Episode 88 – DOACs Part 1: Use and Misuse

This is EM Cases Episode 88 - DOACs Part 1: Use and Misuse, DVTs and atrial fibrillation.

As we get better at picking up thromboembolic disease, and the indications for Direct Oral Anticoagulants (DOACs) widen, we're faced with increasingly complex decisions about when to start these medications, how to start them, when to stop them and how to manage bleeding associated with them. There’s a lot that we need to know about these drugs to minimize the risk of thromboembolism in our patients while at the same time minimizing their risk of bleeding.

So with these goals in mind, Dr. Walter Himmel - the walking encyclopedia of EM, Dr. Jim Douketis, one of the world's most published researchers in thrombosis and Dr. Ben Bell, internist extraordinaire will answer such questions as: What are the important patient factors to take into account before starting a DOAC? What baseline blood work is required? How do DOACs work? How does their bleeding risk compare to Warfarin? Are there any practical blood tests to help monitor these drugs? Which patients with isolated calf DVTs require anticoagulation? Which patients with superficial venous thrombosis require anticoagulation? Which patients taking antiplatelet agents who you're starting on a DOAC should be kept on the antiplatelet agent? Which patients with atrial fibrillation should be started on a DOAC in the ED? and many more...



Written Summary and blog post by Anton Helman, edited by Benjamin Bell, November, 2016

Cite this podcast as: Helman, A, Himmel, W, Douketis, J, Bell, B. DOACs Part 1: Use and Misuse. Emergency Medicine Cases. https://emergencymedicinecases.com/doacs-use-misuse/. Accessed [date].

Go to part 2 of this 2-part podcast on DOACs

Important patient factors to take into account before considering DOACs

The following are contraindications, relative contraindications or patient populations in which the evidence for DOACs' effectiveness and safety has not been established.

Older age: In patients >80 years old with atrial fibrillation dose reductions may be required for the DOACs for stroke prevention

Extremes of body weight: Safety data is limited for DOACs in patients 120kg

GFR 3 times the upper limit of normal are contraindications to DOACs.

Pregnancy: DOACs are contraindicated in pregnacy as they cross the placenta and may be teratogenic.

Any history of major bleeding

Baseline bloodwork before starting a DOAC in the ED



* CBC (to look for occult anemia, thrombocytopenia)

* Cr/GFR to screen for renal dysfunction as DOACs are partially metabolized through the kidney

* INR/PTT to screen for underlying bleeding or thrombotic disorder

* Liver panel for patients at risk for liver failure as DOACs are metabolized partially through the liver



How the DOACs work

Dabigatran works as a thrombin inhibitor inhibiting the conversion of fibrinogen to fibrin.

Rivaroxiban and Abixiban are Xa inhibitors and prevent the conversion of prothrombin to its active form thrombin.

Anticoagulation options for patient populations who have a contraindication to DOACs

For patients with active cancer or pregnancy: Full dose LMWH

For patients with severe renal failure: Full dose IV Heparin overlapping with Warfarin for at least 5 days AND until the INR is at least 2.0 for at least 2 days

For patients with body weight 120kg: LMWH overlapping with Warfarin

Anticoagulation assays: Are there practical blood tests for detecting the ...