Atrial fibrillation (AF)

Atrial fibrillation (AF) causes an irregular heartbeat.

In AF:

  • the heart rate is usually (but not always) a lot faster than normal.
  • the heartbeat is irregular – that is, an abnormal heart rhythm (an arrhythmia).
  • The force of each heartbeat can vary in intensity.

Describing AF

AF is commonly divided into the following types:

  • Paroxysmal AF. In the case of paroxysmal AF episodes of AF come and go. Each episode comes on suddenly, but will stop without treatment within seven days (usually within two days). Each episode stops just as suddenly as it starts and the heartbeat goes back to a normal rate and rhythm. The period of time between each episode (each paroxysm) can vary greatly from case to case.
  • Permanent AF. This means that the AF is present long-term and the heartbeat has not been reverted back to a normal rhythm. This may be because cardioversion treatment was tried and was not successful, or because cardioversion has not been tried. People with permanent AF are treated to bring their heart rate back down to normal, but the rhythm remains irregular (see below). Permanent AF is sometimes called established AF.

Most people with AF have permanent AF.

How common is atrial fibrillation (AF)?

It is common, but mainly occurs in older people.

What causes atrial fibrillation (AF)?

Causes of AF include the following:

  • High blood pressure is the most common cause. High blood pressure puts a strain on the heart muscle.
  • AF is a common complication of various heart conditions. For example, AF is a complication of ischaemic heart disease. This is the condition that causes chest pains (angina) and heart attacks and is common in older people. Various other heart problems that may also trigger AF include heart valve problems

Other conditions and situations that may trigger AF to develop include:

Symptoms of atrial fibrillation (AF)

Symptoms often develop quickly, soon after the AF develops. Possible symptoms include:

Many people with AF have no symptoms, particularly if their heart rate is not very fast. The AF may then be diagnosed by chance when a doctor or nurse feels your pulse.

Diagnosis for atrial fibrillation (AF).

  • A heart tracing called an electrocardiogram (ECG) usually confirms the diagnosis. This test can also rule out other causes of an erratic or fast heart rate. Sometimes a 24-hour ECG is needed if the AF comes and goes and the resting ECG has not showed it.
  • Other tests such as blood tests and an ultrasound scan of the heart (echocardiogram) are often advised. These tests look for an underlying cause of AF, such as a heart problem or an overactive thyroid gland.
  • Often an underlying cause is already known about. For example, chest pains (angina). Further tests may not be needed if AF develops as a complication.

What are the possible complications of atrial fibrillation (AF)?

An increased risk of having a stroke (or other blood clot problem)

The main complication of AF is an increased risk of having a stroke. AF causes turbulent blood flow in the heart chambers. This sometimes leads to a small blood clot forming in a heart chamber.

A clot can travel in the blood vessels until it gets stuck in a smaller blood vessel in the brain (or sometimes in another part of the body). Part of the blood supply to the brain may then be cut off, which causes a stroke.

The risk of developing a blood clot and having a stroke varies, depending on various factors. The level of risk can be calculated by your doctor using a set of specific questions. This will help to decide what treatments are required. All people except those at the lowest risk will be offered medication to help prevent clots from forming.

Other complications

Less common complications of AF include the following:

  • Heart failure – this develops in some cases.
  • Weakness of the heart muscle (dilated cardiomyopathy). The reason why cardiomyopathy develops in some people with AF is not clear.
  • Chest pains (angina) may get worse if you have angina.

What are the treatment options for atrial fibrillation (AF)?

Treatments that may be considered include:

  • Rate control. This means bringing the heart rate back down to normal. This is done for all people with AF who have a fast heart rate (that is, most cases).
  • Rhythm control. This means converting the irregular rhythm back to a normal regular rhythm. This is only possible in some cases.
  • Anticoagulation treatment which aims to prevent a stroke.

Rate control treatment

In untreated AF, the heart rate may be as fast as 180 beats per minute, although it is more commonly between 120 and 160 beats per minute. If the heart rate is brought down to normal, the heart becomes efficient again and symptoms usually improve. The pulse may still feel irregular, but not fast.

The aim of medication is to bring the heart rate back down to normal (ideally, to less than 90 beats per minute when resting). Several medicines can slow the heart rate down. Treatment is usually successful, but the dose needed can vary from person to person. Also, in some people a combination of medicines may be needed if the heart rate is not brought down low enough with a single medicine.


Rhythm control treatment

Rhythm control means reverting the erratic heartbeat back to a normal regular rhythm. This is called cardioversion.

One method of cardioversion is to give your heart an electric shock. Another method is to use a medicine that may convert the heart rhythm back to a regular beat. Both of these methods have only limited success. For example, after cardioversion, within a year, in about half of cases, the heart has reverted back to AF.

Cardioversion is usually not an option in certain situations – for example:

  • for heart diseases that include a structural problem to the heart – for example, certain valve problems such as mitral stenosis.
  • If AF has persisted for a long time (usually for more than 12 months).
  • If previous attempts at cardioversion have not worked, or only worked for a short time before the heart reverted back to AF.

A newer technique to restore the heart rhythm is called catheter ablation. This treatment is only suitable in certain cases and is not a routine treatment. It does not always work and there is a small risk of serious complications.


All people with AF (except those with the lowest risk of having a stroke) should be offered anticoagulation treatment. Anticoagulation means that you take a medicine to reduce the chance of forming a blood clot and having a stroke. The most commonly used anticoagulant medicine has been warfarin, although others have recently been developed.

They reduce the risk of stroke by nearly two thirds. In other words, these treatments can prevent about 6 in 10 strokes that would have occurred in people with AF.

As with all treatments, there is a small risk that a bleeding problem may develop as the blood will not clot so well. For example, some people develop a serious bleeding ulcer in the gut.

Aspirin is another medicine that helps to prevent blood clots forming and was used extensively in the past. It is now known that it is not as effective as warfarin, but is just as likely to cause problems. Aspirin is therefore no longer recommended.

Other treatments

Other treatments may be advised, depending on the need to treat any underlying problems such as chest pains (angina), heart valve problems, high blood pressure (hypertension), and overactive thyroid (hyperthyroidism).

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