Atrial Fibrillation Chemical Cardioversion

No significant left atrial enlargement
1. Consider Echocardiogram prior to cardioversion
2. Left atrium >4.5 cm poorly maintains sinus rhythm
Short duration of Atrial Fibrillation (<48 hours)
1. Chronic Atrial Fibrillation less likely to convert
2. Risk of Thromboembolism (i.e. Cerebrovascular Accident) for Atrial Fibrillation >48 hours

Atrial Fibrillation >48 hours without Anticoagulation
1. Delay cardioversion until Anticoagulation has been therapeutic for at least 3-4 weeks
2. Risk of embolization from atrial thrombi
3. Early cardioversion ok if cleared with TEE first
  1. See Atrial Fibrillation Anticoagulation

No evidence that Thromboembolism risk is less for pharmacologic cardioversion than for electrical cardioversion
1. See Atrial Fibrillation Cardioversion for thromboembolic risk (even under 48 hours)
Avoid administering agents from more than one Antiarrhythmic class (if the first fails to convert)
1. Risk of induced worse Arrhythmia (e.g. Torsades de Pointes), QT Prolongation
Slow Heart Rate to <120/min prior to cardioversion (otherwise risk of increased ventricular rate)
1. Beta Blocker (e.g. Metoprolol, Esmolol) or
2. Calcium Channel Blocker (e.g. Diltiazem)

See Ottawa Aggressive Atrial Fibrillation Protocol
Amiodarone (commonly used)
1. Bolus: 5-7 mg IV over 30-60 minutes
2. Next: 1.2 to 1.8 g/day continuous IV or divided in oral doses until 10 grams total
Flecainide (commonly used)
1. Dose: 1.5 to 3 mg/kg IV over 10-20 minutes
Ibutilide (commonly used)
1. Bolus: 1 mg IV (0.01 mg/kg if under 60 kg) over 10 minutes
2. Next: Repeat as needed with conversion occurring in 20 minutes if successful
Procainamide (risk of Hypotension, preferred agent in Canadian protocol)
1. Dose: 15 mg/kg (up to 1500 mg) in 500 ml NS infused over 60 minutes
2. Requires close monitoring and modifications based on systolic Blood Pressure, and QTc and QRS width
3. See Ottawa Aggressive Atrial Fibrillation Protocol
Propafenone
1. Dose: 450 to 600 mg orally
Dofetilide
1. Dose: 500 mcg orally every 12 hours

Admission not needed for one hour Procainamide infusion in emergency department
1. See Ottawa Aggressive Atrial Fibrillation Protocol
Observe for proarrhythmic effect
1. Antiarrhythmics Class Ia and III
  1. Cause Torsades (with Prolonged QT)
  2. Incidence within first 4 days is common
Admission is standard of care in U.S.
1. Not admitted in Europe and Canada
Admit especially for
1. Antiarrhythmics Class Ia and Ic drugs
2. Poor left ventricular function
3. Coronary Artery Disease
4. History proarrhythmia
Admission not necessary
1. Implanted Defibrillator in place

General
1. Consider for Atrial Fibrillation <48 hours
2. See Atrial Fibrillation Anticoagulation for >48 hours
Avoid Harmful agents
Recommended agents (Use only 1 agent)
1. Electrical Synchronized Cardioversion (See above)
2. Class IA Agents
  1. Procainamide
3. Class IC Agents
  1. Propafenone (Rythmol)
  2. Flecainide (Tambocor)
4. Class III Agents
  1. Sotalol (Betapace)
Mixed Evidence
1. Amiodarone (Cordarone) may induce ventricular Arrhythmias in WPW (per 2010 ACLS guidelines)