ANTIARRHYTHMIC DRUG SCHEME

β-Adrenoceptor antagonists (class II)
Clinical uses of class I antidysrhythmic drugs
• Class Ia (e.g. disopyramide)
o ventricular dysrhythmias
o prevention of recurrent paroxysmal atrial fibrillation triggered by vagal overactivity.
• Class Ib (e.g. intravenous lidocaine )
o treatment and prevention of ventricular tachycardia and fibrillation during and immediately after myocardial infarction.
• Class Ic
o to prevent paroxysmal atrial fibrillation (flecainide)
o recurrent tachyarrhythmias associated with abnormal conducting pathways (e.g. Wolff-Parkinson-White syndrome).
Clinical uses of class II antidysrhythmic drugs (e.g. propranolol, timolol )

• To reduce mortality following myocardial infarction.
• To prevent recurrence of tachyarrhythmias (e.g. paroxysmal atrial fibrillation) provoked by increased sympathetic activity.
Clinical uses of class III antidysrhythmic drugs
• Amiodarone: tachycardia associated with the Wolff-Parkinson-White syndrome. It is also effective in many other supraventricular and ventricular tachyarrhythmias but has serious adverse effects.
• (Racemic) sotalol combines class III with class II actions. It is used in paroxysmal supraventricular dysrhythmias and suppresses ventricular ectopic beats and short runs of ventricular tachycardia
Adenosine (unclassified in the Vaughan Williams classification)
Clinical uses of class IV antidysrhythmic drugs
• Verapamil is the main drug. It is used:
o to prevent recurrence of paroxysmal supraventricular tachycardia (SVT)
o to reduce the ventricular rate in patients with atrial fibrillation, provided they do not have Wolff-Parkinson-White or a related disorder.
• Verapamil was previously given intravenously to terminate SVT; it is now seldom used for this because adenosine is safer.