If your pulse is irregular, your doctor may suspect that you have AF whether you feel symptoms or not. If this is the case, your doctor may send you for an electrocardiogram (an ECG) and/or refer you to a cardiologist to confirm the diagnosis.1,2,4,7

Watch a short animation on what to expect from an ECG

 An ECG is a simple and painless test that measures your heart’s electrical signals and assesses its rhythm

An ECG usually takes about 5 minutes and is usually carried out by a specially trained healthcare professional at a hospital, a clinic or at your general practice (GP).4,7 Sometimes your ECG may take place on the same day that you visit your doctor – but sometimes it might take a few days to get an appointment.


During this test, small sensors – the electrodes – will be placed onto your skin

These sensors allow the device to measure the electrical signals that your heart produces every time it beats to assess your heart’s rhythm.4 These sensors are attached to wires, which will transmit the signals from your heart to a recording device.7 Often, the sensors will be placed on your chest, but they may be also placed on your shoulders and ankles.4,7 Although the test itself is painless, you might find the adhesive from the sensors irritating if you have sensitive skin.7


To help the sensors stay on:7

  • Avoid using skin creams or lotions beforehand
  • You may need to shave your chest


You do not need to do anything special to prepare for the test

You can eat as normal,7 but you should try to avoid things that contain caffeine – like coffee, tea, or fizzy drinks – as caffeine can make your heart beat faster.

An ECG machine usually shows your heart’s rhythm and activity graphically on a monitor

This graph can then be printed on paper, and when the test is complete, the information about your heart will be stored electronically by the machine and your doctor can look at the results.7 It may take some time until you get the results of your ECG – but do not worry! Sometimes your results may need to be looked at by a specialist to spot any small irregularities.7

Sometimes an arrhythmia cannot be detected, even if your heart has felt fluttery on other days

If you have had symptoms of AF and a standard ECG has not detected an arrythmia, your doctor may also look at whether you have paroxysmal AF. This means that you have an irregular heartbeat that does not happen all of the time.8 The symptoms of paroxysmal AF may come and go spontaneously – and, if you have an AF episode, your heartbeat will usually return to normal within 7 days without any treatment. Often, this happens within 48 hours.2 If this is your case, it can feel very frustrating that your irregular heartbeat has not been detected during your ECG.

If your doctor suspects you have paroxysmal AF, they may suggest you take home a portable device to wear for longer periods of time

This device can record your heartbeat over several days, or even weeks, and provides a better chance that your irregular heartbeat will be detected.7,8 With this information, your doctor can make the right diagnosis and create an informed treatment plan for you.


Other tests may be carried out alongside an ECG to help confirm an AF diagnosis

These include (among others):

  • An echocardiogram, which is an ultrasound scan of the heart used to measure the structure and function of the heart and valves – this test uses sound waves and a computer to create a moving picture of your heart and it can help identify any other heart-related problems7,9
  • A chest X-ray, which helps identify any lung problems that may be causing AF4
  • Blood tests, which can help your doctor find out what might be causing your AF – these tests may check for anaemia, infection, thyroid and kidney problems, signs of a heart attack, and more9
  • A stress test, which is a test that puts extra stress on your heart to see how it responds to working hard and beating fast9
  • If your doctor suspects you have paroxysmal AF: 2,10-12
    • A 24-hour ECG recorder, also called Holter monitor or ambulatory ECG monitor, which is a device that records your heart’s electrical signals continuously – this test is often recommended for home use over periods from 24 hours to 2 weeks in order to detect asymptomatic or symptomatic AF episodes that do not occur all the time, and are therefore difficult to detect with a regular ECG test
    • An ECG event recorder, which is a device that detects symptomatic AF episodes that do not occur very often

1.Heart Foundation. Clinical fact sheet: atrial fibrillation screening and diagnosis work up. February 2019. Available at https://www.heartfoundation.org.au/getmedia/44a3ff91-01a7-4ee6-bb2c-cd50ddd79cb2/Clinical_Fact_Sheet_-_AF.pdf. Last accessed November 2020.

2. NICE NG196. Atrial fibrillation: diagnosis and management. 2021. Available at https://www.nice.org.uk/guidance/ng196/resources/atrial-fibrillation-diagnosis-and-management-pdf-66142085507269. Last accessed May 2021.

3. Taggar JS et al. Eur J Prev Cardiol 2016; 23: 1330-1338.

4. NHS. Diagnosis – atrial fibrillation. April 2018. Available at https://www.nhs.uk/conditions/atrial-fibrillation/diagnosis/. Last accessed November 2020.

5. PeaceHealth. Pulse Measurement – Test overview. March 2019. Available at https://www.peacehealth.org/medical-topics/id/hw233473. Last accessed November 2020.

6. Arrhythmia Alliance. Know Your Pulse Factsheet. April 2009; reviewed January 2017. Available at https://www.heartrhythmalliance.org/resources/view/389/pdf. Last accessed November 2020.

7. NHS. Electrocardiogram (ECG). June 2018. Available at https://www.nhs.uk/conditions/electrocardiogram/. Last accessed November 2020.

8 PMS Instruments. Why You Should Use ECG Event Recorders in Primary Care. October 2014. Available at https://www.pmsinstruments.co.uk/blog/why-you-should-use-ecg-event-recorders-in-primary-care/. Last accessed November 2020.

9. WebMD. How Atrial Fibrillation Is Diagnosed. May 2018. Available at https://www.webmd.com/heart-disease/atrial-fibrillation/afib-diagnosis#1. Last accessed November 2020.

10. British Heart Foundation. ECG. Available at https://www.bhf.org.uk/informationsupport/tests/ecg. Last accessed November 2020.

11. Galli A, et al. Arrhythm Electrophysiol 2016; 5: 136-143.

12. ECG event recorder (R test). Royal Brompton & Harefield NHS Foundation Trust. Available at https://www.rbht.nhs.uk/our-services/ecg-event-recorder-r-test. Last accessed November 2020.

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