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Just the facts: Atrial fibrillation or flutter in patients who are candidates for rate control

Clinical scenario

An 82-year-old female with diabetes and hypertension presents to the emergency department (ED) with generalized weakness for 3 days. She denies chest pain or dyspnea. Medications include hydrochlorothiazide, ramipril, and metformin. She is alert, ambulates normally, and speaks in full sentences. She is afebrile, her heart rate is 110 beats/min and irregular, her blood pressure is 130/80 mmHg, and her oxygen is 94% on room air. Initial electrocardiogram (ECG) shows atrial fibrillation at 110 beats/min without ischemic changes; no prior ECGs are available (Fig. 1).

Fig. 1

Approach to patients with atrial fibrillation or flutter who are candidates for rate control

Key clinical questions

Is this rapid atrial fibrillation or flutter a primary arrhythmia or secondary to a medical issue?

This article is Part 1 of the two-part series that addresses the management of acute atrial fibrillation or flutter in the ED. Part 2 describes the approach to patients who are candidates for urgent rhythm control [1]. These articles are based upon the Canadian Association of Emergency Physicians (CAEP) 2018 Acute Atrial Fibrillation or Flutter Best Practices Checklist which was adapted from the Canadian Cardiovascular Society Atrial Fibrillation Guidelines [2, 3]. The CAEP Checklist distinguishes between rapid acute atrial fibrillation or flutter that is due to acute-onset [primary] arrhythmia or secondary to a medical illness in a patient with permanent acute atrial fibrillation or flutter. The latter situation may be due to acute medical conditions such as heart failure, sepsis, or acute coronary syndrome. Approximately one-third of ED acute atrial fibrillation or flutter presentations have a secondary cause [4]. This is a critical distinction since primary acute atrial fibrillation or flutter is typically managed with rate or rhythm control, whereas secondary acute atrial fibrillation or flutter is managed by addressing the underlying illness. Use of rate or rhythm control in such patients is associated with treatment failure and increased adverse events.

Distinguishing between a primary or secondary cause may be difficult if prior ECGs are not available. Consider secondary acute atrial fibrillation or flutter in older patients, if there is no sudden onset or palpitations, if there is known permanent atrial fibrillation or the patient is taking oral anticoagulation, if no history of emergent electrical cardioversion, if the heart rate is less that 150 beats/min, or if there is fever, dyspnea, or chest pain. For these patients, a diagnostic workup includes (but is not limited to) a complete blood count, metabolic panel, cardiac biomarkers, and chest radiography.

Is this patient unstable? For an unstable patient, what is the appropriate strategy?

It is rare for patients to be unstable due to primary acute atrial fibrillation or flutter (defined as blood pressure less than 90 mmHg, altered mental status, cardiac ischemia, or pulmonary edema). An exception is a rapid pre-excitation syndrome such as Wolf-Parkinson-White [1]. For patients who are unstable due to primary acute atrial fibrillation or flutter with onset less than 48 h, urgent electrical cardioversion is indicated. For onset greater than 48 h, a trial of rate control may be acceptable. However, most unstable patients will have a secondary cause.

The patient is alert, speaks in full sentences, denies chest pain, and is therefore stable.

Is this patient high risk or low risk for short-term stroke? How does this affect your management?

Physicians can use CHADS-65 criteria (heart failure, hypertension, age > 65, diabetes, stroke), to identify high-risk patients [3]. According to the Canadian Cardiovascular Society 2018 Update for Atrial Fibrillation, patients without anticoagulation or no stroke or transient ischemic attack are candidates for rhythm control if they present within (a) 12 h of onset even with two or more CHADS-65 criteria, or (b) 48 h of onset if they have fewer than two CHADS-65 criteria [5]. In other cases, rate control is the preferred strategy. If urgent transesophageal echocardiography can rule out left atrial clot, rhythm control is acceptable.

What are the best practices for rate control?

Rate control with either calcium channel blockers (unless known decreased ejection fraction) or beta-blockers is appropriate. If the patient is already taking one of these medications, the same class is preferred. Appropriate doses are intravenous (IV) diltiazem 0.25 mg/kg over 10 min, repeated every 15–20 min at 0.35 mg/kg up to three doses, followed by oral diltiazem 30–60 mg after 30 min of effective IV rate control. Alternately, use IV metoprolol 2.5–5 mg over 2 min, repeated every 15–20 min up to three doses, followed by oral metoprolol 25–50 mg after 30 min of effective IV rate control. Physicians should titrate medications carefully to avoid hypotension. If minimal response, physicians can trial the other first-line agent, or initiate digoxin IV loading at 0.25–0.5 mg, followed by 0.25 mg every 4–6 h. If the patient is hypotensive or has acute heart failure, physicians may consider digoxin first-line management.

Should this patient be discharged? What are best discharge practices?

Patients with primary acute atrial fibrillation or flutter rarely require hospital admission unless they (a) are highly symptomatic despite adequate treatment or cannot achieve a heart rate less than 100 beats/min; (b) have an acute coronary syndrome with increasing troponin (although a small demand rise is expected) and corresponding EKG changes; or (c) have heart failure not improved with ED treatment.

For patients who are discharged, physicians should provide a prescription of whichever agent was used in the ED: metoprolol 25–50 mg twice daily or diltiazem 30–60 mg four times daily (or extended release 120–240 mg daily). For patients requiring new anticoagulation, physicians should (a) include patient preferences during shared decision-making, (b) prefer novel oral anticoagulants over warfarin, and (c) recommend primary care follow up within 7 days or specialist follow up within 4–6 weeks. Do not initiate oral antiarrhythmics in the ED.

Given her age and potential for acute underlying causes, the physician ruled out heart failure, sepsis, or other secondary causes, and administered 2.5 mg of intravenous metoprolol twice over 15 min, then 25 mg of oral metoprolol. After 4 h, her heart rate was irregular at 85 beats/min, her blood pressure remained stable at 125/80 mmHg, and her symptoms improved considerably. The physician discussed discharge planning with the patient and her family; she was prescribed 25 mg metoprolol twice daily and a novel oral anticoagulant; she had an appointment with an internist in 4 weeks.

Key points

  1. 1.

    It is critical to distinguish between primary and secondary acute atrial fibrillation or flutter, and it may take a careful history and thorough investigations to arrive at a conclusion.

  2. 2.

    It is very rare for a patient to be unstable due to acute atrial fibrillation or flutter.

  3. 3.

    Short-term stroke risk is estimated by time of onset of acute atrial fibrillation or flutter, as well as the CHADS-65 score. Patients at higher stroke risk are not candidates for rhythm control.

  4. 4.

    Titrate rate control agents frequently to achieve rapid control carefully to avoid hypotension.

  5. 5.

    For patients with primary acute atrial fibrillation or flutter, they may be candidates for discharge if they are minimally symptomatic with a heart rate less than 100 beats/min may be candidates for discharge. Patients with secondary acute atrial fibrillation or flutter require management of the underlying cause and are rarely candidates for discharge. Physicians should mitigate downstream stroke risk.


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Correspondence to Ian Stiell.

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Scheuermeyer, F.X., Targonsky, E. & Stiell, I. Just the facts: Atrial fibrillation or flutter in patients who are candidates for rate control. Can J Emerg Med 23, 437–440 (2021).

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