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Three Part Question

In [acute onset atrial fibrillation] is [amiodarone better than flecainide] at [restoring normal sinus rhythm]?

Clinical Scenario

A 50 year old woman presents to the emergency department with acute onset of palpitations of less than two hours duration. She does not have chest pain, her heart rate is about 140-160 with a good systolic blood pressure and respiratory examination is normal. An ECG confirms the rhythm to be atrial fibrillation. You consider which method of pharmacological cardioversion would be most suitable as the medical and cardiological opinions differ between amiodarone and flecainide.

Search Strategy

Medline 1966-11/03 using the Ovid interface.
{[exp Atrial Fibrillation/ OR (atrial adj5 fibrillation).af. OR af.af] AND [exp Amiodarone/ OR amiodarone.af. OR cordarone.af] AND [exp Flecainide/ OR flecainide.af. OR tambocor.af] AND maximally sensitive RCT filter} LIMIT to human AND English language.

Search Outcome

Altogether 42 papers were found of which 4 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
Capucci A et al, 1992, Italy	62 patients with recent onset atrial fibrillation (<= 7 days), placebo versus amiodarone iv bolus followed by infusion or flecainide po	Randomised single blind trial	Conversion to sinus rhythm	As a percentage	Small numbers Placebo group discontinued monitoring after 8 hours
			At 3 hours	Placebo 29, amiodarone 16, flecainide 68
			At 8 hours	Placebo 48, amiodarone 37, flecainide 91
			At 12 hours	Amiodarone 47, flecainide 91
			At 24 hours	Amiodarone 89, flecainide 95
Donovan KD et al, 1995, Australia	98 patients with acute onset atrial fibrillation (<= 72 hrs), placebo versus amiodarone iv or flecainide iv	RCT	Conversion to sinus rhythm		Small numbers Power not shown
			<2 hours	placebo 7/32, amiodarone 11/32, flecainide 20/34
			>2 and <8 hours	placebo 18/32, amiodarone 19/32, flecainide 23/34
Boriani G et al, 1998, Italy	417 patients with recent onset atrial fibrillation (<= 7 days), placebo versus amiodarone iv, flecainide po, propafenone iv or propafenone po	Cohort	Conversion to sinus rhythm	As a percentage
			At 1 hour	Placebo 9, amiodarone 6, flecainide 13
			At 3 hours	Placebo 18, amiodarone 25, flecainide 57
			At 8 hours	Placebo 37, amiodarone 57, flecainide 75
Martinez-Marcos FJ et al, 2000, Spain	150 patients with acute onset atrial fibrillation (<= 48 hrs). Amiodarone iv versus flecainide iv or propafenone iv	Randomised single blind trial	Conversion to sinus rhythm	As a percentage
			At 1 hour	Amiodarone 14, flecainide 29
			At 8 hours	Amiodarone 42, flecainide 82
			At 12 hours	Amiodarone 64, flecainide 90

Comment(s)

There were no significant differences in the patient groups or adverse effects in all studies. Most adverse effects were mild and self limiting, with no fatal events reported.

Clinical Bottom Line

In the stable patient with acute onset atrial fibrillation and uncompromised left ventricular function, flecainide is the most efficacious drug at restoring normal sinus rhythm expediently. However approximately 60% of patients will revert with no treatment.

References

1. Capucci A, Lenzi T, Boriani G et al. Effectiveness of loading oral flecainide for converting recent-onset atrial fibrillation to sinus rhythm in patients without organic heart disease or with only systemic hypertension. Am J Cardiol 1992;70(1):69-72.
2. Donovan KD, Power BM, Hockings BE et al. Intravenous flecainide versus amiodarone for recent-onset atrial fibrillation. Am J Cardiol 1995;75(10):693-697.
3. Boriani G, Biffi M, Capucci A et al. Conversion of recent-onset atrial fibrillation to sinus rhythm: effects of different drug protocols. Pacing Clin Electrophysiol 1998;21(11 pt 2):2470-2474.
4. Martinez-Marcos FJ, Garcia-Garmendia JL, Ortega-Carpio A et al. Comparison of intravenous flecainide, propafenone, and amiodarone for conversion of acute atrial fibrillation to sinus rhythm. Am J Cardiol 2000;86(9):950-953.