EBQ:Ottawa Aggressive ED Cardioversion Protocol

Complete Journal Club Article
Stiell I. et al.. "Association of the Ottawa Aggressive Protocol with rapid discharge of emergency department patients with recent-onset atrial fibrillation or flutter". CJEM. May 2010. =12(3):181-91.
PubMed Full text PDF

Clinical Question

What is the effectiveness and safety of the Ottawa Aggressive Protocol to perform rapid cardioversion and discharge of patients with new onset atrial fibrillation?


In patients with new onset atrial fibrillation or flutter with symptoms onset <48 hours, rapid conversion with procainamide or electrical cardioversion is safe and will also decrease treatment time and hospital admissions.

Major Points

Reviews of the literature have shown that stable patients with close followup who have recent-onset atrial fibrillation after cardioversion in the ED can be safely discharged after cardioversion in the ED.[1] Also Among patients with Atrial Fibrillation clinically estimated to be <48 hours, the likelihood of cardioversion-related clinical thromboembolism is very low.[2]

  • The relapse rate for atrial fibrillation is 3% -17% and close followup and ability to return to the ED if there is return of symptoms is essential.[1]

The following is a reproduction of the ED Cardioversion Protocol

1. Assessment for Cardioversion
Stable without ischemia, hypotension or acute CHF?
Onset clear and less than 48 hours?
Severity of symptoms?
Previous episodes and treatments?
Anticoagulated with warfarin and INR therapeutic?
2.Rate Control If highly symptomatic or not planning to convert
Diltiazem IV (0.25 mg/kg over 10 min; repeat at 0.35 mg/kg)
Metoprolol IV (5 mg doses every 15 min)
3. Pharmacologic Cardioversion
Procainamide IV (1 g IV over 60 min; hold if blood pressure < 100 mm Hg)
4. Electrical cardioversion
Consider keeping patient NPO × 6 h
Procedural sedation and analgesia given by emergency physician (propofol IV and fentanyl IV)
Start at 150–200 J biphasic synchronized*
Use anterior–posterior pads, especially if not responding
5. Anticoagulation
Usually no heparin or warfarin for most patients if onset clearly < 48 h or if therapeutic INR for > 3 wk
6. Disposition
Home within 1 h after cardioversion
Usually no antiarrhythmic prophylaxis or anticoagulation given
Arrange outpatient echocardiography if first episode
Cardiology follow-up if first episode or frequent episodes
7. Patients not treated with cardioversion
Achieve rate control with diltiazem IV (target heart rate < 100 beats/min)
Discharge home on diltiazem (or metoprolol)
Discharge home on warfarin and arrange INR monitoring
Arrange outpatient echocardiography
Follow-up with cardiology at 4 wk for elective cardioversion
8. Recommended additions to protocol
Consider transesophageal echocardiography if onset unclear
Alternate rhythm-control drugs: propafenone, vernakalant, amiodarone
If TEE-guided cardioversion > 48 h, start warfarin
If CHADS2 score ≥ 1, consider warfarin and arrange early follow-up

Study Design

  • Single study retrospective cohort of ED patients presenting with recent onset atrial fibrillation (<48hrs)
  • 660 patients
  • June 2000-June 2005
  • Consecutive review of the retrospective record


Patient Demographics

  • Mean age: 64
  • Male: 55%
  • Mean duration of arrhythmia 8.9hr
  • Previous atrial fibrillation: 83%
  • Hypertension: 42.1%
  • CAD: 21%
  • Thyroid disease: 15%
  • Valvular heart disease: 4%
  • CHF: 7.7%
  • Thromboembolic disease: 6.5%
  • Chronic lung disease 6%

Inclusion Criteria

  • Recent onset (<48 hrs) of atrial flutter
  • Use of ED cardioversion
  • No recent cardioversion within 7 days

Exclusion Criteria

  • Atrial fibrillation >48hrs
  • Presence of other diagnosis requiring admission


  • Patients were cardioverted with procainamide or electrically


Primary Outcome

  • Proportion of patients converted to sinus rhythm before discharge from ED
    • 58% of all cases responded to procainamide
    • 92% responded to electrical cardioversion
  • Length of stay in ED
    • Mean length of stay <5 hours
  • Final disposition and adverse events (hypotension or arrhythmia)
    • 97% discharged home
    • 90 discharged with normal sinus rhythm

Secondary Outcomes

  • Death, stroke or relapse to atrial fibrillation within 7 days
    • Stroke: 0%
    • Death: 0%
    • Relapse within 7 days: 8.7%

Criticisms & Further Discussion

  • In general, practice guidelines recommended anticoagulation for the conversion of atrialfibillatin or flutter if duration of dysrhythmia is > 48 hours. More recent literature suggests that the 12-48 hour window in this study still only represented a 1.1% risk for 30-day thromboembolism, compared to the ~2% risk after 48 hours.
  • Although this study demonstrates the safety and efficacy of a cardioversion first strategy in the ED in new onset (<48hr) Atrial Fibrillation it was performed in a system with very good outpatient followup. Results of this study should be individualized the healthcare system of practice.

Anticoagulation prior to cardioversion

  • Anticoagulation with Heparin or LMWH should be considered before cardioversion if time permits, otherwise immediately after cardioversion. (unless you are sure it has been <48 hours since onset of afib) [3][4] [5]
  • Generally cardioversion while anti-coagulated is believed to be safe with a 1.3% risk of thromboembolism if on aspirin or other anticoagulant[6] However the risk may be as great as 2% risk after 48 hours and preference should be given to anticoagulation prior to cardioversion in longer cases[7]

Anticoagulation after cardioversion

Anticoagulation Therapy

  • ACCP Recommendations
    • In patients with AF, including those with paroxysmal AF, with only one of the risk factors listed immediately above, we recommend long-term antithrombotic therapy (Grade 1A), either as anticoagulation with an oral VKA, such as warfarin (Grade 1A), or as aspirin, at a dose of 75-325 mg/d (Grade 1B)[8]
    • In patients with AF, including those with paroxysmal AF, who have two or more of the risk factors we recommend long-term anticoagulation with an oral VKA (Grade 1A).[8]
  • CCS Recommendations
    • Oral anticoagulants are recommended for all AF patients aged 65 or older or who have any one of the traditional CHADS2 risk factors of stroke, hypertension, heart failure, or diabetes (remember as CHADS-65). Otherwise, patients with a history of coronary artery disease or arterial vascular disease should be prescribed ASA. CCS recommends that the first choice for oral anticoagulation should be the novel direct-acting oral anticoagulants (i.e. NOACs, for non-valvular AF). The big paradigm change is that ED physicians should prescribe OACs to at-risk AF patients before they leave the ED.[9]


  • Dr Dickinson, a author on the paper is a paid consultant for Cardiome Pharma Corp but none of the other members were paid or had disclosures

External Links


  1. 1.0 1.1 von Besser K. et al. Is discharge to home after emergency department cardioversion safe for the treatment of recent-onset atrial fibrillation? Ann Emerg Med. 2011 Dec;58(6):517-20
  2. Weigner MJ et al. "Risk for clinical thromboembolism associated with conversion to sinus rhythm in patients with atrial fibrillation lasting less than 48 hours". Ann Intern Med. 1997. 126(8):615-620.
  3. You JJ, Singer DE, Howard PA, Lane DA, Eckman MH, Fang MC, Hylek EM, Schulman S, Go AS, Hughes M, Spencer FA, Manning WJ, Halperin JL, Lip GY. Antithrombotic therapy for atrial fibrillation: antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012 Feb;141(2 Suppl):e531S-75S
  4. FusterV et al;American Collegeof Cardiology/ American Heart Association Task Force on Practice Guidelines; European Society of Cardiology Committee for Practice Guidelines; European Heart Rhythm Association; Heart Rhythm Society. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation. 2006;114(7):e257-e354.
  5. Camm AJ, Kirchhof P, Lip GY, et al; European Heart Rhythm Association; European Association for Cardio-Thoracic Surgery. Guidelines for the management of atrial fibrillation: the task force for the management of atrial fibrillation of the European Society of Cardiology (ESC). Eur Heart J. 2010;31(19):2369-2429.
  6. 48hr Cardioversion for A.fib.
  7. Nuotio I. et al. Time to cardioversion for acute atrial fibrillation and thromboembolic complications. JAMA. 2014 Aug 13;312(6):647-9
  8. 8.0 8.1 Singer DE et al. Antithrombotic therapy in atrial fibrillation: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition).Chest. 2008 Jun;133(6 Suppl):546S-592S
  9. Verma A, et al. 2014 Focused Update of the Canadian Cardiovascular Society Guidelines for the Management of Atrial Fibrillation Canadian Journal of Cardiology 30 (2014) 1114e1130