Research on InStability in Coronary Artery Disease (1990)


Treatment of unstable coronary artery disease

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To examine if low-dose ASA (75 mg/day) for up to 1 year and/or heparin during the initial 5 days have any effect on the incidence of myocardial infarction and mortality in men after an episode of unstable coronary artery disease

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Trial design

Prospective, randomized, double-blind placebo-controlled study
Active treatment: ASA 75 mg once daily up to 1 year; heparin 5000 IU/ml, injected 6-hourly (2 ml) during the first 24 hours followed by 15 ml 6-hourly for 4 days
Control treatment: oral and i.v. placebo
2x2 factorial design:

  • ASA + heparin placebo (n=189)
  • ASA + heparin (n=210)
  • ASA placebo + heparin (n=198)
  • ASA placebo + heparin placebo (n=199)


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Primary efficacy endpoint: myocardial infarction and death
Secondary efficacy endpoint: revascularization
Safety endpoints: hemorrhagic and other adverse events

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Trial participants

796 patients (only male, aged >70 years, mean age 58 years) with unstable coronary artery disease (defined as non-Q wave myocardial infarction or increasing angina within last 4 weeks)

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Efficacy outcome: At 5 days and thereafter, low-dose ASA given alone or with heparin reduced the rate of myocardial infarction and death by
57–69% compared with heparin alone and placebo treatment. The highest risk reduction was seen in the patients treated with ASA plus heparin. Treatment with heparin alone did not alter the event rates. In the ASA + placebo group occurred fewer cases of revascularization than in the oral placebo group: 0.8% vs. 2.8% after 1 month, 2.5% vs. 5.3% after 3 months
Safety outcome: Hemorrhages due to ASA ware rare and minor, but more frequent than with placebo

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Efficacy: Treatment with ASA 75 mg daily reduces the risk of myocardial infarction by 50% at 3 months after an episode of unstable coronary artery disease in men. The combination of ASA and heparin may be more effective during the initial hospital period
Safety: There was no increased risk of severe bleeding

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The RISC Group. Risk of myocardial infarction and death during treatment with low dose aspirin and intravenous heparin in men with unstable coronary artery disease. Lancet 1990;326:827-830

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Corresponding author

L. Wallentin, MD, Division of Cardiology, University Hospital, S-581 85 Linköping, Sweden

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