Can dual antiplatelet therapy (aspirin and a P2Y12 inhibitor) be given before thrombolysis in a patient with ST‑segment‑elevation myocardial infarction?

Can DAPT Be Given Prior to Thrombolysis in STEMI?

Yes, dual antiplatelet therapy should be given before thrombolysis in STEMI patients, specifically aspirin plus clopidogrel, with aspirin administered at 162-325 mg and clopidogrel at 300 mg loading dose (not 600 mg) in patients under 75 years old. 1

Aspirin Administration Before Thrombolysis

• Aspirin 162-325 mg must be given before fibrinolytic therapy as a loading dose 1
• This is a Class I, Level B recommendation from ACC/AHA guidelines 1
• After thrombolysis, aspirin should be continued indefinitely at 81-325 mg daily, with 81 mg being the preferred maintenance dose 1, 2

P2Y12 Inhibitor (Clopidogrel) Before Thrombolysis

• Clopidogrel 300 mg loading dose is recommended on top of aspirin in STEMI patients receiving thrombolysis 1
• This lower loading dose (300 mg, not 600 mg) is specifically for patients under 75 years receiving fibrinolytic therapy 1
• The maintenance dose is 75 mg daily after the loading dose 1

Critical Dosing Distinction Based on Timing

If PCI follows thrombolysis, the clopidogrel dosing changes based on timing:

• Within 24 hours of fibrinolysis: If the patient did not receive a loading dose with thrombolysis, give 300 mg loading dose before or at time of PCI 1
• More than 24 hours after fibrinolysis: Give 600 mg loading dose if no prior loading dose was administered 1
• If already loaded with clopidogrel during thrombolysis: Continue 75 mg daily without additional loading 1

Why Not Prasugrel or Ticagrelor Before Thrombolysis?

• Prasugrel is contraindicated before thrombolysis - it should not be given sooner than 24 hours after administration of a fibrin-specific agent 1
• Ticagrelor and prasugrel are reserved for patients undergoing primary PCI or after coronary anatomy is known 1
• In NSTE-ACS patients where coronary anatomy is unknown, prasugrel is not recommended 1

Safety Profile of DAPT with Thrombolysis

• The combination of aspirin plus clopidogrel with fibrinolytic therapy has demonstrated safety in large trials 1
• No significant excess risk of major bleeding was observed when clopidogrel was added to aspirin in the COMMIT trial, which used 75 mg daily clopidogrel without a loading dose 1
• The 300 mg loading dose recommendation balances efficacy with bleeding risk in the thrombolysis setting 1

Common Pitfall to Avoid

Do not give a 600 mg loading dose of clopidogrel before thrombolysis - this higher dose is reserved for stable CAD patients undergoing PCI or ACS patients receiving PCI more than 24 hours after fibrinolysis 1. The 300 mg dose is specifically chosen for the thrombolysis population to minimize bleeding risk while maintaining antiplatelet efficacy.