Photo of man with atrial fibrillation (PantherMedia / Alice Day)

In atrial fibrillation, there’s a problem with the heart’s natural pacemaker signals. The heart rate is irregular and often too fast. As a result, the heart can no longer pump as much blood around the body. This can cause noticeable symptoms such as palpitations or feeling faint.

Atrial fibrillation is usually caused by another chronic medical condition, such as coronary artery disease or high blood pressure. Sometimes no clear cause is found, though.

Atrial fibrillation is the most common type of abnormal heartbeat (arrhythmia). Although it isn’t immediately life-threatening, it increases the risk of a stroke and can weaken the heart over time.

Various things can be done to reduce the symptoms and decrease the risk of a stroke. Most people can live a normal life despite having atrial fibrillation.


The most common symptom of atrial fibrillation is a clearly noticeable heartbeat, known as palpitations. The person's pulse is usually higher and less regular than normal: A healthy resting heart rate usually ranges between 60 and 100 beats per minute. People who have atrial fibrillation often have a much higher heart rate.

Other possible symptoms include feeling weak, drowsy, or dizzy. But atrial fibrillation isn’t always noticeable: Up to 30 out of 100 people don’t have any symptoms, or only have non-specific symptoms that you wouldn’t immediately associate with atrial fibrillation.

People who also have other heart problems might have other symptoms too. For instance, if someone has heart failure (cardiac insufficiency), atrial fibrillation can clearly reduce their heart performance, leading to symptoms like shortness of breath and exhaustion – particularly during more strenuous physical activities.


The heart is a muscle that contracts (tightens and squeezes) rhythmically. An electrical conduction system regulates the heartbeat. The heartbeat is generated in the sinus node, also known as the sinoatrial or SA node. This is a group of special cells in the wall of the upper right chamber of the heart (the right atrium). The sinus node is sometimes described as the heart’s “natural pacemaker.” It sends out electrical signals that travel along conduction pathways to the atrioventricular (AV) node. From there, they are passed on to the chambers of the heart. A normal heartbeat is also known as the sinus rhythm.

Illustration: Normal heartbeat and atrial fibrillation – as described in the article

In atrial fibrillation, irregular electrical signals fire in the atria (upper heart chambers), rapidly spreading across them. The sinus node doesn’t send any signals during this time. As a result, the atria no longer contract and relax in a regular rhythm, but “twitch” (fibrillate) in a fast and chaotic way.

The atria usually squeeze blood into the ventricles (lower heart chambers), helping them to quickly fill with blood. They provide about 20% of the heart’s pumping power. In atrial fibrillation, the heart is weaker than usual, but its ventricles still pump blood into the body – just at an irregular rate.

There are several reasons why atrial fibrillation may occur. The most common causes include:

Other possible causes include an overactive thyroid gland and taking certain medications. The cause remains unknown in about a third of all people with atrial fibrillation.

Risk factors

The biggest risk factor is increasing age: Older people are more likely to develop atrial fibrillation. It is estimated that about 2% of the total population and about 7% of people over the age of 65 are affected.

Some risk factors can be influenced to a certain extent. These include heavy or regular alcohol consumption, smoking, having diabetes, high blood pressure, being very overweight and sleep apnea (pauses in breathing at night).


Atrial fibrillation typically starts with rare, short episodes. It may progress over time, leading to longer episodes or even permanent atrial fibrillation. Depending on how long the episodes last, four different types of atrial fibrillation can be distinguished between:

But diagnoses based on these definitions aren’t always that reliable: It often isn’t clear whether someone has already had episodes of atrial fibrillation in the past, or how long they have already had it for. What’s more, persistent atrial fibrillation can go away and then become paroxysmal again.

The main thing to know is that all types of atrial fibrillation increase the risk of a stroke. So the specific type of atrial fibrillation isn’t all that relevant when deciding whether or not to have treatment with anticoagulant (anti-clotting) medication.


Although atrial fibrillation is associated with various symptoms, it is usually not an acutely life-threatening condition. But it can lead to various health problems in the long term. These include, in particular:

  • Heart failure (cardiac insufficiency): Because the heart usually beats faster and the atria (upper heart chambers) no longer squeeze properly, the rest of the heart has to work harder. This can become too much for the heart to handle in the long term, making it weaker over time. If someone already has heart failure, atrial fibrillation can make it worse.
  • Stroke: In atrial fibrillation, the blood is no longer completely squeezed out of the atria. The blood may build up in these chambers, which increases the likelihood of blood clots forming, particularly in a part of the left atrium known as the left atrial appendage. If a blood clot is carried to the brain in the bloodstream, it may block a blood vessel there and cause a stroke.

A person’s individual risk of stroke will depend on whether they have risk factors other than atrial fibrillation. People who have atrial fibrillation often have other medical conditions too, such as high blood pressure or coronary artery disease.


Because atrial fibrillation doesn’t always cause symptoms, it is sometimes discovered by chance, for instance when the electrical activity of the heart is measured for a different medical reason. The following things help to get an accurate diagnosis, find out the cause, and plan the treatment.

  • A talk about your medical history (anamnesis): The doctor asks questions about your symptoms, other medical conditions, age and family history, as well as risk factors for heart disease.
  • Physical examination: This includes measuring your pulse rate and blood pressure.
  • Electrocardiogram (ECG): In an ECG, the electrical activity that regulates the heartbeat is shown in the form of a graph. This is a very reliable way to diagnose atrial fibrillation. To measure the electrical activity of the heart, several electrodes are placed on the body. The ECG itself usually takes less than ten minutes. If it is thought the person might have atrial fibrillation that comes and goes in episodes, and the ECG results are normal, a 24-hour or 48-hour ECG is sometimes done. This involves wearing a small ECG device that measures the electrical activity of your heart for one or two days. If the electrical activity of your heart has to be measured over several months, an implantable ECG device can be placed under the skin on your chest. The device is about the size of a USB stick.
  • Blood test: Blood tests can be used to check various things, including thyroid function. Atrial fibrillation is sometimes caused by an overactive thyroid gland, or taking too high a dose of thyroid medication. The electrolytes in your blood can be measured too. Atrial fibrillation is sometimes associated with an electrolyte imbalance.
  • Echocardiography: This is an ultrasound scan of the heart. It can be used to, for example, determine how well the heart is pumping and discover less common causes of atrial fibrillation, such as certain heart valve problems.

Some tests are particularly helpful when planning treatment. For example, kidney and liver function tests are important because some medications aren’t suitable for people with kidney or liver problems.


People who are diagnosed with atrial fibrillation are faced with several treatment-related decisions. On the one hand, there is the question of how to treat the irregular heartbeat. The main goal here is to keep the pulse (heart rate) under control in order to relieve the symptoms and reduce the heart's workload. There are also treatments that try to restore a normal heart rhythm (sinus rhythm). So there are two main treatment approaches:

  • In treatment to control the heart rate, the too-high heart rate is constantly reduced with medication. This is usually done using a beta blocker. The pulse is the number of heartbeats per minute. It is measured when the person is at rest. Heart rate control treatment doesn't aim to restore a normal heart rhythm.
  • Treatments to restore the heart rhythm aim to reset the sinus rhythm and try to make sure it doesn’t become abnormal again. The sinus rhythm is usually reset by delivering controlled electric shocks to the heart. People typically take medication afterwards, to try to keep the heart rhythm normal. Even if this treatment leads to a normal heart rhythm, many people still have to take a low dose of beta blockers in order to reduce their heart rate.

Treatment to control the heart rate is usually the preferred option because it is less complicated and less likely to cause side effects. Treatment to restore the heart rhythm is mainly considered if someone has had treatment to control their heart rate and their symptoms haven't improved enough.

On the other hand, there is the question of whether you would like to take medication to lower your risk of stroke – and if so, which kind. Medications called oral anticoagulants reduce blood clotting and can greatly lower this risk.

It is best to talk with your doctor about whether or not to use anticoagulants, and decide together. Here it is a good idea to carefully weigh the pros (stroke prevention) and cons (risk of bleeding). Your personal risk of a stroke and bleeding can be determined by entering information about your personal risk factors into special risk calculators.

Sometimes there are very good reasons not to take anticoagulants even if someone is at high risk of having a stroke – for instance, because they have a very high risk of bleeding. Doctors can then try to lower the risk of having a stroke using a surgical procedure known as left atrial appendage closure. This involves placing an implant in a part of the heart called the left atrial appendage. But the treatment methods used here haven’t been tested enough and can lead to serious complications.

In rare cases, atrial fibrillation can become dangerous and, for example, lead to a big drop in blood pressure. If that happens, the heart rhythm is usually quickly restored using controlled electric shocks.

Sometimes atrial fibrillation is caused by a treatable condition such as a leaky heart valve or an overactive thyroid gland. If that is the case, the atrial fibrillation might go away following heart valve surgery or thyroid treatment.

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Everyday life

Most people aren’t aware of their heart if it beats normally. People who have atrial fibrillation may notice that their heart isn’t beating as it should. Many find this so worrying that they see a doctor about it. Being diagnosed with atrial fibrillation might come as a shock at first, but the symptoms can usually be effectively managed using various treatments. Patient education courses can be helpful too: Here people can learn how to cope with the condition in everyday life, and adjust their medication properly themselves.

But many people still feel worried. Some wonder whether they should try to avoid strenuous activities and whether they can carry on doing their usual hobbies and sports. Research suggests that there is no cause for concern, though: Moderate physical activity doesn't seem to be harmful, and can even improve physical fitness.