Acute Effects of Amiodarone and Dronedarone on Epicardial, M and Endocardial Cells of the Canine Ventricle

pp 351-363

Abstract

Introduction

Amiodarone is an antiarrhythmic agent widely used for the treatment of supraventricular and ventricular arrhythmias. Dronedarone is a recently developed compound structurally related to amiodarone, free of iodine substituents. In a previous work it was demonstrated that chronic treatment with amiodarone reduces transmural dispersion of repolarization in the canine heart.

Objectives and methods

We studied the acute effects of amiodarone (100á1M)and dronedarone (10-30pM) on epicardial, endocardial and M region tissues obtained from left ventricular wall of the canine heart using a standard microelectrode technique.

Results

Amiodarone (100.tM, 120 min) exerted a weak change on epicardial and endocardial action potential duration, but decreased it on M cell, specially at low rates, leading to a decrease in the trans-mural dispersion of repolarization. Similar results were observed with dronedarone.

Conclusions

The decrease in transmural dispersion of repolarization and the elimination, rather than the induction of early after depolarization differentiates amiodarone from the other class III agents, and may explain in part its efficacy and less proarrhythmogenic effects. The similarities between amiodarone and dronedarone suggest the potential rol of dronedarone in the treatment of ventricular and supraventricular arrhythmias