Cardiovascular Medicine Book

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Electrical Synchronized Cardioversion of Atrial Fibrillation

Aka: Electrical Synchronized Cardioversion of Atrial Fibrillation, Atrial Fib Synchronized Cardioversion, Atrial Flutter Synchronized 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. Synchronized Cardioversion
    8. Atrial Fibrillation Rate Control
    9. Atrial Fibrillation Rhythm Control (and Atrial Fibrillation Chemical Cardioversion)
    10. Ottawa Aggressive Atrial Fibrillation Protocol (Chemical Cardioversion of Acute Atrial Fibrillation With Procainamide)
  2. Indications
    1. Atrial Fibrillation with hemodynamic instability
    2. Atrial Fibrillation >48 hours on Anticoagulation for >4 to 6 weeks (or cleared of atrial thrombus by TEE)
    3. Atrial Fibrillation <48 hours and not on Anticoagulation
      1. See precautions in Atrial Fibrillation Cardioversion
        1. Thromboembolism risk still exists despite short duration of Atrial Fibrillation
      2. Consider Transesophageal Echocardiogram prior to cardioversion
      3. Other required criteria
        1. No significant left atrial enlargement
          1. Left atrium >4.5 cm poorly maintains sinus rhythm
        2. CHADS2-VASc Score <2 in men or <3 in women
          1. If CHADS-VASc Score higher, avoid cardioversion unless <12 hours from known onset
        3. NO history of stroke or Transient Ischemic Attack in prior 6 months
        4. NO valvular Atrial Fibrillation (Mechanical Heart Valves, Mitral Stenosis)
  3. Contraindications
    1. Digoxin Toxicity
    2. Atrial Fibrillation without Anticoagulation (or Anticoagulation <4 weeks)
      1. Onset >48 hours before presentation
      2. History of stroke or Transient Ischemic Attack in prior 6 months
      3. Valvular Atrial Fibrillation (Mechanical Heart Valves, Mitral Stenosis)
    3. Atrial Fibrillation >48 hours with significant left atrial enlargement (left atrium >4.5 cm)
    4. Atrial Fibrillation >12 hours in high risk patients (CHADS2-VASc Score >=2 in men or >=3 in women)
      1. Increased risk of CVA if onset >12 hours (esp. with elevated CHADS2-VASc Score)
      2. Andrade (2018) Can J Cardiol 34(1): 1371-92 [PubMed]
      3. Garg (2016) JACC Clin Electrophysiol 2(4): 487-94 [PubMed]
      4. Stiell (2018) Can J Emerg Med 20:334-42 [PubMed]
  4. Efficacy
    1. Conversion Rate: 86-94% (contrast 51% efficacy of chemical cardioversion)
      1. Higher success rates in Atrial Flutter than with Atrial Fibrillation
    2. Emergency department electrical cardioversion is safe and effective
      1. Stiell (2017) Ann Emerg Med 69(5): 562-71 +PMID:28110987 [PubMed]
  5. Dosing
    1. Dose adjustments
      1. Adjust dose if on Digoxin (see below)
      2. Higher dose (200 Joules) needed in Atrial Fibrillation, whereas lower doses are effective in Atrial Flutter
    2. Monophasic dose
      1. Synchronized: 200 joules (up to 360 joules)
      2. Starting at monophasic 200 joules minimizes cummulative shock exposure
        1. Justification: 100 J dose in Atrial Fibrillation has only 50% success rate (requiring second shock)
    3. Biphasic dose (preferred)
      1. Synchronized: 150 joules (up to 200 joules)
    4. Consider Antiarrhythmic pre-treatment prior to cardioversion in stable patients (controversial)
      1. Based on anecdotal experience, may improve electrical cardioversion success rate
      2. Option 1: Procainamide
        1. Procainamide 1 gram IV over 1 hour, then Synchronized Cardioversion if needed
        2. See Ottawa Aggressive Protocol in Atrial Fibrillation Cardioversion
      3. Option 2: Amiodarone
        1. Amiodarone 150 mg IV, then Synchronized Cardioversion if needed
  6. Precautions: Digoxin
    1. Do not use electrical cardioversion in Digoxin Toxicity (risk of malignant ventricular Arrhythmia)
    2. Modified electrical cardioversion dosing in patients on Digoxin
      1. Start at 10-20 Joules biphasic
      2. Increase in 10-20 Joule increments until cardioversion
  7. Protocol
    1. Consider alternative protocol (Procainamide followed by electrical cardioversion if fails)
      1. See Ottawa Aggressive Atrial Fibrillation Protocol
    2. Informed Consent
      1. See Atrial Fibrillation Cardioversion for risks
    3. Conscious Sedation
      1. See Synchronized Cardioversion for protocol
    4. Unfractionated Heparin or Low Molecular Weight Heparin indications
      1. Atrial Fibrillation of unknown duration or >48 hours (emergent, unstable cases requiring immediate cardioversion) or
      2. High risk of Cerebrovascular Accident (e.g. prior TIA or CVA, Rheumatic Heart Disease, Mechanical Heart Valve)
  8. Management: Post-cardioversion
    1. See Atrial Fibrillation Acute Management
      1. Describes overall approach and disposition planning (including safe for discharge indications)
    2. Atrial Fibrillation Anticoagulation
      1. Describes indications for Anticoagulation and agents (Warfarin, Dabigatran, Oral Xa Inhibitors)
      2. Expert opinion typically recommends Anticoagulation for 3 weeks following cardioversion due to myocardial stunning
        1. Increased risk of stroke in the first 3 weeks after cardioversion
    3. See Atrial Fibrillation Rate Control
      1. Discharge patient on Metoprolol Tartrate (25 mg bid) or Metoprolol Succinate (25-50 mg daily) in most cases
  9. Complications
    1. Thromboembolism (see Atrial Fibrillation Cardioversion for risk)
    2. Conscious Sedation complication
    3. Burn Injury
    4. Ventricular Tachycardia
    5. Unstable Bradycardia
  10. References
    1. Casaletto (2014) Crit Dec Emerg Med 28(4): 10-19
    2. Orman and Berg in Herbert (2016) EM:Rap 16(2): 6-10
    3. Burton (2004) Ann Emerg Med 44(1): 20-30 [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]
    10. King (2002) Am Fam Physician 66:249-56 [PubMed]

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