BACKGROUND: With the high morbidity and mortality associated with AF, it is important to define safe effective treatments to convert AF to sinus rhythm. Although patients with underlying cardiac disease are at higher risk for developing serious arrhythmias and hypotension from Class III antiarrhythmics, comparable risks have not been shown in a low-risk population with new-onset AF. The authors of this study evaluated the risks and benefits of using the Class III antiarrhythmics sotalol and amiodarone versus digoxin in conversion of new-onset AF to sinus rhythm at 48 hours.
POPULATION STUDIED: The authors of this study enrolled 115 patients with new-onset (<24 hours) AF. Patients with significant left ventricular dysfunction (ejection fraction <30% or requiring >40 mg of furosemide daily) or wide complex tachycardia were excluded. Patients who had used any of the study drugs within a defined period of time or who were prescribed a b-blocker were also excluded.
STUDY DESIGN AND VALIDITY: This was a prospective randomized trial. Concealed allocation did not occur for the majority of patients enrolled in the study. Patients were randomized to receive amiodarone, sotalol, or digoxin; all 3 groups had similar baseline characteristics. The trial medication was discontinued before 48 hours of treatment in 5 patients because of stroke, hypotension, or bradyarrhythmia, but these patients were still included in the analysis. At 24 hours those patients still in AF were started on heparin. Cardioversion was attempted in 20 of 29 patients who remained in AF after 48 hours of the study drug. The 9 patients excluded from cardioversion had significant left ventricular dysfunction, stroke, inadequate anticoagulation, or hypotension. Adverse events from all medications were recorded and analyzed. This study lacked long-term follow-up for monitoring of subsequent spontaneous reversion to AF, which may be a major factor in the drug to choose for sinus rhythm conversion. In addition, this study excluded those patients who had left ventricular dysfunction, a group that is at particular risk for developing complications from new-onset AF.
OUTCOMES MEASURED: The primary outcome measured was successful conversion to sinus rhythm within 48 hours of antiarrhythmic treatment or cardioversion. Secondary outcomes considered were time to conversion; ventricular rate if in AF at 4, 24, and 48 hours; and adverse events.
RESULTS: The number of patients in sinus rhythm after 48 hours of medication was greater in both the amiodarone (77%) and sotalol (88%; number needed to treat=3) groups compared with the digoxin group (58%) This was statistically significant (P <.01) for the sotalol group and the combined sotalol and aminodarone groups. There was also a nonsignificant trend toward more successful cardioversion in those receiving either study drug. The average time to reversion was greater for digoxin-treated patients (27 hours) than amiodarone-treated (18 hours; P <.05) or sotalol-treated (13 hours; P <.01) patients. Major adverse events included left ventricular failure, bradyarrhythmia, hypotension, and stroke. Digoxin treatment was associated with a significantly higher risk of major complications compared with either other drug (22% vs 7.7% and 5%).
For patients with new-onset AF and good systolic function, active treatment with sotalol or amiodarone can be used for more effective and faster conversion to sinus rhythm with fewer major adverse events than treatment with digoxin. These results may not be applicable to patients with AF of an unknown duration or in those with left ventricular dysfunction.