EFFECT OF TREATMENT WITH LOW-DOSE WARFARIN-ASPIRIN ON ACTIVATED FACTOR-VII

Factor VII is an independent risk factor for ischemic heart disease, W e performed a prospective study to evaluate the effect of combined low -dose warfarin-aspirin on activated factor VII (factor VIIa) and to de termine if abruptly stopping this treatment is associated with a rebou nd in the level of factor VIIa. Thirty-three patients with clinically stable coronary artery disease were treated with combined 3 mg warfari n acid 80 mg aspirin daily for 8 weeks. The factor VIIa level was meas ured before treatment, weekly during treatment, and 2 weeks after stop ping treatment. The mean percent of pretreatment levels of factor VIIa for weeks 1 through 8 of treatment were 60%, 60%, 72%, 70%, 71%, 70%, 74%, and 87%, respectively (P < .05 compared with pretreatment for we eks 1 through 7 inclusive); 2 weeks after stopping treatment, the leve l was 122% (95% confidence interval [Cl]; 111% to 133%; P < .001 compa red with pretreatment). The mean percent level of factor VIIa on-treat ment was 74% (P < .001). Factor VIIa is reduced by 26% on average duri ng treatment, This finding provides further rationale for the antithro mbotic effect of low-dose warfarin, The results suggest a rebound in t he factor VIIa level may occur after treatment is stopped, The potenti al rebound and its clinical importance should be evaluated by further studies. (C) 1995 by The American Society of Hematology.