Restoring Sinus Rhythm in Atrial Fibrillation: Electrical or Pharmacological Cardioversion

Abstract

Restoration of sinus rhythm represents a desirable endpoint in patients with persistent (nonselfterminating) episode of paroxysmal atrial fibrillation (AF) and in selected patients with chronic AF. The decision whether to cardiovert AF pharmacologically or electrically is unresolved. Pharmacological cardioversion with oral quinidine first used to terminate recent onset AF is no longer used in Europe because its safety has been questioned. Other oral antiarrhythmic agents were used orally in this indication including procaînamide, disopyramide, and oral amiodarone. More recently, oral flecaînide and oral propafenone have been used in recent onset AF. Success rates ranging between 67% and 95% were reported in placebo‐controlled studies. Pharmacological cardioversion can also routinely be obtained in hospital practice using intravenous injection of an antiarrhythmic agent. Intravenous digoxin, although commonly used, has shown in controlled studies to be no better than placebo. Intravenous amiodarone in open studies was associated with high success rates. Intravenous flecaînide, intravenous propafenone, and intravenous cibenzoline have been reported to be sucessful in recent onset AF. It is important to keep in mind that pharmacological cardioversion carries the risk of flutter with 1:1 conduction and ventricular proarrhythmia. The safety of pharmacological cardioversion using oral agents should be assessed in a hospital environment before allowing outpatient use. External (transthoracic) electrical cardioversion remains the technique of choice for restoring sinus rhythm in chronic AF. The success rates range from 65% to 90%. A technique of high energy electrical DC (200J or 300J) internal cardioversion has been shown to be useful in patients who failed external conversion. Recently, a technique for low‐energy (> 6J) cardioversion of AF using biphasic shocks, electrode catheters positioned in the right atrium (cathode), and the coronary sinus (anode), was found to restore sinus rhythm in 70%‐88% of patients. Internal cardioversion is emerging as a therapeutic alternative in selected groups of AF patients, particularly in those who failed external cardioversion.