Systolic heart failure is a common syndrome whose incidence is expected to increase. Several treatment modalities, such as beta-blockers and angiotensin-converting enzyme inhibitors, improve survival. Whether antithrombotic treatment is effective remains to be elucidated, although observations suggest a prothrombotic state in heart failure. This article focuses on this prothrombotic state and discusses the risk of thromboembolic events, pathophysiological mechanisms, and the potential role of anticoagulant treatment.