Atrial fibrillation (AF) is a type of irregular heartbeat that can cause blood clots to form in your heart. Having atrial fibrillation increases your risk of stroke by five times.

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On this page: 
What is atrial fibrillation?
Example of an AF heartbeat
Why does AF increase your risk of stroke?
Atrial fibrillation symptoms
How is atrial fibrillation diagnosed?
Treating atrial fibrillation
Reducing your risk of a stroke with atrial fibrillation

What is atrial fibrillation?

Atrial fibrillation (AF) is a type of irregular heartbeat. In AF, your heartbeat is irregular and may be abnormally fast. The heart might not empty itself of blood at each beat, and a clot can form in the blood left behind. 

Example of an AF heartbeat

Why does AF increase your risk of stroke?

If a blood clot forms in your heart, there is a risk that it will travel in your bloodstream towards your brain. If a clot blocks one of the arteries leading to your brain, it could cause a stroke or transient ischaemic attack (TIA or mini-stroke).

If you have atrial fibrillation, you are five times more likely to have a stroke. And atrial fibrillation contributes to just under 20% of all strokes in the UK. 

Atrial fibrillation symptoms

Some common symptoms of AF include:

  • Palpitations (being aware of your heart beating fast).
  • Breathlessness.
  • Chest pain.
  • Fatigue.

However, some people do not have any symptoms and AF is often only diagnosed during a general medical check up or after a stroke or TIA.

There are four types of AF:

  • Paroxysmal AF comes and goes – it’s not there all the time. Your heart goes back to its normal rhythm without any treatment, usually within 48 hours,
  • Persistent AF is where you have AF episodes that last more than seven days and it's unlikely that they'll stop on their own. You'll need treatment to restore your normal heart rate.
  • Permanent AF is there all the time. You might be diagnosed with permanent AF if you’ve had it for more than one year.
  • Long-standing persistent AF is when you have had continuous atrial fibrillation for a year or longer.

As well as these four types, a small number of people may be diagnosed with "lone" AF. This is when doctors cannot find what is causing your AF, or you don’t have any risk factors for it. 

How is atrial fibrillation diagnosed?

If you suspect your pulse is irregular, make an appointment with your GP. They may refer you for further tests to confirm whether you have AF.

These tests may include the following:

  • An electrocardiogram (ECG) tests the electrical activity of your heart. It’s painless and usually takes less than 10 minutes. It may be done by your GP or in hospital.
  • An echocardiogram uses sound waves to check your heart’s structure and how it’s working.
  • Blood tests check for conditions that can cause AF, such as an overactive thyroid gland.
  • A chest X-ray will check whether a lung problem could have caused your atrial fibrillation. 

AF that comes and goes can be hard to detect. To help diagnose it, you may be asked to wear a portable ECG monitor for 24 hours or more to check how your heart works over a longer period of time. 

Treating atrial fibrillation

Your doctor will talk to you about whether you need treatment, and which options will work best for you.

If your heart is beating too fast, you may be offered medication to make it beat at a normal rate. You might need to try several types of medication before you find the right one for you. You should also have regular checks to monitor your blood pressure and heart rate.

You may also be offered treatment to make your heart beat more regularly. This can include medication, or a procedure called cardioversion. This uses a brief electric shock or medication to restore a normal rhythm. 

There are other treatments for AF, including surgical procedures such as catheter ablation where radio frequency energy is used to remove the area of the heart causing the abnormal rhythm. 

Reducing your risk of a stroke with atrial fibrillation

If you are diagnosed with AF, your doctor will assess your risk of a stroke. If you are at a high risk, they will talk to you about using anticoagulant medication. Your doctor will discuss the options with you and carry out checks to make sure the medication is working well for you. 

There are several types of anticoagulant. These include apixaban, dabigatran etexilate, edoxaban, rivaroxaban and warfarin. Each one needs to be taken in a certain way, and you may need regular checks while you're on the medication. 

Are you taking aspirin?  

Aspirin used to be prescribed to people with AF, but this is no longer recommended. However, aspirin is still prescribed for other conditions. If you have AF and take aspirin, you should discuss with your doctor whether it is the best treatment for you. Some people will need to switch to an anticoagulant, but you must not stop taking any treatments without speaking to your doctor.

You should also be given advice about things you can do to stay healthy. These could include giving up smoking, losing weight, drinking less alcohol and being more active. Read more about healthy lifestyle choices that can help reduce your risk of a stroke.