Atrial fibrillation (AF) is a heart condition that causes irregular and often abnormally fast heart rates.
A normal heart rate should be regular and between 60 and 100 beats a minute when you're resting. In atrial fibrillation, the heart rate is irregular and can be very fast.
This can cause symptoms including dizziness, shortness of breath and tiredness. You may be aware of noticeable heart palpitations, where your heart feels like it's pounding, fluttering or beating irregularly, often for a few seconds or, in some cases, a few minutes. Sometimes, atrial fibrillation doesn't cause any symptoms and a person with it is completely unaware that their heart rate isn't regular.
It is estimated that more than 1.2 million people in the UK have atrial fibrillation.
The most significant risk associated with AF is the risk of Stroke.
Having AF means that blood clots are more likely to form in your heart, these can find their way to your brain and cause a stroke. The American Heart Association reports that the risk of a stroke is 5 times higher if you have AF and the stroke itself is likely to be more severe than for someone without AF.