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Thromb Haemost 1997; 77(05): 0845-0848
DOI: 10.1055/s-0038-1656065
Clinical Studies
Schattauer GmbH Stuttgart

Effect of Fixed Minidose Warfarin, Conventional Dose Warfarin and Aspirin on INR and Prothrombin Fragment 1 + 2 in Patients with Atrial Fibrillation

B G Koefoed
1   The AFASAK 2 Study Center The Copenhagen General Practitioners’ Laboratory, Copenhagen
,
C Feddersen
2   The Copenhagen General Practitioners’ Laboratory, Copenhagen
,
A L Gulløv
1   The AFASAK 2 Study Center The Copenhagen General Practitioners’ Laboratory, Copenhagen
,
P Petersen
3   The Department of Neurology, Hvidovre University Hospital, Denmark
› Author Affiliations
Further Information

Publication History

Received 19 June 1996

Accepted after revision 10 January 1997

Publication Date:
11 July 2018 (online)

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Summary

The efficacy of conventional dose adjusted oral anticoagulation for stroke prevention in patients with non-valvular atrial fibrillation is well- documented but not considered ideal as primary antithrombotic treatment in elderly patients. The antithrombotic effect of fixed minidose warfarin 1.25 mg/day alone or in combination with aspirin 300 mg/day, of conventional dose adjusted warfarin (INR 2.0-3.0), and of aspirin 300 mg/day have been investigated in outpatients with chronic nonvalvular atrial fibrillation in the second Copenhagen Atrial Fibrillation, Aspirin and Anticoagulant Therapy Study (AFASAK 2). In order to investigate the effect on the coagulation system of the treatments, the International Normalized Ratio of the prothrombin time (INR) and prothrombin fragment 1 + 2 (F1 +2) were monitored at baseline and after three months of treatment in 100 patients consecutively included in the trial. At baseline no differences in INR and F1+2 between the four treatment groups were present. After three months of therapy the level of INR increased significantly from baseline in patients receiving warfarin in any dose and the level of F1+2 decreased significantly by combined minidose warfarin-aspirin and by dose adjusted warfarin. When comparing the changes over time in FI +2 (three-month value minus baseline value) during therapy with fixed minidose warfarin, combined minidose warfarin-aspirin and aspirin alone no significant difference between the groups was found. In conclusion, INR was changed by all three warfarin regimens but only dose adjusted warfarin (INR 2.0-3.0) had a marked effect on F1+2.

 

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