Does low-intensity warfarin anticoagulation reduce plasma levels of prothrombin activation fragment F1+2 in patients with nonvalvular atrial fibrillation?
Low-intensity warfarin, but not aspirin, significantly suppresses in vivo prothrombin activation (F1+2 levels) in patients with nonvalvular atrial fibrillation, correlating with its clinical efficacy in stroke reduction.
BACKGROUND AND PURPOSE: The Boston Area Anticoagulation Trial for Atrial Fibrillation (BAATAF) demonstrated that low-intensity warfarin anticoagulation can, with safety, sharply reduce the rate of stroke in patients with nonvalvular atrial fibrillation. The beneficial effect of warfarin was presumably related to a decrease in clot formation in the cardiac atria and subsequent embolization. METHODS: To assess the effect of warfarin therapy on in vivo clotting in patients in the BAATAF, we measured the plasma level of prothrombin activation fragment F1+2. One sample was obtained from 125 patients from the BAATAF; 62 were taking warfarin and 63 were not taking warfarin (control group). RESULTS: The warfarin group had a 71% lower mean F1+2 level than the control group (mean F1+2 of 1.57 nmol/L in the control group compared with a mean of 0.46 nmol/L in the warfarin group; P .1). CONCLUSIONS: We conclude that prothrombin activation was significantly suppressed in vivo by warfarin but not aspirin among patients in the BAATAF. These findings correlate with the marked reduction in ischemic stroke noted among patients in the warfarin treatment group observed in the BAATAF.
Kistler et al. (Wed,) studied this question.
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