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Diagnosis - Atrial fibrillation

Checking your pulse is a useful first step in helping to diagnose atrial fibrillation.

Checking your pulse

To check your pulse:

  1. Sit down for 5 minutes. Do not smoke or drink caffeine before checking your pulse.
  2. Hold your left hand out with your palm facing up and elbow slightly bent.
  3. Firmly place your index and middle finger of your right hand on your left wrist, at the base of the thumb - between the wrist and the tendon attached to the thumb.
  4. Using the second hand on a clock or watch, count the number of beats for 30 seconds, and then double that number to get your heart rate in beats per minute.

At rest, a normal heart rate should be 60 to 100 beats per minute. In atrial fibrillation, the heart rate can often be much higher than 100 beats per minute, and the rhythm is irregular.

Assessing your pulse can give you a good indication of whether you have atrial fibrillation. But a full medical investigation will be needed before a diagnosis can be made.

Check your pulse (video) -

If they think you might have atrial fibrillation, your GP may arrange a trace of your heart (electrocardiogram) and refer you to a heart specialist (cardiologist) for more tests.

Electrocardiogram (ECG)

An ECG is a test that records your heart's rhythm and electrical activity. It's usually done in a hospital or GP surgery. It takes about 5 minutes, and is painless.

During an ECG, small stickers called electrodes are attached to your arms, legs and chest. These are connected by wires to an ECG machine.

Every time your heart beats, it produces tiny electrical signals. An ECG machine traces these signals onto paper.

During an episode of atrial fibrillation, your heart rate will be irregular and over 100 beats per minute.

If you have an episode of atrial fibrillation during an ECG, your abnormal heart rate will be recorded. This will confirm the diagnosis of atrial fibrillation and rule out other conditions.

But often it can be difficult to capture an episode of atrial fibrillation, so you may be asked to wear a small portable ECG recorder.

The recorder will either trace your heart rate continuously over 24 hours or when you switch it on at the start of an episode.

Electrocardiogram (ECG)

Other tests

If you have atrial fibrillation, you may need other tests, including:

  • an echocardiogram – an ultrasound scan of the heart, which can help identify any other heart-related problems
  • a chest x-ray can help identify any lung problems that may be causing atrial fibrillation
  • blood tests can highlight other problems such as infection, anaemia, problems with kidney function, or an overactive thyroid gland that may cause atrial fibrillation

Page last reviewed: 26 July 2023
Next review due: 26 July 2026