More on Venous Thrombosis during Spaceflight

To the Editor: Auñón-Chancellor and colleagues (Jan. 2 issue)¹ report a case of internal jugular venous thrombosis during spaceflight. The astronaut was initially treated with low-molecular-weight heparin that was available on-board the International Space Station. Subsequently, apixaban was delivered to the space station for longer-term anticoagulation, along with protamine and prothrombin complex concentrate for potential anticoagulation reversal. The ability of protamine to reverse the anticoagulant effect of low-molecular-weight heparin is limited, and its use for this purpose is not supported by scientific data.² However, the effects of low-molecular-weight heparin and apixaban are reversible with andexanet alfa, which we would have . . .