We tested the efficacy of intravenous
amiodarone (5 mg/kg) in slowing ventricular response and/or restoring sinus rhythm in 26 patients with paroxysmal or new
atrial fibrillation with fast ventricular response. There were 16 men and 10 women with ages ranging from 35 to 84 years, mean 63 years. Intravenous
amiodarone initially slowed the ventricular response in all patients from 143 +/- 27 to 96 +/- 10 beats/min (P less than 0.001). Twelve patients (46%) reverted to sinus rhythm within the first 30 min (range 5 to 30 min, mean 14 +/- 9 min). One patient reverted to
atrial flutter after 10 min and 40 min later to sinus rhythm. Six patients (23%) converted to sinus rhythm after 2 to 8 hr and in these 6 cases, the initial slowing in ventricular response obtained with
amiodarone persisted until conversion. Seven patients (27%) did not convert to sinus rhythm following
amiodarone administration and they required further medical
therapy to slow the ventricular response and/or to convert to sinus rhythm. No serious side effects from
drug administration were noted. Intravenous
amiodarone appears as a highly effective medication in the conversion or control of new onset
atrial fibrillation with fast ventricular response.