Yes, absolutely give an aspirin loading dose in acute coronary syndrome (ACS).
In patients with ACS, administer an initial oral loading dose of 162-325 mg aspirin as soon as possible on presentation, followed by daily low-dose aspirin (75-100 mg) to reduce death and major adverse cardiovascular events (MACE). 1, 2
Loading Dose Administration
The aspirin loading dose should be:
- 162-325 mg orally (non-enteric coated)
- Chewed when possible for faster onset of antiplatelet action
- Given immediately upon ACS presentation, regardless of whether invasive or noninvasive management is planned
- Administered even if the patient is already on chronic aspirin therapy 1, 2
For patients unable to take oral medication, rectal or intravenous routes (where available) are acceptable alternatives 1.
Maintenance Dosing
After the loading dose, transition to:
- 75-100 mg daily (non-enteric coated aspirin)
- This low-dose regimen exceeds the minimal effective dose for platelet thromboxane A₂ suppression while accounting for interindividual variability 1
Evidence Strength
This is a Class I, Level of Evidence A recommendation from the 2025 ACC/AHA/ACEP/NAEMSP/SCAI guidelines 1, 2. The recommendation applies to both NSTE-ACS and STEMI patients.
Important Caveats
Avoid high-dose maintenance: Continuing full-dose aspirin (300-325 mg daily) for 30 days after the loading dose was not superior to low-dose aspirin for reducing MACE but increased minor and gastrointestinal bleeding 1.
Ticagrelor interaction: When using ticagrelor as the P2Y12 inhibitor, always use aspirin doses ≤100 mg daily for maintenance based on post-hoc analysis from the PLATO trial showing better outcomes with lower aspirin doses 1.
Aspirin hypersensitivity: If the patient reports aspirin allergy, aspirin desensitization is preferred whenever possible to allow dual antiplatelet therapy. A P2Y12 inhibitor should still be administered with a loading dose as early as possible for patients unable to take aspirin 2.
Reloading Consideration
Even patients already on chronic aspirin therapy should receive the loading dose 1. Recent evidence suggests aspirin reloading reduces thromboxane B₂ and improves platelet reactivity markers 3, though one study raised concerns about potential association with coronary no-reflow after PCI 4. The guideline recommendation remains clear that loading should occur regardless of prior aspirin use.