Pharmacologic versus direct-current electrical cardioversion of atrial flutter and fibrillation

Conversion of atrial flutter and atrial fibrillation (AF) can be achieved b y either pharmacologic or direct-current (DC) electrical cardioversion. DC electrical cardioversion is more effective and restores sinus rhythm instan taneously; however, general anesthesia is necessary, which can cause severe complications. On the other hand, pharmacologic cardioversion is less effe ctive. First, time to conversion is unpredictable and may be relatively lon g, especially with oral drug therapy. Also, the rate of conversion is lower and depends on duration of AF. In addition, safety is an important issue. Adverse drug reactions include bradycardia, paradoxical tachycardia due to enhanced atrioventricular conduction, ventricular proarrhythmia, and acute heart failure. In paroxysmal AF, drug therapy is usually aimed at an acute conversion. Class IA and IC drugs are more efficacious than the class III d rugs sotalol, amiodarone, and ibutilide. By contrast, class III drugs are m ore effective for the conversion of atrial flutter. Acute conversion out-of -hospital ("pill in the pocket approach") should be done only if the drug u sed appeared effective and safe after a few in-hospital trials. In persiste nt AF, DC conversion is preferred because drugs are particularly ineffectiv e if the arrhythmia has lasted >24-48 hours. The tatter probably relates to electrical and anatomical remodeling of the atria during ongoing atrial fi brillation and flutter. Nevertheless, a wait-and-see approach using, for ex ample, oral amiodarone may be adopted with late DC conversion if the drug f ails to convert persistent AF. However, the consequences of remodeling seem to dictate an early conversion. In this respect, echocardiography-guided D C cardioversion may become increasingly important in AF. It will prevent tr eatment resistance and potentially reduces embolic complications. In a hybr id approach, antiarrhythmic drugs may be used to enhance DC conversion and prevent (sub)acute recurrences of AF. However, it may increase the defibril lation threshold, especially if class IC drugs are used. New treatment opti ons such as automatic defibrillation (implantable atrioverter) are still in vestigational. (C)1999 by Excerpta Medica, Inc.