Amiodarone has been used as an anti-arrhythmic drug since the 1970s and has an 
established role in the treatment of ventricular tachyarrhythmias. Although 
considered to be a class III anti-arrhythmic, amiodarone also has class I, II 
and IV actions, which gives it a unique pharmacological and anti-arrhythmic 
profile. Amiodarone is a structural analogue of thyroid hormone and some of its 
anti-arrhythmic properties and toxicity may be attributable to interactions with 
nuclear thyroid hormone receptors. The lipid solubility of amiodarone gives it 
an exceptionally long half-life. Oral amiodarone takes days to work in 
ventricular tachyarrhythmias, but iv. amiodarone has immediate effect and can be 
used in life threatening ventricular arrhythmias. Intravenous amiodarone 
administered after out-of-hospital cardiac arrest due to ventricular 
fibrillation improves survival to hospital admission. Many survivors of 
myocardial infarction (MI) die during the subsequent year, probably due to 
ventricular arrhythmia. Amiodarone reduces sudden death after MI and this 
benefit is predominantly observed in patients with preserved cardiac function. 
Sudden cardiac death, predominantly due to ventricular arrhythmias, is also 
commonly seen in patients with heart failure. The Grupo de Estudio de la 
Sobrevida en lsuficiencia Cardiaca en Argentina (GESICA) and Estudio Piloto 
Argentino de Muerte Subita y Amiodarona (EPAMSA) trials showed survival benefit 
of amiodarone in heart failure, whereas Congestive Heart Failure-Survival Trial 
of Anti-arrhythmic Therapy (CHF-STAT) did not. Subsequent meta-analysis 
established a survival benefit of amiodarone in heart failure. Implanted 
Cardioverter Def ibrillators (ICDs) also give survival benefit to patients at 
risk of sudden death. In patients with a history of ventricular fibrillation or 
haemodynamically-compromising ventricular tachycardia, ICDs have been shown to 
be superior to anti-arrhythmic drugs, principally amiodarone. Further analysis 
has been undertaken to ascertain which patients are most likely to benefit from 
ICDs, as these are more expensive than treatment with amiodarone. Patients with 
severely depressed ejection fractions should be the first to be considered for 
ICDs. A new indication for amiodarone is atrial fibrillation or flutter. 
Amiodarone is effective in chronic and recent onset atrial fibrillation and 
orally or iv. for atrial fibrillation after heart surgery. In atrial 
fibrillation amiodarone is more than or equi-effective with flecainide, 
quinidine, racemic sotalol, propafenone and diltiazem and therefore should be 
considered for first line therapy. Amiodarone is also safe and effective in 
controlling refractory tachyarrhythmias in infants and is safe after cardiac 
surgery.