When should aspirin (acetylsalicylic acid) be started after surgery in patients with high risk of thromboembolic events?

When to Start Aspirin After Surgery

In patients with established cardiovascular disease or coronary stents undergoing noncardiac surgery, aspirin should be restarted within 24 hours postoperatively once adequate hemostasis is achieved, and ideally within 6-48 hours for patients undergoing coronary artery bypass grafting (CABG). 1, 2

For Patients with Coronary Stents (Highest Priority)

Aspirin must be continued throughout the perioperative period whenever possible in patients with prior PCI, and if interrupted, should be restarted immediately postoperatively. 3

• In patients with drug-eluting stents (DES) placed less than 3 months ago or bare-metal stents (BMS) placed less than 30 days ago who require time-sensitive surgery, dual antiplatelet therapy (DAPT) should be continued unless bleeding risk outweighs stent thrombosis prevention. 3

• The P2Y12 inhibitor should be resumed as soon as possible after surgery while maintaining aspirin throughout. 3, 1

• Never substitute aspirin or P2Y12 inhibitors with heparin or low-molecular-weight heparin, as these do not protect against stent thrombosis. 2

For Patients with Established Cardiovascular Disease (No Stents)

Aspirin should be restarted within 24 hours postoperatively once hemostasis is adequate. 1

• For patients with coronary artery disease, prior stroke, or peripheral arterial disease, aspirin discontinuation increases the absolute risk of stroke recurrence or cardiovascular events by approximately 2% within 30 days. 1

• The only exception is closed-space surgery (intracranial, spinal canal, or posterior chamber eye surgery), where aspirin resumption should be delayed until the surgeon confirms adequate hemostasis and acceptable bleeding risk. 1, 2

For Cardiac Surgery (CABG)

Aspirin should be initiated within 6-48 hours postoperatively to reduce saphenous vein graft closure. 2

• The 2024 ACC/AHA guidelines recommend that patients either continue aspirin through the perioperative period OR be started within 6 hours postoperatively if not previously taking it. 2

• Initial dosing of 100-325 mg daily is appropriate, with higher doses (up to 325 mg daily) continued for up to 1 year, followed by maintenance doses of 75-162 mg daily indefinitely. 2

• Do not delay aspirin initiation beyond 48 hours after CABG, as this increases the risk of graft occlusion. 2

For High Bleeding Risk Procedures

For neurosurgery and other high bleeding risk procedures, aspirin resumption should be delayed until the surgeon confirms adequate hemostasis, but should not be withheld indefinitely. 1

• Thrombotic events cluster early after aspirin discontinuation, with the highest risk in the first 30 days. 1

• The decision requires balancing bleeding risk against thrombotic risk, but aspirin should generally be restarted within 24-48 hours once bleeding concerns are addressed. 1

Dosing Recommendations

• Maintenance dose: 75-100 mg daily for long-term secondary prevention. 3, 2

• Higher initial doses (325 mg daily) may be used for 1-6 months after PCI with stent placement, depending on stent type and thrombotic risk. 2

• For minor procedures (dental, dermatologic, cataract surgery), aspirin should be continued without interruption. 2

Critical Pitfalls to Avoid

Never discontinue both aspirin and clopidogrel simultaneously in patients with recent stent placement (within 6-12 months for DES or 4-6 weeks for BMS). 2

• Avoid withholding aspirin indefinitely postoperatively in cardiovascular disease patients, as the thrombotic risk significantly outweighs bleeding concerns in most cases. 1

• Be aware that clopidogrel takes 4-5 days with maintenance dosing to achieve maximal effect, prasugrel takes 3 days, and ticagrelor takes 2 hours—plan P2Y12 inhibitor resumption accordingly. 1

• Ensure medication reconciliation to identify over-the-counter NSAIDs that can impair aspirin's cardioprotective effects and increase bleeding risk. 1

Patients Without Established Cardiovascular Disease

For patients taking aspirin for primary prevention who underwent noncardiac surgery, aspirin can be discontinued perioperatively and does not need to be restarted, as the POISE-2 trial showed no protective effect and increased bleeding risk in this population. 3