EKG

Atrial Fibrillation Cardioversion

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Atrial Fibrillation Cardioversion, Ottawa Aggressive Protocol in Atrial Fibrillation Cardioversion, Atrial Flutter Cardioversion

  • Precautions
  1. Exercise caution in cardioversion if electrolyte disturbance (e.g. Hypokalemia, Digoxin Toxicity)
  2. Patients with Atrial Fibrillation are unreliable in judging Atrial Fibrillation duration (i.e. longer or shorter than 48 hours)
    1. Less than 70% of patients can actively predict when they are in paroxysmal Atrial Fibrillation
      1. Montenero (2004) J Interv Card Electrophysiol 10(3): 211-20 [PubMed]
    2. Patients with Atrial Fibrillation are asymptomatic as often as 40-60% of the time
      1. Savelieva (2000) J Interv Card Electrophysiol 4(2):369-82 [PubMed]
  3. Non-anticoagulated patients may form atrial thrombus at any time (even within 48 hours) and may not be detected by TEE
    1. Non-anticoagulated emergency department cardioversion-related Thromboembolism rate: <7% (mean 1.5%)
      1. Kinch (1995) Arch Intern Med 155(13): 1353-60 [PubMed]
    2. Left atrial thrombus is present in 14% of non-anticoagulated patients with Atrial Fibrillation <48 hours (by TEE)
      1. Left atrial thrombus is present in 27% of non-anticoagulated patients with chronic Atrial Fibrillation
      2. Left atrial thrombus may be present as early as 12 hours after Atrial Fibrillation onset
      3. Stoddard (1995) J Am Coll Cardiol 25(2): 452-9 [PubMed]
      4. Nuotio (2014) JAMA 312(6): 647-9 +PMID:25117135 [PubMed]
    3. Thromboembolism occurs in 6% of cardioversion patients who had normal TEE prior to cardioversion
      1. Postulated acute clot formation from cardioversion-induced atrial stunning (persists for days to weeks)
      2. Fatkin (1994) J Am Coll Cardiol 23(2): 307-16 [PubMed]
    4. One study suggested Atrial Fibrillation duration for safe cardioversion might be as short as 12 hours (not 48 hours)
      1. Airaksinen (2013) J Am Coll Cardiol 62(13): 1187-92 +PMID:23850908 [PubMed]
    5. However, electrical Cardioversion in Atrial Fibrillation <48 hours appears safe with a low overall Thromboembolism risk
      1. Weigner (1997) Ann Intern Med 126(8): 615-20 +PMID:9103128 [PubMed]
      2. Stiell (2017) Ann Emerg Med 69(5):562-571 +PMID:28110987 [PubMed]
  4. Cardioversion may not offer initial benefit for hemodynamically stable patients
    1. Spontaneous conversion to sinus rhythm occurs in 66% of patients within 24 hours and 80% within 48 hours
    2. However, many patients feel un-well while in Atrial Fibrillation
  5. Left Ventricular Dysfunction and valvular defect patients may have even less benefit AND Thromboembolism risk
    1. Theoretical benefit of potentially increased atrial kick may not be beneficial in practice
    2. Atrial kick (10-15% of Cardiac Output) does not return for days to weeks after cardioversion (due to atrial stunning)
    3. Successful cardioversion rates are significantly worse in Left Ventricular Dysfunction
    4. Left Ventricular Dysfunction significantly increases the risk of Thromboembolism
  6. Risk factors for stroke after cardioversion
    1. Unknown time of Atrial Fibrillation onset
    2. History of Transient Ischemic Attack or stroke in the last 6 months
    3. Mechanical Heart Valve
    4. Rheumatic Heart Disease
  7. Caveat
    1. Emergent cardioversion is indicated in a hemodynamically unstable patient
    2. See Atrial Fibrillation Synchronized Cardioversion
  1. See Atrial Fibrillation Cardioversion regarding precautions
  2. See precautions above (as Thromboembolism risk still exists despite short duration of Atrial Fibrillation)
  3. Consider Heparin while considering cardioversion
  4. Consider early Atrial Fibrillation Cardioversion
    1. Many patients prefer this when presenting with recurrence of Atrial Fibrillation to the Emergency Department
    2. Atrial Fibrillation is uncomfortable (Dyspnea, light headedness) and rate control medications have adverse effects
    3. Discharge after emergency department cardioversion is safe with a low complication rate
      1. von Besser (2011) Ann Emerg Med 58(6):517-20 +PMID:22098994 [PubMed]
  5. Cardioversion options
    1. Atrial Fibrillation Synchronized Cardioversion (preferred, most effective, safest option)
      1. May be preceded by chemical cardioversion attempt (e.g. Ottawa protocol as below)
    2. Atrial Fibrillation Chemical Cardioversion
  6. Ottawa Aggressive Protocol
    1. First: Procainamide 1 g over 1 hour
      1. Risk of Hypotension and QRS Widening
    2. Next: Atrial Fibrillation Synchronized Cardioversion (if no effect with Procainamide)
    3. Efficacy
      1. Sinus rhythm conversion rate at time of ED discharge: 90%
      2. ED discharge rate: 97%
      3. Relapse rate: 9% at 7 days
    4. Safety
      1. Patients must be stable
      2. No Thromboembolism
    5. References
      1. Stiell (2007) Acad Emerg Med 14(5 Supplement 1): 59 +PMID:20522282 [PubMed]
  1. Warfarin (or other approved Anticoagulant) for 3 weeks before cardioversion
  2. Consider Atrial Fibrillation Cardioversion
  3. Continue Warfarin (or other approved Anticoagulant) for 4 weeks after cardioversion
    1. See Atrial Fibrillation Anticoagulation
  4. Early cardioversion acceptable if cleared with TEE first
    1. See Atrial Fibrillation Anticoagulation
  • Management
  • Disposition
  1. See Atrial Fibrillation Acute Management for disposition management
  2. See Atrial Fibrillation Anticoagulation
    1. Expert opinion recommends Atrial Fibrillation Anticoagulation for 3 weeks after electrical cardioversion
    2. Reduces risk of Thromboembolism formation from stunned Myocardium