Editor's Note: This article is based on Gillis AM, Skanes AC. Comparing the 2010 North American and European Atrial Fibrillation Guidelines. Can J Cardiol. 2011; 27: 7-13.

Over the last five years major advances in the management of atrial fibrillation (AF) have occurred. These include the publication of clinical trials on pharmacologic approaches for management of AF,^(1-3) clinical trials of new antithrombotic therapies for prevention of stroke,^(4-6) as well as the continuing evolution of catheter ablation for treatment of AF.^(7-9) The European Society of Cardiology (ESC) published guidelines for the management of AF in September 2010.⁽¹⁰⁾ A focused update on the management of AF was been published by the American College of Cardiology Foundation (ACCF)/the American Heart Association (AHA)/Heart Rhythm Society (HRS) in their respective journals in January 201111 and a second update addressing dabigatran in Mar 201112. The Canadian Cardiovascular Society (CCS) 2010 AF Guidelines were presented at the Canadian Cardiovascular Congress in October 2010⁽¹³⁾ and published in the Canadian Journal of Cardiology February 2011.^(14-21) We have been invited to comment on some of the important differences in the recommendations that exist among the three sets of guidelines.⁽²²⁾

1. Both the ESC and the ACCF/AHA/HRS guideline panels used the ACC/AHA process for rating the quality of evidence and grading the strength of the recommendations.^(10-12) In contrast, the CCS used the GRADE (Grading of Recommendations Assessment Development and Evaluation) approach.^{(14, 23, 24)} GRADE has recently been adopted by the World Health Organization for guideline development and allows separation of the quality of evidence from the strength of the recommendation. In addition to evaluating the quality of the evidence, GRADE considers the balance of desirable and undesirable effects, patients’ values and preferences and resource utilization to determine the strength of a recommendation (Strong or Conditional, i.e., weak).

2. The CCS guidelines were the first set of guidelines to recommend the use of dabigatran for prevention of stroke in patients with a CHADS2 score ≥1 and suggest that dabigatran is preferred over warfarin in most patients.⁽¹⁸⁾ The CCS guidelines suggest that warfarin is preferred over dabigatran in patients with coronary artery disease at high risk of ischemic events. The European guidelines make no specific recommendation regarding the use of dabigatran as it has not yet been approved in Europe for prevention of stroke.⁽¹⁰⁾ The ACCF/AHA/HRS recently published focused update state that dabigatran may be used as an alternative to warfarin for stroke prevention.⁽¹²⁾

3. The Canadian guidelines recommend that treatment for rate control of persistent/permanent AF should aim for a resting heart rate of <100 bpm⁽¹⁵⁾ whereas the European and American guidelines suggest that it is reasonable to aim for a resting heart rate of <110 bpm and aim for stricter rate control if patients remain symptomatic.^{(10, 11)} The Canadian recommendation is more conservative because only 22% of patients in RACE II randomized to the lenient rate control strategy had a target heart rate of >100-110 bpm.⁽²⁾

4. All guidelines recommend that the selection of antiarrhythmic drug therapy for maintenance of sinus rhythm be based on the underlying cardiovascular disease. The American and European guidelines do not recommend the use of Class IC antiarrhythmic drugs or sotalol in patients with left ventricular hypertrophy.^{(10, 11)} The Canadian guidelines do not make the presence of left ventricular hypertrophy an exclusion factor for the use of class IC agents or sotalol feeling that the scientific data supporting this recommendation was weak.⁽¹⁶⁾ The CCS guidelines suggest that the decision not to use these drugs in the presence of left ventricular hypertrophy should be based on the presence of significant repolarization abnormalities which is a risk marker for proarrhythmia.

5. Dronedarone has been incorporated into the antiarrhythmic drug algorithms.^{(10, 11, 16)} Unlike the American and European guidelines, the Canadian guidelines did not make a specific recommendation that dronedarone could be considered to decrease the risk of hospitalization for cardiovascular causes. The efficacy of dronedarone for maintenance of sinus rhythm is modest and equivalent to other first line agents based on the clinical condition. Both the Canadian and European guidelines suggest that dronedarone may be used as a second line therapy for rate control in the absence of unstable heart failure.^{(10, 16)}

6. All guidelines recommend catheter ablation for symptomatic patients with paroxysmal AF who have failed at least one anti-arrhythmic drug, although interpretation of the data led to differences in how these recommendations were graded.^{(10, 11, 17)} The American guidelines assign a Class I recommendation based on high level of evidence, whereas, the European and Canadian guidelines assign a IIa or conditional recommendation based on high and moderate quality of evidence, respectively. The ACCF/AHA/HRS recommendation comes with an important footnote that these procedures be performed in experienced center with a volume >50 cases per year. All three guidelines give a Class IIa or conditional recommendation for catheter ablation in symptomatic patients with persistent AF. Recommendations for catheter ablation as first line therapy are highly nuanced and graded as either conditional or Class IIb.

7. The European guidelines have incorporated what have traditionally been “less validated risk factors” such as female gender, age >75 years and the presence of vascular disease into a new validated scheme – CHA2DS2-VASc score.⁽¹⁰⁾ In addition to the traditional CHADS2 score, two points are now allotted for age >75 years and a single point each for female gender, age over 65, and vascular disease (coronary, carotid or peripheral). The Canadian and American guidelines have maintained use of the traditional risk factors incorporated into the CHADS2 score.^{(11, 18)}

8. Both the Canadian and European guidelines have become more aggressive in the recommendation that oral anticoagulation is preferred over aspirin (ASA) in low risk patients (CHADS2 =1, CHA2DS2-VASc =1) based on new data that these patients receive substantial benefit over ASA alone.^{(10, 18}) ASA is reserved for those with substantial bleeding risk where the benefit of oral anticoagulation is outweighed by the risk of a significant complication. In the American guidelines either ASA or warfarin are recommended in this “lower risk” group.⁽¹¹⁾ All guidelines recommend oral anticoagulation for patients at higher risk with CHADS2 ≥2 or CHA2DS2-VASc ≥2 in the case of European guidelines. Because the latter includes added risk factors, oral anticoagulation will be recommended in a greater proportion of patients with AF, including populations of patients that would not otherwise receive oral anticoagulation using the traditional CHADS2 risk score recommended by the Canadian or American guidelines.

References

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Keywords: American Heart Association, Anti-Arrhythmia Agents, Aspirin, Atrial Fibrillation, Canada, Catheter Ablation, Coronary Artery Disease, Europe, Heart Failure, Heart Rate, Hypertrophy, Left Ventricular, Sotalol, Stroke, United States

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