Atrial fibrillation (AF) and stroke

Atrial fibrillation (AF) is a type of irregular heartbeat. It means that your heart may not be pumping as well as it should.

What is Atrial fibrillation (AF)?

Atrial fibrillation is the most common heart rhythm disturbance. If you have atrial fibrillation your heart is not pumping as well as it should. The upper chambers of your heart contract and relax in an uncoordinated and irregular way due to abnormal electrical activity.

If your heartbeat is irregular and fast, your heart may not have a chance to empty properly before filling up with blood again. Blood can collect inside the upper chamber of the left side of the heart, and this increases the risk of blood clots forming.

If blood clots form in your heart, there is a risk they can 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 TIA.

Atrial fibrillation makes your risk of a stroke five times higher. So if you have AF, it’s important that you get the right treatment to control your heartbeat, and reduce your risk of stroke.

What are the symptoms of AF?

Palpitations (being aware of your heart beating fast), breathlessness, chest pain or fatigue are common symptoms of AF. However, some people do not have any symptoms at all, and AF is often only diagnosed during a medical check-up or after a stroke.

AF is usually described by how long it has lasted:

  • 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 is unlikely that they will stop on their own. You may need treatment to restore your normal heart rhythm.

  • Long-standing persistent AF means you have had continuous atrial fibrillation for a year or longer.

  • Permanent AF is there all the time. You might be diagnosed with permanent AF if you’ve had it for more than one year and treatment with cardioversion hasn’t helped.

You might also hear your condition described as “lone” AF. This is when doctors cannot find what is causing your AF, or you don’t have any risk factors for it.

What causes AF?

Atrial fibrillation can happen to anyone, but some things increase your chances of developing it. These include heart disease and high blood pressure. It can also be caused by other conditions including an overactive thyroid gland, lung infections, or a blood clot in the lung (pulmonary embolism). AF is more common in older people.

Drinking too much alcohol, taking illegal drugs, such as cocaine or amphetamines, or smoking can trigger an episode of AF.

How is AF diagnosed?

AF can sometimes be detected by a healthcare professional checking your pulse. If your pulse feels very fast and/or irregular, they may refer you for further tests to confirm whether you have AF, and if so, what type you have. 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 like an overactive thyroid gland, anaemia, or any problems with your kidney function.

  • A chest X-ray will check whether a lung problem could have caused your AF.

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.

How is AF treated?

If you have AF, you should consider with your doctor whether you need treatment to reduce your risk of stroke. You may also require treatment to help your heart beat more effectively. This often means medication to regulate your heart rate, or treatments to change your heart rhythm back to normal.

Regulating your heart rate

The aim of this type of treatment is to help your heart to work more effectively. Most medication used to regulate your heart rate will not change the rhythm back to normal. However, some types of medication used to control your heart rate are the same as those used to control your heart rhythm, including some types of beta blocker.

Regulating your heart rhythm

To get your heart beating with a normal rhythm you may be prescribed antiarrhythmic drugs. There are different types and they work in different ways. Beta blockers are one example. Your doctor will talk to you about which treatment will be best for you.

Cardioversion is a treatment that uses medication or a brief electrical shock (sometimes both), to help your heart return to its normal rhythm. It is more likely to work if you have not had AF for very long, and there is a risk that your AF will return.

Other treatments

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.

Treatments to reduce your risk of stroke

As well as treatment for your AF, you may also need treatment to reduce your risk of stroke. Your doctor should talk to you about all the available treatment options, along with their risks and benefits. You should then decide together which one would be the most suitable for you.


The main type of drug used to reduce the risk of stroke in AF is anticoagulant medication. They reduce your risk of stroke by slowing down the clotting process and making a clot less likely to form.

Warfarin is a common type of anticoagulant medication used to reduce your risk of stroke if you have AF.

Taking warfarin requires careful monitoring, and you need to be mindful of the foods you eat. Certain foods contain high levels of vitamin K. Too much vitamin K can affect how warfarin works.

Other anticoagulants are increasingly being used that work differently to warfarin. These include dabigatran etexilate, rivaroxaban, apixaban and edoxaban. All these drugs are administered orally.

The advantage of newer anticoagulants is that their effect on your blood is more stable and they are not affected by any foods that you eat, so they do not need to be monitored as carefully.

What else do I need to know?

Never stop taking your medication if you feel unwell. Always contact your GP for advice before stopping, because your risk of a stroke may rise, and some medicines cause withdrawal symptoms if you stop suddenly. In a medical emergency, always call 999.

If you are taking anticoagulants, you must always check any medication you plan to take with your GP or pharmacist before taking it. You should also read the patient information leaflets that come with your medication.

You should be given a patient alert card before you start taking an anticoagulant. Always carry your alert card with you in case of an emergency. You should also tell your dentist you are taking anticoagulant medication before you have any treatment.


Other resources

Stroke Association
Helpline: 0303 3033 100
Contact us for information about stroke, emotional support and details of local services and support groups.

Anticoagulation UK
Phone: 020 8289 6875
Provides information and peer support groups for people with anticoagulation medications.

Arrhythmia Alliance
Phone: 01789 867 501
Supports people with all types of heart arrhythmias.

Atrial Fibrillation Association
Phone: 01789 867 502
Supports people with all AF, offering a range of leaflets, treatments and types of medication, plus details of AF specialists.

British Heart Foundation
Phone: 0300 330 3311
Provides information and support on heart issues including a nurse-led helpline.

Disclaimer: The Stroke Association provides the details of other organisations for information only. Inclusion on My Stroke Guide does not constitute a recommendation or endorsement.