New Guidelines for the Treatment of Atrial Fibrillation
By Harold L. Karpman, MD, FACC, FACP Clinical Professor of Medicine, UCLA School of Medicine. Dr. Karpman reports no financial relationships relevant to this field of study.
Synopsis: The updated practice guidelines for the treatment of atrial fibrillation include information on the newer treatments for rhythm control, treatment options to reduce atrial fibrillation complications, and updated anticoagulant management for thromboprophylaxis.
Source: Curtis AB. Practice implications of the atrial fibrillation guidelines. Am J Cardiol 2013;111:1660-1670.
An estimated 3 million americans are currently affected by atrial fibrillation (AF) and it is estimated that by 2050, between 6 and 16 million Americans will be affected by the arrhythmia.1-3 The guidelines for the management of AF have recently been updated by the various cardiology consensus groups including the European Society of Cardiology (ESC), the American College of Chest Physicians (ACCP), the Canadian Cardiovascular Society (CCS), and a task force of three societies from the United States, the American College of Cardiology Foundation, American Heart Association, and the Heart Rhythm Society (ACCF/AHA/HRS).4-15 The guidelines were updated because of the relatively recent availability of newer treatments for rhythm control and treatments to reduce AF complications. Because much of the mortality and morbidity in AF is due to stroke and thromboembolism, thromboprophylaxis has been deemed critical to reduce the embolic risk.16 Yet, despite these recommendations, many patients with AF still have not received appropriate thromboprophylaxis.17-19
Criteria for Rate Control
Although the parameters for optimal rate control in patients with AF had been controversial, the new ACCF/AHA/HRS guidelines have included a change in the recommended target heart rate. It has been determined that strict control of the heart rate (i.e., < 80 beats per minute [bpm] at rest) is less beneficial compared with lenient control (i.e., a heart rate < 110 bpm at rest). A larger proportion of patients treated with the lenient strategy achieve their target heart rate goal with lower drug doses and fewer drug combinations, resulting in fewer outpatient visits to achieve the intended target.14,20 It should be noted that the CCS has recommended a target heart rate of < 100 bpm at rest for most patients, although some of the organizations do not provide criteria for a target heart rate or specific recommendations for rate control strategies.
Rhythm-Control Strategy
The Atrial Fibrillation and Congestive Heart Failure Trial21 reported that a routine rhythm-control strategy (including electrical cardioversion in patients who did not achieve sinus rhythm after antiarrhythmic drug therapy) for patients with AF with systolic heart failure did not reduce the death rate from cardiovascular causes compared with the rate-control strategy in patients with AF and congestive heart failure. In that trial, amiodarone was the antiarrhythmic drug of choice and either sotalol or dofetilide was used if necessary. Rate-control therapy included adjusted doses of beta-blockers with digitalis to achieve the target heart rate. Several of the review panels recommended that the rhythm-control therapy be used for patients with AF who remained symptomatic with rate-control therapy despite adequate rate control or the rhythm-control strategy may be initially selected because of factors such as the degree of symptoms, younger age, or greater activity levels. Paroxysmal AF can be managed by either rate-control or rhythm-control therapy, although the latter is especially attractive in highly symptomatic patients with little or no associated underlying heart disease.22 Long-term anticoagulant therapy has been recommended by the ACCP, and such therapy should be determined by the patient's underlying risk of stroke and not the underlying rhythm. Finally, with respect to the use of dronedarone in the management of AF, it should not be used in patients with permanent AF nor for the sole purpose of rate control. In addition, it should not be used in patients with a history of heart failure or an ejection fraction < 0.40, and should be used with caution in patients who are taking digoxin.
Stroke Prevention: New Recommendations for Combining Anticoagulants with Antiplatelet Therapy
The ACCP group has recommended the addition of clopidogrel (75 mg per day) to oral aspirin (75-100 mg per day) for patients with AF who are unsuitable for or who choose not to take oral anticoagulation therapy. In contrast, the CCS has not recommended the aspirin plus clopidogrel approach, but instead has recommended the use of dabigatran because it will reduce the risk of stroke and has a lower risk of bleeding compared with warfarin.6,23,24 In fact, the CCS has recommended that dabigatran should be preferred to warfarin in most patients who need antithrombotic therapy for AF. Furthermore, the CCS has recommended a period of triple therapy (combined use of warfarin with dual antiplatelet therapy) for optimal prophylaxis in patients at high risk of stroke who have undergone percutaneous coronary intervention. Triple therapy has also been recommended for 3-6 months after an acute coronary syndrome with or without percutaneous coronary intervention.13 Finally, the ACCP guidelines noted that patients with AF who have received a drug-eluting stent and who are at increased risk of late stent thrombosis might choose to continue triple therapy for 12 months after stent placement.
Catheter Ablation Therapy
Catheter ablation has been recommended for patients with symptomatic paroxysmal AF in whom one or more antiarrhythmic drugs have failed and in patients with significant left atrial dilatation or significant left ventricular dysfunction.14 The CCS has also suggested catheter ablation as the first-line therapy in highly selected patients (i.e., those with a strong intolerance or aversion to antiarrhythmic drugs) with symptomatic, paroxysmal AF. The ACCP has recommended that decisions about long-term antithrombotic therapy should be determined by the underlying risk of stroke and not the underlying rhythm in patients with AF receiving catheter ablation.
Dabigatran, Rivaroxaban, and Apixaban
The newer guidelines and comprehensive risk stratification protocols re-emphasized the available management options, and especially the importance of the early initiation of antithrombotic therapy in most patients with AF or paroxysmal AF. However, the ACCF/AHA/HRS guidelines now recommend that dabigatran be considered a useful alternative to warfarin to reduce the risk of stroke and systemic embolism in patients with nonvalvular AF.4 Of course, it should be carefully noted that there is no antidote currently available for dabigatran. Rivaroxaban has been found to be not inferior to warfarin for the prevention of stroke or systemic embolism in patients with AF. In fact, in 2012, the ECS and CCS both published focused updates to the guidelines recommending either dabigatran or rivaroxaban over warfarin for stroke prevention in patients with AF.25 Although the jury is still out, thromboprophylaxis is becoming much safer and certainly much easier for both the patient and clinician because of the newer antithrombotic drugs that are now available and also possibly because of newer agents that are now in the research pipeline.
Because of the large number of recent publications focused on AF, therapeutic options with respect to rate control and rhythm control have broadened. In addition, newer anticoagulants continue to reach the marketplace and, in fact, recommendations regarding anticoagulant therapy for AF and paroxysmal AF continue to change quite frequently. The various cardiology organizations in the United States, Canada, and Europe review their guidelines for AF treatment on a regular basis and their conclusions will help practicing clinicians determine the best approaches for this arrhythmia that has been increasing in frequency in a dramatic fashion.
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