The number of people in the UK diagnosed with a heart rhythm condition that puts them at increased risk of a stroke has now passed 1.5 million for the first time, figures show.
The British Heart Foundation (BHF) said the number of people diagnosed with atrial fibrillation – a condition which causes an irregular heartbeat – has increased from one million in 2013.
The new total means that one in 45 people in the UK are known to be living with the condition.
Atrial fibrillation is the most common form of abnormal heart rhythm and is believed to contribute to one in five strokes.
The BHF said better recognition and diagnosis of the condition is likely to be the key factor behind the rise in the number of people known to have atrial fibrillation.
But it is estimated that there are at least another 270,000 people in the UK who remain undiagnosed and unaware.
The charity said further research is needed to find new ways to identify people who are at risk so they can be diagnosed earlier.
The most common symptoms of atrial fibrillation are palpitations, breathlessness and dizziness.
However, many people do not experience any symptoms, meaning that they are unaware of the condition and treatments, as well as their increased risk of stroke.
Professor Sir Nilesh Samani, medical director at the BHF, said: “These figures show a quite astonishing rise in the number of people diagnosed with atrial fibrillation.
“Research has helped us understand the links between atrial fibrillation and stroke and that has spurred the efforts we have seen in recent years to identify people with this potentially dangerous heart rhythm.
“What remains troubling is the sheer number of people who are undiagnosed and unaware that they are living with a heightened risk of stroke. Finding people with this hidden threat must remain a priority.”