From the Guidelines
The recommended dose of aspirin for acute ischemic stroke is at least 160 mg, given as soon as possible after symptom onset, with a daily maintenance dose of 81-325 mg. According to the 2018 guidelines for the early management of patients with acute ischemic stroke from the American Heart Association/American Stroke Association 1, the safety and benefit of aspirin in the treatment of patients with AIS were established by 2 large clinical trials administering doses between 160 and 300 mg. The Canadian Stroke Best Practice Recommendations for acute stroke management also support this dose, recommending at least 160 mg of acetylsalicylic acid (ASA) immediately as a one-time loading dose after brain imaging has excluded intracranial hemorrhage and after dysphagia screening has been performed and passed 1.
Key points to consider when prescribing aspirin for acute ischemic stroke include:
- The initial dose should be given as soon as possible after symptom onset
- The daily maintenance dose should be continued indefinitely or until an alternative antithrombotic regime is started
- Patients should take aspirin with food to minimize gastrointestinal side effects
- Those with aspirin allergies, active bleeding, or certain other conditions may require alternative antiplatelet therapy
- Aspirin is not recommended for hemorrhagic strokes as it may worsen bleeding
It's also important to note that in patients treated with tissue plasminogen activator (alteplase), initiation of antiplatelet agents should be delayed until after the 24-h post-thrombolysis scan has excluded intracranial hemorrhage 1. In dysphagic patients, ASA may be given by enteral tube or by rectal suppository 1.
From the Research
Aspirin Dose in Stroke Prevention
- The appropriate dose of aspirin for stroke prevention is still a topic of debate, with various studies suggesting different doses 2, 3.
- A study published in 2009 found that aspirin doses as low as 30 mg/day can reduce secondary stroke, MI, or vascular death in patients with ischemic stroke 2.
- Another study published in 2006 suggested that the appropriate dose of aspirin for primary and secondary prevention of stroke and MI is 160 mg/day, as it consistently lowered the risk of MI in men and was effective in preventing recurrent stroke or death in patients with a history of stroke or TIA 3.
- In acute stroke, a dose of 160 mg/day is effective in preventing recurrent stroke or death, with a similar risk of major bleeding as 80 mg/day 3.
- The Examining the Safety of Loading of Aspirin and Clopidogrel in Acute Ischemic Stroke and TIA (LOAD) study used a dose of 325 mg of aspirin, which showed improvement in 37.5% of patients 2.
Combination Therapy with Aspirin and Clopidogrel
- Dual antiplatelet therapy (DAPT) with clopidogrel and aspirin may provide greater protection against subsequent stroke than monotherapy 4, 5, 6.
- A meta-analysis published in 2019 found that DAPT was associated with significantly lower rates of any stroke and ischemic stroke, but also increased the risk of intracranial bleeding and major bleeding 4.
- Another study published in 2019 found that the addition of clopidogrel to aspirin significantly reduced the risk of ischemic stroke recurrence, but increased the risk of bleeding compared to aspirin alone 5.
- A systematic review and meta-analysis published in 2021 found that clopidogrel plus aspirin was more effective than aspirin alone in reducing the risk of recurrent stroke, but increased the risk of major bleeding events 6.