"Thousands of lives" could be saved thanks to a new project which aims to map all of Britain's public defibrillators.
That's the claim from the British Heart Foundation (BHF), which has teamed up with the NHS and Microsoft to ensure emergency service call handlers know the whereabouts of the potentially life-saving equipment.
Information about the availability of the devices – which give a high energy electric shock to the heart – is patchy and not all are known to ambulance services.
Therefore currently when the public calls 999 after finding someone whose heart has stopped they might not be directed to one.
Previous research found just 3% of patients who suffer cardiac arrests outside of hospital are treated with public access defibrillators.
If someone is suffering from cardiac arrest and no defibrillator is available, the London Ambulance service says chest compressions and CPR should be performed until medics arrive.
One parent has welcomed the initiative to map the whereabouts of the devices after saving the life of his son with one.
Stuart Askew used a public access defibrillator on Ethan last April after the 15-year-old collapsed at school.
Mr Askew, who works as a premises manager at his sons school, had helped to set up a defibrillator just two days previously.
After running across the school field to find the school receptionist performing CPR on his son, Mr Askew called on Ethan’s classmates to retrieve the defibrillator.
He then used the device on his son.
The youngster has now made a complete recovery, following surgery to treat a narrowed artery, which was caused by a genetic condition.
Mr Askew added: “I’ve had so many ‘what if’ moments since it happened. What if no-one had known CPR? What if the defibrillator hadn’t arrived in time? What if I hadn’t put the batteries in when I did?
“We were lucky that we knew there was a defibrillator nearby – I know many people aren’t as lucky."
Tens of thousands of defibrillators are placed prominently in workplaces, train stations, leisure centres and public places across the country.
The new project will see a comprehensive map of defibrillators across the UK created over the next 12 months.
There are more than 30,000 out-of-hospital cardiac arrests every year in the UK, but fewer than one in 10 people survive.
In countries where the public are better equipped to recognise and deal with cardiac arrests, survival rates are up to three times higher, the BHF said.
A cardiac arrest occurs when a person’s heart suddenly stops pumping blood around their body, which can starve the brain of oxygen and lead to a person falling unconscious and stopping breathing.
“This innovative project will give every ambulance service immediate access to the location of defibrillators in their areas, so they can direct bystanders to their nearest life-saving device in the event of a cardiac arrest,” said Simon Gillespie, chief executive at the BHF.
“Every minute without CPR or defibrillation reduces a person’s chance of surviving a cardiac arrest by around 10%.
“Thousands more lives could be saved if the public were equipped with vital CPR skills and had access to a defibrillator in the majority of cases.”
The scheme will be piloted by West Midlands Ambulance Service and the Scottish Ambulance Service, before being rolled out across the UK.