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• Class IC Antiarrhythmics

  • propafenone (e.g., Rythmol)
  • flecainide (e.g., Tambocor)

• Class III Antiarrhythmics

  • amiodarone (e.g., Cordarone)
  • dofetilide (e.g., Tikosyn)
  • ibutilide (e.g., Covert Injection)
  • sotalol (e.g., Betapace CR)

• Class IA Antiarrhythmics

  • quinidine (e.g., Quinaglute)
  • procainamide (e.g., Pronestyl)
  • disopyramide (e.g., Norpace)

In general, the following principles apply to the use of antiarrhythmic medications for pharmacological cardioversion of atrial fibrillation:

• Pharmacological cardioversion is usually more effective for the treatment of recent-onset as compared to persistent atrial fibrillation.

• Class IC antiarrhythmics (propafenone and flecainide) are most effective for cardioversion of recent-onset atrial fibrillation but are less effective in cardioversion of persistent atrial fibrillation.

• The use of Class IC antiarrhythmics is contraindicated in patients with abnormal ventricular function or structural heart disease because of the high risk of ventricular proarrhythmia (a puzzling side-effect of antiarrhythmic medications that causes the onset of other types of arrhythmias, such as a type of ventricular tachycardia known as torsades de pointes).

• The problem of ventricular proarrhythmia is common to almost all antiarrhythmic medications with the exception of amiodarone. Amiodarone is the only antiarrhythmic drug approved by the U.S. Food and Drug Administration (FDA) that can be safely administered for pharmacological cardioversion of atrial fibrillation in patients with significant left ventricular hypertrophy.

• Quinidine, a class IA antiarrhythmic drug, has been shown to be very effective in cardioversion of patients with recent-onset atrial fibrillation, however, it is rarely used for pharmacological cardioversion because of the risk of serious adverse events, including sudden death.

More recently, several new antiarrhythmic agents have been developed that are currently under investigation for the prevention and treatment of atrial fibrillation. These newer agents include:

• Azimilide
• Dronedarone
• Serotonin 5-HT receptor antagonists

• Angiotensin-converting enzyme (ACE) inhibitors

  • trandolapril (e.g., Mavik)
  • enalapril (e.g., Vasotec)

• Angiotensin receptor blockers

  • candesartan (e.g., Atacand)
  • valsartan (e.g., Diovan)
  • irbesartan (e.g., Avalide)

• Aldosterone blockers

  • spironolactone (e.g., Aldactone)
  • eplernone (e.g., Inspra)

• Anti-inflammatory agents

  • statins (e.g., atorvastatin)
  • steroids (e.g., prednisone)

Electrical Cardioversion

Electrical cardioversion is another treatment option that may be used to revert atrial fibrillation back to normal sinus rhythm and has been available since the 1960s. Electrical cardioversion for atrial fibrillation is accomplished by delivering a direct current (DC) shock to the heart and is usually recommended for termination of atrial fibrillation that causes the patient to be hemodynamically unstable. This includes atrial fibrillation patients with hypotension, left ventricular failure, cardiogenic shock, refractory angina, and a rapid ventricular rate. If the duration of atrial fibrillation is less than 24 hours and is not associated with hemodynamic instability, pharmacological cardioversion can usually be used to restore the patient back to normal sinus rhythm.

Electrical cardioversion is performed under conscious sedation to avoid pain related to delivery of the electrical shock. The success rates of electrical cardioversion reported in the medical literature range from 70% to 90%. In general, restoration and maintenance of sinus rhythm with electrical cardioversion is more difficult to achieve in patients who have had atrial fibrillation for longer than one year. The rate of relapse of atrial fibrillation one to two years after electrical cardioversion is high unless concomitant antiarrhythmic drug therapy is instituted.