Atrial fibrillation

Atrial fibrillation is a heart condition that causes an irregular and often abnormally fast heart rate. Speak to your GP immediately or contact GP out of hours service if you notice a sudden change in your heartbeat, that makes you feel unwell, or if you have chest pain.

Heart rate

A normal heart rate should be regular and between 60 and 100 beats a minute when you're resting.

You can measure your heart rate by feeling the pulse in your neck or wrist.

In atrial fibrillation, the heart rate is irregular and can sometimes be very fast. In some cases, it can be considerably higher than 100 beats a minute.

Symptoms of atrial fibrillation

Some people with atrial fibrillation, particularly older people, do not have any symptoms.

The abnormality in heart rhythm is often only discovered during routine tests or investigations for another condition.

People often link tiredness and feeling lethargic to ageing. But once normal rhythm is restored, they realise these symptoms were caused by atrial fibrillation.

Heart palpitations

The most obvious symptom of atrial fibrillation is heart palpitations. This is where the heart feels like it's pounding, fluttering or beating irregularly, often for a few seconds or possibly a few minutes.

As well as an irregular heartbeat, your heart may also beat very fast (often much higher than 100 beats per minute).

You can work out your heart rate by checking the pulse in your neck or wrist.

Other symptoms you may experience if you have atrial fibrillation include:

The way the heart beats in atrial fibrillation reduces the heart's performance and efficiency.

This can lead to low blood pressure (hypotension) and heart failure.


An electrocardiogram (ECG) can be used to confirm a diagnosis of atrial fibrillation. An ECG is a test that records the rhythm and electrical activity of your heart.

When to see your GP

You should make an appointment to see your GP if:

  • you notice a change in your heartbeat which does not go away, or keeps happening
  • your heart rate is consistently lower than 60 or above 100, particularly if you're experiencing other symptoms of atrial fibrillation, (see above)

Speak to your GP urgently or contact GP out of hours service if you have palpitations and feel unwell, or if you have chest pain. If you are unable to contact them, call 999.

About atrial fibrillation

When the heart beats normally, its muscular walls contract (tighten and squeeze) to force blood out and around the body. They then relax so the heart can fill with blood again. This process is repeated every time the heart beats.

In atrial fibrillation abnormal electrical impulses suddenly start firing in the atria. This causes you to have a highly irregular pulse rate.

The heart's upper chambers (atria) contract randomly and sometimes so fast that the heart muscle cannot relax properly between contractions. This reduces the blood flow, from the heart, round the body. This can cause symptoms depending on how much the flow is reduced.

Causes of atrial fibrillation

Atrial fibrillation is the most common heart rhythm disturbance. Usually the cause is known but sometimes it is not fully understood. It can affect adults of any age, but it's more common in older people. It affects about 7 in 100 people aged over 65. More men than women have atrial fibrillation. 

Atrial fibrillation is more likely to occur in people with other conditions including:

It may be triggered by certain situations, such as drinking too much alcohol or smoking, or taking some medication.

Treating atrial fibrillation

Atrial fibrillation is not usually life threatening. But the condition can be uncomfortable and often requires treatment.

Treatment may involve: 

  • medication to prevent a stroke (people with atrial fibrillation are more at risk of having a stroke)
  • medication to control the heart rate or rhythm
  • cardioversion – where the heart is given a controlled electric shock to restore normal rhythm
  • catheter ablation – where the area inside the heart that's causing the abnormal heart rhythm is destroyed using radiofrequency energy; afterwards you may then need to have a pacemaker fitted to help your heart beat regularly

Atrial flutter

Atrial flutter is less common than atrial fibrillation, but shares the same symptoms, causes and possible complications.

About a third of people with atrial flutter also have atrial fibrillation.

Atrial flutter is similar to atrial fibrillation, but the rhythm in the atria is more organised and less chaotic than the abnormal patterns caused by atrial fibrillation.

Treatment for atrial flutter is also slightly different. Catheter ablation is considered to be the best treatment for atrial flutter. Medication is often the first treatment used for atrial fibrillation.

The information on this page has been adapted from original content from the NHS website.

For further information see terms and conditions.

This page was published December 2018

This page is due for review August 2021

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