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Overview - Atrial fibrillation

Atrial fibrillation is a heart condition that causes an irregular heart rhythm.

A normal heart rhythm should be regular and between 60 and 100 beats a minute when you're resting.

You can measure your heart rate by checking your pulse in your wrist or neck.

Check your pulse (video) -

Symptoms of atrial fibrillation

In atrial fibrillation, your heart rhythm is irregular and can sometimes be very fast. In some cases, it can be much higher than 100 beats a minute.

This can cause problems including dizziness, tiredness and shortness of breath.

You may be aware of heart palpitations. This is where your heart feels like it's pounding, fluttering or beating irregularly. This can last for a few seconds or minutes.

Very often, atrial fibrillation does not cause any symptoms. You may have it and be unaware that your heart rate is irregular.

Symptoms of atrial fibrillation

Causes of atrial fibrillation

When the heart beats, its walls tighten and contract to force blood out and around the body.

Then the walls relax so the heart can fill with blood again. This happens every time the heart beats.

In atrial fibrillation, the heart's upper chambers (atria) contract randomly. Sometimes they contract so fast that the heart muscle cannot relax between contractions. This reduces the heart's ability to pump blood around the body.

It can cause you to feel fatigued and short of breath. It can also lead to the heart forming clots.

Atrial fibrillation happens when abnormal electrical impulses suddenly start firing in the atria.

These impulses override the heart's natural pacemaker. This means it can no longer control the rhythm of the heart. This causes you to have a highly irregular pulse. The cause is not fully understood.

Who is affected by atrial fibrillation

Atrial fibrillation is the most common heart rhythm disturbance in Ireland.

It can affect adults of any age, but it's more common in older people.

Atrial fibrillation is more likely to happen in people with other conditions, such as:

  • high blood pressure
  • obesity
  • other heart issues
  • thyroid conditions

It may be triggered by certain situations, such as drinking too much alcohol, drug use or strenuous exercise.

Causes of atrial fibrillation

Types of atrial fibrillation

There are different types of atrial fibrillation but all can carry a risk of stroke.

Paroxysmal atrial fibrillation

Episodes come and go, and usually stop within 48 hours without any treatment.

Persistent atrial fibrillation

Each episode lasts for longer than 7 days. These may become shorter with treatment.

Permanent atrial fibrillation

This is when it's present all the time.

Long-standing atrial fibrillation

This is where you've had atrial fibrillation usually for over a year.

Treating atrial fibrillation

Atrial fibrillation is not usually life threatening but it can lead to a stroke. It can be uncomfortable and often needs treatment.

Treatment may involve:

  • medicines to prevent a stroke
  • medicines to control the heart rate or rhythm
  • cardioversion - the heart is given a controlled electric shock to restore normal rhythm
  • catheter ablation - where the area inside the heart that's causing the abnormal heart rhythm is destroyed using radio frequency energy; you may then need to have a pacemaker fitted to help your heart beat regularly

Treating atrial fibrillation

Page last reviewed: 26 July 2023
Next review due: 26 July 2026