What is the dose of aspirin for ST-Elevation Myocardial Infarction (STEMI) and Non-ST-Elevation Myocardial Infarction (NSTEMI)?

From the Guidelines

For STEMI and NSTEMI, the recommended aspirin dose is 162-325 mg given as soon as possible as a loading dose, followed by a maintenance dose of 81 mg daily indefinitely. The initial higher dose should be chewed for faster absorption during the acute event, as this helps to rapidly achieve therapeutic levels of aspirin in the bloodstream, thereby reducing the risk of further clot formation in the coronary arteries 1. Aspirin works by irreversibly inhibiting cyclooxygenase-1 (COX-1), preventing the formation of thromboxane A2 and reducing platelet aggregation, which is crucial in the setting of myocardial infarction where a ruptured plaque has triggered thrombosis 1. Some key points to consider when administering aspirin for STEMI and NSTEMI include:

• The use of non–enteric-coated aspirin to ensure rapid absorption 1
• The avoidance of high-dose aspirin (≥160 mg) for maintenance therapy due to increased bleeding risk without improved outcomes 1
• The potential interaction between aspirin and other medications, such as NSAIDs, which may cause prothrombotic effects 1
• The importance of continuing aspirin therapy even in patients with aspirin allergy, unless they have had anaphylaxis, as the benefit outweighs the risk in this emergency situation 1. Patients should be instructed to take aspirin with food to minimize gastrointestinal side effects during long-term therapy. It is also worth noting that the American College of Cardiology/American Heart Association guidelines recommend a maintenance dose of aspirin (81 mg/d to 325 mg/d) to be continued indefinitely for patients with STEMI and NSTEMI 1.

From the FDA Drug Label

adults and children 12 years and over: take 4 to 8 tablets every 4 hours not to exceed 48 tablets in 24 hours unless directed by a doctor The dose of aspirin for ST-Elevation Myocardial Infarction (STEMI) and Non-ST-Elevation Myocardial Infarction (NSTEMI) is not explicitly stated in the provided drug labels.

• The provided information does not directly address the dose for STEMI or NSTEMI.
• The labels only provide general dosing instructions for adults and children 12 years and over 2. The FDA drug label does not answer the question.

From the Research

Aspirin Dose for STEMI and NSTEMI

• The dose of aspirin for STEMI and NSTEMI has been studied in several trials 3, 4, 5, 6, 7
• A loading dose of 250-500 mg of aspirin is recommended, followed by 75-100 mg/day 4
• In the acute phase of myocardial infarction, a dose of 162.5 mg has been shown to be effective, but higher doses (500 mg to 1 g) may have the advantage of more rapidly and completely blocking platelets 3
• For long-term treatment, doses less than 100 mg, generally 75 mg, have been demonstrated to decrease infarction and sudden death by more than 30% 3
• A study comparing the initial use of 162 versus 325 mg aspirin in fibrinolytic-treated STEMI patients found that the 162 mg dose may be as effective as and perhaps safer than 325 mg for the acute treatment of STEMI 7
• Another study found that high dose IV aspirin loading in STEMI increased intra-hospital mortality, suggesting that further study is necessary to define the optimal dose of intravenous aspirin in STEMI 6

Specific Dosing Recommendations

• For STEMI patients treated with primary angioplasty, a loading dose of 160 mg to 325 mg aspirin, followed by 75-100 mg/day, is recommended 5, 6
• For NSTEMI patients, a loading dose of 250-500 mg of aspirin, followed by 75-100 mg/day, is recommended 4
• For long-term treatment of patients with coronary disease, a dose of less than 100 mg, generally 75 mg, is recommended 3, 5