A Cochrane review included 59 studies with a total of 21 305 subjects. Several class IA (disopyramide, quinidine), IC (flecainide, propafenone) and III (amiodarone, dofetilide, dronedarone, sotalol) drugs significantly reduced recurrence of AF (OR 0.19 to 0.70, number needed to treat 3 to 16). Beta-blockers (metoprolol) also reduced significantly AF recurrence (OR 0.62, 95% CI 0.44 to 0.88, NNT 9). All analysed drugs increased withdrawals due to adverse effects and all but amiodarone, dronedarone, and propafenone increased pro-arrhythmia. The effectiveness of antiarrhythmics is limited - atrial fibrillation still recurred in 43 to 67% of treated patients.
Compared with controls, class IA drugs quinidine and disopyramide (OR 2.39, 95% CI 1.03 to 5.59, number needed to harm (NNH) 109, 95% CI 34 to 4985) and sotalol (OR 2.23, 95% CI 1.1 to 4.50, NNH 169, 95% CI 60 to 2 068) were associated with increased all-cause mortality. Other antiarrhythmics did not seem to modify mortality, but data could be underpowered to detect mild increases in mortality for several of the drugs studied.
Only 11 studies reported data on stroke. None of them found any significant difference with the exception of a single study that found less strokes in the group treated with dronedarone compared to placebo. This finding was not confirmed in others studies on dronedarone. It was not possible to analyse heart failure and use of anticoagulation because few original studies reported on these measures.
Comment: The quality of evidence is downgraded by study quality (unclear or not well reported allocation concealment and lack of blinding in some studies). Most of the studies did not assess the complications associated with atrial fibrillation (heart failure, stroke, embolisms), so the effect of antiarrhythmic drugs on these endpoints is unknown.