Should Aspirin Be Stopped Before CABG in NSTEMI?
No—aspirin should be continued preoperatively in patients with NSTEMI undergoing CABG. 1
Guideline-Based Recommendation
Non-enteric-coated aspirin (81 mg to 325 mg daily) should be administered preoperatively to all patients undergoing CABG, including those with NSTEMI (Class I, Level of Evidence: B). 1 This represents the highest-quality guideline evidence from the 2014 AHA/ACC NSTE-ACS guidelines, which explicitly state that aspirin continuation reduces operative morbidity and mortality with only a modest increase in bleeding risk. 1
Key Algorithmic Approach:
For NSTEMI patients proceeding to CABG:
- Continue aspirin through surgery at 81-325 mg daily 1
- Stop P2Y12 inhibitors (clopidogrel/ticagrelor for ≥24 hours ideally, prasugrel for ≥24 hours) in urgent CABG to reduce major bleeding 1
- Resume aspirin immediately postoperatively if not continued intraoperatively 2
- Restart P2Y12 inhibitor 24-72 hours post-CABG when bleeding risk acceptable 1
Evidence Strength and Nuances
The 2014 AHA/ACC guidelines are unequivocal: preoperative aspirin reduces operative morbidity and mortality, and CABG can be performed safely in patients on aspirin therapy. 1 This recommendation applies specifically to NSTEMI patients, who represent a high-risk population where the thrombotic risk of aspirin discontinuation outweighs bleeding concerns. 1
The most recent 2025 ACC/AHA/ACEP guideline reinforces aspirin continuation during CABG and emphasizes starting P2Y12 inhibitors postoperatively when safe. 1 The 2025 guideline explicitly states aspirin should be continued during CABG surgery itself. 1
Contrasting Research Evidence:
While the ATACAS trial (2016, NEJM) found no difference in death/thrombotic complications or major bleeding between preoperative aspirin vs. placebo in elective CABG, 3 this study is superseded by guideline recommendations that prioritize NSTEMI patients specifically. 1 The ATACAS trial enrolled predominantly elective patients, not acute coronary syndrome patients. 3
A 2018 Iranian RCT showed increased bleeding with aspirin continuation until surgery day, 4 but this contradicts multiple meta-analyses demonstrating that low-dose aspirin (≤100 mg) reduces perioperative MI by 63% and 30-day mortality by 27% without significantly increasing bleeding when dosed appropriately. 5
Critical Distinction: NSTEMI vs. Elective CABG
The context of NSTEMI fundamentally changes the risk-benefit calculation. 1 In NSTEMI:
- Thrombotic risk is acutely elevated due to active plaque rupture and ongoing ischemia 1
- Aspirin discontinuation risks catastrophic re-infarction during the vulnerable preoperative period 6, 5
- Guidelines explicitly recommend aspirin continuation in this high-risk subset 1
A 2012 multicenter study found that aspirin discontinuation >3 days before CABG was associated with significantly higher postoperative stroke rates (5.9% vs. 0.7%, p=0.02) in propensity-matched analysis. 6
Dosing Specifics
Use 81-325 mg non-enteric-coated aspirin preoperatively. 1 The 2014 guidelines specify non-enteric-coated formulation because enteric coating delays absorption. 1 Post-CABG, continue aspirin indefinitely at 81 mg daily (Class I, Level A). 2 Lower maintenance doses (81 mg) provide equivalent cardiovascular protection with reduced bleeding risk compared to higher doses. 2
Common Pitfalls to Avoid
Do not confuse aspirin management with P2Y12 inhibitor management. While clopidogrel/ticagrelor should be stopped ≥24 hours before urgent CABG, 1 aspirin is continued. 1
Do not extrapolate elective CABG data to NSTEMI patients. The ATACAS trial enrolled low-risk elective patients, 3 whereas NSTEMI patients have fundamentally different thrombotic risk profiles. 1
Do not use enteric-coated aspirin preoperatively due to delayed absorption. 1
Do not delay CABG solely to discontinue aspirin in NSTEMI. A 2025 study found optimal CABG timing for NSTEMI is 3-7 days post-catheterization, 7 and aspirin should be continued throughout this period. 1
Bleeding Risk Management
The modest increase in bleeding with aspirin continuation does not translate to increased mortality or major morbidity. 1, 3 The 2014 guidelines explicitly state CABG can be performed safely on aspirin with "only a modest increase in bleeding risk." 1
For patients with documented severe bleeding risk, the decision becomes more nuanced, but in NSTEMI the default remains aspirin continuation unless active life-threatening bleeding or intracranial hemorrhage is present. 2
Post-CABG Management
Resume aspirin immediately postoperatively (typically within 6-24 hours when hemostasis achieved). 1, 2 Add clopidogrel 75 mg daily starting 24-72 hours post-CABG and continue for 12 months to improve vein graft patency in NSTEMI patients. 1, 2 This dual antiplatelet therapy (DAPT) strategy is Class I for post-ACS CABG patients. 1