Atrial Fibrillation (AF) | Acute Management | ABCDE

New-onset atrial fibrillation (AF) is a potentially life-threatening condition which needs to be rapidly recognised, effectively managed, and escalated to appropriate senior staff. This guide provides an overview of the recognition and immediate management of atrial fibrillation (using an ABCDE approach).

This guide has been created to assist students in preparing for emergency simulation sessions as part of their training. It is not intended to be relied upon for patient care.

Tips before you begin

  • Treat all problems as you find them
  • Re-assess regularly and after every intervention to see if your management is effective
  • Make use of the team around you to delegate tasks where appropriate – is another clinical member of staff available to help you?
  • All critically unwell patients should have continuous monitoring equipment attached for accurate observations (e.g. blood pressure)
  • If you need senior input for your patient, call for help early using an appropriate SBARR handover structure (check out the guide here)
  • Review results (e.g. laboratory investigations) as they become available
  • Make use of medical school/hospital guidelines and algorithms for managing specific situations such as AF
  • Any medications or fluids will need to be prescribed
  • Your assessment and management should be documented in the notes (however this should not delay clinical management)


A bit of background

What is AF?

AF is an atrial tachydysrhythmia, ‘tachy’ meaning fast and ‘dysrhythmia’ indicating chaotic and uncoordinated electrical activity.

In AF multiple waves of electrical activity compete with each other in the atrium and bombard the AV node. This results in irregular conduction down the bundle of His, an irregular ventricular rhythm and ultimately decreased cardiac output.

The causes of AF are vast and complex but usually, a patient with AF has an underlying abnormal atrium, both anatomically (dilated) and histologically (fibrotic from inflammation).

Patients may suffer from symptoms of AF constantly or intermittently, some patients may be completely ‘asymptomatic’ and may not even be aware that they have AF.


What is ‘fast’ AF?

Some patients present with a new-onset of AF symptoms such as rapid palpitations, breathlessness or fluttering in the chest. You may hear some clinicians referring to this presentation as ‘fast AF’, however, this term should be avoided because all patients with AF have rapid and chaotic atrial activity. Instead, this presentation is AF with a rapid ventricular response (sometimes written as AF with RVR).

If a patient experiences new or worsening AF symptoms, then it is important to thoroughly investigate them in order to identify and treat any underlying triggering factors.


What can trigger a change in AF?

There are many conditions that can either trigger new AF or make pre-existing AF worse. The Royal College of Emergency Medicine have created a useful mnemonic, PIRATES, to remember common causes:

  • Pulmonary embolism
  • Ischaemia
  • Respiratory disease
  • Atrial enlargement or myxoma
  • Thyroid disease
  • Ethanol
  • Sepsis/sleep apnoea


Why is it important to learn about?

AF is very prevalent, and it is considered to be the most common sustained arrhythmia. Recent data estimates that 0.5-1% of the general population have AF, and the frequency increases with age to ~10% in those older than 65 years. This means that you are very likely to meet and care for patients with AF when you start work as a doctor.

In addition, patients presenting with new-onset AF may be unwell, and therefore it is important to recognise, manage and escalate their care promptly.

Clinical features of new-onset AF

Signs and Symptoms

Patients may report the following symptoms as a result of their arrhythmia

  • Palpitations
  • Fluttering in the chest
  • Dizziness
  • Shortness of breath
  • Anxiety
  • Chest pain


Signs you might detect include

  • A rapid, irregularly irregular pulse


You may also identify signs of the underlying cause of worsening AF

  • Bibasal crepitations on chest auscultation (heart failure)
  • Raised JVP (heart failure)
  • Tremor, sweating or neck goitre (thyroid disease)
  • Signs in keeping with focal infection or sepsis



  • A 12 lead ECG will likely show an irregularly irregular rhythm and an absence of P waves
  • Routine blood tests (including TFTs) and a CXR should be performed

Initial steps

You are likely to see this patient after a brief handover from another member of staff.



  • Introduce yourself to the patient
  • Ask the patient how they are feeling and if they have any pain
  • Pay attention to their ability to speak in full sentences (an inability to do this suggests significant respiratory distress)



Perform a quick general inspection of the patient to get a sense of how unwell they are:

  • Check consciousness level using AVPU
  • How do they look?
  • How is their breathing?
  • What is around the bedside? (look for cardiac monitors and ECG leads, cardiac medications, warfarin booklets)



  • Make sure the patient notes, observation chart and prescription chart are on hand (this should not delay your immediate clinical assessment)
  • Ask for another clinical member of staff to assist you if possible

If the patient is unconscious or unresponsive, start the basic life support (BLS) algorithm as per resuscitation guidelines.



Can the patient talk?


  • Airway is patent; move on to breathing assessment


  • Look for signs of airway compromise (e.g. see-saw breathing, use of accessory muscles, diminished breath sounds, added sounds)
  • Is the patient cyanosed?
  • Open the mouth and inspect: is there anything obviously compromising the airway (e.g. secretions)?



In any case of airway obstruction, seek immediate expert help from an anaesthetist. You may need the crash team. In the meantime, you can perform some basic airway manoeuvres to help maintain the airway.


Maintain the airway whilst awaiting senior input

1. Perform head tilt, chin lift manoeuvre.

2. If noisy breathing persists try a jaw thrust.

3. If airway still appears compromised use an airway adjunct:

  • Insert an oropharyngeal airway (Guedel) only if unconscious (as otherwise patient may gag/aspirate)
  • Alternatively, use a nasopharyngeal airway (better tolerated if the patient is partially conscious)




  • Oxygen saturations: aim for 94-98%
  • Respiratory rate: tachypnoea (high respiratory rate in this context may indicate pulmonary oedema or an underlying respiratory pathology causing hypoxemia)



  • Look: watch the patient breathing from the end of the bed – do they seem distressed?
  • Feel: check the position of the trachea  is it central?


  • Listen:
    • Auscultate the lungs to identify potential triggers of AF (e.g. pneumonia)
    • Assess air entry bilaterally and listen for added sounds (see our respiratory examination guide here)
    • Can you hear crackles indicative of an infection or bilateral crepitations indicative of heart failure?



  • Depending on the patient’s oxygen saturations, they may require supplemental oxygen
  • If required, titrate to pulse oximetry saturations aiming for 94-98%



  • A plain film chest radiograph is indicated for patients presenting acutely with symptomatic AF to investigate potential precipitating illnesses such as pneumonia (see our CXR interpretation guide)


It is important to establish the duration of the dysrhythmia – is it new? (this will guide management).



  • Heart rate: Tachycardia (>120 bpm) is common in symptomatic AF


  • Blood pressure:
    • Most patients with AF will be haemodynamically stable.
    • However a minority of patients may become haemodynamically unstable and present with hypotension, this usually occurs in combination with prolonged periods of tachycardia >150 bpm.
    • If your patient has symptomatic AF and is haemodynamically unstable, seek urgent senior input because this may require DC cardioversion.


  • Capillary refill time: If the peripheral CRT is prolonged (>2 seconds), this may be a sign that the patient is shocked secondary to inadequate left ventricular function.



  • Palpate radial pulses (bilaterally): an irregularly irregular pulse is characteristic of AF. Tap out the rhythm on the table whilst palpating if you are struggling to determine whether it’s regular or not.


  • Palpate apex beat: Can you feel the apex beat in the correct place or is it deviated? If the latter, it may imply an enlarged heart and an underlying anatomical abnormality.


  • Auscultation: Are the heart sounds regular and is there any added sounds? (if you hear murmurs then this may indicate underlying structural cardiac pathology)



12 Lead ECG

Blood tests

  • Full blood count (FBC) – to assess for raised white cells (infection) and anaemia
  • Urea and electrolytes (U&Es) – to assess for electrolyte disturbances
  • C-reactive protein – to assess for evidence of infection
  • Thyroid function tests (TFTs) – hyperthyroidism is a potential trigger for AF
  • Troponin – if there is a history of recent chest pain this may be appropriate
  • Coagulation studies – might be relevant if the patient is already anticoagulated (e.g. INR)


In order to manage AF, you must consider the following:

  1. Treating any precipitating factors that may have triggered AF
  2. Assessing the patient’s stroke risk and need for anticoagulation
  3. Controlling the rapid heart rate
  4. Controlling the symptoms of an irregular rhythm


NB: the patient may also present with unstable AF with haemodynamic instability (systolic BP <100). Unstable AF is rare and necessitates urgent senior input. The patient will require rapid restoration to sinus rhythm via either DC cardioversion (electrical cardioversion) or antiarrhythmic drugs (pharmacological cardioversion) such as flecainide or amiodarone. Cardioversion should only be performed by somebody with appropriate training, skills and experience, and it will often require sedation and airway management by an anaesthetist. You need to keep your patient nil by mouth from the time at which you identify they may be suitable for cardioversion.


1. Treating any precipitating factors that may have triggered AF

The majority of AF is due to underlying precipitating factors (remember PIRATES). Often AF will resolve to sinus rhythm when the underlying condition ‘driving’ the irregular rhythm has been treated.


2. Stroke risk and need for anticoagulation

Patients with AF are at increased risk of stroke from atrial emboli. Long-term oral anticoagulation with a suitable agent (direct acting oral anticoagulant or warfarin) significantly reduces this risk. The exact risk for a particular patient can be calculated using the CHA2DS2-VASc scoring tool. The benefit of anticoagulation needs to be considered against the risk of a patient having a significant bleed due to anticoagulation, which can be calculated using the HAS-BLED score. Immediate anticoagulation can be achieved with a treatment dose of subcutaneous low molecular weight heparin.


3. Controlling the rapid heart rate

In new-onset AF with rapid ventricular response patients often need heart rate control. For acute rate control, beta-blockers and diltiazem/verapamil are preferred over digoxin because of their rapid onset of action. The choice of drug and target heart rate will depend on patient characteristics (see below). Generally, cardiac output is sufficiently optimised by maintaining a heart rate of <110 bpm at rest. More than one drug may be required. If heart rate cannot be controlled to <110 bpm in the acute setting patients may require admission under a medical team for further rate controlling therapies.


Left ventricular ejection fraction (LVEF)  < 40% OR signs of congestive heart failure

First line:

  • The smallest dose of beta-blocker to achieve rate control:
    • Amiodarone is an option in patients with haemodynamic instability or severely reduced LVEF
    • Initial resting heart rate target < 110 BPM


Second line:

  • Add digoxin (initial resting heart rate target < 110 BPM)


Left ventricular ejection fraction (LVEF) ≥ 40%

First line:

  • Beta-blocker OR Diltiazem OR Verapamil
    • Check previous drug history to avoid concomitant administration
    • Initial resting heart rate target < 110 BPM


Second line:

  • Add digoxin (initial resting heart rate target < 110 BPM)


Further management principles following initial rate control

  • Avoid bradycardia
  • Perform echocardiogram to determine further management/choice of maintenance therapy
  • Consider the need for anticoagulation


4. Controlling the symptoms of an irregular rhythm

Rhythm control therapy is indicated to improve symptoms in patients who remain symptomatic on adequate rate control therapy. It has not been shown to improve long-term outcomes. Rhythm control is generally not indicated in the acute setting unless the patient is unstable. Long-term maintenance of sinus rhythm may be achieved using medications, DC cardioversion or cardiac ablation therapies.



  • Temperature: If higher or lower than normal parameters, consider infection as a cause
  • Assess level of consciousness using AVPU or GCS
  • Check blood glucose: 4.0 – 11.0 mmol/L is normal


The ‘everything else’ part of your assessment will involve exposing the patient to perform a thorough general inspection.


Look for:

  • Peripheral oedema (heart failure)
  • Swollen tender calf (deep vein thrombosis)

Reassess ABCDE

It is essential to continually reassess ABCDE and treat issues as you encounter them. This allows continual reassessment of the response to treatment and early recognition of deterioration.

If the patient does not respond to treatment or deteriorates, critical care input should be involved as soon as possible.

Next steps

Well done! You’ve stabilised the patient and they’re doing much better. Just a few more things to do…


Take a history

Take a more detailed history of what has happened and how the patient has been. Involve staff or family members as appropriate.

Check out our history taking guides here


Review the patient’s notes, observations, fluid charts, and any investigation findings. Double check the medications you have just prescribed, and any routine medications the patient is taking.


Document your ABCDE assessment clearly, including examination, observations, investigations, interventions, and patient response/changing condition. Write down any pertinent details from your history-taking.

See documentation guide


Discuss with seniors

If a senior doctor hasn’t already been involved, it is important to contact them and make them aware of the unwell patient. As a junior doctor, it would be appropriate to give an SBARR handover outlining your assessment and actions, and to discuss the following:

  • Are any further assessments or interventions required?
  • Does the patient need a referral to HDU/ICU?
  • Should they be referred for a review by a speciality doctor?
  • Should any changes be implemented to the management of any underlying conditions?


The next team of doctors on shift should be made aware of any patient in their department who has become acutely unwell.

Further reading



1. ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. European Heart Journal. Published 2016.



Andrew Gowland



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