Hemostatic state and atrial fibrillation (The Framingham Offspring Study)

Atrial fibrillation (AF) is strongly associated with thromboembolic complic ations, although the mechanism for the increased risk has not been fully ex plained. To determine whether AF might be associated with a hypercoagulable state, we studied hemostatic factors in subjects with or without AF in the Framingham Heart Study. In 3,577 subjects, we measured fibrinogen, von Wil lebrand factor antigen, tissue plasminogen activator (tPA) antigen, and pla sminogen activator inhibitor-1 antigen. Forty-seven subjects had AF at the index clinic examination and 15 had AF on a prior examination, but not on t he current examination. Before matching, the 47 subjects with prevalent AF had higher levels of fibrinogen, van Willebrand factor, and tPA antigen tha n those without AF, all p less than or equal to 0.03. Compared with 167 ref erent subjects matched for age, sex, and other risk factors, those with AF had higher tPA antigen levels than those without AF, 11.8 +/- 4.0 ng/ml ver sus 10.5 +/- 3.9 ng/ml (p = 0.04). However, when further stratified accordi ng to their cardiovascular disease status, the differences in hemostatic fa ctors were no longer significant. We conclude that the prothrombotic profil e associated with AF was explained by the risk factors of the subjects and the presence of cardiovascular disease. Nonetheless, the hemostatic changes may contribute toward the propensity for thromboembolic complications in A F. Further prospective studies are needed to evaluate whether measurement o f these and other hemostatic factors will identify patients with AF who are at increased risk for thromboembolic complications, and who may therefore benefit from more intensive therapy. (C) 2001 by Excerpta Medica, Inc.