What is the recommended duration of antiplatelet therapy after coronary artery bypass grafting?

Antiplatelet Therapy Duration Following CABG

All patients undergoing CABG should receive aspirin indefinitely starting within 6-48 hours postoperatively, and those with recent acute coronary syndrome (ACS) must resume a P2Y12 inhibitor postoperatively to complete a full 12 months of dual antiplatelet therapy (DAPT) from the ACS event. 1

Aspirin Monotherapy (Standard for All CABG Patients)

Aspirin should be initiated within 6 hours postoperatively once hemostasis is secured and continued indefinitely. 1 The evidence strongly supports this approach:

• Dosing: Aspirin 75-100 mg daily (range up to 325 mg) should be used, with lower doses (81 mg) preferred for long-term maintenance. 1
• Timing matters critically: Aspirin administered within 6 hours provides optimal vein graft patency, some benefit at 24 hours, and no benefit after 48 hours. 2
• Mechanism: Early aspirin reduces saphenous vein graft occlusion rates from 22.6% to 15.8% at one year, with the greatest benefit in grafts to vessels ≤2.0 mm diameter. 3
• Safety: Multiple randomized trials demonstrate no significant increase in chest tube drainage or transfusion requirements when aspirin is started immediately postoperatively. 4, 2

Dual Antiplatelet Therapy (DAPT) After CABG

The duration and necessity of adding a P2Y12 inhibitor depends entirely on the clinical indication for CABG:

For ACS Patients (NSTEMI/STEMI/Unstable Angina)

P2Y12 inhibitor therapy MUST be resumed postoperatively and continued to complete 12 months total from the ACS event, not from the surgery date. 1, 5 This is a Class I recommendation with the following specifics:

• Resume within 24-48 hours postoperatively when bleeding risk is controlled. 5
• Agent selection: Ticagrelor 90 mg twice daily is preferred over clopidogrel 75 mg daily based on PLATO trial data showing reduced cardiovascular mortality in CABG patients. 5 Prasugrel 10 mg daily is an alternative but showed increased postoperative bleeding. 5
• Critical pitfall: The 12-month clock starts at the ACS event, not at surgery—do not discontinue prematurely after CABG. 5
• Evidence base: The CURE trial demonstrated significant reduction in ischemic events with aspirin plus clopidogrel in ACS patients undergoing CABG. 5

For Stable Ischemic Heart Disease (SIHD) Without Recent ACS

DAPT with clopidogrel 75 mg daily for 12 months may be reasonable to improve vein graft patency, but this is a weaker recommendation (Class IIb). 1, 5 Consider this approach when:

• The patient has no recent ACS (>12 months prior)
• Multiple vein grafts were placed
• The patient is not at high bleeding risk
• Bleeding risk must be carefully weighed against potential graft patency benefit 5

For Patients With Prior Coronary Stents

Resume P2Y12 inhibitor postoperatively to complete the recommended DAPT duration for the stent type: minimum 1 month for bare metal stents, at least 6 months for drug-eluting stents. 5

Bleeding Risk Modifications

In CABG patients with high bleeding risk (PRECISE-DAPT score ≥25), consider discontinuing the P2Y12 inhibitor after 6 months rather than 12 months, but only in stable patients without recent ACS. 1, 5 High bleeding risk includes:

• Treatment with oral anticoagulation
• History of major bleeding on DAPT
• Need for major intracranial surgery
• Coagulopathy 1

Add a proton pump inhibitor in all patients on DAPT with increased gastrointestinal bleeding risk (elderly, prior GI bleeding, chronic NSAID use). 1, 5

Preoperative Management

For elective CABG, antiplatelet agents should be held preoperatively to reduce bleeding:

• Clopidogrel and ticagrelor: Stop at least 5 days before surgery 1
• Prasugrel: Stop at least 7 days before surgery 1
• Aspirin: Continue through the perioperative period (do not stop) 1

For urgent CABG, clopidogrel and ticagrelor should be stopped at least 24 hours before surgery when feasible. 1

Algorithm Summary

All CABG patients:

• Aspirin 75-100 mg daily within 6 hours postoperatively → continue indefinitely 1

Add P2Y12 inhibitor if:

• Recent ACS (within 12 months) → Resume postoperatively, continue to complete 12 months from ACS event 1
• Prior coronary stent → Resume postoperatively, continue to complete stent-specific duration 5
• SIHD without ACS → Consider clopidogrel for 12 months if low bleeding risk (Class IIb) 1, 5

Modify duration if:

• High bleeding risk develops → May stop P2Y12 inhibitor at 6 months in stable patients 1
• Never shorten DAPT in ACS patients unless life-threatening bleeding occurs 1