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Low-dose aspirin therapy for chronic stable angina. A randomized, placebo-controlled clinical trial
P M Ridker1, J E Manson, J M Gaziano
1Harvard Medical School, Boston, Massachusetts.
Insights
Low-dose aspirin significantly reduced the risk of myocardial infarction in men with chronic stable angina. However, aspirin therapy may increase stroke frequency, warranting further investigation.
Area of Science:
- Cardiology
- Preventive Medicine
- Clinical Trials
Background:
- Chronic stable angina patients are at high risk for cardiovascular events.
- Primary prevention strategies are crucial for managing this patient population.
Purpose of the Study:
- To assess the efficacy of low-dose aspirin in preventing myocardial infarction (MI) in patients with chronic stable angina.
- To evaluate the impact of aspirin on stroke and cardiovascular death in this high-risk group.
Main Methods:
- Randomized, double-blind, placebo-controlled trial.
- Inclusion of 333 men with chronic stable angina, no prior MI, stroke, or transient ischemic attack.
- Alternate-day aspirin (325 mg) or placebo, with an average follow-up of 60.2 months.
Main Results:
- Aspirin therapy significantly reduced the risk of first myocardial infarction by 87% (relative risk, 0.13; P < 0.001).
- In patients with chronic stable angina, aspirin showed a relative risk of 0.30 for MI (P = 0.003).
- An increased frequency of stroke was observed in the aspirin group (relative risk, 5.4; P = 0.02), though based on small numbers.
Conclusions:
- Alternate-day low-dose aspirin therapy is effective in reducing the risk of first myocardial infarction among patients with chronic stable angina.
- The apparent increase in stroke frequency with aspirin requires confirmation in larger, adequately powered randomized trials.
Objective:
To evaluate the efficacy of low-dose aspirin in the primary prevention of myocardial infarction among patients with chronic stable angina.
Design:
A randomized, double-blind, trial.
Patients:
The study included 333 men with baseline chronic stable angina but with no previous history of myocardial infarction, stroke, or transient ischemic attack who were enrolled in the Physicians' Health Study, a trial of aspirin among 22,071 male physicians.
Intervention:
Patients were randomly assigned to receive alternate-day aspirin therapy (325 mg) or placebo and were followed for an average of 60.2 months for the occurrence of myocardial infarction, stroke, or cardiovascular death.
Results:
During follow-up, 27 patients had confirmed myocardial infarctions; 7 were among the 178 patients with chronic stable angina who received aspirin therapy and 20 were among the 155 patients who received placebo (relative risk, 0.30; 95% CI, 0.14 to 0.63; P = 0.003). While simultaneously controlling for other cardiovascular risk factors in a proportional hazards model, an overall 87% risk reduction was calculated (relative risk, 0.13; CI, 0.04 to 0.42; P less than 0.001). For the subgroup of patients with chronic stable angina but no previous coronary bypass surgery or coronary angioplasty, an almost identical reduction in the risk for myocardial infarction was found (relative risk, 0.14; CI, 0.04 to 0.56; P = 0.006). Of 13 strokes, 11 occurred in the aspirin group and 2 in the placebo group (relative risk, 5.4; CI, 1.3 to 22.1; P = 0.02). No stroke was fatal, but 4 produced some long-term impairment of function. One stroke, in the aspirin group, was hemorrhagic.
Conclusion:
Our data indicated that alternate-day aspirin therapy greatly reduced the risk for first myocardial infarction among patients with chronic stable angina, a group of patients at high risk for cardiovascular death (P less than 0.001). Although our results for stroke were based on small numbers, they suggested an apparent increase in frequency of stroke with aspirin therapy; this finding requires confirmation in randomized trials of adequate sample size.
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