A normal heart rate should be between 60 and 100 beats a minute when you're resting, and is regular. The main difference between a normal rhythm and atrial fibrillation is that you are unable to predict when the next heart beat will come along, as heart rate is irregular.
This may lead to a number of problems, including dizziness and shortness of breath. You may also be aware of a fast and irregular heartbeat (palpitations) and feel very tired.
How is it treated? Includes videos on the ECG test and ablation
An anticoagulant is a medicine that stops blood from clotting. Warfarin is the main oral anticoagulant used in the UK. It is used in Atrial Fibrillation, but also for pulmonary embolism (a blood clot in the lungs) and deep vein thrombosis (blood clots in the veins of the legs).
The British Heart Foundation provides information on how to check for atrial fibrillation.