What antiplatelet therapy should be used in addition to ticagrelor (ticagrelor) for a patient with ST-Elevation Myocardial Infarction (STEMI) who is allergic to aspirin (acetylsalicylic acid)?

Management of Antiplatelet Therapy in STEMI Patients with Aspirin Allergy

For a STEMI patient with aspirin allergy who has been started on ticagrelor, ticagrelor should be used as monotherapy without adding a second antiplatelet agent. 1

Rationale for Ticagrelor Monotherapy

The ACC/AHA guidelines explicitly state that there are no data supporting therapy with two concurrent P2Y12 receptor inhibitors, and this approach is not recommended in cases of aspirin allergy 1. The guidelines specifically note:

• For aspirin-allergic patients, use either clopidogrel or ticagrelor alone (indefinitely) or try aspirin desensitization 1
• There are no data for therapy with 2 concurrent P2Y12 receptor inhibitors, and this is not recommended in the case of aspirin allergy 1

Management Algorithm for STEMI with Aspirin Allergy

1. Continue ticagrelor monotherapy

   • Dosage: 90 mg twice daily 1
   • Duration: At least 12 months for patients receiving drug-eluting stents (DES) and up to 12 months for patients receiving bare-metal stents (BMS) 1

2. Consider aspirin desensitization

   • This is an alternative approach that may be considered in specialized centers with experience in desensitization protocols 1
   • Would allow for standard DAPT if successfully desensitized

3. Avoid adding a second P2Y12 inhibitor

   • Adding clopidogrel or prasugrel to ticagrelor is not supported by evidence 2
   • Would likely increase bleeding risk without proven additional benefit 2

Important Clinical Considerations

• Ticagrelor efficacy: Ticagrelor provides more potent platelet inhibition compared to clopidogrel, making it a suitable choice as monotherapy 3

• Bleeding risk assessment: Monitor closely for bleeding complications, especially if the patient has other risk factors for bleeding 2

• Drug interactions: Be aware that ticagrelor has different drug interactions than clopidogrel, particularly with CYP3A4 inhibitors/inducers

• Discontinuation timing: When possible, discontinue ticagrelor at least 5 days before any planned surgery 1

• Patient compliance: Emphasize the importance of twice-daily dosing with ticagrelor, as missed doses can lead to inadequate platelet inhibition 1

Common Pitfalls to Avoid

• Adding a second P2Y12 inhibitor: This practice is not evidence-based and may substantially increase bleeding risk 2

• Premature discontinuation: Early cessation of ticagrelor increases risk of stent thrombosis and recurrent ischemic events

• Inadequate patient education: Ensure the patient understands the importance of adherence to the twice-daily dosing schedule

• Failure to consider desensitization: In centers with expertise, aspirin desensitization may be a viable option to allow standard DAPT in selected patients

By following these guidelines, you can provide optimal antiplatelet therapy for your STEMI patient with aspirin allergy while minimizing both thrombotic and bleeding risks.