What is atrial fibrillation?

Atrial fibrillation is a heart rhythm disorder that makes your heart beat irregularly and either too fast or too slow. The condition is the most common irregular heart rhythm (arrhythmia), in the UK it affects approximately one in 45 people.  

If you are diagnosed with atrial fibrillation, your risk of stroke can be increased up to five times. However, your doctor can prescribe blood-thinning medications to greatly reduce your risk. 

When you have atrial fibrillation, the atria (upper chambers of the heart) beat irregularly and out of sync with the ventricles (lower chambers of the heart). For this reason, atrial fibrillation can cause symptoms such as heart palpitations (a rapid, pounding heartbeat), shortness of breath, and fatigue.  

While the condition itself usually isn’t life-threatening, it will require treatment to prevent any serious complications. 

Atrial fibrillation symptoms

You might not experience any symptoms if you have atrial fibrillation. This is one of the main reasons why many people have it and yet remain undiagnosed – approximately 0.5% of the world’s population are currently living with undiagnosed atrial fibrillation. 

Typical symptoms of atrial fibrillation often include: 

• tiredness – due to the heart not pumping sufficient oxygenated blood to the rest of the body 

• weakness – a result of the heart’s inefficiency caused by atrial fibrillation  

• breathlessness – during exercise, everyday activities, or even at rest 

• palpitations – you will suddenly notice your heart beating strongly 

• a heart rate that is consistently lower than 60 or above 100 beats per minute 

• reduced ability to exercise – your increased heart rate can make exercising difficult 

• chest discomfort – pain, pressure, or tightness in the chest 

• dizziness – when your heart beats more quickly than normal, your blood pressure can drop, and you may start to feel faint.

Symptoms of atrial fibrillation are often classified by how long they last: 

• occasional symptoms come and go, may last for anything from a few minutes to several hours or days, could go away on their own, and may need treatment 

• persistent symptoms don’t go away on their own, and medications may be required to restore and retain a normal heart rhythm 

• long-standing persistent atrial fibrillation symptoms are continuous and last for longer than a year 

• permanent atrial fibrillation symptoms mean that a regular heart rhythm cannot be restored and that medications are required to prevent blood clots and control your heart rate.  

You should see your doctor if you experience any of the above symptoms.

Atrial fibrillation causes

The heart is made up of chambers surrounded by muscular walls. There are two chambers at the bottom of the heart, called ventricles, and two at the top, called atria. 

When the heart beats normally, the muscular walls of the atria and ventricles tighten and squeeze (contract) in turn, to push blood out of the heart and around the body. The muscular walls then relax to allow blood to fill the heart.  

When you have atrial fibrillation, the atria (upper chambers) contract randomly and sometimes faster than normal. This means that your heart muscles can’t relax properly, reducing how well your heart can work. 

Atrial fibrillation happens as a result of abnormal electrical impulses in your heart. When these start firing at random in the atria, this overrides your heart’s natural pacemaker, causing an irregular heart rhythm and pulse rate.  

The exact cause of these abnormal electrical impulses remains unknown. But research shows that the chances of having the condition increase with age, typically affecting people aged over 65 most commonly. However, the condition can affect adults of any age.

Atrial fibrillation risk factors

Atrial fibrillation has several risk factors. These include:  

• age – the older you are, the more risk you have of developing the condition  

• high blood pressure 

• diabetes 

• drinking alcohol – especially binge drinking, which can be a trigger for some people  

• obesity. 

You are also more likely to have atrial fibrillation if you have certain other medical conditions, such as: 

• high blood pressure 

• atherosclerosis (narrow arteries due to a build-up of fatty deposits) 

• heart disease 

• thyroid disease 

• heart valve problems 

• diabetes 

• lung disease 

• kidney disease  

• metabolic syndrome (a combination of diabetes, high blood pressure and obesity) 

• sleep apnoea (when breathing stops and starts in your sleep).

Complications of atrial fibrillation

Atrial fibrillation can cause complications, especially if the condition is not treated. 

Atrial fibrillation’s chaotic heart rhythm can result in blood collection in the atria (upper chambers of the heart), forming blood clots. Blood clots in the left atrium (left upper chamber) can break free and travel to the brain, which can then cause a stroke. 

You are also more likely to have a stroke from atrial fibrillation if you are older, have diabetes, have high blood pressure, have heart failure, or have a valvular disease (a disease involving one or more of the heart’s four valves).

Book an appointment

For more information, or to book an appointment, contact our customer care team.

Content verified by Dr Shouvik Haldar.