Atrial Fibrillation

A common heart rhythm problem where the heart beats irregularly and often fast. It raises the risk of stroke.

HeartHeart rhythmLast updated: 21 October 2026

Quick Summary

Primary Symptoms

An irregular or fast heartbeat (palpitations), breathlessness, tiredness, dizziness. Some people have no symptoms.

Common Treatments

Medicines to control heart rate or rhythm, blood thinners to prevent stroke, and sometimes procedures such as ablation.

Risk Factors

Older age, high blood pressure, heart disease, thyroid problems, obesity, sleep apnoea and heavy drinking.

OverviewSymptomsCausesTreatmentFAQ

Overview

In atrial fibrillation (AF), the upper chambers of the heart (atria) beat in a chaotic way. Blood can pool and form clots that may travel to the brain and cause a stroke.

AF can come and go or be permanent. It's often found during a routine pulse check or ECG.

Symptoms

Palpitations

A fluttering, pounding or irregular heartbeat.

Breathlessness

Especially with activity.

Tiredness and dizziness

Feeling weak or lightheaded.

Stroke warning signs

Face drooping, arm weakness or speech problems: call 112 immediately.

Causes & Risk Factors

Biological Causes

Abnormal electrical signals in the atria, often linked to changes in the heart from ageing, high blood pressure or other heart disease.

Key Risk Factors

  • Age More common over 65.
  • Heart and blood pressure problems High blood pressure, heart failure and valve disease.
  • Other conditions Overactive thyroid, obesity, diabetes, sleep apnoea and alcohol.

Management & Treatment

01. Rate or rhythm control

Medicines such as beta blockers slow the heart; others restore a normal rhythm.

02. Blood thinners

Anticoagulants such as apixaban or warfarin lower stroke risk for many people.

03. Procedures

Cardioversion or catheter ablation for some people.

Frequently Asked Questions

Is AF dangerous?
It isn't usually immediately life-threatening, but it increases stroke risk, so treatment matters.
How is it diagnosed?
With an ECG, sometimes a 24-hour or longer heart monitor.
Can I check my pulse?
Yes. An irregular pulse is worth discussing with your doctor.

Sources and further reading

Last updated 21 October 2026. For more detail, see these trusted health organisations.