Medical Encyclopaedia › Atrial fibrillation (short definition)
In brief: Atrial fibrillation is the most common sustained heart rhythm disorder. The atria of the heart no longer contract in an orderly way but quiver in an uncoordinated manner, making the heartbeat irregular and often too fast.
Causes and risk factors
The risk increases with age. Important risk factors are high blood pressure, heart failure, heart valve disease, coronary heart disease, diabetes, overweight, sleep apnoea, an overactive thyroid and regular alcohol consumption.
Symptoms
Many of those affected notice palpitations, a racing heart, reduced performance, shortness of breath, dizziness or inner restlessness. However, some have no symptoms at all, so that atrial fibrillation is sometimes only discovered after a stroke or by chance on an ECG.
Why atrial fibrillation is dangerous
Because blood flows more slowly in the fibrillating atria, blood clots can form, which can be carried to the brain and cause a stroke. The individual risk is estimated using the CHA2DS2-VASc score. A permanently fast heartbeat can also weaken the heart.
Treatment
If the risk of stroke is increased, anticoagulation is recommended, today usually with direct oral anticoagulants. The heart rate can be controlled with beta-blockers or other medicines. To restore normal rhythm, cardioversion, antiarrhythmic drugs or catheter ablation are used; the latter shows good results especially early in the course of the disease. Treating the risk factors is always part of it.
When to see a doctor?
An irregular pulse, a racing heart or newly reduced performance should be assessed by a doctor, for example with an ECG. Chest pain, severe shortness of breath, fainting or signs of a stroke such as paralysis and speech disturbances are an emergency.
Related terms in the encyclopaedia
Arrhythmia, Atria, ECG (electrocardiogram), Holter ECG, Direct oral anticoagulants (DOACs), Cardioversion, Catheter ablation, Stroke, Palpitations
Sources
- European Society of Cardiology (ESC): Leitlinie zum Management von Vorhofflimmern 2024, deutsche Fassung über die Deutsche Gesellschaft für Kardiologie (DGK)
- Deutsche Herzstiftung: herzstiftung.de
- IQWiG: gesundheitsinformation.de – Gesundheitsinformationen des Instituts für Qualität und Wirtschaftlichkeit im Gesundheitswesen
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor or pharmacist. Last updated: October 2026.