What is the recommended antiplatelet regimen after Coronary Artery Bypass Grafting (CABG) and what is the typical duration of treatment?

Antiplatelet Regimen After CABG

All patients undergoing CABG should receive aspirin 75-100 mg daily lifelong, initiated within 6-24 hours postoperatively when bleeding risk is controlled, and for patients with acute coronary syndrome (ACS) or prior coronary stenting, dual antiplatelet therapy (DAPT) with aspirin plus a P2Y12 inhibitor should be resumed postoperatively and continued for 12 months. 1

Standard Aspirin Monotherapy

Aspirin is the cornerstone of post-CABG antiplatelet therapy:

• Low-dose aspirin (75-100 mg daily) should be started within 6-24 hours after CABG once hemostasis is secured and continued indefinitely 1
• Aspirin improves saphenous vein graft patency, particularly during the first postoperative year, and reduces major adverse cardiac events (MACE) and mortality 1, 2
• For patients on aspirin preoperatively, it should be continued through the perioperative period at low daily doses 1

Dual Antiplatelet Therapy (DAPT) After CABG

Mandatory DAPT Scenarios (Class I Recommendations):

1. Patients with Recent ACS (STEMI or NSTE-ACS):

• Resume P2Y12 inhibitor therapy postoperatively to complete 12 months of DAPT after the ACS event 1
• This applies regardless of whether they underwent PCI before CABG 1
• The 12-month duration is calculated from the ACS event, not from the CABG surgery 1

2. Patients with Prior Coronary Stenting:

• Resume P2Y12 inhibitor postoperatively to complete the recommended duration of DAPT for the stent type (minimum 1 month for bare metal stents, at least 6 months for drug-eluting stents) 1

Optional DAPT Scenarios (Class IIb Recommendations):

Stable Ischemic Heart Disease (SIHD) Without ACS:

• DAPT with clopidogrel initiated early postoperatively for 12 months may be reasonable to improve vein graft patency 1
• This is particularly relevant for patients at higher thrombotic risk with low bleeding risk 2

Choice of P2Y12 Inhibitor

The specific P2Y12 inhibitor selection depends on clinical context:

• Clopidogrel 75 mg daily is the most studied agent in CABG patients and is appropriate for most situations 1
• Ticagrelor may be preferred over clopidogrel in ACS patients, as it demonstrated significant reduction in cardiovascular mortality compared to clopidogrel, though with similar overall outcomes at 1 year 1
• Recent meta-analysis data suggest ticagrelor or prasugrel (DAPT-T/P) may reduce all-cause and cardiovascular mortality compared to clopidogrel-based DAPT without increasing bleeding 3

Timing of P2Y12 Inhibitor Resumption

Resume P2Y12 inhibitor therapy as soon as it is deemed safe postoperatively:

• Typically within 24-48 hours when bleeding risk is controlled 1
• Balance individual ischemic risk (ACS, stent thrombosis risk) against bleeding risk 1

Evidence Supporting DAPT vs. Aspirin Alone

The benefit-risk profile of DAPT after CABG:

• Meta-analysis of 77,447 patients showed DAPT reduced all-cause mortality (OR 0.65), cardiovascular mortality (OR 0.53), and MACE (OR 0.68) compared to aspirin monotherapy 3
• However, DAPT increased major bleeding (OR 1.30) and minor bleeding (OR 1.87) 3
• Another meta-analysis of 11,135 patients confirmed DAPT reduced graft occlusion (RR 0.79), MACE (RR 0.84), and all-cause mortality (RR 0.67) without significantly increasing major bleeding 4
• A large propensity-matched study of 3,562 patients found no survival or MACE benefit with DAPT, but higher transfusion rates, suggesting benefits may be context-dependent 5

Bleeding Risk Management

Proton pump inhibitor (PPI) co-therapy:

• Consider adding a PPI in patients at increased risk of gastrointestinal bleeding (elderly, history of GI bleeding, chronic NSAID use, combination antithrombotic therapy) 1, 2
• PPIs are effective in reducing GI bleeding risk with antithrombotic therapy 1
• Avoid omeprazole and esomeprazole with clopidogrel due to CYP2C19 interaction, though clinical significance remains uncertain 1

Preoperative Management

For elective CABG, discontinue P2Y12 inhibitors before surgery:

• Prasugrel: stop ≥7 days before 1, 6
• Clopidogrel: stop ≥5 days before 1, 6
• Ticagrelor: stop ≥3 days before 1, 6
• Continue aspirin through the perioperative period 1

Duration Summary Algorithm

Follow this decision tree:

1. All CABG patients: Aspirin 75-100 mg daily indefinitely 1

2. Add P2Y12 inhibitor for 12 months if:

   • Recent ACS (within 12 months) 1
   • Prior coronary stent (complete recommended stent duration) 1

3. Consider P2Y12 inhibitor for 12 months if:

   • SIHD with high thrombotic risk and low bleeding risk 1, 2
   • Goal is improved vein graft patency 1

4. High bleeding risk patients:

   • May discontinue P2Y12 inhibitor after 6 months in CABG patients with prior MI 1
   • Aspirin monotherapy remains standard if no ACS or stent 1, 5

Common Pitfalls

• Do not automatically continue DAPT in all CABG patients without considering individual ischemic and bleeding risks 2
• Do not confuse PCI-DAPT recommendations with CABG-DAPT recommendations—the evidence base differs 2
• Do not forget to resume P2Y12 inhibitor postoperatively in patients who had ACS or stents—this is a Class I recommendation 1
• Do not use the same preoperative discontinuation intervals for all P2Y12 inhibitors—they have different pharmacokinetics 1, 6