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.
This can cause problems including dizziness, shortness of breath and tiredness. 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 doesn't cause any symptoms and a person with it is completely unaware that their heart rate isn't regular.
Read more about the symptoms of atrial fibrillation.
You should make an appointment to see your GP if:
See your GP as soon as possible if you have chest pain.
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, the heart's upper chambers (atria) contract randomly and sometimes so fast that the heart muscle can't relax properly between contractions. This reduces the heart's efficiency and performance.
Atrial fibrillation occurs 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 isn't fully understood, but it tends to occur in certain groups of people (see below) and may be triggered by certain situations, such as drinking excessive amounts of alcohol or smoking.
Read more about the causes of atrial fibrillation.
Atrial fibrillation can be defined in various ways, depending on the degree to which it affects you. For example:
Atrial fibrillation is the most common heart rhythm disturbance, affecting around one million people in the UK.
Atrial fibrillation can affect adults of any age, but it becomes more common as you get older. It affects about 7 in 100 people aged over 65, and more men than women have it.
Atrial fibrillation isn't usually life-threatening, but it can be uncomfortable and often requires treatment.
Treatment may involve:
If you have atrial fibrillation, your clinical team may pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).
This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.