What is the role of aspirin (acetylsalicylic acid) in the management of Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Role of Aspirin in Non-ST-Elevation Myocardial Infarction (NSTEMI) Management

Non-enteric-coated, chewable aspirin (162 mg to 325 mg) should be given to all patients with NSTEMI without contraindications as soon as possible after presentation, followed by a maintenance dose of aspirin (81 mg/d) indefinitely. 1

Initial Aspirin Administration in NSTEMI

• Aspirin should be administered as soon as possible after presentation in patients with suspected or confirmed NSTEMI 1, 2
• The initial dose should be 162-325 mg of non-enteric-coated, chewable aspirin for more rapid absorption 1, 3
• If oral ingestion is not possible, intravenous (250-500 mg) or rectal administration of aspirin can be considered 2
• Chewing the aspirin tablet hastens absorption, which is critical in acute settings 3, 2

Long-term Aspirin Therapy After NSTEMI

• After the initial loading dose, aspirin should be continued indefinitely at a maintenance dose of 81 mg daily 1, 4
• It is reasonable to use 81 mg per day of aspirin in preference to higher maintenance doses to minimize bleeding risk 1, 4, 5
• For NSTEMI patients treated with bare-metal stents, aspirin 162 to 325 mg per day should be prescribed for at least 1 month, then continued indefinitely at a dose of 75 to 162 mg per day 1
• For NSTEMI patients treated with drug-eluting stents, aspirin 162 to 325 mg per day should be prescribed for at least 3-6 months (depending on stent type), then continued indefinitely at a dose of 75 to 162 mg per day 1

Dual Antiplatelet Therapy (DAPT)

• In addition to aspirin, a P2Y12 inhibitor (clopidogrel, ticagrelor, or prasugrel) should be administered for up to 12 months in NSTEMI patients 1, 6
• Ticagrelor is reasonable to choose over clopidogrel for P2Y12 inhibition in patients with NSTEMI treated with an early invasive strategy 1
• Prasugrel is reasonable to choose over clopidogrel in NSTEMI patients undergoing PCI who are not at high risk of bleeding complications 1
• The combination of aspirin with a P2Y12 inhibitor significantly reduces ischemic events compared to aspirin alone 6, 7

Dosing Considerations and Bleeding Risk

• Lower-dose aspirin (81 mg) is associated with similar efficacy but lower bleeding risk compared to higher doses (325 mg) 4, 5, 8
• High-dose aspirin (325 mg) versus low-dose (81 mg) is associated with greater risk of minor bleeding events, primarily those not requiring hospitalization 5
• The risk of major bleeding requiring hospitalization appears similar between high and low-dose aspirin regimens 5
• For patients at increased risk of bleeding, proton pump inhibitors may be considered, especially in those requiring triple antithrombotic therapy 4

Special Considerations

• For patients with aspirin allergy or intolerance, clopidogrel 75 mg daily is recommended as an alternative 1, 4
• In patients who require long-term anticoagulation (e.g., atrial fibrillation), careful consideration of antithrombotic regimen is needed to balance ischemic and bleeding risks 9
• Triple antithrombotic therapy (anticoagulant plus dual antiplatelet therapy) may be necessary for a limited time in patients with NSTEMI who have indications for anticoagulation 9

Evidence of Benefit

• Aspirin therapy reduces mortality in patients with acute myocardial infarction 1
• The use of aspirin has been shown to reduce recurrent MI and death in patients surviving an initial MI 1, 4
• Meta-analyses have confirmed the benefits of long-term aspirin therapy in patients at high risk of occlusive vascular events, including those with prior MI 4

Aspirin remains a cornerstone of NSTEMI management, with clear benefits for both short and long-term outcomes when used at appropriate doses. The initial loading dose of 162-325 mg followed by a maintenance dose of 81 mg daily provides the optimal balance of efficacy and safety.