Eighteen RCTs were included; 550 patients received amiodarone, 451 patients received another anti-arrhythmic agent, and 202 patients received placebo.
Overall, 76% of patients receiving amiodarone were cardioverted, compared with 72% of those receiving active anti-arrhythmic therapy and 60% receiving placebo.
Amiodarone versus other anti-arrhythmic agents (16 RCTs).
There was no statistically-significant difference in the pooled estimates for conversion rates from 16 cohorts comparing amiodarone and active anti-arrhythmic agents. The pooled estimates were 72.1 and 71.9%, respectively (p=0.84). The cardioversion rate differences between amiodarone and other anti-arrhythmic agents ranged from -56.25 to 74.83. The pooled average rate difference was 0.31 (95% confidence interval: -11.13, 13.91, p=0.84).
Amiodarone versus drugs of questionable effectiveness (6 RCTs).
The unadjusted average cardioversion rates were 78% for amiodarone and 59% for the other drugs. Amiodarone was statistically significantly more effective than the other drugs; the pooled rates were 78.3 and 58.7%, respectively (p=0.03).
Amiodarone versus placebo (5 RCTs).
Amiodarone was associated with a significantly higher rate of cardioversion than placebo in cohorts comparing the two interventions. The pooled rates were 82.4 and 59.7% for amiodarone and placebo, respectively (p=0.03).
The cardioversion rate differences between amiodarone and placebo ranged from -9.43 to 50.11.
Adverse events.
The most commonly reported adverse events with intravenous amiodarone were infusion phlebitis (8%), bradycardia (4%) and hypotension (2%).
Overall, adverse events were reported in 17% of the patients receiving amiodarone, in 14% of those receiving other anti-arrhythmic drugs, and in 11% receiving placebo.
There was no statistically-significant difference in the pooled adverse event rates between amiodarone and other active anti-arrhythmic agents in the cohort comparison studies. The pooled rates were 12.2 and 14.0%, respectively (p=0.64). Amiodarone was associated with significantly higher rates of adverse event than placebo in the cohort comparison studies; the pooled rates were 26.8 and 10.8%, respectively (p=0.02).