NAPLEX Question of the Week: Anticoagulation Assessment

A common disease state is the subject of our question of the week

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An 70 year old female reports to her PCM with reports of mild lightheadedness but is hemodynamically stable and otherwise feels well. Her past medical history is significant for HFrEF, Type II DM, GERD, and allergic rhinitis. She weighs 50kg and has a serum creatinine of 1.0 mg/dL.  Upon workup she is diagnosed with atrial fibrillation. Which of the following regimens would be appropriate for managing her atrial fibrillation long-term? Select all that apply. 

A. Eliquis 10mg BID for one week, followed by 5mg BID

B. Xarelto 15mg once daily with evening meal

C. Savaysa 30mg once daily

D. Lovenox 30mg SC BID

E. Aspirin 81mg daily

Answer with rationale: 

The correct answers are B and C. Our patient has atrial fibrillation which puts her at significant risk for morbidity and mortality related to a potential cardioembolic stroke. In order to gauge her overall risk for stroke, a CHA2DS2-Vasc score should be calculated. The components of the CHA2DS2-VASc score are C (Congestive Heart Failure), H (Hypertension), A (Age > 75), D (Diabetes mellitus), S (Previous stroke or TIA), V (Vascular disease), A (Age 65-74), S (Sex Category-Female). All of these would earn one point for the calculation except previous stroke or TIA or age > 75 which if present would be worth two points. The female sex if only risk factor does not count as a point (only counts if present with another risk factor).  Our patient's CHA2DS2-VASc score would be a 4 due to female sex, diabetes, age 70, and presence of heart failure. Aspirin therapy would not be indicated (answer E) as this is not an anticoagulant which is recommended in all males with a score of 2 or greater and females with a score of 3 or greater. Answer D is incorrect as this is a venous thromboembolism prophylaxis dose, not a treatment dose for atrial fibrillation. Low molecular weight heparins can be used in some circumstances to "bridge" patients to warfarin in acute atrial fibrillation but this is more common in the inpatient setting in patients who are not stable. Answer A is incorrect as this is dosing for apixaban in patients with newly diagnosed DVT/PE, not atrial fibrillation. Therefore this leaves answer B which is correct due to renal dosing requirement of rivaroxaban (calculated CrCl ~41 ml/min) when CrCl between 15 and 50ml/min. Answer C is correct as well as this is the correctly renally dosed edoxaban (60mg once daily used in patients with > 50 to < or = 95ml/min. Of note, Savaysa (edoxaban) is not recommended in patients with estimated CrCl > 95ml/min due to increased risk of stroke likely due to a somewhat abrupt discontinuation each day in patients with excellent kidney function. No direct oral anticoagulants (DOACs) should be stopped abruptly due to increased risk of stroke. The latest 2019 AHA/ACC guidelines recommend DOACs over warfarin when possible. The latest guidelines can be found here: https://www.ahajournals.org/doi/epub/10.1161/CIR.0000000000000665

See everyone next week!

Dr. B

Christopher M. Bland

Clinical Professor, University of Georgia College of Pharmacy

Dr. Christopher M. Bland is a Clinical Professor at the University of Georgia College of Pharmacy at the Southeast GA campus in Savannah, GA. Dr. Bland has over 20 years of academic and clinical experience in a number of clinical areas. He is a Fellow of both the Infectious Diseases Society of America as well as the American College of Clinical Pharmacy. He is co-founder of the Southeastern Research Group Endeavor, SERGE-45, with over 80 practitioners across 14 states involved. Dr. Bland serves as Associate Editor for the NAPLEX Review Guide 4th edition as well as Editor-In-Chief for the Question of the Week. He has provided live, interactive reviews for more than 10 Colleges/Schools of Pharmacy over the course of his career.