Electrocardiographic and antiarrhythmic effects of intravenous amiodarone: Results of a prospective, placebo-controlled study

Abstract

The antiarrhythmic efficacy of intravenously administered amiodarone was examined in a prospective, randomized, placebo-controlled study that involved 77 patients after coronary artery bypass surgery. Amiodarone was given after surgery in a loading bolus of 300 mg for 2 hours followed by 1200 mg every 24 hours for 2 days and 900 mg every 24 hours for the next 2 days. Amiodarone suppressed both supraventricular and ventricular arrhythmias within 12 hours after the start of therapy. Particularly, the incidence of atrial fibrillation (5% vs 21% in the control group;p < 0.05) and of nonsustained ventricular tachycardia (3% vs 16%;p < 0.05) was reduced by amiodarone. Heart rate was slowed (p < 0.001) and repolarization—as judged by JTc interval—was prolonged compared with the control group (p < 0.01). In two patients, amiodarone infusion was stopped because of excessive QTc prolongation. No detrimental hemodynamic effects of the drug were observed. Thus the intravenous administration of amiodarone appears to be suitable for patients in whom rapid suppression of symptomatic supraventricular and ventricular arrhythmias is warrented in the presence of left ventricular dysfunction.