Fluctuations in Coagulation Activity Among Patients with Atrial Fibrillation who are Stably Anticoagulated

Atrial fibrillation is an important independent risk factor for stroke and increases the risk of systemic embolism. The individual risk depends on several clinical, environmental and biological factors. Additionally, a hypercoagulable state with abnormalities of homeostasis, thrombosis and platelet function have been observed in atrial fibrillation. This arrhythmia is also influenced by a disrupted circadian rhythm of hypercoagulable status implicated in the genesis of cardiovascular and cerebral diseases. The beneficial effect of oral anticoagulation therapy in atrial fibrillation has been confirmed by several studies. However, circadian variations in the degree of anticoagulation in these patients have also been described. In this review, the authors analyze the factors that might condition diurnal variations in thrombogenesis, hypercoagulability, and the extent of anticoagulation in patients with atrial fibrillation.