What antiplatelet therapy can be used in patients undergoing angioplasty who cannot take aspirin (acetylsalicylic acid)?

Antiplatelet Therapy Options for Patients Undergoing Angioplasty Who Cannot Take Aspirin

For patients undergoing angioplasty who cannot take aspirin, a P2Y12 inhibitor (clopidogrel, ticagrelor, or prasugrel) should be used as monotherapy, with clopidogrel being the preferred option in most cases. 1

P2Y12 Inhibitor Monotherapy Options

First-line Option:

• Clopidogrel 75 mg daily (with a 300-600 mg loading dose administered at least 6 hours before the procedure)
  • Recommended duration: at least 1 month for bare-metal stents, 3-12 months for drug-eluting stents 1
  • Class IIa recommendation for patients with absolute contraindication to aspirin 1

Alternative P2Y12 Inhibitors:

• Ticagrelor 90 mg twice daily (with a 180 mg loading dose)

  • Consider for acute coronary syndrome (ACS) patients
  • Higher potency than clopidogrel but requires twice-daily dosing 1, 2

• Prasugrel 10 mg daily (with a 60 mg loading dose)

  • Only for patients undergoing PCI for ACS
  • Not recommended in patients ≥75 years or <60 kg due to increased bleeding risk 3

Procedural Adjunctive Options

For patients undergoing angioplasty without aspirin, consider adding one of the following during the procedure to enhance antithrombotic protection:

• Glycoprotein IIb/IIIa inhibitors (abciximab, eptifibatide, or tirofiban)

  • Should be considered for "bail-out" if there is evidence of no-reflow or thrombotic complications
  • May be considered in P2Y12-inhibitor naïve patients undergoing PCI 1

• Cangrelor (intravenous P2Y12 inhibitor)

  • May be considered in P2Y12-inhibitor naïve patients undergoing PCI
  • Provides immediate platelet inhibition with short half-life 1

Anticoagulation During PCI

All patients should receive anticoagulation during PCI, regardless of antiplatelet regimen:

• Unfractionated heparin (UFH) is recommended as first-line (Class I recommendation) 1
• Enoxaparin should be considered in patients pre-treated with subcutaneous enoxaparin 1
• Bivalirudin may be considered as an alternative to UFH 1

Duration of Therapy

The duration of P2Y12 inhibitor monotherapy should follow the same recommendations as for dual antiplatelet therapy:

• ACS patients with stent: at least 12 months 1
• Non-ACS patients with drug-eluting stent: at least 12 months 1
• Non-ACS patients with bare-metal stent: minimum 1 month, ideally up to 12 months 1

Special Considerations

• High bleeding risk: Consider shorter duration of P2Y12 inhibitor therapy (6 months) 1
• High ischemic risk: Consider longer duration (>12 months) 1
• Platelet function testing: May be considered in patients in whom subacute thrombosis may be catastrophic (unprotected left main, bifurcating left main, or last patent coronary vessel) to adjust clopidogrel dosing 1

Clinical Pitfalls and Caveats

1. Never abruptly discontinue P2Y12 inhibitor therapy after stent placement due to risk of stent thrombosis, which carries high mortality 4, 5

2. Medication adherence is critical, especially with ticagrelor's twice-daily dosing schedule 2

3. For patients requiring non-cardiac surgery after stent placement, postpone elective procedures when possible:

   • At least 3 days after discontinuation of ticagrelor
   • At least 5 days after discontinuation of clopidogrel
   • At least 7 days after discontinuation of prasugrel 1

4. Resumption of P2Y12 inhibitor therapy after surgery should occur as soon as deemed safe to complete the recommended duration 1

5. Monitor for bleeding complications, which are the most common adverse events with P2Y12 inhibitors 3

While aspirin remains the cornerstone of antiplatelet therapy in coronary interventions, P2Y12 inhibitor monotherapy provides an effective alternative for patients with aspirin contraindications, with clopidogrel being the most well-established option for this specific scenario.