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Aspirin for Prevention and Treatment of Cardiovascular Disease
- Shamir R. Mehta, MD, MSc
- From McMaster University, Hamilton General Hospital, Hamilton, Ontario L8L 2X2, Canada.
Millions of persons worldwide take aspirin on a daily basis for the prevention and treatment of cardiovascular disease. Aspirin inhibits platelets by irreversibly inactivating cyclooxygenase-1, thereby blocking the generation of thromboxane A2, a potent vasoconstrictor and platelet agonist. Despite decades of research, some fundamental questions about aspirin have yet to be definitively answered. In this issue, 2 studies (1, 2) shed light on 2 of these key questions: What is the optimal dose of aspirin to administer to patients for secondary prevention and treatment of established cardiovascular disease and in whom, and when should aspirin be used for prevention of cardiovascular events in persons with no history of cardiovascular disease (primary prevention)?
As background, the Antithrombotic Trialists' Collaboration overview (3) found that antiplatelet therapy (chiefly aspirin) reduced the risk for a subsequent vascular event by about one quarter and vascular death alone by about 15%. Although most of the trials evaluating the effects of aspirin were performed before the widespread use of other effective therapies, such as statins, antihypertensives, and invasive vascular procedures, the combined evidence from these trials is compelling and has led to the universal recommendation of aspirin as standard therapy in patients with established vascular disease. However, because the dose of aspirin in these trials varied from as high as 1500 mg/d to as low as 50 mg/d, the optimal aspirin dose has been uncertain. In an effort to understand the impact of aspirin dosing, the Antithrombotic Trialists' Collaboration overview indirectly compared trials of different aspirin doses versus placebo and found that the relative benefit of aspirin was no greater in the trials of higher doses of aspirin than in trials of lower doses (3). Further observational analyses of aspirin dose in the CURE (Clopidogrel in Unstable angina to prevent Recurrent ischemic Events) trial …
