open access

Vol 15, No 3 (2008)
Review articles
Published online: 2008-04-14
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Relationship among amiodarone, new class III antiarrhythmics, miscellaneous agents and acquired long QT syndrome

Andrés Ricardo Pérez Riera, Augusto Hiroshi Uchida, Celso Ferreira, Celso Ferreira Filho, Edgardo Schapachnik, Sergio Dubner, Li Zhang, Paulo Jorge Moffa
Cardiol J 2008;15(3):209-219.

open access

Vol 15, No 3 (2008)
Review articles
Published online: 2008-04-14

Abstract

Class III drugs prolong the QT interval by blocking mainly the delayed rectifier rapid potassium outward current (IKr), with little effect on depolarization. This K+ channel in encoded by the human ether-a-go-go-related gene (hERG). Inhibition of hERG potassium currents by class III antiarrhythmic drugs causes lengthening of cardiac action potential, which produces a beneficial antiarrhythmic effect. Excessive prolongation of the action potential may lead to acquired long QT syndrome, which is associated with a risk of “torsade de pointes”. Class III agents can block all types of potassium channels: IKs, IKr, IKur and IK1. The main representing class III agent is amiodarone. It is the gold standard in the prevention of recurrence of atrial fibrillation. Although it is highly effective in treating many arrhythmias, large number of adverse effects limits its clinical use. Dronedarone is a synthetic amiodarone analogue, iodinefree compound, with fewer adverse effects, and shares amiodarone’s multichannel blocking effects, inhibiting transmembrane Na+, IKs, IKur, IK1, and slow Ca++L-type calcium currents. The main new generation class III drugs are: dofetilide, dronedarone, azimilide, and ibutilide. Oral dofetilide did not increase mortality in patients with a recent myocardial infarction or congestive heart failure. It is an alternative for the pharmacological conversion of atrial fibrillation and flutter. Azimilide blocks both rapid and slow potassium channels components. Azimilide is not a methanesulfonanilide compound. Trecitilide, tedisamil, ersentilide, ambasilide, chromanol and sematilide are class III miscellaneous agents. Old mixed agents are sotalol and bretylium. The present article reviews the main trials accomplished with these drugs. (Cardiol J. 2008; 14: 209–219)

Abstract

Class III drugs prolong the QT interval by blocking mainly the delayed rectifier rapid potassium outward current (IKr), with little effect on depolarization. This K+ channel in encoded by the human ether-a-go-go-related gene (hERG). Inhibition of hERG potassium currents by class III antiarrhythmic drugs causes lengthening of cardiac action potential, which produces a beneficial antiarrhythmic effect. Excessive prolongation of the action potential may lead to acquired long QT syndrome, which is associated with a risk of “torsade de pointes”. Class III agents can block all types of potassium channels: IKs, IKr, IKur and IK1. The main representing class III agent is amiodarone. It is the gold standard in the prevention of recurrence of atrial fibrillation. Although it is highly effective in treating many arrhythmias, large number of adverse effects limits its clinical use. Dronedarone is a synthetic amiodarone analogue, iodinefree compound, with fewer adverse effects, and shares amiodarone’s multichannel blocking effects, inhibiting transmembrane Na+, IKs, IKur, IK1, and slow Ca++L-type calcium currents. The main new generation class III drugs are: dofetilide, dronedarone, azimilide, and ibutilide. Oral dofetilide did not increase mortality in patients with a recent myocardial infarction or congestive heart failure. It is an alternative for the pharmacological conversion of atrial fibrillation and flutter. Azimilide blocks both rapid and slow potassium channels components. Azimilide is not a methanesulfonanilide compound. Trecitilide, tedisamil, ersentilide, ambasilide, chromanol and sematilide are class III miscellaneous agents. Old mixed agents are sotalol and bretylium. The present article reviews the main trials accomplished with these drugs. (Cardiol J. 2008; 14: 209–219)
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Keywords

antiarrhythmic drugs; sudden cardiac death; long QT syndrome

About this article
Title

Relationship among amiodarone, new class III antiarrhythmics, miscellaneous agents and acquired long QT syndrome

Journal

Cardiology Journal

Issue

Vol 15, No 3 (2008)

Pages

209-219

Published online

2008-04-14

Bibliographic record

Cardiol J 2008;15(3):209-219.

Keywords

antiarrhythmic drugs
sudden cardiac death
long QT syndrome

Authors

Andrés Ricardo Pérez Riera
Augusto Hiroshi Uchida
Celso Ferreira
Celso Ferreira Filho
Edgardo Schapachnik
Sergio Dubner
Li Zhang
Paulo Jorge Moffa

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