Effect of amiodarone and sotalol on ventricular defibrillation threshold: the optimal pharmacological therapy in cardioverter defibrillator patients (OPTIC) trial.
BACKGROUND
Many patients with implanted cardioverter defibrillators (ICDs) receive adjunctive antiarrhythmic drug therapy, most commonly amiodarone or sotalol. The effects of these drugs on defibrillation energy requirements have not been previously assessed in a randomized controlled trial.


RESULTS
The Optimal Pharmacological Therapy in Cardioverter Defibrillator Patients (OPTIC) trial was a randomized clinical trial evaluating the efficacy of amiodarone plus beta-blocker and sotalol versus beta-blocker alone for reduction of ICD shocks. Within OPTIC, a prospectively designed substudy evaluated the effects of the 3 treatment arms on defibrillation energy requirements. Defibrillation thresholds (DFTs) were measured (binary step-down protocol) at baseline and again after 8 to 12 weeks of therapy in 94 patients, of whom 29 were randomized to receive beta-blocker therapy (control group), 35 to amiodarone plus beta-blocker, and 30 to sotalol. In the control group, the mean DFT decreased from 8.77+/-5.15 J at baseline to 7.13+/-3.43 J (P=0.027); in the amiodarone group, DFT increased from 8.53+/-4.29 to 9.82+/-5.84 J (P=0.091). In the sotalol group, DFT decreased from 8.09+/-4.81 to 7.20+/-5.30 J (P=0.21). DFT changes in the beta-blocker and the amiodarone group were significantly different (P=0.006). In all patients, adequate safety margins for defibrillation were maintained. No clinical variable predicted baseline DFT or changes in DFT on therapy.


CONCLUSIONS
Although amiodarone increased DFT, the effect size with modern ICD systems is very small. Therefore, DFT reassessment after the institution of antiarrhythmic drug therapy with amiodarone or sotalol is not routinely required.
Hohnloser
Stefan H
SH
Department of Medicine, Division of Cardiology, J.W. Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany. Hohnloser@em.uni-frankfurt.de
Dorian
Paul
P
Roberts
Robin
R
Gent
Michael
M
Israel
Carsten W
CW
Fain
Eric
E
Champagne
Jean
J
Connolly
Stuart J
SJ
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000368:Aged; D000638:Amiodarone / Q000627:therapeutic use*; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000503:physiopathology; D017298:Bisoprolol / Q000627:therapeutic use; D002227:Carbazoles / Q000627:therapeutic use; D000077261:Carvedilol; D003131:Combined Modality Therapy; D017147:Defibrillators, Implantable; D005260:Female; D006323:Heart Arrest; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000627:therapeutic use; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology; D011412:Propanolamines / Q000627:therapeutic use; D013015:Sotalol / Q000627:therapeutic use*; D014693:Ventricular Fibrillation / Q000188:drug therapy* / Q000601:surgery*; D016277:Ventricular Function, Left
D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents; D002227:Carbazoles; D011412:Propanolamines; D000077261:Carvedilol; D013015:Sotalol; D008790:Metoprolol; D000638:Amiodarone; D017298:Bisoprolol