For a patient with a confirmed aspirin allergy requiring percutaneous coronary intervention, which drug‑eluting coronary stent and aspirin‑free antiplatelet regimen should be used?

Management of Aspirin Allergy in Patients Requiring Drug-Eluting Coronary Stents

For patients with confirmed aspirin allergy requiring percutaneous coronary intervention, use a drug-eluting stent with clopidogrel monotherapy (after 1-3 months of dual P2Y12 inhibitor therapy if tolerated), or consider bare-metal stents if the clinical scenario permits only 1 month of antiplatelet therapy. 1

Stent Selection Strategy

Drug-Eluting Stents (Preferred in Most Cases)

• Modern drug-eluting stents are the preferred choice because they reduce restenosis rates compared to bare-metal stents, and recent evidence supports abbreviated dual antiplatelet therapy regimens that can accommodate aspirin-free protocols 2, 1
• Any contemporary drug-eluting stent supported by large-scale randomized trials with clinical endpoint evaluation can be used, as the antiplatelet regimen matters more than the specific stent type in aspirin-allergic patients 2

Bare-Metal Stents (Alternative Option)

• Bare-metal stents require only 1 month of dual antiplatelet therapy, making them the option requiring the shortest duration of combination therapy 1, 2
• Consider bare-metal stents specifically when the patient cannot tolerate any P2Y12 inhibitor beyond 1 month, or when urgent non-cardiac surgery is anticipated within 30 days 1
• The trade-off is higher restenosis rates (requiring repeat revascularization) compared to drug-eluting stents 1

Aspirin-Free Antiplatelet Regimens

Initial Post-PCI Period (First 1-3 Months)

Option 1: Dual P2Y12 Inhibitor Therapy (Preferred if tolerated)

• Load with clopidogrel 600 mg plus ticagrelor 180 mg at the time of stenting 2
• Continue clopidogrel 75 mg daily plus ticagrelor 90 mg twice daily for 1-3 months 2, 3
• This dual P2Y12 inhibitor approach (without aspirin) has been studied in patients requiring anticoagulation and demonstrated reduced bleeding without increased thrombotic events 2

Option 2: Single P2Y12 Inhibitor from the Start (If dual P2Y12 therapy not tolerated)

• Load with clopidogrel 600 mg or ticagrelor 180 mg at the time of stenting 2
• Continue with single agent: clopidogrel 75 mg daily OR ticagrelor 90 mg twice daily 2
• This approach has higher theoretical stent thrombosis risk but may be necessary in aspirin-allergic patients who cannot tolerate dual P2Y12 therapy 1

Long-Term Maintenance (After 1-3 Months)

P2Y12 Inhibitor Monotherapy

• Transition to single P2Y12 inhibitor monotherapy after the initial 1-3 month period 2, 3
• Ticagrelor 90 mg twice daily is preferred over clopidogrel for long-term monotherapy based on superior outcomes in recent trials, with reduced net adverse clinical events and major bleeding compared to continued dual therapy 2, 3
• Clopidogrel 75 mg daily is an acceptable alternative if ticagrelor is not tolerated or contraindicated 2
• Continue P2Y12 inhibitor monotherapy for at least 12 months total from the time of stenting 2, 1

Clinical Scenario-Specific Modifications

Acute Coronary Syndrome Presentation

• Use drug-eluting stents with the dual P2Y12 inhibitor approach initially (clopidogrel plus ticagrelor for 1-3 months), as acute coronary syndrome patients have higher thrombotic risk 2, 3
• Transition to ticagrelor monotherapy after 1-3 months, continuing for at least 12 months total 2, 3
• Avoid bare-metal stents in acute coronary syndrome unless absolutely necessary, as the ischemic risk outweighs restenosis concerns 2

Stable Coronary Artery Disease

• Either drug-eluting stents or bare-metal stents are reasonable options 2
• If using drug-eluting stents, the abbreviated DAPT approach (1-3 months dual P2Y12 therapy followed by monotherapy) is supported by recent evidence showing reduced bleeding without increased ischemic events 2, 3
• If using bare-metal stents, 1 month of single P2Y12 inhibitor therapy followed by indefinite monotherapy is acceptable 1

High Bleeding Risk Patients

• Consider bare-metal stents with 1 month of clopidogrel monotherapy (no dual therapy at all), followed by indefinite clopidogrel monotherapy 2, 1
• If drug-eluting stents are used, limit dual P2Y12 therapy to 1 month only, then transition to single agent 2
• Clopidogrel is preferred over ticagrelor in high bleeding risk patients due to lower bleeding rates 2

Critical Safety Considerations

Stent Thrombosis Risk

• Premature discontinuation of P2Y12 inhibitor therapy is the strongest predictor of stent thrombosis, with a hazard ratio of 161 for subacute thrombosis 1, 4
• Stent thrombosis carries a 40-64% risk of death or myocardial infarction 1, 4
• Never discontinue P2Y12 inhibitor therapy before the minimum recommended duration (1 month for bare-metal stents, 1-3 months for drug-eluting stents with transition to monotherapy) 1, 4

Confirming True Aspirin Allergy

• Ensure the "aspirin allergy" is genuine and not aspirin intolerance (gastrointestinal upset) or other non-allergic adverse effects 2
• True aspirin allergy (anaphylaxis, angioedema, severe urticaria) is rare and justifies aspirin-free regimens 2
• Consider aspirin desensitization in consultation with allergy/immunology if the reaction was not life-threatening, as this would allow standard dual antiplatelet therapy 2

Gastrointestinal Protection

• Initiate a proton pump inhibitor prophylactically in all patients receiving P2Y12 inhibitor therapy, especially if on dual P2Y12 therapy, to reduce gastrointestinal bleeding risk 2, 5

Monitoring and Follow-Up

• Assess for signs of stent thrombosis (recurrent chest pain, ST-elevation myocardial infarction) at every follow-up visit 4
• Evaluate bleeding complications and adjust therapy if major bleeding occurs, but maintain at least single P2Y12 inhibitor therapy if at all possible 2, 4
• Do not use platelet function testing to guide de-escalation of therapy, as this approach is not validated and has been associated with adverse outcomes 2
• After 12 months, continuation of P2Y12 inhibitor monotherapy indefinitely should be based on individual ischemic versus bleeding risk assessment 2

Common Pitfalls to Avoid

• Do not use aspirin monotherapy alone in aspirin-allergic patients—this defeats the purpose of avoiding aspirin 2
• Do not stop all antiplatelet therapy within the first year after stenting, even if bleeding occurs; at minimum, maintain single P2Y12 inhibitor therapy 1, 4
• Do not use prasugrel in aspirin-allergic patients requiring aspirin-free regimens, as prasugrel has not been adequately studied in dual P2Y12 inhibitor combinations and has higher bleeding risk than clopidogrel 2
• Do not extend dual P2Y12 inhibitor therapy beyond 3 months unless there is documented very high thrombotic risk, as bleeding risk increases substantially with prolonged dual therapy 2, 3