FECAL HEMOGLOBIN EXCRETION IN ELDERLY PATIENTS WITH ATRIAL-FIBRILLATION - COMBINED ASPIRIN AND LOW-DOSE WARFARIN VS CONVENTIONAL WARFARIN THERAPY

Background: Antithrombotic prophylaxis using combined aspirin and low- dose warfarin is under evaluation in several clinical trials. However, combination therapy may result in increased gastrointestinal blood lo ss and clinical bleeding vs conventional single-agent antithrombotic t herapy. Methods: To assess differences in gastrointestinal blood loss, we measured quantitative fecal hemoglobin equivalents (HemoQuant, May o Medical Laboratory, Rochester, Minn) in 117 patients, mean age 71 ye ars, 1 month after initiation of assigned therapy in the Stroke Preven tion in Atrial Fibrillation III Study. Sixty-three of these patients w ho had characteristics for high risk of stroke were randomly assigned to conventional adjusted-dose warfarin therapy (international normaliz ed ratio, 2.0 to 3.0) or low-dose combined therapy (warfarin [internat ional normalized ratio, <1.5] plus 325 mg/d of enteric-coated aspirin) . The remaining 54 patients with low risk of stroke received 325 mg/d of enteric-coated aspirin. Results: hmong the 63 patients at high risk of stroke, abnormal values (>2 mg of hemoglobin per gram of stool) we re detected in 11% and values greater than 4 mg of hemoglobin per gram of stool were found in 8%, Mean (+/-SD) values were more for those ra ndomly assigned to receive combined therapy (1.7+/-3.3 mg of hemoglobi n per gram of stool vs adjusted-dose warfarin therapy, 1.0+/-1.9 mg/g; P=.003), The 54 nonrandomized patients with low risk of stroke receiv ing aspirin alone had a mean (+/-SD) HemoQuant value of 0.8+/-0.7 mg o f hemoglobin per gram of stool 1 month after entry in the study. Concl usions: Abnormal levels of fecal hemoglobin excretion were common in e lderly patients with high risk of atrial fibrillation 1 month after ra ndomization to prophylactic antithrombotic therapy. Combined warfarin and aspirin therapy was associated with greater fecal hemoglobin excre tion than standard warfarin therapy, suggesting the potential for incr eased gastrointestinal hemorrhage.