Treating the non-electrical risks of atrial fibrillation

Atrial fibrillation is a common condition and carries a risk of thromboembolism. There is general acceptance that those patients with atrial fibrillation secondary to valvular (and in particular mitral) heart disease or following valve replacement require anticoagulation. Since patients with non-valvular causes of atrial fibrillation are a more heterogeneous group, the indications for anticoagulation have been less clear. A number of benchmark studies clearly indicate that the risk of stroke can be reduced by up to 70% in those treated with warfarin, but only by a variable 30% with aspirin. Problems with interpretation of the results of these studies relate to the younger age range included and a low recruitment rate, leading to a possible under-estimate of the bleeding risk. Subgroup analysis provides risk stratification for patients with non-valvular atrial fibrillation so that those with three or more of any of the five following risk factors: congestive heart failure, hypertension, previous stroke, left atrial enlargement or left ventricular hypertrophy, have an 18% chance of new thromboembolic events, whereas this falls to one third of this with only one or two risk factors, and 1% with none. Those with so-called lone atrial fibrillation aged < 60 years have a very low incidence of atrial fibrillation and can be considered for aspirin alone. The trials supporting in these statements are presented.