What is atrial fibrillation?

Dr Dhiraj Gupta

Atrial fibrillation (AF) is the most common type of irregular heart rhythm and is a major cause of stroke. Dr Dhiraj Gupta, Consultant Electrophysiologist at the Liverpool Heart and Chest Hospital, explains what atrial fibrillation is and why a pulse check could help detect it.

What does atrial fibrillation mean?

Normally, the heart’s natural pacemaker sends out a regular electrical impulse that travels through the heart. But when someone has atrial fibrillation (AF), impulses fire off from different places in the atria (the top heart chambers), causing chaotic electrical activity, which makes them have an irregular, and sometimes fast, pulse.

The word fibrillation means an uncontrolled, uncoordinated twitching of individual muscle fibres.

AF affects about one million people in the UK – or 1.7 per cent of the population – but many more are undiagnosed and don’t know they have it.

Why is it such a problem?

AF increases the risk of a blood clot developing, which can lead to a stroke. Even if you don’t have symptoms, AF can increase the risk of stroke by five times. The disorganised electrical activity also means that the heart doesn’t pump as efficiently as it should. This can increase the risk of heart failure further down the line. The good news for people with AF is that with the right treatment these risks can be dramatically reduced.

Why do people get AF?

The chances of having the condition increase substantially as you get older, and about seven in every 100 people over the age of 65 have it. An ageing population means that AF is becoming more common. High blood pressure and obesity also make it more likely, as they put extra strain on the heart, which can trigger impulses to fire off erratically. Coronary heart disease, heart valve disease or an overactive thyroid can also cause AF.

What are the signs and symptoms?

It’s common to feel breathless and tired, although some people don’t have any symptoms at all.


Palpitation (being aware of your heart beat) is a common symptom. People describe it as if their heart is jumping all over the place. It’s also common to feel breathless and tired, although some people don’t have any symptoms at all. An irregular pulse is a sign that you might have AF, so it’s important to know how to check yours. If your pulse doesn’t follow a steady pattern, tell your GP.

How is it diagnosed?

An electrocardiogram (ECG) test is used to diagnose AF. But if the AF comes and goes – known as paroxysmal AF – it can be difficult to detect with an ECG, unless you are in AF at that particular moment. In this case, a cardiac event recorder can be useful to help with diagnosis. It’s a small device that you keep with you so that you can record your heart rate and rhythm when symptoms occur.

What can people with AF do to prevent an episode?

Alcohol can irritate the cells in the heart that can trigger an attack. So if you drink any kind of alcohol, it’s important to do so in moderation. Contrary to popular belief, cutting back on caffeine doesn’t usually make much of a difference for most people with AF, and there is little evidence that suggests avoiding stressful situations can help prevent it. However, preventing AF from developing in the first place is key. Although we can’t stop our bodies from ageing, we can try to keep our weight and blood pressure under control by making sure that we have a healthy lifestyle.

What medicine do people with AF need to take?

The earlier someone is diagnosed and treated, the higher the chances of success.


Controlling your heart rate and rhythm helps to improve symptoms and reduce the risk of heart failure. Amiodarone, sotalol and flecainide are some of the medicines that are used to try to get people’s hearts back to their normal rhythm. The earlier someone is diagnosed and treated, the higher the chances of success. If someone has had continuous AF for a long time, it can be hard to control their rhythm, so it may be that they are given medicines such as digoxin or beta blockers to slow down their heart rate.

Taking warfarin, a medicine that makes blood clots less likely to form, substantially reduces the risk of stroke. Levels of warfarin in the bloodstream can vary, so people need to go for regular blood tests to make sure they are on the right dose. However, medicines that don’t require frequent monitoring are becoming available for people with AF. These are alternative options for people who struggle with their warfarin control or for those who find it difficult to get to a clinic.

Are there any other treatments?

A treatment called ablation is used to try to get people’s heart rhythms back to normal. It involves using radio frequency energy to heat up and destroy an area of tissue. The most common form of ablation is pulmonary vein isolation. Pulmonary veins are the tubes that drain blood from the lungs into the heart. AF is usually triggered by rapid impulses within the pulmonary veins, so isolation electrically disconnects the veins to stop these impulses entering the heart. This treatment has a success rate of about 80 to 90 per cent for people with paroxysmal AF.

If you’ve had continuous AF for a long time, you might need more than one ablation or a treatment called a catheter maze. This involves having more widespread ablation to stop the AF from spreading further. Another procedure called cardioversion involves using a machine called a defibrillator to give a controlled electrical shock in order to make the heartbeat return to a normal rhythm. It can restore a normal rhythm for a short while, but because it doesn’t sort the underlying problem out, the AF often returns.

How does this condition affect people’s day-to-day lives?

Because AF can be unpredictable, and therefore you don’t know when an attack might happen, some people worry about going out or being active, but most find that they are able to carry on as normal with the help of medicines. Getting your warfarin levels checked can be inconvenient, but most people realise how important it is in helping to protect them from a stroke.

Read Jim Kelly's story of living with AF

How to check your pulse

You can check to see if you might have AF by feeling your pulse at your wrist. A normal pulse should follow a steady beat. If you have AF, your pulse will feel irregular, erratic and possibly fast, and the strength will vary. If your pulse feels like this, or if you’re concerned, see your GP.

  1. Put one of your hands out so you’re looking at your palm.
  2. Use the index finger and middle finger of your other hand and place the pads of these fingers on the inside of your wrist. You should place them at the base of your thumb near where the strap of a watch would sit.
  3. Press lightly and feel the pulse. If you can’t feel anything, press slightly harder or move your fingers around until you find your pulse.
  4. Once you’ve found your pulse, continue to feel it for about 20–30 seconds. Note the rhythm of the pulse to see if it’s regular or irregular. Visit our pulse check page to hear what a regular and irregular pulse sound like, and to watch our video on how to check your pulse.

Find out more

For more information, visit our atrial fibrillation web page or see the Atrial Fibrillation Association website

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