Oral antiarrhythmic drugs in converting recent onset atrial fibrillation.

Aim: This article reviews clinical studies on oral antiarrhythmic drugs in converting recent onset atrial fibrillation. An oral loading dose of an antiarrhythmic drug for cardioversion of atrial fibrillation could be an option, due to its simplicity, both for patients admitted to outpatient departments and for episodic treatment by self administration outside the hospital. The latter treatment strategy has recently been pointed out by the American College of Cardiology, the American Heart Association and the European Society of Cardiology as the 'pill in the pocket approach'.

Methods: Articles were identified by Medline 1966 to November 2001 and Embase 1966 to November 2001. Randomized studies of oral antiarrhythmic drugs versus placebo or comparative treatment, which are written in the English language, were selected. Non-randomized or non-comparative studies were selected if the results of an analysis to identify predictors for successful conversion are described. The review of clinical trials is followed by a description of pharmacokinetic parameters of the antiarrhythmic drugs.

Results: Studies meeting the inclusion criteria were on propafenone, flecainide, sotalol, amiodarone, quinidine, digoxin and verapamil. Conversion rates of a single oral loading dose of 600 mg propafenone varied between 37% and 41% at 4 h after ingestion. Propafenone was more effective than quinidine, amiodarone and placebo. A single oral dose of 300 mg flecainide restored sinus rhythm in 59% and 68% of patients at 3 h. Flecainide was more effective than amiodarone and placebo. Oral sotalol, digoxin and verapamil were not effective in converting atrial fibrillation to sinus rhythm.

Conclusion: Propafenone and flecainide are effective in converting recent onset atrial fibrillation. No serious ventricular arrhythmia, other serious proarrhythmic effects or serious non cardiac adverse events were observed. Regular supraventricular tachyarrhythmias with 1:1 AV conduction were rare and were also observed in placebo treated patients. Propafenone and flecainide are more effective in patients with atrial fibrillation of less than 24 h. The association between cardioversion and patient characteristics are not consistent between studies. The pharmacokinetics of flecainide, with lower interindividual variability of absorption kinetics, no genetically determined formation of an active metabolite and a more rapid distribution to myocardial tissue, are more favourable for episodic treatment as compared to propafenone. Both flecainide and propafenone are safe in hospitalized patients. Out of hospital self administration of antiarrhythmic drugs, also described as the 'pill in the pocket approach', could be an option for selected patients, after the treatment has proven to be safe in hospital.