Atrial Fibrillation Chemical Cardioversion

Aka: Atrial Fibrillation Chemical Cardioversion, Atrial Fibrillation Pharmacologic Cardioversion, Atrial Flutter Pharmacologic Cardioversion

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II. Indications: Acute Atrial Fibrillation

  1. No significant left atrial enlargement
    1. Consider Echocardiogram prior to cardioversion
    2. Left atrium >4.5 cm poorly maintains sinus rhythm
  2. 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

III. Contraindications

  1. 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

IV. Precautions

  1. 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)
  2. 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
  3. 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)

V. Medications

  1. See Ottawa Aggressive Atrial Fibrillation Protocol
  2. Precautions: Reduced Ejection Fraction (EF)
    1. Only Dofetilide and Amiodarone should be used to maintain sinus rhythm in reduced EF
  3. 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
    3. Efficacy in returning to sinus rhythm (acute chemical cardioversion)
      1. Less effective than other agents in acute return to sinus rhythm
      2. Return to sinus rhythm may be delayed 8 hours
    4. Higher adverse effects than other agents with longterm use (pulmonary fibrosis, Neuropathy)
    5. May be used in patients with reduced ejection fraction
  4. Flecainide (commonly used)
    1. Dose: 1.5 to 3 mg/kg IV over 10-20 minutes
    2. Administer rate control agent at least 30 minutes before dosing
    3. Efficacy in returning to sinus rhythm: Doubles chance of returning to sinus rhythm within 4 hours
    4. Often prescribed by electrophysiologists as "pill in the pocket" single use prn paroxysmal Atrial Fibrillation
    5. Avoid if recent cardiac events or Heart Failure history
  5. 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
    3. Efficacy in returning to sinus rhythm: 30% in those with normal ejection fraction
  6. 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
  7. Propafenone
    1. Dose: 450 to 600 mg orally
    2. Administer rate control agent at least 30 minutes before dosing
    3. Efficacy in returning to sinus rhythm: Doubles chance of returning to sinus rhythm within 4 hours
    4. Avoid if recent cardiac events or Heart Failure history
    5. May be prescribed by electrophysiologists as "pill in the pocket" single use prn paroxysmal Atrial Fibrillation
  8. Dofetilide
    1. Dose: 500 mcg orally every 12 hours
    2. May be used in patients with reduced ejection fraction
    3. Efficacy in maintaining sinus rhythm (chronic use to maintain sinus rhythm)
      1. Doubles chance of still being in sinus rhythm at one year

VI. Protocol: Admit to hospital to start Antiarrhythmics

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

VII. Protocol: Chemical Cardioversion Preferred agent summary

  1. No organic heart disease
    1. First choice: Flecainide or Propafenone
    2. Second choice: Sotalol
    3. Other: Amiodarone, Dofetilide
  2. Coronary Artery Disease
    1. First choice: Sotalol
    2. Second choice: Amiodarone, Dofetilide
  3. Congestive Heart Failure
    1. Amiodarone
    2. Dofetilide
  4. Left Ventricular Hypertrophy (>1.4 cm thick wall)
    1. Amiodarone

VIII. Protocol: Pharmacologic Cardioversion if WPW Syndrome

  1. General
    1. Consider for Atrial Fibrillation <48 hours
    2. See Atrial Fibrillation Anticoagulation for >48 hours
  2. Avoid Harmful agents
    1. Adenosine
    2. Beta Blocker
    3. Calcium Channel Blocker
    4. Digoxin
  3. 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)
  4. Mixed Evidence
    1. Amiodarone (Cordarone) may induce ventricular Arrhythmias in WPW (per 2010 ACLS guidelines)

IX. Protocol: Pharmacologic Cardioversion if Normal Cardiac Function

  1. General
    1. See precautions regarding Atrial Fibrillation Cardioversion
    2. Consider for Atrial Fibrillation <48 hours
    3. See Atrial Fibrillation Anticoagulation
  2. 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. Amiodarone (Cordarone)
      2. Ibutilide (Corvert)
      3. Dofetilide (Tikosyn)

X. Protocol: Pharmacologic Cardioversion if Ejection Fraction <40%

  1. General
    1. Consider for Atrial Fibrillation <48 hours
    2. See Atrial Fibrillation Anticoagulation for >48 hours
  2. Recommended agents
    1. Electrical Synchronized Cardioversion (See above)
    2. Amiodarone (Cordarone)

XI. Complications (overall rate 13%, most within first 24 hours)

  1. Bradycardia (accounted for 60% of complications)
  2. QT Prolongation
  3. Ventricular Arrhythmias

XII. References

  1. Casaletto (2014) Crit Dec Emerg Med 28(4): 10-19
  2. (2000) Circulation, 102(Suppl I):86-9
    1. http://www.circulationaha.org
  3. Chevalier (2003) J Am Coll Cardiol 41:255-62 [PubMed]
  4. Stiell (2011) Canadian J Cardiol 27(1): 38-46 [PubMed]
  5. Wann (2011) Circulation 123(1): 104-23 [PubMed]
  6. King (2002) Am Fam Physician 66(2):249-56 [PubMed]
  7. Gutierrez (2011) Am Fam Physician 83(1): 61-8 [PubMed]
  8. Falk (2001) N Engl J Med 344:1067-78 [PubMed]
  9. Li (1998) Emerg Med Clin North Am 16:389-403 [PubMed]

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