Antithrombotic treatment in atrial fibrillation.

In comparison with the incidence of a cerebrovascular accident in the general population, atrial fibrillation increases the risk by a factor of five. Although age is without doubt the main risk factor for cerebrovascular accidents in patients with permanent or paroxysmal non-valvular atrial fibrillation, other independent risk factors have been identified : a previous history of hypertension, cerebrovascular accident, heart failure or diabetes. These factors enable identification of a population at risk in which oral anticoagulation may be recommended with an excellent efficacy/risk ratio. Six large scale randomised controlled multicenter trials of primary prevention have been published with a total of over 2 800 patients with non-valvular atrial fibrillation. The combined results of these trials show that treatment with a vitamin K antagonist (INR 2-3) leads to a significant reduction in the risk of an ischaemic cerebrovascular accident of 64 % (95 % CI [51-74]; p < 0.001) and in the risk of death from all causes of 28 % (95 % CI [12-47]; p = 0.038) with a slight increase in the risk of cerebral haemorrhage (+ 2.7 % NS). Although the benefits of aspirin therapy are not as impressive (reduction of the risk of an ischaemic cerebrovascular accident of 22 %; 95 % CI [0-39]; p = 0.053), this alternative may be proposed in patients under 75 years of age without the previously mentioned risk factors. The value of combined aspirin-oral anticoagulant therapy, especially in high risk patients, has not yet been established and is under evaluation.