By Michael P Gulseth, Pharm. D., BCPS, FASHP

Wow, has it been a long time since I wrote a blog post…….

If you read my past posts or spoken to me, you know I’ve had serious concerns on how many were handling factor Xa inhibitor to heparin drip transitions. Some had recommended simply using aptt to manage the transition, such as this article:

http://www.ajhp.org/content/early/2017/02/21/ajhp160168

That article had correctly stated the factor Xa inhibitors have a residual effect on heparin anti-Xa levels…..this is 100% correct. However, my concern from the beginning was this indicates some level of factor Xa inhibition meaning starting heparin immediately may or may not be a good idea. (And we later got data showing heparin anti-Xa levels tend to be linear with apixaban/rivaroxaban serum concdentrations.) I’ve had many, many patients who need to transition to heparin with acute kidney injury where the thrombosis risk to the patient is low, where this approach simply does not make sense in my mind.

We took a different approach. After we published this article

https://academic.oup.com/ajhp/article-abstract/77/Supplement_3/S59/5877082?redirectedFrom=fulltext&login=false

we developed a factor Xa inhibitor to heparin transition guideline that uses either heparin anti-Xa levels or drug specific apixaban/rivaroxaban anti-Xa levels as key drivers in decision making. Our goal was to avoid unnecessary heparin use in low risk situation where we very well may over-anticoagulate the patient, and only risk over-anticoagulation in the highest risk situations. (That is when we would use aPTT monitoring.)

We have now completed and published our comparison of this strategy to a hospital that used aPTT and started heparin when the next apixaban/rivaroxaban dose would be due. We would encourage you to read our article:

https://doi.org/10.1177/10600280221090211

We are so excited to share these results with everyone. We are aware of no other study that has compared large cohorts of patients looking at different strategies to manage this dilemma. While this is not the final word on this topic, we feel these results are promising and do not endorse routine use of aPTT to manage this transition in every patient.  Ignorance of residual apixaban/rivaroxaban may not be bliss……