A Cochrane review 1 on antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation included 59 studies with a total of 20,981 subjects. Amiodarone was included in 13 of the studies (n=2,630), and 6 of them compared amiodarone with placebo or no treatment.
Compared to placebo/no treatment amiodarone reduced atrial fibrillation recurrence (RR 0.52, 95% CI 0.46 to 0.58; 6 studies, n=812). This corresponded to a recurrence rate of 81.2% in people not receiving active treatment and 42.2% (95% CI 37.3% to 47.1%) in people receiving amiodarone. The NNTB for amiodarone was 3 (95% CI 2 to 4) participants treated for one year to avoid one recurrence. In direct comparisons between antiarrhythmics, amiodarone appeared to reduce recurrence of atrial fibrillation more than combined class I drugs, more than dronedarone, and more than sotalol.
There was no statistically dignificant increase in proarrhythmia with amiodarone compared to placebo or no treatment (RR 2.22, 95% CI 0.71 to 6.96; 4 studies, n=673). In direct comparisons between antiarrhythmics, amiodarone seemed to produce fewer proarrhythmic events than class I drugs combined, but showed no clear differences compared with dronedarone or sotalol.
Amiodarone seemed to produce fewer withdrawals than class I drugs combined, but showed no difference compared with dronedarone or sotalol. However, compared to placebo or no treatment, amiodarone had a high RR for increasing withdrawals due to an adverse event (RR 6.70, 95% CI 1.91 to 23.45; 4 studies, n=319) The NNTH for amiodarone was 25 (95% CI 6 to 157) subjects treated for one year to have one additional withdrawal. When compared with placebo or no treatment, amiodarone showed no significant difference in mortality (RR 1.66, 95% CI 0.55 to 4.99; 2 studies, n=444).
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