Thrombosis and thromboprophylactic strategies in the adult with Fontan circulation

The Fontan procedure has evolved into the treatment of choice for infants with single ventricle physiology. The procedure and its modifications have extended survival of such patients into adulthood. However, adult patients face late complications, of which thromboembolic events (TEE) are considered complex and challenging in pathophysiology and management. All three components of Virchow's triad are affected in Fontan circulation. Remarkably, thromboembolic risk varies among the different iterations of the Fontan procedure and is highest with the atrio-pulmonary connection. Regarding TEE prevention, vitamin K antagonists (VKAs) are considered the agent of choice, although not clearly superior versus antiplatelet treatment. Data on non-vitamin K antagonist oral anticoagulants (NOACs) in adult Fontan individuals are recently mounting, showing short-term safety and efficacy. This paper aims to discuss the main pathophysiological mechanisms of Fontan thromboembolism, present strengths and limitations of current TEE prevention therapies and summarise current data regarding the use of NOACs as an emerging thromboprophylactic strategy in the Fontan population.