Effect of Chronic Amiodarone Therapy on Defibrillation Energy Requirements in Humans

• Published in: Journal of cardiovascular electrophysiology Vol. 11; no. 7; pp. 736 - 740
• Main Authors: PELOSI, FRANK, ORAL, HAKAN, KIM, MICHAEL H., STICHERLING, CHRISTIAN, HORWOOD, LAURA, KNIGHT, BRADLEY P., MICHAUD, GREGORY E., MORADY, FRED, STRICKBERGER, S. ADAM
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-07-2000
• Subjects: Adult; Aged; Aged, 80 and over; Amiodarone - pharmacokinetics; Amiodarone - therapeutic use; Anti-Arrhythmia Agents - therapeutic use; defibrillation threshold; Defibrillators, Implantable; Female; Humans; implantable defibrillator; Male; Middle Aged; ventricular fibrillation
• ISSN: 1045-3873; 1540-8167
• DOI: 10.1111/j.1540-8167.2000.tb00043.x

Amiodarone Effect on Defibrillation Energy Requirement. Introduction: The effect of oral amiodarone therapy on defibrillation energy requirements in patients with an implantable defibrillator has not been established.
Methods and Results: Twenty‐one consecutive patients with implantable biphasic waveform defibrillators underwent a step‐down determination of the defibrillation energy requirement 211 ± 12 days before and 73 ± 22 days after initiation of amiodarone therapy (mean total dose 26.7 ± 11.1 g). Serum amiodarone and desethylamiodarone concentrations were measured at the time of defibrillation energy requirement determination. The mean defibrillation energy requirement before amiodarone therapy was 9.9 ± 4.6 J. After initiation of amiodarone therapy, the mean defibrillation energy requirement increased to 13.7 ± 5.6 J (P = 0.004). A linear relationship between the amiodarone (P = 0.02, r = 0.6), desethylamiodarone (P = 0.02, r = 0.6), and combined amiodarone‐desethylamiodarone concentrations (P = 0.001, r = 0.6) and the defibrillation energy requirement was noted. Stepwise regression analysis demonstrated that the combined amiodarone‐desethylamiodarone concentration was the only independent predictor of increase in the defibrillation energy requirement.
Conclusion: Chronic oral amiodarone therapy increases the defibrillation energy requirement by approximately 62% in patients with an implantable defibrillator. The combined amiodarone‐desethylamiodarone concentration is directly related to the increase in the defibrillation energy requirement.