun et al. demonstrated that aspirin plus clopidogrel therapy increased early venous graft patency at 3 months after CABG compared to aspirin alone (91.6% vs 85.7%, p=0.043) 2
• Gurbuz et al. found that clopidogrel therapy was independently associated with decreased symptom recurrence and adverse cardiac events following off-pump CABG, with no significant difference between short-term (30 days) and long-term use 3

Practical Implementation

1. Timing of initiation:

   • Start clopidogrel as soon as possible after CABG once hemostasis is achieved
   • Typically within 6 hours postoperatively when chest tube drainage is minimal 2

2. Dosing:

   • Clopidogrel 75 mg daily
   • Aspirin 81-325 mg daily (with lower doses preferred for long-term therapy) 1

3. Duration:

   • 12 months for most patients 1
   • Consider longer duration in high-risk patients with prior MI and low bleeding risk 1

Special Considerations

Bleeding Risk

• For patients at high risk of bleeding, a shorter duration may be considered
• Monitor for bleeding complications, especially when combined with other anticoagulants

Type of Graft

• Radial artery grafts may particularly benefit from DAPT
• A study by Kulik et al. showed significantly lower occlusion rates in radial artery grafts with clopidogrel plus aspirin versus aspirin alone (10.5% vs 43.8%, p=0.05) 4

Preoperative Management

• If patient was on clopidogrel before CABG:
  • For elective CABG: Discontinue clopidogrel at least 5 days before surgery 1
  • For urgent CABG: Discontinue for at least 24 hours to reduce major bleeding complications 1

Common Pitfalls to Avoid

1. Premature discontinuation: Stopping clopidogrel too early may increase risk of graft occlusion
2. Delayed initiation: Waiting too long after CABG to start clopidogrel may miss the critical period for preventing early graft thrombosis
3. Failure to balance bleeding and thrombotic risks: Individual assessment is needed, especially in patients with high bleeding risk

In conclusion, while aspirin remains the cornerstone of post-CABG antiplatelet therapy, the addition of clopidogrel for 12 months provides additional benefit for graft patency, particularly for venous and radial artery grafts, with an acceptable safety profile.