Amiodarone therapy in patients implanted with cardioverter-defibrillator for life-threatening ventricular arrhythmias

Background: Whether amiodarone can improve the patient's clinical outcome by reducing implantable cardioverter-defibrillator (ICD) therapy deliveries for ventricular tachycardia or fibrillation (VT/VF) has not been clearly evaluated. Methods and Results: A total of 507 patients with VT/VF due to organic heart disease who had ICDs implanted were enrolled in this study. The patients were divided into 3 groups: Amiodarone (n=247), Class I antiarrhythmic drug (n=103) and Control (n=157) groups, and the total cause mortality and arrhythmic event free survival rates were evaluated between the groups. The mean follow-up period was 38±27 months. The left ventricular ejection fraction was significantly decreased in the Amiodarone group (Amiodarone: 37±15%; Class I: 39±16%; Control: 44±17%). The mortality and arrhythmic events were significantly higher in the Class I group than the Amiodarone group (p<0.05), but there was no significant difference between the Amiodarone and Control groups (arrhythmic event free rate at 5 years: Amiodarone: 53%; Class I: 35%; Control: 48%; 5 year survival: 86%, 74% and 77%, respectively). Side effects from amiodarone were found in 12% of the patients, but no fatal events were observed. Conclusions: The present study could not demonstrate the benefit of amiodarone in ICD patients, probably due to a significant clinical bias exerted in selecting this drug.