By Hind Hassan, Sky News Reporter
A condition that causes the heart to stutter, leading to strokes and heart attacks, now afflicts more than a million people in the UK, campaigners say.
Those with atrial fibrillation often experience irregular and often abnormally fast heart rates, dizziness, breathlessness, palpitations and tiredness.
However, some people who have it display none of these symptoms and are completely unaware of it.
Without treatment, the disease can significantly increase the risk of a blood clot forming inside the heart, which increases the risk of stroke five-fold.
Rates of the illness have soared 20% in the past five years, according to the British Heart Foundation (BHF), which says it is responsible for 22,500 strokes a year in the UK.
High blood pressure, heart valve disease and binge drinking are all blamed for the increase, as well as the fact people are living longer.
Richard Elgar, 43, from Dorset, was diagnosed with the condition last September.
The father-of-two, who is a builder, said: "I'd already had a heart attack when I was 36, so finding out I had atrial fibrillation was another blow.
"I didn't tell my wife about the risk of stroke until I was on medication to help prevent it. I didn't want to worry her and the children.
Richard Elgar, 43, and his eight-year-old son Alfie "But every tiny ache or twinge still makes me panic that something could be starting that could devastate my family. It's incredibly stressful."
Mr Elgar's eldest son Alfie, eight, completed a 40-mile bike ride last summer to raise funds for the BHF.
He continued despite falling off his bike twice because of the heat and exhaustion.
The schoolboy has said he wants to be a heart surgeon when he grows up so he can "fix Daddy".
BHF chief executive Simon Gillespie said more research into the illness was urgently needed.
"The real danger with atrial fibrillation is that some people don't realise they have it," he said.
"You can be going about your daily routine oblivious to the fact you're five times more likely to have a devastating stroke."
Professor Nicholas Peters, consultant cardiologist at Imperial College Healthcare, said: "The incidence of atrial fibrillation (AF) increases dramatically with age so an ageing population, along with better awareness and diagnosis, are the main reasons for the rise in the number of people known to have it.
"In addition, improvements in the treatment of other causes of heart disease means that more of these patients survive to get atrial fibrillation.
"We have a research programme, funded principally by British Heart Foundation, focussed on helping large numbers of patients by combating this important medical challenge."
:: The BHF is leading a fundraising event on February 7 to raise money for research into AF and other heart conditions. Visit www.rampupthered.org.uk to sign up.
:: Watch Sky News live on television, on Sky channel 501, Virgin Media channel 602, Freeview channel 82 and Freesat channel 202.
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