My elderly patient on anticoagulation for non-valvular atrial fibrillation was admitted for evaluation of a fall. Should I discontinue her anticoagulation long term because of potential for intracranial hemorrhage from future falls?

Although there may always be hesitation in resuming anticoagulation (AC) in patients with non-valvular atrial fibrillation (NVAF) and recent fall(s), the weight of the evidence suggests that most patients are still more likely to benefit from AC than be adversely impacted by intracranial hemorrhage.
An often-quoted systematic review article on the risks and benefits of anti-thrombotic (AC or aspirin) therapy in patients with NVAF at risk estimated that persons taking warfarin must fall 295 times in 1 year for warfarin to not be the optimal therapy for reducing the risk of stroke (1). The authors concluded that “a history of and/or the presence of risk factors for falls should not be considered important factors in the decision whether to offer antithrombotic (especially warfarin) therapy to elderly patients with atrial fibrillation”.
In another study involving older adults with NVAF, although a history of falls or documented high risk of falling was associated with a risk of intracranial hemorrhage, this risk did not differ among patients treated with warfarin, aspirin or no antithrombotic therapy (2).
Ultimately, the decision to prescribe AC in patients with NVAF at risk for falls should be made based on shared decision making with patients and caregivers. However, in the absence of absolute contraindications for AC in these patients (eg, intracranial hemorrhage or neurosurgical procedure with high risk for bleeding within the past 30 days, an intracranial neoplasm or vascular abnormality with high risk of bleeding, recurrent life-threatening gastrointestinal or other bleeding events, and severe bleeding disorders), perceived or actual risk of falls by itself should not automatically exempt a patient from receiving AC in NVAF (3).

 

Although much of the data on the relative risk of bleeding against prevention of strokes has been derived from studies involving warfarin, it is reassuring that the risk of intracranial bleed has been lower than that of warfarin for several newer non-vitamin K antagonist direct oral anticoagulants (NOACs or DOACs),  including dabigatran, rivaroxaban, edoxaban and apixaban (4). 

 

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References

1. Man-Son-Hing M, Nichol G, Lau A, et al. Choosing antithrombotic therapy for elderly patiets with atrial fibrillation who are at risk for falls. Arch Intern Med 1999;159:677-685.
2. Gage BF, Birman-Deych E, Kerzner R, et al. Incidence of intracranial hemorrhage in patients with atrial fibrillation who are prone to fall. Am J Med 2005;118:612-617.
3. Hagerty T, Rich MW. Fall risk and anticoagulation for atrial fibrillation in the elderly: a delicate balance. Clev Clin J 2017;84:35-40.

4. Lopez RD, Guimaraes PO, Kolls BJ, et al. Intracranial hemorrhage in patietns with atrial fibrillation receiving anticoagulation therapy. Blood 2017;129:2980-87. 

My elderly patient on anticoagulation for non-valvular atrial fibrillation was admitted for evaluation of a fall. Should I discontinue her anticoagulation long term because of potential for intracranial hemorrhage from future falls?

Should prothrombin complex concentrates be used to reverse anticoagulation from direct factor Xa inhibitors?

Due to insufficient and occasionally conflicting evidence, the use of prothrombin complex concentrates (PCCs) for reversal of direct factor Xa inhibitors (eg, rivaroxaban, apixaban, and edoxaban) is NOT recommended.1 This is because PCCs have no effect on the anti-Xa assay, the most accurate measure of anticoagulation for direct factor Xa inhibitors.

Although several in vitro and in vivo studies initially suggested that PCCs may be effective for this purpose, anti-Xa activity has not been measured in these studies2-4; PT and aPTT are not reflective of the anticoagulation activity of direct factor Xa inhibitors.

In fact, a 2014 study found no difference in the anti-Xa activity between 11 patients on rivaroxaban who were given a 4-factor PCC (Beriplex®, the European brand name for Kcentra®) and 12 patients on rivaroxaban receiving saline.5 Though small, this is the best published in vivo data to date examining the effect of 4-factor PCC on the anti-Xa levels of patients on direct factor Xa inhibitors.

A theoretical concern with the use of PCCs is increased risk of thrombosis when the therapeutic effect of these direct oral anticoagulant (DOACs) is gone (half-life ~12 h) while the thrombogenic effects of PCCs persist (eg, in critically ill, postoperative, or sedentary patients).

The good news is that more specific reversal agents are in the pipeline. 1 Stay tuned! 

 

References:

  1. Dzik WH. “Reversal of oral factor Xa inhibitors by prothrombin complex concentrates: a re-appraisal.” J Thromb Haemost 2015;13 (Suppl 1):S187-94. https://www.ncbi.nlm.nih.gov/pubmed/26149022
  2. Perzborn E, Heutmeier S, Laux V, et al. “Reversal of rivaroxaban-induced anticoagulation with prothrombin complex concentrate, activated prothrombin complex concentrate and recombinant activated factor VII in vitro.” Thromb Res 2014 Apr;133:671-81. https://www.ncbi.nlm.nih.gov/pubmed/24529498
  3. Eerenberg ES, Kamphuisen PW, Sijpkens MK, et al. “Reversal of rivaroxaban and dabigatran by prothrombin complex concentrate: a randomized, placebo-controlled, crossover study in healthy subjects.” Circulation 2011 Oct 4;124:1573-9. https://www.ncbi.nlm.nih.gov/pubmed/21900088
  4. Zahir H, Brown KS, Vandell AG, et al. “Edoxaban effects on bleeding following punch biopsy and reversal by a 4-factor prothrombin complex concentrate.” Circulation 2015 Jan 6;131:82-90. https://www.ncbi.nlm.nih.gov/pubmed/25403645
  5. Levi M, Moore KT, Castillejos CF, et al. “Comparison of three-factor and four-factor prothrombin complex concentrates regarding reversal of the anticoagulant effects of rivaroxaban in healthy volunteers.” J Thromb Haemost 2014;12:1428-36. https://www.ncbi.nlm.nih.gov/pubmed/24811969

Contributed by Hanny Al-Samkari MD, Mass General Hospital, Boston, MA.

 

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Should prothrombin complex concentrates be used to reverse anticoagulation from direct factor Xa inhibitors?

Should I consider a direct oral anticoagulant for treatment of pulmonary embolism in my obese patient?

Evidence supporting the efficacy of direct oral anticoagulants (DOACs) in obesity is limited. A major concern is the possibility of subtherapeutic anticoagulation in obese patients when standard doses of DOACs are used.

The International Society on Thrombosis and Haemostasis recommends1:

  • Standard fixed dosing of DOACs for patients with BMI ≤ 40 kg/m2 or weight ≤ 120 kg.
  • Avoiding DOACs in patients with BMI > 40 kg/m2 or weight > 120 kg. However, if a DOAC is needed, laboratory confirmation of therapeutic drug concentrations (eg, by checking anti-factor Xa depending on the agent) should be performed, and if subtherapeutic, a vitamin K antagonist (eg, warfarin) is recommended instead.

Based on the individual comparison of DOACs with warfarin in patients with “high” body weight (cut-off of 90 kg or 100 kg, depending on the study) and limited data, apixaban may be more effective in preventing recurrent venous thromboembolism or its related deaths. However, other DOACs, such as rivaroxaban, dabigatran, and edoxaban have also been used in patients with high body weight2.  

To add to the controversy, the efficacy of fixed dose dabigatran in obese patients has been questioned3 and some have recommended avoiding DOACs altogether in patients with BMI ≥ 35 kg/m2 or weight > 120 kg, until more data become available4.

As in many situations in medicine, a case-by-case decision based on clinical judgment and patient preferences may be the best way to go!

References

  1. Martin K, Beyer-Westendorf J, Davidson BL, et al. Use of the direct oral anticoagulants in obese patients: guidance from the SSC of the ISTH. J Thromb Haemost 2016; 14: 1308–13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4936273
  2. Di Minno MN, Lupoli R, Di Minno A, et al. Effect of body weight on efficacy and safety of direct oral anticoagulants in the treatment of patients with acute venous thromboembolism: A meta-analysis of randomized controlled trials. Ann Med 2015; 47: 61-8. https://www.ncbi.nlm.nih.gov/pubmed/25665582
  3. Breuer L, Ringwald J, Schwab S, et al. Ischemic Stroke in an Obese Patient Receiving Dabigatran. N Engl J Med 2013; 368: 2440–2. http://www.nejm.org/doi/pdf/10.1056/NEJMc1215900
  4. Burnett AE, Mahan CE, Vasquez SR, et al. Guidance for the practical management of the direct oral anticoagulants (DOACs) in VTE Treatment. J Thromb Thrombolysis 2016; 41: 206-32. https://www.ncbi.nlm.nih.gov/pubmed/26780747

 

Contributed by Mahesh Vidula, MD, Mass General Hospital, Boston, MA.

Should I consider a direct oral anticoagulant for treatment of pulmonary embolism in my obese patient?

Can novel oral anticoagulants (NOAC) be reversed?

Since their relatively recent introduction, a major concern over NOAC use has been the lack of available reversal agents akin to vitamin K or fresh frozen plasma used to reverse anticoagulation effect of warfarin.

Fortunately, there are currently 2 FDA-approved NOAC reversal agents (idarucizumab and andexanet alfpha) and 1 NOAC on breakthrough or fast-track status at the FDA (1,2):

  • Idarucizumab, a humanized mouse antibody fragment, or Fab, targeted specifically for reversal of dabigatran. FDA approved
  • Andexanet alfa, a class-specific antidote for reversal of direct factor Xa inhibitors (apixaban, rivaroxaban, edoxaban), as well as an indirect factor Xa inhibitor, enoxaparin. FDA approved
  • Ciraparantag (PER977), a synthetic water-soluble compound that reverses direct thrombin (dabigatran), direct factor Xa (apixaban, rivaroxaban, edoxaban), and indirect factor Xa inhibitors (enoxaparin). Currently under investigation.

 

1. Ansell JE. Universal, class-specific, and drug-specific reversal agents for the new oral anticoagulants. J Thromb Thrombolysis 2016;41:248-52.  https://www.ncbi.nlm.nih.gov/pubmed/26449414

2. Connolly SJ, Milling TJ, Eikelboom JW, etal.  Andexanet alfa for acute major bleeding associated with factor Xa inhibitors. N Eng J Med 2016;375:1131-41. https://www.nejm.org/doi/full/10.1056/NEJMoa1607887

Contributed in part by William L. Hwang, MD, Mass General Hospital, Boston, MA.

Can novel oral anticoagulants (NOAC) be reversed?