Activity 1: Thromboprophylaxis in Atrial Fibrillation: Current Issues and Challenges

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: Antithrombotic therapy to prevent thromboembolism is recommended for all patients with atrial fibrillation (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 #3: 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 #4: Aspirin, 81 mg-325 mg daily, is recommended as an alternative to vitamin K antagonists in low-risk patients or in those with contraindications to oral anticoagulation.
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: 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

Recommendation #6: For patients with a CHADS2 score ≥2, chronic oral anticoagulant therapy with a vitamin K antagonist is recommended in a dose-adjusted regimen to achieve an INR range of 2.0-3.0 (target: 2.5), unless contraindicated.
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: IA

Recommendation #7: In patients beginning vitamin K antagonist therapy (VKA), the guidelines recommend the initiation of oral anticoagulation with doses between 5 mg and 10 mg for the first 1 or 2 days for most individuals, with subsequent dosing based on the INR response.
Source: Pharmacology and management of vitamin K antagonists. Chest 2008;133(suppl 6):160S-198S.
Website: http://chestjournal.chestpubs.org/content/133/6_suppl/160S.full
Strength of Evidence: 1B

Recommendation #8: At the present time, for patients beginning VKA therapy, without evidence from randomized trials, the guidelines suggest against the use of pharmacogenetic-based dosing to individualize warfarin dosing.
Source: Pharmacology and management of vitamin K antagonists. Chest 2008;133(suppl 6):160S-198S.
Website: http://chestjournal.chestpubs.org/content/133/6_suppl/160S.full
Strength of Evidence: 2C

Recommendation #9: Following surgical procedures, resumption of oral anticoagulant therapy should be considered at the “usual” maintenance dose (without a loading dose) on the evening of (or the next morning after) surgery, assuming there is adequate hemostasis.
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: IIa B

Recommendation #10: In patients with atrial fibrillation who do not have mechanical heart valves, it is reasonable to interrupt anticoagulation for up to 1 week without substituting heparin for surgical or diagnostic procedures that carry a risk of bleeding.
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: IIa C

Recommendation #11: When surgical procedures require interruption of oral anticoagulant therapy for longer than 1 week in high-risk patients, unfractionated heparin may be administered or low-molecular-weight heparin may be given by subcutaneous injection, although the efficacy of these alternatives in this situation is uncertain.
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: IIb C

Recommendation #12: 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: IB

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: Current Issues and Challenges

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.

ACTIVE Writing Group of the ACTIVE Investigators, Connolly S, Pogue J, Hart R, Pfeffer M, Hohnloser S, et al. Clopidogrel plus aspirin versus oral anticoagulation for atrial fibrillation in the Atrial fibrillation Clopidogrel Trial with Irbesartan for prevention of Vascular Events (ACTIVE W): a randomised controlled trial. Lancet 2006;367:1903-12.

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.

Connolly SJ, Ezekowitz MD, Yusuf S, Reilly PA, Walletin L, and the Randomized Evaluation of Long-Term Anticoagulation Therapy Investigators. Newly identified events in the RE-LY trial. N Engl J Med 2010;363:1875-6.

Cromheecke ME, Levi M, Colly LP, de Mol BJ, Prins MH, Hutten BA, et al. Oral anticoagulation self-management and management by a specialist anticoagulation clinic: a randomised cross-over comparison. Lancet 2000;356:97-102.

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.

Go AS, Hylek EM, Phillips KA, Chang Y, Henault LE, Selby JV, et al. Prevalence of diagnosed atrial fibrillation in adults: national implications for rhythm management and stroke prevention: the AnTicoagulation and Risk factors In Atrial fibrillation (ATRIA) Study. JAMA 2001;285:2370-5.

Harrison L, Johnston M, Massicotte MP, Crowther M, Moffat K, Hirsh J. Comparison of 5-mg and 10-mg loading doses in initiation of warfarin therapy. Ann Intern Med 1997;126:133-6.

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.

Holmes DR Jr, Kereiakes DJ, Kleiman NS, Moliterno DJ, Patti G, Grines CL. Combining antiplatelet and anticoagulant therapies. J Am Coll Cardiol 2009;54:95-109.

Prasad S, Wootten MR, Kulinski N, Chapman SA. What to do when warfarin therapy goes too far. J Fam Pract. 2009;58:346-52.

Singer DE, Chang Y, Fang MC, Borowsky LH, Pomernacki NK, Udaltsova N, et al. Abstract 2634: Warfarin INR-response curves in subgroups of patients with nonvalvular atrial fibrillation: should target anticoagulation intensity be adjusted for patient characteristics?: The ATRIA study. Circulation 2008; 118: S_757.

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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