Reversal of anti-coagulation--when should you get excited?
Friends and Colleagues:
When I attended the 2008 ASH (American Society of Hematology) annual meeting in San Francisco in
December, I attended a very informative and practical talk by Dr. Mark Crowther of McMaster University on the
topic of anticoagulation reversal.
When you have a patient who is having major bleeding and an INR > 15, it seems pretty clear that immediate
action in the form of factor replacement is needed. What is possibly less well appreciated is that the non-bleeding
patient with prolonged INR of almost any degree rarely if ever should be given infusions of plasma or factor
concentrates.
Dr. Crowther began his talk with fundamental principles: don't lose your cool, stop warfarin, assess the situation, administer antidotes if needed, allow time for anticoagulant drugs to clear.
If the INR is between 5 and 9 and there is no bleeding, the American College of Chest Physicians (ACCP)
recommends holding warfarin and monitoring. If the situation is urgent (i.e. there is high risk of bleeding or
surgery is needed) one can consider giving Vitamin K 1 mg orally (subcutaneous administration is not advised
due to erratic absorption). Dr. Crowther cited four clinical trials that demonstrated that while vitamin K
administration was superior to simple withdrawal of warfarin in reducing the INR, it was not superior in reducing
the incidence of bleeding. Therefore, if you can wait it out, the moral of the story is that simply stopping warfarin and monitoring the INR is an appropriate management strategy, even with an INR as high as 9.
If the INR is higher than 9 and there is insignificant bleeding, higher doses of oral vitamin K (2.5 to 5 mg) and INRmonitoring are suggested.
What if there is major bleeding? The ACCP recommends stopping warfarin, giving IV vitamin K (10 mg, slowly),
giving plasma and/or factor concentrates and repeating IV vitamin K every 12 hours. Dr. Crowther recommended the use of factor concentrates in addition to FFP, since the latter rarely completely corrects the factor deficit,
unless given in unacceptably large volumes. Factor concentrates can provide dramatically fast correction of the INR, in comparison to FFP.
