Big thanks to Dr. Paul Page for leading discussions this month.
All cases are theoretical, but highlight important discussion points.
Authored and Edited by Dr. Mandy Peach
Reviewed by Dr. Kavish Chandra
Atrial fibrillation
• Review risk factors and complications
• Features of primary vs secondary arrythmia
• Risk stratifying a patient for stroke
• CHADS-65
• Sedation and cardioversion
Case
A 45 yo male presents to the ED feeling unwell for 2 days. He has a known history of atrial fibrillation but doesn’t consistently take rate control medications. He describes feeling like his heart is racing and he has trouble breathing that ‘comes and goes’. He currently complains of palpitations for 4 consecutive hours. He denies any chest pain or shortness of breath.
His vitals: BP 125/76, HR 134, RR 18, O2 98% RA, T 37.2
His ECG:
He appears to be in atrial flutter.
If this patient didn’t have a known history of arrhythmia, what are some risk factors for atrial fibrillation/flutter 1?
What are the life threatening complications with atrial fibrillation and their mechanisms?
Stroke – formation of clots in the atria secondary to blood stasis that embolize
Acute Coronary Syndrome – rapid rate decreases coronary blood flow
Pulmonary edema/heart failure – increased pulmonary arterial pressures secondary to increased afterload in atria2
The patient is brought in and attached to cardiorespiratory monitoring. The nurse applies pads and asks if you would like to immediately cardiovert.
What are the indications to immediately cardiovert a patient with any tachycardia? Does this patient require cardioversion?
Any sign of clinical instability:
• New severe hypotension (SBP < 90 mmHg) or signs of hypoperfusion
• Chest pain or ST depression > 2mm on ECG
• Acute heart failure2 – shortness of breath, hypoxia, clinical findings on exam
Your patient is experiencing palpitations, has a stable blood pressure and has no shortness of breath. He does not require cardioversion.
Is it common for atrial fibrillation to cause instability as the primary arrhythmia? What presentations make secondary arrhythmia more likely?
No – generally there will be a secondary cause for the arrhythmia that should be addressed.
The differential can include:
• ACS
• PE
• Heart failure
• Bleeding
• Sepsis3
Presentations that would make it more likely that this is a secondary cause with an underlying medical condition are:
• Insidious onset onset with no palpitations
• Known atrial fibrillation on previous ECGs and currently on anti-coagulation
• No history of cardioversion
• HR < 150
• Fever, shortness of breath, pain3.
On further history you discover that the patient has presented 2 previous times to the ED and required cardioversion. He has known atrial fibrillation and is on anticoagulation. His previous transthoracic echocardiogram does not indicate a valvular cause You screen him for multiple secondary causes and come up empty. You feel this is a primary arrhythmia.
What is one primary arrhythmia that causes instability that should be ruled out and why? What are the ECG features?
Atrial fibrillation/flutter + rapid ventricular pre-excitation (Wolff-Parkinson-White).
In WPW there is an accessory pathway that bypasses the AV node, causing early activation of the ventricles and leading to a tachyarrhythmia. Up to 20% of these patients can also have atrial fibrillation where there are multiple areas of the atria firing at different times as well. It is imperative to recognize this pattern as the use of AV blocking medications will cause more rapid conduction through the accessory pathway – leading to ventricular fibrillation or ventricular tachycardia.4
“Rate > 200 bpm
Irregular rhythm
Wide QRS complexes due to abnormal ventricular depolarization via accessory pathway
QRS Complexes change in shape and morphology
Axis remains stable unlike Polymorphic VT
Atrial Flutter results in the same features as AF in WPW except the rhythm is regular and may be mistaken for VT.”4
How do you control this patient’s heartrate?
The patient is stable, you have some time. First consider their risk of stroke.
LOW RISK 3
• onset < 48 hours AND no high risk factors OR
• On anticoagulation ≥ 3 weeks AND
• < 2 risk factors according to CHADS-65
HIGH RISK 3
• No anticoagulation/inadequate (< 3 weeks) AND
• Onset > 48 hours (or unknown) OR
• Onset < 24 hours but ≥ 2 risk factors according to CHADS-65 OR
• Stroke/TIA within 6 months OR
• Valvular heart disease
CHADS-65
You review with your patient and his CHADS-65 is 1 – he has history of hypertension. So based on the fact that he has been anticoagulated long term (and has been med compliant), his time with symptoms is 2 days with clear onset within 4 hours, and he scores < 2 on CHADS-65 you consider him LOW RISK.
LOW RISK
These patients can be treated with rhythm or rate control, however rhythm control is preferable in this population3. Their symptoms resolve immediately, they leave the ED faster and often happier as they don’t have to be admitted to hospital.
You discuss with the patient and decide to do a cardioversion as he is low risk, opting for rhythm control. He is agreeable.
What should I use to cardiovert – electricity or pharmacology?
Really either – it’s physician and patient dependent.
The RAF2 trial compared both electricity + pharmacology to electricity + placebo. Both were effective: procainamide followed by electricity had a 97% success rate in converting the patient to sinus rhythm, while the placebo infusion followed by shock was 93% effective. 97% of patients in the trial were discharged from the ED and on follow up 2 weeks later, 95% were still in sinus rhythm5.
Regardless of the method, rhythm control is a good option unless there is a patient preference.
Still not sure what to pick? Whatever worked in the past for the patient.
Our patient has previously had successful electrical cardioversion, so you decide to go with electricity.
You let the team know you will be proceeding with electrical cardioversion so they can prepare the room and patient. RT is on their way and the nurse is asking what drugs to draw up.
What are options for sedating a patient for electrical cardioversion? At what dose?
Many options – a systemic review in 2015 looked at studies including IV agents (ie. propofol and etomidate), inhaled agents (ie. Isoflurane) and benzodiazepines (ie. Midazolam) for electrical cardioversion. The primary outcome was adverse events: hypotension, apnea and patient awareness – unfortunately there is little high quality data available to suggest one drug over another6.
In a retrospective chart review from a Canadian ED the most common medications used were fentanyl, propofol, midazolam and ketamine in descending order. Practitioners primarily used combination drugs at that particular facility. The most commonly combined sedatives were propofol and fentanyl followed by midazolam and fentanyl. Adverse outcomes were rare overall. Apneic episodes were similar between these two combinations (both < 1%), as was hypotension (1.3% overall).7 Although a helpful study, this site had very few single agent sedatives, like ketamine, to compare to.
Here is a chart of suggested medications for procedural sedation for painful procedures like cardioversion 8:
Really it comes down to your comfort with your drug of choice. Even though adverse events seem to be rare, still consider the potential for increased risk of apnea and hypotension when combining sedatives and analgesia.
You gather your team, give the plan with your drug of choice, consent the patient and complete an appropriate airway assessment. You are ready to begin.
Does pad placement matter?
No – anterior-lateral vs anterior-posterior placement is not deemed to be a critical factor in cardioversion for atrial fibrillation/flutter9
You successfully convert the patient to normal sinus rhythm. He is discharged from the department and advised to continue his anticoagulation (a NOAC) as previously prescribed.
What if this was a first presentation of atrial fibrillation – would he require anticoagulation for long term stroke prevention?
We go back to our CHADS-65. This patient had a score of 1.
If CHADS-65 positive : anticoagulation
If CHADS-65 negative: no anticoagulation
If CHADS-65 negative with stable CAD, PVD or aortic vascular disease – add ASA 81 mg3
According to the CCS guidelines for Atrial fibrillation anticoagulation is required for ALL patients undergoing cardioversion, regardless of risk factors, for 4 weeks.10 This is not based on strong evidence. Therefore,
Anticoagulation and the decision to start should involve shared decision making with the patient.
For details on rate control and treatment of high risk patients please see the CAEP Acute Atrial Fibrillation/Flutter Best Practices
Checklist
References and further reading:
- Cichon, C (2019). PIRATES illustration on twitter @DocScribbles
- Smarandache (2020. The Simple Guide to Management of Non-Valvular Atrial Fibrillation in the ED. CanadiaEM https://canadiem.org/the-simple-guide-to-management-of-non-valvular-atrial-fibrillation-in-the-ed/
- Stiell, Scheuermeyer, Vadeboncoeur, Angaran, Eagles, Graham et al. (2018). CAEP Acute Atrial Fibrillation/Flutter Best Practices Checklist. CJEM 20 (3): 334-342
- Burns (2020). Pre-excitation syndromes. Life in the fast lane. https://litfl.com/pre-excitation-syndromes-ecg-library/. Accessed Dec 9, 2020.
- Helman, A. Swaminathan, A. Juurlink, D. Long, B. Stiell, I. Morgenstern, J. Klaiman, M. Lloyd, T. EM Quick Hits 7 – Status Epilepticus, Codeine Interactions, Anticoagulants in Malignancy, Atrial Fibrillation rate vs rhythm control, Peripheral Vasopressors, Motivational Interviewing. Emergency Medicine Cases. August, 2019. https://emergencymedicinecases.com/em-quick-hits-august-2019/. Accessed Dec 9, 2020].
- Lewis, Nicholson, Reed, Kenth, Alderson & Smith (2015). Anaesthetic and sedative agents used for electrical cardioversion (review) Cochrane Database of Systematic Reviews , Issue 3. Art. No.: CD010824
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010824.pub2/epdf/full - Campbell, Magee, Kovacs, Petrie, Tallon, McKinley et al. (2006). Procedural sedation and analgesia in a Canadian adult tertiary care emergency department: a case series. Can J Emerg Med ;8(2):85-93
- Scheirer (2018). Procedural Sedation and Analgesia. CanadiaEM https://canadiem.org/crackcast-e195-procedural-sedation-and-analgesia/
- Kirkland, Stiell, AlShawabkeh, Campbell, Dickinson & Rowe (2014). The efficacy of pad placement for electrical cardioversion of atrial fibrillation/flutter: a systematic review. Acad Emerg Med Jul;21(7):717-26
- Andrade, Verma, Mitchell, Parkash, Leblanc, Atzema & al. (2018) Management of Atrial Fibrillation: Complete CCS Guidelines Listing. Canadian Cardiovascular Society. https://www.ccs.ca/images/Guidelines/Guidelines_POS_Library/2018%20AF%20Update_Supplement_Final.pdf