Detection of a hypercoagulable state in nonvalvular atrial fibrillation and the effect of anticoagulant therapy.

The purpose of the study was to evaluate alterations of the hemostatic system and the effect of anticoagulant therapy in nonvalvular atrial fibrillation. A set of molecular hematologic markers was measured prospectively in 69 patients with atrial fibrillation and 28 age-matched patients in sinus rhythm. Significantly elevated levels of thrombin-antithrombin III complex (8.5 +/- 1.6 vs. 2.5 +/- 0.3 micrograms/l; p < 0.001), fibrin monomers (27.1 +/- 3.2 vs. 13.4 +/- 3.7 nM; p < 0.001), D-dimers (788 +/- 76 vs. 405 +/- 46 micrograms/l; p < 0.005), and tissue-type plasminogen activator (9.6 +/- 0.5 vs. 7.2 +/- 0.5 micrograms/l; p < 0.05) were observed in patients with atrial fibrillation compared to those in sinus rhythm. In a subgroup of patients in whom anticoagulant therapy with oral coumadin or standard intravenous heparin was established after the initial study, hemostatic activation decreased significantly. In conclusion, molecular hematologic markers indicate a hypercoagulable state in atrial fibrillation which may characterized a group of patients at elevated risk of thromboembolic disease.