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Prevention of myocardial infarction and stroke by aspirin: different mechanisms? Different dosage?
1Department of Medicine and Aging, University of Chieti, G. D'Annunzio School of Medicine, Italy. cpatrono@unich.it
Insights
Aspirin (acetylsalicylic acid) at 75 mg daily effectively prevents stroke and death in patients with TIA or minor ischemic stroke. This dose is comparable to higher doses for cardiovascular disease prevention.
Area of Science:
- Cardiovascular Medicine
- Neurology
- Pharmacology
Background:
- Aspirin (acetylsalicylic acid) is a widely used antiplatelet and cardiovascular drug with over 50 trials documenting its efficacy and safety.
- The optimal dosage of aspirin for preventing coronary and cerebral thrombosis remains a subject of debate.
Purpose of the Study:
- To investigate the optimal dose of aspirin for preventing cerebrovascular events.
- To compare the efficacy and safety of different aspirin dosages and antiplatelet agents in patients with cerebrovascular disease.
Main Methods:
- Review of over 50 randomized trials on aspirin's efficacy and safety.
- Analysis of the SALT study (1360 patients with TIA or minor ischemic stroke) comparing 75 mg aspirin/day with placebo.
- Meta-analysis of five trials involving 55,000 patients with ischemic cerebrovascular disease, comparing aspirin (30-300 mg/day) with placebo, clopidogrel, or oral anticoagulants.
Main Results:
- The SALT study demonstrated an 18% reduction in stroke or death risk with 75 mg aspirin/day.
- Aspirin (30-300 mg/day) was found to be more effective than placebo.
- Aspirin was safer than oral anticoagulants and demonstrated comparable efficacy to clopidogrel.
Conclusions:
- The optimal dose of aspirin for preventing secondary events in ischemic heart disease (75-160 mg/day) appears applicable to cerebrovascular disease.
- Mechanistic studies and clinical trials suggest a consistent dose-response relationship for aspirin's antithrombotic effect in both cardiovascular and cerebrovascular diseases.
Abstract:
More than 50 randomized trials have documented the efficacy and safety of aspirin as an antiplatelet agent and a cardiovascular drug. However, the optimal dose for preventing coronary and cerebral thrombosis has long been a cause of debate. For patients with ischaemic heart disease the range recommended for the prevention of a secondary event, based on strong clinical evidence, is 75-160 mg aspirin/day. For patients with cerebrovascular disease, recommendations range from 30-1300 mg/day. If these patients require a higher dose of aspirin it suggests that a different mechanism of action is involved. This paper considers hypotheses and reports the findings of recent clinical trials. The SALT study compared aspirin with placebo in 1360 patients with TIA or minor ischaemic stroke. It showed an 18% reduction in the risk of stroke or death in patients receiving 75 mg aspirin/day. Five other trials of 55,000 patients with ischaemic cerebrovascular disease compared the protective effect of aspirin (range 30-300 mg/day) with placebo, clopidogrel, or oral anticoagulants. Aspirin was better than placebo, safer than oral anticoagulants, and no different from clopidogrel. The implications of these findings are discussed. Mechanistic studies and randomized clinical trials strongly suggest that the mechanism of action and dose requirement of the antithrombotic effect of aspirin in patients with cerebrovascular disease is the same as that for ischaemic heart disease.