• 
• 

Three Part Question

In [patients presenting to the Emergency Department with atrial fibrillation requiring rate limitation] are [beta blockers superior in efficacy and safety to digoxin] in [achieving rate control]?

Clinical Scenario

A 60 year old man comes to the Emergency Department with symptoms of palpitations. ECG recording confirms atrial fibrillation with a ventricular rate of 140bpm. He tells you he has been experiencing these palpitations for 4 days. There are no signs of haemodynamic instability and you decide that a rate control strategy is most suitable according to the duration of his symptoms. You wonder whether to start him on digoxin or a beta-blocker.

Search Strategy

Embase 1980 to 2008 Week 39.
Medline 1950 to September Week 3 2008 using Ovid interface.
The Cochrane Library Issue 3 2008
Embase and Medline: [exp Atrial Fibrillation/ or (atrial adj fibrillation).mp.] AND [carvedilol.mp. OR atenolol.mp. OR bisoprolol.mp OR exp Adrenergic beta-Antagonists/ OR beta-blocker.mp OR esmolol.mp. OR metoprolol.mp OR propranolol.mp OR adrenergic beta-antagonists.mp. OR beta adrenergic receptor blocking agent.mp] AND [ventricular response.mp OR rate control.mp OR exp Heart Rate/ OR ventricular rate.mp.] AND [exp Digoxin/ OR digoxin.mp. OR exp Digitalis Glycosides/ OR exp Digitalis/ OR digitalis.mp.] LIMIT to humans AND english language
Medline: LIMIT to "all adult (19 plus years)"
Embase: LIMIT to adult <18 to 64 years> OR aged <65+ years>

The Cochrane Library:

((atrial fibrillation):ti,ab,kw OR (MeSH descriptor Atrial fibrillation, explode all trees)) AND ((digoxin):ti,ab,kw OR (MeSH descriptor Digoxin))

Search Outcome

100 papers were identified in Medline, 226 in Embase and 199 in the Cochrane Library. None were directly relevant to the three part question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses

Comment(s)

No study was found which directly compared beta-blockers with digoxin for ventricular rate control in recent-onset atrial fibrillation (AF). The study by JP Anthony et al. primarily looked at time to reversion, and compared sotalol (a class III anti-arrhythmic) with digoxin. As a secondary outcome they also compared the ventricular rate of those remaining in AF at 4, 24, and 48 hours in figure 3. This showed that at 24 and 48 hours the ventricular rate of the patients taking sotalol was significantly lower than the rate for patients taking either digoxin or amiodarone. Sotalol is a racemic mixture, which has both class III and ß-adrenergic blocking effects. Segal et al. (2000) carried out a systematic literature review for evidence regarding the drugs used for ventricular rate control comparing control while at rest and during exercise. They found 4 trials which directly compared ß-blockers with digoxin for rate control, though this was not specifically in new-onset AF. They found that digoxin was less efficacious than metoprolol in resting heart rate reduction and less efficacious than labetalol at rate reduction during exercise. Also, time on the treadmill was longer with both labetalol and metoprolol than with digoxin. The American Heart Association (AHA) and European Society of Cardiology (ESC) released guidelines for the management of atrial fibrillation in 2006. While they do not cite any comparative trials they recommend that, in acute settings (and in the absence of pre-excitation), beta-blockers or calcium channel blockers are first line agents for rate control (expert opinion, level of evidence C). Digoxin is recommended in the acute setting for heart rate control in patients with heart failure.

Clinical Bottom Line

There have no comparative trials of conventional beta-blockers and digoxin for rate control of AF in the Emergency Department. According to expert opinion beta-blockers are preferable as a first line therapy.

References

1. Segal JB, McNamara RL, Miller MR, Kim N, Goodman SN, Powe NR, Robinson K, Yu D, Bass EB The evidence regarding the drugs used for ventricular rate control. Journal of Family Practice 2000; 49(1):47-59
2. Fuster V, Rydén LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, Halperin JL, Heuzey JYL, Kay GN, Lowe JE, Olsson SB, Prystowsky EN, Tamargo JL, and Wann S. ACC/AHA/ESC 2006 Guidelines 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 Journal of American College Cardiology 2006;48;149-246
3. Anthony JP, Ward MR A Prospective, Randomized Controlled Trial Comparing the Efficacy and Safety of Sotalol, Amiodarone, and Digoxin for the Reversion of New-Onset Atrial Fibrillation Annals of Emergency Medicine 2000; 36(1):1-9