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Atrial fibrillation

Atrial fibrillation is a condition in which your heart beats in an irregular rhythm (arrhythmia) which may often be too fast. It’s one of the most common types of long-lasting (sustained) arrhythmia.

Video: the different types of arrthythmia

About atrial fibrillation

Your heartbeat is controlled by electrical signals (impulses), which travel through your heart making it contract. The signals travel from the atria (the upper chambers of your heart) to the ventricles (the lower chambers) through an area called the atrioventricular (AV) node. The AV node helps to synchronise the pumping action of your heart.

Illustration showing the electrical impulses in a normal heart and a heart with atrial fibrillation

Atrial fibrillation occurs when the electrical signals in your atria become disorganised, overriding your heart's normal rate and rhythm. This causes your atria to contract irregularly (also known as fibrillation).

Atrial fibrillation affects around 800,000 people a year in the UK. It can affect anyone at any age, but it’s more common in people aged 55 and over.

Types of atrial fibrillation

There are three types of atrial fibrillation. Atrial fibrillation can change from one type to another over time.

  • Paroxysmal atrial fibrillation. This type of atrial fibrillation comes and goes for a few minutes or hours at a time. It can last for up to seven days (but usually only lasts one or two days). Your heartbeat may return to normal by itself or you may need medicines to return your heartbeat to its normal rhythm.
  • Persistent atrial fibrillation. This type of atrial fibrillation can last for longer than seven days. You will need medical treatment, such as cardioversion, to restore your heart to its normal rhythm (see Treatment section for more information).
  • Permanent atrial fibrillation. This type of atrial fibrillation is when your heartbeat is permanently affected, and doesn’t return to its normal rhythm even after medical treatment.

Symptoms of atrial fibrillation

You may have atrial fibrillation but not have any symptoms at all; or just have mild symptoms that don’t cause you any problems.

If you have symptoms of atrial fibrillation, these may include:

  • palpitations – when you're aware of your heart beating faster or in an irregular way
  • chest pain or discomfort
  • finding it difficult to exercise
  • shortness of breath
  • feeling dizzy or light-headed

If you have any of these symptoms, see your GP straight away.

Complications of atrial fibrillation

If you have atrial fibrillation, you may be up to five times more likely to have a stroke than someone who doesn’t have the condition. This is because your blood doesn't flow through your heart properly, so a blood clot can form. The blood clot can then travel to your brain where it can block your blood supply and cause a stroke. However, your risk of having a stroke will depend on many aspects of your health, such as your blood pressure and cholesterol level, and whether you have diabetes. Take our stroke risk assessment to find out your risk of stroke.

If you have atrial fibrillation and your doctor thinks you’re at risk of a stroke, he or she may prescribe you an anticoagulant medicine, such as warfarin, to prevent a blood clot forming. If you can't take anticoagulant medicines, you may be prescribed aspirin or clopidogrel instead, but these aren’t as effective. For more information, speak to your doctor.

Causes of atrial fibrillation

Many conditions that affect the heart or blood circulation can cause atrial fibrillation, including:

Certain other factors can also trigger atrial fibrillation, including:

  • drinking too much alcohol or caffeine
  • being overweight
  • taking certain medicines
  • emotional or physical stress
  • having surgical procedures

About one in 10 people develop atrial fibrillation without having any known underlying cause. This is called lone atrial fibrillation.

Diagnosis of atrial fibrillation

You may not be aware that you have atrial fibrillation, and it may only be discovered by chance if your GP or nurse checks your pulse for some other reason. However, if you experience any symptoms or have any concerns about your heart rhythm, see your GP. He or she will ask about your symptoms and examine you.

Your GP will check your blood pressure, listen to your heartbeat and take your pulse. If your pulse is irregular, you’re likely to have a test called an electrocardiogram (ECG). This records the electrical activity of your heart to see how well it’s working.

If your GP suspects you have atrial fibrillation, he or she may refer you to a cardiologist – a doctor who specialises in identifying and treating heart and blood vessel conditions. He or she may suggest you have other tests including the following.

  • Blood tests.
  • An echocardiogram. This is an ultrasound scan that produces a clear image of your heart muscles and valves to check the structure of your heart and how well it's functioning.
  • Ambulatory ECG. This takes a recording of your heartbeat while you carry on with your usual activities for 24 hours or more.

If you have symptoms that have come on suddenly, such as chest pain or shortness of breath, your GP may refer you to hospital immediately to have these tests.

Treatment of atrial fibrillation

There are many treatment options available for atrial fibrillation. Your treatment will be tailored to you, and will depend on your symptoms, the type of atrial fibrillation you have and what is causing it.

Your treatment may aim to control your heart rhythm and stop the arrhythmia, or it may aim to control your heart rate and reduce your risk of having a stroke. If your symptoms are mild, you may not need any treatment at all.

Your doctor will discuss your treatment options with you.


There are several different types of medicine that are used to treat atrial fibrillation. Your doctor may prescribe you a combination of medicines or try one type first before trying another. You may need to take them for a short time to control your heartbeat, or you may need to take them for several months or years to manage your condition.

Medicines to control your heart rate

You may be given medicines to control how fast your heart is beating. This means you will still have atrial fibrillation, but your heart will beat more slowly and effectively. These medicines include digoxin, beta-blockers and calcium-channel blockers.

Medicines to control your heart rhythm

You may be given medicines to control your heart rhythm. These are called antiarrhythmic medicines and include flecainide and beta-blockers.

If your atrial fibrillation has come on suddenly (usually within 48 hours), you may also be given antiarrhythmic medicines in hospital as tablets or through a vein in your hand or arm to try to get your heart rhythm back to normal (this is called pharmacological or chemical cardioversion).

If you have paroxysmal atrial fibrillation (the type that comes and goes), your doctor may give you an antiarrhythmic medicine to take only when you have symptoms. This is known as the ‘pill in the pocket’ approach. Examples of medicines used for this treatment include flecainide and propafenone.

Medicines to reduce blood clotting

As atrial fibrillation increases your risk of stroke, your doctor may give you medicines to try to prevent a blood clot forming. These are called anticoagulants and include heparin, warfarin and aspirin. You may be given these in addition to medicines to control your heart rate or if you’re having a procedure called electrical (DC) cardioversion (see below).

Hospital treatment

Your doctor will usually only recommend further treatment if medicines haven't controlled your atrial fibrillation. Options include electrical (DC) cardioversion and catheter ablation. All these procedures are carried out in hospital by a cardiologist, usually under local anaesthesia and sedation.

Electrical (DC) cardioversion

DC cardioversion is a procedure that involves giving a controlled electric shock to restore your heart's normal rhythm. You may be offered DC cardioversion straight away if your atrial fibrillation started less than 48 hours ago and medicines haven’t helped, or if you are very unwell. If your symptoms have lasted more than 48 hours, you may be prescribed medicines such as anticoagulants to take first, before having DC cardioversion about four to six weeks later. You may also need to have a transoesophageal echocardiogram before having a cardioversion, to check for any blood clots in your heart. DC cardioversion is less likely to work if you have had arrhythmia for over a year. For more information on cardioversion, see Related topics.

Catheter ablation

Ablation means freezing or burning your heart tissue. Catheter ablation can be carried out to destroy the areas of your heart that are sending out the irregular signals (known as atrial fibrillation ablation).

Your cardiologist will insert catheters (thin flexible tubes) into a vein in your groin and pass them up into your heart. The affected area is then ablated using very high or low temperatures. This procedure may not be suitable for everyone, and sometimes you may need a repeat procedure to control your atrial fibrillation. See our frequently asked questions for more information about catheter ablation.

If you're unable to have atrial fibrillation ablation or the procedure hasn't worked for you, you may be able to have another type of catheter ablation procedure, called AV node ablation. This destroys the AV node, preventing irregular signals being passed through your heart, so that your heart rhythm is kept regular. You will also be fitted with a pacemaker – a small device that controls your heart beat. This may be done as a separate procedure.

Produced by Louise Abbott, Bupa Health Information Team, December 2012.

For answers to frequently asked questions on this topic, see FAQs.

For sources and links to further information, see Resources.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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