Atrial fibrillation (AF), the most common type of cardiac arrhythmia, is a significant factor in stroke. It increases the risk fivefold and is responsible for 20 per cent of strokes.

Prevalence has been increasing so that 3.3 per cent of the population – that’s 1.5 million people in England - have an AF diagnosis, but an estimated on in eight of them are not treated effectively. A further 200,000 people may have AF but are undiagnosed.1-4 

Normal heart rate is set by the sinoatrial node, a group of cells in the wall of the right atrium, one of the two upper chambers of the heart. The SA node initiates the electrical pulses that start the muscle contractions which pump the blood returning to the heart into the ventricles.5 

AF is a misfiring of the electrical impulses, making the heart rate highly irregular and reducing the heart’s efficiency and performance. Uncoordinated muscle fibre contractions mean the heart muscles do not relax sufficiently and the atria are unable to refill with blood properly.6,7 

The heart rate can reach over 100 beats per minute (bpm) with no apparent cause (such as exercise), with palpitations lasting seconds, minutes, hours or longer. Other symptoms include chest pain, breathlessness, feeling dizzy or faint, and tiredness. People may find it harder to exercise. 

Patients should see a doctor if their heart rate is consistently below 60 bpm or above 100 bpm, especially if other symptoms are present.