Cardiovascular Medicine Book

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Atrial Fibrillation Chemical Cardioversion

Aka: Atrial Fibrillation Chemical Cardioversion, Atrial Fibrillation Pharmacologic Cardioversion, Atrial Flutter Pharmacologic Cardioversion
  1. See Also
    1. Atrial Fibrillation
    2. Atrial Flutter
    3. Atrial Fibrillation Causes
    4. Electrocardiogram in Atrial Fibrillation
    5. Atrial Fibrillation Acute Management
    6. Atrial Fibrillation Anticoagulation
    7. Electrical Synchronized Cardioversion of Atrial Fibrillation
    8. Synchronized Cardioversion
    9. Atrial Fibrillation Rate Control
  2. 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
  3. 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
  4. 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)
  5. Preparations
    1. Dofetilide
      1. Dose: 500 mcg orally every 12 hours
    2. Flecainide
      1. Dose: 1.5 to 3 mg/kg IV over 10-20 minutes
    3. Ibutilide
      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
    4. Propafenone
      1. Dose: 450 to 600 mg orally
    5. Amiodarone
      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
  6. Protocol: Admit to hospital to start Antiarrhythmics
    1. Observe for proarrhythmic effect
      1. Antiarrhythmics Class Ia and III
        1. Cause Torsades (with Prolonged QT)
        2. Incidence within first 4 days is common
    2. Admission is standard of care in U.S.
      1. Not admitted in Europe and Canada
    3. Admit especially for
      1. Antiarrhythmics Class Ia and Ic drugs
      2. Poor left ventricular function
      3. Coronary Artery Disease
      4. History proarrhythmia
    4. Admission not necessary
      1. Implanted Defibrillator in place
  7. 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
  8. 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)
  9. 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)
  10. 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)
  11. Complications (overall rate 13%, most within first 24 hours)
    1. Bradycardia (accounted for 60% of complications)
    2. QT Prolongation
    3. Ventricular arrhythmias
  12. 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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