F10 and cardiac arrest: By binding the factor Xa inhibitor medications, andexanet alfa can rapidly reduce anti-factor Xa activity.9,10 Andexanet alfa can therefore reverse factor Xa inhibition and restore endogenous thrombin activity.11 The increased thrombin activity relates to the increased pro-coagulant risks of andexanet alfa, so the package insert carries a boxed warning for the risk of arterial and venous thromboembolic events, ischemic risks, cardiac arrest, and sudden death.11