From the Guidelines
For acute coronary syndrome (ACS), the recommended initial aspirin dose is 150-300 mg, and a maintenance dose of 75-100 mg daily is advised long-term. This recommendation is based on the most recent and highest quality study, which prioritizes minimizing gastrointestinal bleeding risk while maintaining adequate antiplatelet effect 1. The initial loading dose ensures rapid absorption and platelet inhibition during the acute phase, while the lower maintenance dose provides a balance between efficacy and safety.
Key Considerations
- Aspirin should be given as soon as possible after symptom onset, and it is crucial to use a non-enteric coated formulation to ensure rapid absorption.
- The maintenance dose of aspirin should be continued indefinitely, and patients should be advised not to discontinue it without consulting their healthcare provider.
- A P2Y12 inhibitor, such as prasugrel or ticagrelor, is recommended in addition to aspirin, maintained over 12 months unless there are contraindications such as an excessive risk of bleeding 1.
Aspirin Dosing
- Initial dose: 150-300 mg
- Maintenance dose: 75-100 mg daily It is essential to note that high-dose aspirin (≥160 mg) is associated with increased bleeding risk without improved outcomes, and therefore, the lower maintenance dose is recommended 1. Additionally, enteric-coated aspirin should be avoided initially due to its delayed and reduced absorption 1.
From the Research
Aspirin Dosing in Acute Coronary Syndrome
- The recommended dose of aspirin for patients with acute coronary syndrome (ACS) is not explicitly stated in the provided studies, but it is generally agreed that aspirin should be administered unless contraindicated 2.
- A study from 1995 suggests that a high initial dose of aspirin (500 mg to 1 g) may be beneficial in the acute phase of myocardial infarction, followed by a lower dose (less than 100 mg) for long-term prevention 3.
- Another study from 2007 found that most patients with non-ST-elevation ACS received a dose of 325 mg of aspirin, despite recent studies suggesting that low-dose aspirin (81 mg) may have a better safety profile 4.
- A more recent study from 2024 compared different antiplatelet strategies for patients with ACS undergoing percutaneous coronary intervention and found that aspirin and ticagrelor for 3 months, followed by aspirin and clopidogrel, may be the optimal strategy 5.
Comparison of Aspirin Doses
- A dose of 162.5 mg of aspirin has been shown to be effective during the acute phase of myocardial infarction 3.
- Low-dose aspirin (less than 100 mg) has been demonstrated to decrease infarction and sudden death by more than 30% in stable angina and unstable angina 3.
- A dose of 81 mg of aspirin is commonly used for long-term prevention, but its use is less common in the acute phase of ACS 4.
- Higher doses of aspirin (500 mg to 1 g) may be beneficial in the acute phase of myocardial infarction, but may also increase the risk of bleeding 3.
Clinical Guidelines
- Aspirin is recommended for all patients with suspected ACS unless contraindicated 2.
- Dual antiplatelet therapy (DAPT) with aspirin and another antiplatelet agent (such as clopidogrel, prasugrel, or ticagrelor) is recommended for most patients with ACS 2, 6.
- The choice of antiplatelet agent and the duration of therapy should be individualized based on the patient's risk factors and clinical presentation 5.