Activity 2: Thromboprophylaxis in Atrial Fibrillation: A Case-Based Approach to Management

Warfarin Dose Adjustment Algorithm: Download PDF

Recommendation #1: The CHADS2 score is recommended as a simple initial means of assessing stroke risk in nonvalvular atrial fibrillation.
Source: Guidelines for the Management of Atrial Fibrillation. European Heart Journal 2010;31:2369-429.
Website: http://www.escardio.org/guidelines-surveys/esc-guidelines/GuidelinesDocuments/guidelines-afib-FT.pdf
Strength of Evidence: I A

Recommendation #2: Patients with no risk factors (essentially patients aged <65 years with lone AF, with none of the risk factors) are at low risk of stroke. In these patients, the use of aspirin, 75 mg–325 mg daily, or no antithrombotic therapy is recommended.
Source: Guidelines for the Management of Atrial Fibrillation. European Heart Journal 2010;31:2369-429.
Website: http://www.escardio.org/guidelines-surveys/esc-guidelines/GuidelinesDocuments/guidelines-afib-FT.pdf
Strength of Evidence: I B

Recommendation #3: Antithrombotic therapy to prevent thromboembolism is recommended for all patients with AF, except those with lone AF or contraindications.
Source: ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation. Circulation 2006;114:e257-e354.
Website: http://circ.ahajournals.org/cgi/content/full/114/7/e257
Strength of Evidence: I A

Recommendation #4: Anticoagulation with a vitamin K antagonist is recommended for patients with more than one moderate risk factor. Such risk factors include age 75 years or greater, hypertension, heart failure, impaired left ventricular systolic function (ejection fraction 35% or less, or fractional shortening less than 25%), and diabetes mellitus.
Source: ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation. Circulation 2006;114:e257-e354.
Website: http://circ.ahajournals.org/cgi/content/full/114/7/e257
Strength of Evidence: I A

Recommendation #5: In patients with atrial fibrillation (AF), including those with paroxysmal AF, who have two or more of the following risk factors for future ischemic stroke, the guidelines recommend long-term anticoagulation with an oral vitamin K antagonist, such as warfarin, targeted at an INR of 2.5 (range: 2.0 to 3.0) because of the increased risk of future ischemic stroke faced by this set of patients.

Risk factors: Age >75 years, history of hypertension, diabetes mellitus, and moderately or severely impaired left ventricular systolic function and/or heart failure

Source:Singer DE, Albers GW, Dalen JE, Fang MC, Go AS, Halperin JL, et al. Antithrombotic Therapy in Atrial Fibrillation. Chest 2008;133(Suppl 6):546S-92S.
Website: http://chestjournal.chestpubs.org/content/133/6_suppl/546S.full
Strength of Evidence: I A

Recommendation #6: Dabigatran is useful as an alternative to warfarin for the prevention of stroke and systemic thromboembolism in patients with paroxysmal to permanent atrial fibrillation and risk factors for stroke or systemic embolization who do not have a prosthetic heart valve or hemodynamically significant valve disease, severe renal failure (creatinine clearance <15ml/min), or advanced liver disease (impaired baseline clotting function).
Source: 2011 ACCF/AHA/HRS Focused Update on the Management of Patients with Atrial Fibrillation (Update on Dabigatran). J Am Coll Cardiol 2011;57:1330-7.
Website: http://content.onlinejacc.org/cgi/content/full/j.jacc.2011.01.010
Strength of Evidence: I B

Recommendation #7: The selection of antithrombotic agent should be based on the absolute risks of stroke and bleeding, and the relative risk and benefit for a given patient.
Source: ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation. Circulation 2006;114:e257-e354.
Website: http://circ.ahajournals.org/cgi/content/full/114/7/e257
Strength of Evidence: I A

Recommendation #8: The addition of clopidogrel to aspirin to reduce the risk of major vascular events, including stroke, might be considered in patients with atrial fibrillation in whom oral anticoagulation with warfarin is considered unsuitable due to patient preference or physician assessment of the patient’s ability to safely sustain anticoagulation.
Source: 2011 ACCF/AHA/HRS Focused Update on the Management of Patients with Atrial Fibrillation (Updating the 2006 Guideline). Circulation 2011;123:104-23.
Website: http://circ.ahajournals.org/cgi/content/full/123/1/104
Strength of Evidence: IIb B

Download PDF of EB Recs

AHRQ Guide to Blood Thinner Pills:  http://www.ahrq.gov/consumer/btpills.htm

USDA Standard Reference for Vitamin K Content of Selected Foods: http://www.nal.usda.gov/fnic/foodcomp/Data/SR16/wtrank/sr16a430.pdf

Presentation Slides for Thromboprophylaxis in Atrial Fibrillation: A Case-Based Approach to Management

ACTIVE Investigators, Connolly SJ, Pogue J, Hart RG, Hohnloser SH, Pfeffer M, et al. Effect of clopidogrel added to aspirin in patients with atrial fibrillation. N Engl J Med 2009;360:2066-78.

Connolly SJ, Ezekowitz MD, Yusuf S, Eikelboom J, Oldgren J, Parekh A, et al., and the RE-LY Steering Committee and Investigators. Dabigatran versus warfarin in patients with atrial fibrillation. N Engl J Med 2009;361:1139-51.

EAFT (European Atrial Fibrillation Trial) Study Group. Secondary prevention in nonrheumatic atrial fibrillation after transient ischaemic attack or minor stroke. Lancet 1993;342:1255-62.

Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA 2001;285:2864-70.

Gullov AL, Koefoed BG, Petersen P. Bleeding during warfarin and aspirin therapy in patients with atrial fibrillation: the AFASAK 2 study. Atrial Fibrillation Aspirin and Anticoagulation. Arch Intern Med 1999;159:1322-8.

Hart RG, Benavente O, McBride R, Pearce LA. Antithrombotic therapy to prevent stroke in patients with atrial fibrillation: a meta-analysis. Ann Intern Med 1999;131:492-501.

Petersen P, Boysen G, Godtfredsen J, Andersen ED, Andersen B. Placebo-controlled, randomised trial of warfarin and aspirin for prevention of thromboembolic complications in chronic atrial fibrillation. The Copenhagen AFASAK study. Lancet 1989;1:175-9.

Roy D, Talajic M, Nattel S, Wyse DG, Dorian P, Lee KL, et al. Rhythm control versus rate control for atrial fibrillation and heart failure. N Engl J Med 2008;358:2667-77.

van Walraven C, Hart RG, Singer DE, Laupacis A, Connolly S, Petersen P, et al. Oral anticoagulants vs aspirin in nonvalvular atrial fibrillation: an individual patient meta-analysis. JAMA 2002;288:2441-8.

Wyse DG, Waldo AL, DiMarco JP, Domanski MJ, Rosenberg Y, Schron EB, et al. A comparison of rate control and rhythm control in patients with atrial fibrillation. N Engl J Med 2002;347:1825-33.

CHADS2 Risk Assessment Tool: Download PDF

CHADS2 Score and Recommended Therapy: Download PDF

Practical Rate and Rhythm Management of Atrial Fibrillation Pocket Guide: http://www.hrsonline.org/ClinicalGuidance/upload/2010_rate-rhythm_guide1.pdf

Warfarin Initiation: Download PDF

 

 

 

 

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