Replacement of traditional prothrombin time monitoring with the new Fiix prothrombin time increases the efficacy of warfarin without increasing bleeding. A review article.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadThe antithrombotic effect of vitamin K antagonists (VKA) depends on controlled lowering of the activity of factors (F) II and X whereas reductions in FVII and FIX play little role. PT-INR based monitoring, however, is highly influenced by FVII, which has the shortest half-life of vitamin K-dependent coagulation factors. Hence, variability in the anticoagulant effect of VKA may be partly secondary to an inherent flaw of the traditional monitoring test itself. The Fiix prothrombin time (Fiix-PT) is a novel test that is only sensitive to reductions in FII and FX and is intended to stabilize the VKA effect. Two clinical studies have now demonstrated that when warfarin is monitored with the Fiix-PT based normalized ratio (Fiix-NR) instead of PT-INR, anticoagulation is stabilized and less testing and fewer dose adjustments are needed. Furthermore, the relative risk of thromboembolism was reduced by 50-56% in these studies without an increase in major bleeding. Keywords: Fiix; Monitoring; Oral anticoagulation; Prothrombin time; Warfarin.RANNIS technology development fund (The Icelandic Center for Research