The 2014 American Heart Association (AHA)/American College of Cardiology (ACC)/Heart Rhythm Society (HRS) guidelines for the management of patients with atrial fibrillation (AF)¹ have been met with tremendous enthusiasm. They are a complete revision of the 2006 guidelines with updates to classification and risk assessment strategies as well as incorporation of novel pharmacologic and procedural therapies. Below we review the most clinically relevant updates.

To begin with, the diagnosis of AF has been simplified.^2,3 The definition now requires just one episode of AF and no longer requires a duration of at least 30 seconds. The classification scheme by duration of episode has also been "simplified" (Table 1). Note that permanent AF has been de-emphasized as this classification is largely determined by the decision of the patient and provider to cease attempts to restore and/or maintain sinus rhythm, not specific physiologic or clinical criteria.

Table 1: Simplified Atrial Fibrillation (AF) Classification Paroxysmal AF AF that terminates spontaneously or with intervention within 7 days of onset Persistent AF Continuous AF that is sustained >7 days Longstanding, persistent AF Continuous AF of >12 months Permanent AF Term used when there has been a joint decision by the patient and provider to cease further attempts to restore and/or maintain sinus rhythm.

The CHA₂DS₂-VASc score is now recommended over the CHADS₂ score for determination of thromboembolic risk in non-valvular AF (Figure 1), largely because of the limited discrimination the CHADS₂ score offers for patients with intermediate risk (i.e., CHADS₂ score of 1). Oral anticoagulation is recommended for a CHA₂DS₂-VASc score of 2 or greater (Table 2). The CHA₂DS₂-VASc score contains more risk factors and has a greater range of points, thus switching to the CHA₂DS₂-VASc score will increase the number of patients eligible for anticoagulation. This will be true especially for women, younger patients, and those with a prior atherosclerotic event.

For those patients to be treated with anticoagulation, the guidelines recommend either warfarin or one of the novel oral anticoagulants (NOACs). These include the direct thrombin inhibitor, dabigatran, or either of the factor Xa inhibitors, rivaroxaban or apixaban. If warfarin-treated patients have difficulty maintaining a therapeutic INR, then switching to a NOAC is recommended. For patients with AF and a mechanical heart valve, vitamin K antagonists, such as warfarin, remain the only recommended oral anticoagulant.

While the treatment of patients with anticoagulants is expected to increase, the 2014 AHA/ACC/HRS guidelines de-emphasize the use of antiplatelet therapy to reduce thromboembolic risk. The benefits of aspirin have been limited to the Stroke Prevention in Atrial Fibrillation Trial.⁵ While dual antiplatelet therapy with aspirin and clopidogrel is more effective than aspirin monotherapy, the added benefit is accompanied by an equivalent absolute increase in major bleeding. In patients with the lowest thromboembolic risk (CHA₂DS₂-VASc score of 0), antithrombotic therapy should not be routinely recommended. For patients with "intermediate" risk (CHA₂DS₂-VASc score of 1), the option of anticoagulation, aspirin monotherapy, or no therapy is left to a consensus decision between the provider and patient.

In comparison to the 2006 AHA/ACC/HRS guidelines, rhythm control receives a more favorable recommendation. Prior guidelines have emphasized trial data,⁸ which did not demonstrate a benefit of rhythm control on mortality but did demonstrate an increase in hospitalizations compared to a rate-control strategy. The new guidelines remind readers that in some patients, maintenance of sinus rhythm is associated with improvements in symptoms and quality of life. Patients should be carefully evaluated for persistent symptoms from atrial fibrillation and should be considered for rhythm control. Atrial fibrillation is associated with electrical and structural remodeling; thus early intervention with a rhythm control strategy may be beneficial.⁹ While identification of underlying structural heart disease remains important in the selection of antiarrhythmic therapy, the new guidelines no longer include the broad exclusion of left ventricular hypertrophy (LVH) for multiple agents. Instead the guidelines recommend avoiding flecainide, propafenone, sotalol, and dofetilide in patients with severe LVH (i.e., wall thickness >1.5 cm).

Rhythm control via radiofrequency catheter ablation has continued to evolve. The efficacy of ablation for maintaining sinus rhythm is superior to antiarrhythmic therapy in selected patient populations, particularly in younger patients with minimal structural heart disease. In the 2014 AHA/ACC/HRS guidelines, catheter ablation now receives a Class I recommendation as useful in the setting of symptomatic paroxysmal AF refractory to at least one class I or III antiarrhythmic medication or if the patient is intolerant to these medications and a rhythm control strategy is desired (LOE: A). As an initial rhythm control strategy, ablation receives a Class IIa (LOE: B) recommendation. Randomized clinical trials are currently underway to determine whether ablation may provide benefit beyond improvement in quality of life.

The 2014 AHA/ACC/HRS AF guidelines have successfully addressed the clinically relevant concerns regarding diagnosis of atrial fibrillation and better discrimination of patients with a CHADS₂ score of 1. In addition, following recent trials results, they appropriately recommend the NOACs as alternative therapies for patients with non-valvular AF and catheter ablation for those suffering for symptomatic AF. It is likely that these guidelines will lead to expansion of these effective therapies for patients with AF.

Table 2: Antithrombotic therapy by CHA2DS2-VASc score CHA2DS2-VASc score Treatment Recommendation/LOE ≥2 Warfarin, dabigatran, rivaroxaban, or apixaban Class I (LOE: A for warfarin, LOE: B for dabigatran, rivaroxaban, or apixaban) 1 No antithrombotic therapy or oral anticoagulation or aspirin Class IIb (LOE: C) 0 No antithrombotic therapy is reasonable Class IIa (LOE: B)

References

1. January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. Circulation 2014 April 10; [Epub ahead of print].
2. Hart RG, Pearce LA, Aguilar MI. Meta-analysis: antithrombotic therapy to prevent stroke in patients who have nonvalvular atrial fibrillation. Ann Intern Med 2007;146:857-67.
3. Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design: a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. Developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC) and the European Cardiac Arrhythmia Society (ECAS); and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). Endorsed by the governing bodies of the American College of Cardiology Foundation, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, the Asia Pacific Heart Rhythm Society, and the Heart Rhythm Society. Heart Rhythm 2012;9:632-96.
4. Camm AJ, Kirchhof P, Lip GY, et al. Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Eur Heart J 2010;31:2369-429.
5. Hart RG, Pearce LA, Aguilar MI. Meta-analysis: antithrombotic therapy to prevent stroke in patients who have nonvalvular atrial fibrillation. Ann Intern Med 2007;146:857-67.
6. Gage BF, Waterman AD, Shannon W, et al. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA 2001;285:2864-70.
7. Lip GY, Tse HF, Lane DA. Atrial fibrillation. Lancet 2012;126:860-5.
8. Olshansky B, Rosenfeld LE, Warner AL, et al. The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study: approaches to control rate in atrial fibrillation. J Am Coll Cardiol 2004;43:1201-8.
9. Van Gelder IC, Haegeli LM, Brandes A, et al. Rationale and current perspective for early rhythm control therapy in atrial fibrillation. Europace 2011;13:1517-25.

Keywords: Anti-Arrhythmia Agents, Anticoagulants, Aspirin, Atrial Fibrillation, Benzimidazoles, Catheter Ablation, Complementary Therapies, Fibrinolytic Agents, Pyrazoles, Risk Factors, Sotalol, Sulfonamides, Thiophenes, Ticlopidine

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