The use of drugs for cardioversion of recent onset atrial fibrillation and flutter: Focus on ibutilide

Atrial fibrillation (AF) is the most common sustained arrhythmia, particularly in the elderly population. It is well recognised that AF is a major cause of stroke, even in the absence of underlying heart disease. Although AF and atrial flutter share many causes and may be seen in the same patient, there are differences between these arrhythmias: atrial flutter is less common, and the risk of stroke associated with it is less than that with AF. In addition to stroke, both AF and atrial flutter may cause cardiomyopathy, which may be fully reversible with effective treatment of the arrhythmia. Both AF and atrial flutter can result in severe symptoms and may precipitate heart failure, ischaemia and syncope. Recent research indicates that AF is a self-perpetuating arrhythmia, and that the longer it is left untreated the less likely it is that effective cardioversion will be possible. Drugs are an attractive option for the cardioversion of AF and atrial flutter because their use does not require anaesthesia. Antiarrhythmic drugs in class III of the Vaughan-Williams classification are effective in the treatment of AF, but they have adverse effects; several new 'pure' class III agents are under development. The first of these to be made available is ibutilide, a methanesulphonamide derivative. Initial results are encouraging, particularly for atrial flutter. However the drug has the potential for proarrhythmic effects and physicians who use it will need to be aware of these.