From the Guidelines
Yes, 325 mg aspirin can potentially save a life during a heart attack, and it is recommended to take it immediately if symptoms of a heart attack are present, unless there are contraindications, as it can reduce mortality by preventing further heart damage.
Key Points to Consider
- Aspirin works by inhibiting platelets from forming clots that can block coronary arteries, which can reduce the risk of death during a heart attack 1.
- The recommended dose of aspirin for a heart attack is 1 adult 325-mg tablet, or 2 to 4 low-dose “baby” aspirins (81 mg each), chewed and swallowed, as stated in the 2015 American Heart Association guidelines 1.
- Aspirin should only be taken if the signs and symptoms suggest a heart attack and there are no allergies or contraindications, such as recent bleeding, and the decision to administer aspirin may be deferred to an EMS provider with physician oversight 1.
- It is crucial to call emergency services first, as aspirin is not a substitute for emergency medical care, and people with aspirin allergies, certain bleeding disorders, or who are taking blood thinners should consult with their healthcare provider before taking aspirin 1.
Important Considerations
- Regular low-dose aspirin (usually 81 mg) may be prescribed for some people at high risk of heart attack, but this preventive use should only be done under medical supervision as aspirin carries bleeding risks 1.
- The American College of Cardiology and American Heart Association recommend that patients with STEMI should immediately chew 162 to 325 mg of aspirin on recognition of symptoms, unless there is an absolute contraindication, as stated in the 2009 ACC/AHA guidelines 1.
From the Research
Aspirin Dosage and Cardiovascular Events
- The effectiveness of 325 milligrams of aspirin in preventing cardiovascular events has been studied in various clinical trials 2, 3, 4, 5, 6.
- A study published in the American Journal of Cardiology found that chewing a 325-mg aspirin tablet is the most effective way of accelerating absorption of aspirin into the blood and shortening the time required for an antiplatelet effect 2.
- Another study published in the Journal of the American Heart Association estimated that self-administering 325 mg aspirin within 4 hours of severe chest pain onset could delay 13,016 deaths annually in the US population, after accounting for deaths due to bleeding 3.
Optimal Aspirin Dosage
- The optimal dose of aspirin for preventing myocardial infarction and stroke is uncertain, with different studies recommending various doses ranging from 50 to 325 mg per day 4, 5, 6.
- A study published in the American Journal of Medicine suggested that the appropriate dose of aspirin for primary prevention of stroke and myocardial infarction is at least 160 mg/day 4.
- Another study published in the American Journal of Cardiovascular Drugs found that the optimal aspirin dose remains uncertain, but that a dose range of 75 to 160 mg/day is commonly recommended for secondary prevention of myocardial infarction, stroke, and vascular death 5.
Aspirin and Bleeding Risk
- The risk of major bleeding with aspirin use is a concern, with studies suggesting that the risk is not dose-dependent and can occur even with low doses 4, 5, 6.
- A study published in Current Treatment Options in Cardiovascular Medicine found that bleeding complications are not dose-dependent and can occur with even the lowest doses of aspirin 6.