Facilitated conversion of acute atrial fibrillation by rapid high-dose IV amiodarone infusion

Intravenous (IV) amoidarone (AM.) is utilized for conversion of acute atrial fibrillation (AF) to normal sinus rythm (NSR). However it is not determined whether AM. facilitates acute AF conversion and which is the efficient rate of administration. Methods: 20 patients (Pts.) with acute (< 48 hours) AF were randomized to receive: (1) Group A, (n=10): Placebo infusion. (2) Group B, (n=10): IV AM. 100 mg/hour for 24 hours (total 2.4g). Group A Pts. that not converted to NSR by 24 hours were crossed over to AM. therapy All Pts. received Digoxin loading. Results: After 24 hours of treatment one Pt. developed MI in group A compared to no cardiac adverse events in group B. The pulse decreased to 80±8 beats/min. in group B vs. 94±16 in group A (p=0.03). 5 Pts. (50%) in group A converted to NSR compared to 14 out of 15 (93%) AM. treated Pts. (group B and Pts. from group A crossed over to B)(p=0.023).The dose of AM required for conversion to NSR was 536±254 mg. This dose is lower than the total dose used in studies that have not demonstrated AM. efficacy. Conclusion: IV administration of AM. at a rate of 100 mg/hour is safe and facilitates conversion of acute AF to NSR. It is possible that the rate of AM. administration rather than total dose is important in conversion of acute AF to NSR.