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Another Study of Anticoagulation After MI

Aspirin plus low-intensity warfarin (INR, 2.0-2.5) was superior to aspirin alone in secondary prevention of MI.

Aspirin is used routinely for secondary prevention after myocardial infarction, but is warfarin better? In this open-label, multicenter, Norwegian trial, 3630 MI patients were randomized to receive warfarin (target international normalized ratio, 2.8-4.2), aspirin (160 mg daily), or both (75-mg aspirin plus warfarin with a target INR of 2.0-2.5).

Mean follow-up was about 4 years. A composite outcome of death, nonfatal MI, and thromboembolic stroke occurred in 20% of the aspirin group, 16.7% of the warfarin group (rate ratio compared with aspirin, 0.81), and 15% of the combination-therapy group (RR compared with aspirin, 0.71). The difference between the 2 warfarin groups was not significant. Serious bleeding (per treatment year) occurred in 0.62% of patients who received any warfarin and in 0.17% of patients who received aspirin only.

Comment: These data support the conclusions of another recent study (Journal Watch Aug 27 2002) that suggested that anticoagulation or combination therapy with aspirin and anticoagulants was superior to aspirin alone in preventing recurrent cardiac events. In earlier studies, investigators had failed to show such an association, possibly because lower INRs were achieved in those trials. However, an editorialist points out that percutaneous coronary interventions (such as angioplasty with stenting), which are common among MI patients in the U.S., make antiplatelet therapies to prevent thrombosis particularly attractive. He predicts that antiplatelet therapy will remain the standard of care in many countries, but the reduction in event rates with combination therapy suggests an added benefit from low-intensity warfarin therapy. It remains to be seen if the safety profile achieved for combination therapy in these clinical trials can be maintained in routine clinical practice.

— Kirsten E. Fleischmann, MD, MPH

Published in Journal Watch General Medicine October 22, 2002

Citation(s):

Hurlen M et al. Warfarin, aspirin, or both after myocardial infarction. N Engl J Med 2002 Sep 26; 347:969-74.

• Medline abstract (Free)

Becker RC. Antithrombotic therapy after myocardial infarction. N Engl J Med 2002 Sep 26; 347:1019-22.

• Medline abstract (Free)

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