Episode 73 - Anticoagulants in Afib - a podcast by Rio Bravo Family Medicine Residency Program

Episode 73: Anticoagulation in Afib. 

When should you start anticoagulation in atrial fibrillation? What medications are appropriate? Virginia Bustamante, Charizza Besmanos and Dr Arreaza discuss this topic.  
By Charizza Besmanos, MS4; Virginia Bustamante, MS4; and Hector Arreaza, MD

Charizza: Hello, welcome to today’s episode of Rio Bravo qWeek Podcast. My name is Charizza Besmanos, a 4th year medical student from American University of the Caribbean and I am joined here today by Virginia Bustamante. 

 

Virginia: I’m Virginia Bustamante, an incoming 4th year medical student from Ross University. 

 

Arreaza: And I’ll be here just to make sure that you guys behave during this episode.

 

Charizza: Before we get started on our discussion, I have a quick patient case to share with you. 

 

This is a 66-year-old woman who is brought to the ED with sudden onset of severe difficulty speaking and weakness while having breakfast. She has hypertension, hyperlipidemia, severe left atrial enlargement seen on previous ECHO, and is noncompliant with her medications. She is a lifetime nonsmoker and does not drink alcohol. On admission, her blood pressure is 152/90 and pulse is 124/min and irregularly irregular. She is awake and alert but has difficulty finding words while trying to speak. She has severe right lower facial droop and marked weakness and sensory loss in the right arm and mild weakness in right leg. Fingerstick glucose is at 105. ECG shows atrial fibrillation. Acute stroke management is started right away. CT shows occlusion of the left MCA. What management could have prevented this complication? 

 

Virginia: This patient clearly has multiple risk factors for thromboembolism events but given her irregularly irregular pulse consistent with atrial fibrillation, she would’ve warranted long-term anticoagulation to prevent stroke, which she most likely had. 

 

Charizza: Exactly. Today’s topic is atrial fibrillation, specifically the use of anticoagulation.

 

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This is Rio Bravo qWeek, your weekly dose of knowledge brought to you by the Rio Bravo Family Medicine Residency Program from Bakersfield, California. Our program is affiliated with UCLA, and it’s sponsored by Clinica Sierra Vista, Let Us Be Your Healthcare Home. 

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Virginia: Anticoagulation is indicated to decrease the risk of thromboembolic events such as ischemic stroke in patients with atrial fibrillation (A-fib). Not all patients receive anticoagulation. Like most things in medicine, you must decide to start anticoagulation when the benefits of decreasing the risk of stroke outweighs the risk of bleeding. So, for assessing the risk of stroke in A-fib, the American College of Cardiology along with American Heart Association and the Heart Rhythm Society published a guideline in the Journal of the American College of Cardiology in 2014 and was recently updated in 2019[1] detailing in which patients anticoagulation is recommended. 

 

Charizza: Yes, according to the guideline, “high risk patients” are all patients with valvular A-fib, and those with nonvalvular A-fib with a CHADVASC score of >/= 2 in men or >/= 3 in women, and those with nonvalvular Afib and hypertrophic cardiomyopathy. Those with “medium risk” are patients with nonvalvular Afib with CHAD2VASc score of 1 in men or 2 in women. In these patients, anticoagulation is considered but the risk and benefits are discussed with the patient. Those with “low risk” are patients with CHAD2VASc score of 0 in men or 1 in women and anticoagulation is not routinely recommended in these patients. Can you tell us briefly what CHA2DVASc score is? 

 

Virginia: CHA2DS2-VASc score is the stroke risk assessment tool of choice by the AHA/ACC/HRS guideline. It is great because it is a mnemonic. Each letter is assignment 1 point except for 2 criteria. C stands for congestive heart failure, H for HTN defined as >140/90, A2 is for or Age>75 which is for 2 points, D for diabetes, S2 is for stroke or TIA and it’s for 2 points, V for vascular disease such as MI, A for age 65-74, S for female sex. 

 

Charizza: That certainly makes it easy to remember. Not only that, but you can also find CHA2DS2-VASc score of MDCalc to make it even easier.

 

Virginia: Now that we’ve established which patients should receive anticoagulation, how do we choose which anticoagulant? 

 

Charizza: For this discussion today, I would like to focus on nonpregnant patients. There really are 2 main anticoagulants, DOACs (or the direct oral anticoagulants) and warfarin. DOACs are the direct thrombin INH (dabigatran) and the direct factor Xa INH (rivaroxaban, apixaban, and edoxaban). DOAC is recommended as first-line in the long-term management of nonvalvular afib as trials have shown DOACs are more successful at reducing risk of thromboembolic events and have a lower risk of bleeding than warfarin and warfarin requires INR monitoring with dose adjustments. Although, in patients with valvular Afib, warfarin is preferred.

 

Arreaza: All of them are by mouth. 

 

Virginia: Dosing of DOACs depends on the kidney function, so it is important to obtain the creatinine clearance. For dabigatran, the direct thrombin INH, the recommended dose for patients with CrCl >30 mL/min is 150mg PO twice daily based on the results from the RE-LY trial (2), which evaluated the efficacy and safety of dabigatran with warfarin in patients with Afib. For patients with CrCl of 15-30 mL/min, the recommended dose is 75mg PO BID. Those with CrCl <15 mL/min or on dialysis, dabigatran is not recommended. 

 

Charizza: For the apixaban (Eliquis®), a direct factor Xa inhibitor, the dosing is 5mg BID for patient with normal renal function. For those with moderate kidney dysfunction such as Cr is >1.5, patient who is > 80years old or body weight <60kg, dosing of apixaban is decrease to 2.5 mg PO BID. There is not enough data for use of apixaban in patients with CrCl <15 or in dialysis. 

 

Virginia: For another direct factor Xa INH rivaroxaban (Xarelto®), dose is 20 mg once per day for CrCl >50 mL/min, 15 mg once per day for CrCl 15 to 50 mL/min, and for CrCl <15 mL/min do not use rivaroxaban.

 

Charizza: Essentially, any DOACs is not recommended for severe kidney impairment which is CrCl <15 mL/min or those on dialysis. 

 

Virginia: Yes, and for those patients where DOAC cannot be used, warfarin can be initiated. 

 

Charizza: Initiating warfarin for long-term anticoagulation in patient with atrial fibrillation does not necessarily require heparin bridge(4). 

 

Virginia: Before starting warfarin, a baseline INR is obtained. Usually, the initial dose of warfarin is 5mg PO daily for 3 days (5). And on day 4, INR is check in the morning and adjusting the dose of warfarin depending on the INR. 

 

Charizza: Warfarin dose is adjusted for a target INR of 2-3(6). Warfarin can be complicated to maintain, however, there are anticoagulation clinic to make sure they compliant with theirs and INR is therapeutic.

 

Thank you for your attention.

 

Now we conclude our episode number 73 “Anticoagulation in Afib.” Anticoagulation is an essential part of the management of Afib, mainly to prevent embolic stroke. Even without trying, every night you go to bed being a little wiser.

 

Thanks for listening to Rio Bravo qWeek. If you have any feedback about this podcast, contact us by email RBresidency@clinicasierravista.org, or visit our website riobravofmrp.org/qweek. This podcast was created with educational purposes only. Visit your primary care physician for additional medical advice. This week we thank Hector Arreaza, Virginia Bustamante, and Charizza Besmanos. Audio edition: Suraj Amrutia. See you next week! 

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References:

January, C. T., Wann, L. S., Calkins, H., Chen, L. Y., Cigarroa, J. E., Cleveland, J. C., Ellinor, P. T., Ezekowitz, M. D., Field, M. E., Furie, K. L., Heidenreich, P. A., Murray, K. T., Shea, J. B., Tracy, C. M., & Yancy, C. W. (2019, January 28). 2019 AHA/ACC/HRS FOCUSED update of the 2014 Aha/acc/hrs guideline for the management of patients with atrial fibrillation: A report of the American College of Cardioloy /American Heart Association Task force on clinical practice guidelines and the heart Rhythm Society. Journal of the American College of Cardiology. https://www.sciencedirect.com/science/article/pii/S0735109719302098?via%3Dihub . 

Bavry, Anthony A., MD, MPH, FACC, Randomized evaluation of long-term anticoagulant therapy RE-LY. American College of Cardiology. (2020, August 25). https://www.acc.org/latest-in-cardiology/clinical-trials/2013/07/19/12/25/rely. 

Warren J Manning, MD; Daniel E Singer, MD; Gregory YH Lip, MD, FRCPE, FESC, FACC. Atrial fibrillation in adults: Use of oral anticoagulants. Up to Date. (n.d.). https://www.uptodate.com/contents/atrial-fibrillation-use-of-oral-anticoagulants?search=atrial+fibrillation&source=search_result&selectedTitle=3~150&usage_type=default&display_rank=3#H416912985 .

Ebell MH. Evidence-based initiation of warfarin (Coumadin). Am Fam Physician. 2005 Feb 15;71(4):763-5. PMID: 15742915. https://www.aafp.org/afp/2005/0215/p763.html. 

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