What are the guidelines for the prevention of stroke in patients with atrial fibrillation (Afib) (AF)?

Updated: Nov 18, 2019
  • Author: Lawrence Rosenthal, MD, PhD, FACC, FHRS; Chief Editor: Jeffrey N Rottman, MD  more...
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Answer

Guidelines have been issued by the following organizations for prevention of stroke in atrial fibrillation (AF) patients:

  • 2014 American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS)
  • 2012 European Society of Cardiology (ESC)
  • 2014 American Academy of Neurology (AAN)
  • 2012 American College of Chest Physicians (ACCP)

All major guidelines note that one of the major management decisions in AF is determining the risk of stroke and the appropriate anticoagulation regimen for low-, intermediate-, and high-risk patients. For each anticoagulant, the benefit in terms of stroke reduction must be weighed against the risk of serious bleeding, with the risk-benefit ratio generally considered not advantageous in low-risk patients with AF. Thus, the guidelines stress that clinical judgment and patient preferences should play a major role in shared decision making. [1, 97, 149, 150]

The CHADS2 score (Cardiac failure, Hypertension, Age >75 years, Diabetes, prior Stroke or TIA [transient ischemic attack]) is the most widely used algorithm to determine yearly thromboembolic risk. Two points are assigned for a history of stroke or TIA, and 1 point is given for age older than 75 years or a history of hypertension, diabetes, or heart failure. [65]

The ACCP bases its recommendations for antithrombotic therapy in patients with nonvalvular atrial fibrillation (NVAF) on the CHADS2 score, as follows [150] :

  • CHADS 2 score = 0 (low risk): No antithrombotic therapy
  • CHADS 2 score ≥1 (intermediate or high risk): Oral antithrombotic therapy

However, the 2014 AHA/ACC/HRS and 2012 updated ESC guidelines both recommend that the CHADS2 score be replaced with the more comprehensive CHA2DS2-VASc score. [1, 149] In this scoring system, points are assigned as follows [66] :

  • Congestive heart failure (CHF): 1 point
  • Hypertension: 1 point
  • Age ≥75 years: 2 points
  • Diabetes: 1 point
  • Stroke, TIA, or thromboembolism history: 2 points
  • Vascular disease (myocardial infarction [MI], peripheral arterial disease, aortic plaque): 1 point
  • Age 65-74 years: 1 point
  • Sex category (female sex): 1 point

The AHA/ACC/HRS further recommends that antithrombotic therapy should be based on the risk of thromboembolism irrespective of whether the AF pattern is paroxysmal, persistent or permanent. [1]

In 2014, the American Heart Association (AHA) also issued joint guidelines with the American Stroke Association (ASA) for the primary prevention of stroke, which included specific recommendations for stroke prevention in patients with AF. The main advantage of the CHA2DS2-VASc score (range, 0-9) is that it provides significantly improved risk prediction for individuals at low to moderate risk compared with the CHADS2 (scores of 0 or 1), particularly for elderly women. [151]

The AHA/ACC/HRS recommendations for antithrombotic therapy in patients with AF, based on CHA2DS2-VASc scores, are as follows [1] :

  • NVAF and CHA 2DS 2-VASc score = 0: No antithrombotic therapy
  • NVAF and CHA 2DS 2-VASc score = 1: No antithrombotic therapy or oral antithrombotic therapy
  • Prior stroke, TIA or CHA 2DS 2-VASc Score ≥2: Oral antithrombotic therapy

The ESC offers varying recommendations for patients with AF based on CHA2DS2-VASc scores, as follows [149] :

  • CHA 2DS 2-VASc score = 0: No antithrombotic therapy
  • CHA 2DS 2-VASc score = 1: Oral anticoagulants
  • CHA 2DS 2-VASc score ≥2: Oral anticoagulants

The shift from the CHADS2 score to the CHA2DS2-VASc score has not been without controversy. The number of patients eligible for oral anticoagulant therapy in the United States is estimated to increase by nearly 1 million, raising concerns about the associated increase in bleeding complications. An analysis by O’Brien and colleagues concluded that using the 2014 AHA/ACC/HRS recommendations to guide the management of AF would result in 98.5% of patients 65 years of age and older and 97.7% of women with AF receiving a definitive recommendation for oral anticoagulant therapy. [152]

The 2014 AAN revised guidelines for stroke prevention in NVAF recommend use of risk stratification to aid in clinical decision making, but do not recommend the use of any specific tool. Furthermore, the guidelines caution against use of strictly interpreted thresholds as definitive indicators for which patients require anticoagulation therapy. Additional recommendations for patient selection included the following [97] :

  • Anticoagulation therapy should be offered to all patients with NVAF and a history of ischemic attack or stroke
  • Anticoagulation therapy should not be offered to patients with NVAF who lack additional risk factors; these patients may be offered aspirin therapy or no antithrombotic therapy

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