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The article presents an overview of the mechanisms involved with thrombogenesis in atrial fibrillation. Atrial fibrillation, the most common cardiac arrhythmia, is associated with the the risk of stroke and thromboembolism. Abnormal changes in the vessel walls including endocardial denudation and aedematous or fibroelastic infiltration of the extracellular matrix are discussed. Changes in the blood constituents including haemostatic and platelet activation and inflammation and growth factor changes comprise Virchow's triad for thrombogenesis.

This article reports on a clinical trial that sought to compare the use of idraparinux to vitamin K antagonists to prevent thromboembolism in patients with atrial fibrillation. Non-valvular atrial fibrillation is the leading cause of stroke and studies have showed that anticoagulation with vitamin K antagonists can reduce the risk of stroke by a third. Despite that, the use of the drugs in clinical practice is limited due to the risk of bleeding and the complexity of monitoring the dosage. Researchers are hoping to find an unmonitored, fixed-dose anticoagulant that will be effective. This study was not the answer. It had to be stopped after patients getting the idrapariux bled excessively.

This article comments on a study in this issue which looked at the risk of stroke in older patients on warfarin or aspirin for atrial fibrillation. The study found warfarin was superior to aspirin in the prevention of stroke and was no more harmful to the patients in terms of major haemorrhage. The author maintains that the subjects of the study had a lower prevalence of risk factors for stroke overall and that the challenge will be to see if the results are the same on higher risk patients.