A. Assessment and risk stratification 1. Is AF/AFL with rapid ventricular response a primary arrhythmia or secondary to medical causes? A. Rapid rate secondary to medical causes (usually in patients with pre-existing/permanent AF) e.g., sepsis, bleeding, PE, heart failure, ACS, etc.: - Investigate and treat underlying causes aggressively - Cardioversion may be harmful - Avoid aggressive rate control B. Primary arrhythmia, e.g., sudden onset of AF/AFL# Is the patient unstable?
- Instability due to acute primary AF/AFL is uncommon, except for AF with rapid ventricular pre-excitation (WPW):
- Hypotension: SBP  2 mm) on ECG despite therapy - Pulmonary edema: significant dyspnea, crackles, and hypoxia
- Treat unstable patient:
- Urgent electrical CV if onset  48 h

# Is it safe to cardiovert this patient with primary AF/AFL?
- When it is safe, rhythm control is usually preferable to rate control: patient quality of life, shorter length of stay, fewer hospital resources - It is safe to cardiovert if: A. The patient has been adequately anticoagulated for a minimum of 3 weeks, OR B. The patient is not adequately anticoagulated for > 3 weeks, has no history of stroke or TIA, AND does not have valvular heart disease, AND: 

# Background and methods
The 2021 CAEP Acute Atrial Fibrillation/Flutter Best Practices Checklist has been updated from the original version published in 2018 . These checklists have been created to assist emergency physicians in Canada and elsewhere manage patients who present to the emergency department (ED) with acute/recent-onset atrial fibrillation (AF) or flutter (AFL). The checklist focuses on symptomatic patients with acute AF or AFL, i.e. those with recent-onset episodes (either first detected, recurrent paroxysmal or recurrent persistent episodes) where the onset is generally less than 48 h but may be as much as seven days. These are the most common acute arrhythmia cases requiring care in the ED. Canadian emergency physicians are known for publishing widely on this topic and for managing these patients quickly and efficiently in the ED . The 2018 Checklist project was funded by a research grant from the Cardiac Arrhythmia Network and the resultant guidelines were formally endorsed by the Canadian Association of Emergency Physicians (CAEP). We chose to adapt, for use by emergency physicians, existing high-quality clinical practice guidelines (CPG) previously developed by the Canadian Cardiovascular Society (CCS) . These CPGs were developed and revised using a rigorous process that is based on the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system of evaluation . With the assistance of our PhD methodologist (IG), we used the recently developed Canadian CAN-IMPLEMENT process adapted from the ADAPTE Collaboration . We created an Advisory Committee consisting of ten academic emergency physicians (one also expert in thrombosis medicine), four community emergency physicians, three cardiologists, one PhD methodologist, and two patients. Our focus was four key elements of ED care: assessment and risk stratification, rhythm and rate control, short-term and longterm stroke prevention, and disposition and follow-up. The advisory committee communicated by face-to-face meetings, teleconferences, and email. The checklist was prepared and revised through a process of feedback and discussion on all issues by all panel members. These revisions went through ten iterations until consensus was achieved. We then circulated the draft checklist for comment to approximately 300 emergency medicine and cardiology colleagues. Finally, the CAEP Standards Committee posted the Checklist online for all CAEP members to provide feedback (Fig. 1).
Early in 2021 the same Checklist Advisory Committee reconvened (with one additional academic cardiologist) to discuss updates based upon new evidence , the 2018 and 2020 CCS guidelines , and several commentaries that had expressed the concern of the Canadian ED community . The Advisory Committee met twice virtually and reached consensus on updates through repeated email exchanges. The panelists then sought further feedback from their own colleagues in emergency medicine and cardiology. Finally, the 2021 Checklist was posted by CAEP for further member feedback prior to final approval. The panel continues to believe that, overall, a strategy of ED cardioversion and discharge home from the ED is preferable from both the patient and the healthcare system perspective, for most patients. Many notable revisions were incorporated, including:
- The safety of urgent cardioversion for acute AF/AFL depends upon anticoagulation status, prior stroke, valvular heart disease, time since onset, and CHADS criteria. Patients presenting between 12 and 48 h may only be cardioverted if they have 0 or 1 of the CHADS-65 crite-ria. We found that the CCS reference to CHADS 2 Scale problematic as most ED physicians no longer use that scale. 2. Anticoagulation for CHADS-65 positive patients should be initiated in the ED unless there are contradictions as per the "McMaster Checklist" created by Dr. de Wit. 3. We disagree with the CCS suggestion of 4 weeks of anticoagulation for patients who are CHADS-65 negative as this was a weak recommendation per the GRADE system, based upon low quality evidence. We suggest that oral anticoagulation might be considered for a 4-week period after careful consideration of risks and benefits and a shared decision-making process with the patient.
Our hope is that the 2021 CAEP Acute Atrial Fibrillation/Flutter Best Practices Checklist will standardize and improve care of AF and AFL in large and small EDs alike. We believe that these patients can be managed rapidly and safely, with early ED discharge and return to normal activities. from Boehringer Ingelheim, Bayer, Pfizer, and Servier. Dr. Tebbenham has received honoraria from Cardiome Pharma Corp. We thank the hundreds of Canadian emergency physicians and cardiologists who reviewed the draft guidelines and who provided very helpful feedback.
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