Warfarin-Aspirin Reinfarction Study II (2002)


Secondary prevention of myocardial infarction

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To compare the efficacy and safety of warfarin, ASA or both after myocardial infarction

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Trial design

Randomized, open-label study
Active treatment: warfarin (INR 2.8–4.2) (n=1216), or ASA 75 mg daily combined with warfarin (INR 2.0–2.5) (n=1208)
Control treatment: ASA 160 mg daily (n=1206)

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Primary efficacy endpoint: composite of death, non-fatal reinfarction, or thromboembolic stroke, whichever came first
Secondary efficacy endpoints: number of therapeutic interventions (percutaneous coronary intervention, coronary-artery bypass grafting)
Primary safety endpoint: major bleeding events

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Trial participants

3630 patients, younger than 75 years (mean age 60 years), hospitalized for acute myocardial infarction

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Efficacy outcome: A primary outcome event occurred in 203 of 1216 of patients (16.7%) receiving warfarin alone, in 241 of 1206 patients (20.0%) receiving ASA, and in 181 of 1208 (15.0%) of patients receiving both. As compared with ASA alone, the risk reduction in the warfarin plus ASA group was 29% and in the warfarin alone group it was 19%. Between the two groups receiving warfarin the difference was not significant. The total number of therapeutic interventions was 1300: 224 with ASA, 204 with warfarin, and 188 in the combined-therapy group for coronary-artery bypass grafting and 230, 212, and 242, respectively, for percutaneous coronary intervention
Safety outcome: The rates of major, non-fatal bleeding were 0.17% per treatment-year in patients receiving ASA, 0.68% in the group receiving warfarin, and 0.57% in the combined-therapy group. The incidence of minor bleeding episodes was 0.84%, 2.14% and 2.70% per year, respectively

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Efficacy: As compared with ASA alone, therapy with moderate-intensity warfarin combined with ASA and high-intensity warfarin alone resulted in a reduced risk of reinfarction and ischemic stroke
Safety: There were approximately four times as many major bleeding episodes in the two groups receiving warfarin than in the group receiving ASA alone

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Hurlen M, Abdelnoor M, Smith P, Erikssen J, Arnesen H. Warfarin, aspirin, or both after myocardial infarction. N Engl J Med 2002;347:969-9

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Corresponding author

Mette Hurlen, MD, Medical Department, Ullevål University Hospital, N-0407 Oslo, Norway

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