Atrial fibrillation is a heart condition that causes an irregular and often abnormally fast 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.
You may be aware of noticeable heart palpitations, where your heart feels like it's pounding, fluttering or beating irregularly, often for a few seconds or, in some cases, a few minutes.
Sometimes atrial fibrillation does not cause any symptoms and a person who has it is completely unaware that their heart rate is irregular.
You should make an appointment to see a GP if:
See a GP as soon as possible if you have chest pain.
When the heart beats normally, its muscular walls tighten and squeeze (contract) 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, the heart's upper chambers (atria) contract randomly and sometimes so fast that the heart muscle cannot relax properly between contractions. This reduces the heart's efficiency and performance.
Atrial fibrillation happens when abnormal electrical impulses suddenly start firing in the atria.
These impulses override the heart's natural pacemaker, which can no longer control the rhythm of the heart. This causes you to have a highly irregular pulse rate.
The cause is not fully understood, but it tends to affect certain groups of people, such as those over 65.
It may be triggered by certain situations, such as drinking too much alcohol or smoking.
Atrial fibrillation can be defined in various ways, depending on the degree to which it affects you.
Atrial fibrillation is the most common heart rhythm disturbance, affecting around 1 million people in the UK.
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.
Our guide to care and support explains your options and where you can get support.
Atrial fibrillation is not usually life threatening, but it can be uncomfortable and often requires treatment.
Treatment may involve:
Atrial flutter is less common than atrial fibrillation, but shares the same symptoms, causes and possible complications.
Around 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, whereas medicine is often the first treatment used for atrial fibrillation.
Page last reviewed: Sat Apr 2021 Next review due: Sat Apr 2021