In clinical practice, low-molecular-weight heparins are used relatively frequently in patients with atrial fibrillation to prevent embolic events. In this article, it is revised the available evidence in the following clinical situations: rapid onset of anticoagulation, bridging therapy (replacing long-term oral anticoagulant therapy around an invasive procedure) and transesophageal echocardiography-guided cardioversion. (C) 2016 Elsevier Espana, S.L.U. and Sociedad Espanola de Medicina Interna (SEMI). All rights reserved.