Atrial fibrillation

Expert reviewer, Dr Tim Cripps, Consultant Cardiologist
Next review due November 2022

Atrial fibrillation is a type of abnormal heartbeat (arrhythmia) in which your heartbeat is irregular and often too fast. Around one in every 100 to 200 people in the UK have it. You’re more likely to get it as you get older.

Older man carving at a workbench

What happens in atrial fibrillation?

Your heartbeat is controlled by electrical signals (impulses) that travel through your heart to make it contract. Normally, the electrical signal starts in an area of your heart called the sinus or sinoatrial node.

In atrial fibrillation, you get multiple faulty electrical signals in the upper chambers of your heart, which are called the atria. The signals become disorganised and out of control, so that your atria twitch (fibrillate) rather than contracting properly. This passes to the lower chambers (ventricles), so that they also contract irregularly and usually too fast.

Watch our animation to see how your heart beats normally and what happens in atrial fibrillation.

There are different types of atrial fibrillation.

  • Paroxysmal atrial fibrillation is when you have recurring episodes of atrial fibrillation that start and stop on their own or in response to medication. The episodes can last for anywhere from 30 seconds up to a week but usually less than a couple of days.
  • Persistent atrial fibrillation is when your heart rhythm remains abnormal for more than a week or you’ve had treatment with cardioversion to stop it.
  • Permanent atrial fibrillation is when your abnormal heart rhythm doesn’t respond to treatment or you’ve decided not to treat the abnormal rhythm. It’s normally classed as permanent if you’ve had it for a year or more.

You might only get short or occasional episodes of atrial fibrillation at first. But this can often progress to longer and more frequent episodes before becoming permanent.

Symptoms of atrial fibrillation

Symptoms of atrial fibrillation can include:

  • palpitations (a thumping or fluttering feeling in your chest)
  • breathlessness
  • feeling very tired
  • feeling dizzy or light-headed or actually passing out
  • finding it difficult to exercise or not being able to exercise as much as normal

If you have any of these symptoms, see your GP. If your symptoms come on suddenly and you have chest pain or feel out of breath, go to your nearest accident and emergency department. If necessary, call for medical help.

You might have atrial fibrillation but not get any symptoms or they may be so mild that you don’t notice them. In these cases, you might only find out you have atrial fibrillation if you’re having medical tests or treatment for something else.

Diagnosis of atrial fibrillation

If you see your GP, they’ll ask about your symptoms and examine you. Your GP will want to know how often you’ve had symptoms, what they feel like and if anything in particular seems to set them off.

They’ll take your pulse, check your blood pressure and listen to your heartbeat. Your GP will also ask you about your medical history. You’ll need to have a test called an electrocardiogram (ECG). An ECG records the electrical activity in your heart to see how well it’s working.

Your GP may arrange for you to have a number of other tests. These may include the following.

  • A 24-hour heart monitor (ambulatory ECG). This records the electrical activity of your heart while you go about your usual activities over 24 hours (or longer if necessary).
  • An event recorder ECG. This is a device that you activate yourself to record your heart rhythm when you have symptoms. You may be asked to use one if you don’t get symptoms very often.
  • Blood tests. These will check for certain substances in your blood that can be associated with atrial fibrillation or other conditions that may be causing your symptoms.
  • Chest X-ray. This allows your doctor to look for any changes in your heart or lungs that might be causing the problem.
  • Transthoracic echocardiogram. This is a type of scan using ultrasound to produce a clear image of your heart to see how well it's working. Sometimes, you may have a transoesophageal echocardiogram instead. This involves passing a probe into your oesophagus (the pipe from your mouth to your stomach) to take ultrasound images of your heart.

Treatment of atrial fibrillation

Treatment for atrial fibrillation may aim to:

  • control your heart rhythm
  • control your heart rate
  • reduce your risk of complications associated with blood clotting (for example, stroke)

What treatments you’re offered will depend on a number of factors, including your symptoms, the type of atrial fibrillation you have and what’s causing it. Your GP will usually refer you to a cardiologist for treatment – a doctor who specialises in identifying and treating heart conditions.

Controlling heart rhythm

If possible, your doctor will try treatments aimed at controlling your heart rhythm. There are a number of different treatments that act to control heart rhythm.


Cardioversion is a procedure to help return your heart’s rhythm to normal using a controlled electric shock to your chest. You might have cardioversion in an emergency situation, if you have a sudden episode of atrial fibrillation with very severe symptoms.

You may also be offered it as a treatment option if you’ve had an episode that’s lasted for 48 hours or more and medicines haven’t worked. You’ll usually need to take anticoagulants for a period of time before the procedure when it’s planned in advance.

Medicines to control your heart rhythm

Your doctor may offer you antiarrhythmic medicines to control your heart rhythm over the long term. These include beta-blockers, amiodarone and flecainide.

Catheter ablation

This is a procedure to destroy the tissue in your heart that’s sending out irregular electrical signals and causing atrial fibrillation. A small tube called an electrode catheter is passed up to your heart via a vein in your groin. Your doctor may suggest this if medicines aren’t controlling your symptoms or aren’t suitable for you.

Ablation can also be done via open heart surgery, but you’ll usually only have this if you’re already having heart surgery for other reasons.

Pace and ablate

This involves destroying the part of your heart tissue that carries electric signals from the upper to lower chambers of your heart (the atrioventricular or AV node). You’ll need to have a pacemaker fitted to take over the role of controlling your heart beat. A pacemaker is a small device inserted under your skin, which monitors your heartbeat and sends electrical signals to stimulate your heart. This procedure is usually only considered if other treatments haven’t worked. Your doctor will tell you if it’s an option for you.

Controlling heart rate

Your doctor will offer you treatment to control your heart rate if your heart rhythm can’t be restored. Medicines to control heart rate include beta-blockers, calcium-channel blockers and digoxin. Sometimes you may need to take more than one medicine if the first one you try doesn’t work on its own.

Preventing strokes

If you have atrial fibrillation, you’re at greater risk of having a stroke than someone who doesn’t have the condition. This is because if you have atrial fibrillation, the blood doesn’t flow properly through your heart and can lead to clots forming. If the clot breaks off, it could travel through your body and block a blood vessel in your brain and cause a stroke.

Your doctor will assess your risk of stroke and may prescribe you a medicine called an anticoagulant. This medicine is to thin your blood and reduce your risk. Examples include warfarin, apixaban, dabigatran, edoxaban and rivaroxaban.

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Causes of atrial fibrillation

About nine out of every 10 people with atrial fibrillation have another health condition that causes their heart rhythm problems. Such conditions include:

There are also some lifestyle factors that can trigger atrial fibrillation. These include:

Frequently asked questions

  • No, there are lots of other reasons why you may have palpitations and most aren’t serious. They aren’t usually anything to worry about and you don't usually need any treatment.

    If you have palpitations, you’ll be aware of your heart racing, beating in a strange pattern or thumping in your chest. Sometimes your heart might feel like it has skipped a beat or there’s an extra beat. This is called an ectopic beat and is really common. Many people experience palpitations or ectopic beats at some time – including people without atrial fibrillation. While palpitations can be unpleasant and distressing, they may be harmless and go away on their own.

    Palpitations can be triggered by many things, including:

    • other types of irregular heart beat (arrhythmias)
    • heart valve disease
    • anxiety, panic attacks or depression
    • an overactive thyroid gland
    • diabetes
    • the menopause
    • pregnancy
    • fever
    • anaemia (where your blood isn’t carrying enough oxygen)
    • some medicines (such as certain antihistamines and antibiotics)
    • alcohol, cigarettes and illegal drugs such as cocaine and cannabis

    If your palpitations don't seem to be triggered by anything in particular or you also have other symptoms such as dizziness or chest pain, see your GP.

  • So long as your atrial fibrillation is under control, you should be able to exercise.

    Generally speaking, exercise is good for your heart and helps you to stay healthy. Our Cardiology Clinical Adviser, Dr Yassir Javaid, explains why in our video: What can you do to improve your heart health?

    You might find that you get tired easily with exercise at first. But if you build up the amount you do gradually, this should improve as you get fitter. Always stop if you feel sick, dizzy, get palpitations or other symptoms and talk through what happened with your doctor before you start again.

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Related information

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  • Reviewed by Pippa Coulter, Freelance Health Editor, November 2019
    Expert reviewer, Dr Tim Cripps, Consultant Cardiologist
    Next review due November 2022