Show notes
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].
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 <50kg or >120kg
GFR <30: DOACs are metabolized renally so poor renal function can lead to toxic DOAC concentrations and bleeding.
Active cancer: For patients who are being considered for treatment for venous thromboembolism who have active cancer, DOACs should be avoided because they have not been studied rigorously in this patient population. LMWH remains the drug of choice for venous thromboembolism in patients with cancer.
Drug interactions: Anti-platelet agents, NSAIDs, phenytoin, carbemazepine, antifungals, marcolides, rifampin and anti-retrovirals in combination with DOACs may result in excess bleeding and/or upredictable drug levels.
Poor compliance: The half-life of DOACs are short (approximately 12 hours), and one missed dose may result in a normal coagulation system, increasing the risk for venous and arterial thrmobosis. There is no reliable way to monitor compliance as we do with INR monitoring in patients taking Warfarin.
Liver failure: Overt liver failure or liver enzymes >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
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].
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 <50kg or >120kg
GFR <30: DOACs are metabolized renally so poor renal function can lead to toxic DOAC concentrations and bleeding.
Active cancer: For patients who are being considered for treatment for venous thromboembolism who have active cancer, DOACs should be avoided because they have not been studied rigorously in this patient population. LMWH remains the drug of choice for venous thromboembolism in patients with cancer.
Drug interactions: Anti-platelet agents, NSAIDs, phenytoin, carbemazepine, antifungals, marcolides, rifampin and anti-retrovirals in combination with DOACs may result in excess bleeding and/or upredictable drug levels.
Poor compliance: The half-life of DOACs are short (approximately 12 hours), and one missed dose may result in a normal coagulation system, increasing the risk for venous and arterial thrmobosis. There is no reliable way to monitor compliance as we do with INR monitoring in patients taking Warfarin.
Liver failure: Overt liver failure or liver enzymes >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