[Atrial fibrillation and thromboembolic events prevention. State of the art].

Atrial Fibrillation (AF) is a common cardiac arrhythmia and stroke is its most devasting complication. The rate of ischemic stroke among people with AF is approximately six times that of people without AF and varies importantely with coexistent cardiovascular diseases; therefore stratification of AF patients into those at high and low risk of thromboembolism has become a crucial determinant of optimal antithrombotic prophylaxis. Multivaria-te analyses of prospective studies consistently show prior TIA/stroke, diabetes, age, heart failure to be independently predictive of stroke; left ventricular dysfunction is also strongly associated with stroke risk. Several randomized clinical trials demonstrated that treatment with adjusted-dose warfarin reduces the risk of stroke in AF patients by about two thirds. The efficacy of aspirin for prevention of stroke is controversial, but supported by pooled results of 3 placebo-controlled trials yelding a 21% reduction in stroke. The inherent risk of stroke should be considered in selection of AF patients for lifelong anticoagulation. Patients with AF and a recent stroke or TIA or multiple risk factors for stroke are likely to benefit from anticoagulation therapy; at present a target INR 2,5 appears optimal for most patients, although INR closer to 2.0 may be safer for patients at increased risk for bleeding events. The addition of aspirin to low- dose warfarin regimen does not provide any significant benefits and should be avoided. Therapy with aspirin is appropriate for patients who are at low risk of stroke or are unable to receive anticoagulants. AF patients treated with aspirin, should be periodically evaluated for development of high-risk features favoring anticoagulation.