Atrial fibrillation (AF) is a common condition, affecting more than 2 million Americans.1 Hospital admissions due to AF have increased 66% in the past two decades. Hospitalization accounts for 52% of the cost of AF management, and the mortality rate of patients with this arrhythmia is twice that of patients in sinus rhythm.1
AF management decisions include choices for rate control, rhythm control, and prevention of thromboembolism. The benefits of a rhythm-control versus a rate-control strategy continue to be evaluated, along with consideration regarding an appropriate heart-rate goal. The modifiable risk factor of stroke in atrial fibrillation also continues to be a target for intervention as atrial fibrillation accounts for one-sixth of all strokes.
The American College of Cardiology Foundation and American Heart Association (ACC/AHA), in conjunction with the European Society of Cardiology, released practice guidelines on the management of patients with atrial fibrillation in 2006. The ACCF/AHA, writing with the Heart Rhythm Society, released focused updates in early 2011 to be incorporated into the previous guidelines, given new data from major clinical trials and the FDA approval of new medications with indications for AF treatment.2,3
The new recommendations address components of all three major management decisions for AF: rate control, rhythm control, and prevention of thromboembolism.
When managing AF with a rate-control strategy, new guidelines no longer recommend the goal of a resting heart rate of <80 bpm or <115 bpm with activity. This is based on data from the RACE II trial that show no difference in meaningful outcomes with a more aggressive heart-rate goal. Achieving a resting heart rate of 110 bpm was deemed a reasonable approach, as long as the patient has stable ventricular function and acceptable symptoms.
The new drug dronedarone has been introduced in the algorithm for maintenance of sinus rhythm strategy, based on the DIONYSOS, ATHENA, and ANDROMEDA studies. The new algorithm excluded the use of dronedarone in patients with left ventricular hypertrophy, decompensated heart failure, or Class IV heart failure because it was shown to increase mortality in these groups. The guidelines also recommend that it should also be used with caution in patients with bradycardia, prolonged QT interval, increased creatinine, and in patients on agents that moderate CYP3A4 function.
The risks of interventions to decrease thromboembolism against bleeding risk continue to be evaluated in specified patient populations. Although dabigatran did not have FDA approval prior to submission of the 2011 updated guidelines, the 2011 “focused update” incorporated the results of the RE-LY trial. Publication of RE-LY resulted in a Class 1 recommendation for dabigatran as a useful alternative to warfarin in patients with nonvalvular AF without severe renal failure or advanced liver disease.3 However, there is no specific antidote, and dabigatran use is associated with higher rates of dyspepsia and a nonsignificant increase in rates of myocardial infarction. In patients for whom oral anticoagulation with warfarin is considered unsuitable, aspirin with clopidogrel may be considered, although warfarin therapy continues to be a superior therapy to this dual antiplatelet regimen based on the ACTIVE-W and ACTIVE-A studies.2
Established Guideline Analysis
Apart from the listed updates, the management of AF has not changed considerably in the past decade. Rate control continues to be the recommended strategy for older patients along with appropriate symptom control, particularly if they have hypertension or heart disease. Rhythm control is a frequent strategy in AF management, but several studies have not found any difference in quality of life, development or progression of heart failure, or stroke rates in patients for whom a rhythm-control strategy was chosen.
Additionally, these patients still require anticoagulation, and the side effects of anti-arrhythmic drugs might offset the benefits of sinus rhythm. Therefore, rate control is an appropriate strategy. The stroke rate and side-effect risks with anti-arrhythmics are considerably lower in younger patients or those with paroxysmal lone AF, and so a rhythm-control strategy in these groups is reasonable.
Stroke rate in AF increases with known high-risk factors (prior thromboembolism or rheumatic mitral stenosis) and moderate-risk factors (heart failure, hypertension, age over 75, and diabetes). Less validated risk factors include female gender, age 65-74, thyrotoxicosis, and the presence of coronary artery disease.
There are well-defined recommendations for how to anticoagulate specific subgroups that pose clinical challenges not directly addressed in studies, but the guidelines do assist with:
- Patients who have a stroke with a therapeutic INR: Rather than adding antiplatelet agents, INR goal can be raised to 3-3.5;
- Patients >75 years old who are at a high risk for bleeding: A target INR of 2.0 (target range 1.6-2.5) seems reasonable;1 and
- Patients with stable coronary artery disease and AF: Warfarin anticoagulation alone should provide satisfactory antithrombotic prophylaxis against cerebrovascular and coronary atheroembolic events.1
Decisions involving perioperative management of anticoagulation in patients with AF frequently arise. Per the guidelines, in patients with nonvalvular AF, anticoagulation can be stopped for up to one week without bridging for surgical or diagnostic procedures, but bridging should be considered in high-risk patients.
Hospitalists are likely to manage AF, whether alone or in conjunction with cardiology consultation. These new comprehensive guidelines deal with rate control, rhythm control, and prevention of thromboembolism. Hospitalists should take particular interest in the guidelines regarding lenient rate control, dronedarone for rhythm control, and dabigatran as a new alternative for anticoagulation in appropriate populations.
Drs. Farrell and Carbo are hospitalists at Beth Israel Deaconess Medical Center in Boston.
- Fuster V, Rydén LE, Cannom DS, et al. 2011 ACCF/AHA/HRS focused updates incorporated into the ACC/AHA/ESC 2006 Guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines developed in partnership with the European Society of Cardiology and in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. J Am Coll Cardiol. 2011;57(11):e101-98.
- Wann LS, Curtis AB, January CT, et al. 2011 ACCF/AHA/HRS focused update on the management of patients with atrial fibrillation (Updating the 2006 Guideline): a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Heart Rhythm. 2011;8(1):157-76.
- Wann LS, Curtis AB, Ellenbogen KA, et al. 2011 ACCF/AHA/HRS focused update on the management of patients with atrial fibrillation (update on dabigatran): a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. J Am Coll Cardiol. 2011;57(11):1330-7.