For the first time, the exact walking distance from any defibrillator registered in the UK has been mapped out, with lifesaving devices being an average of 19 minutes away.
Experts said the delays in reaching the machines cost thousands of lives every year.
The chances of survival from cardiac arrest are 70 percent if a defibrillator is used within five minutes.
But this drops by 10 percent for every minute of delay after that, often causing people to get to the equipment late.
The nearest defibrillator is an average of 19 minutes’ walk away – too far to save lives, a charity warns
The British Heart Foundation (BHF) analyzed data from 78,000 public defibrillators.
It turned out that they were typically 726 meters from the center of a given zip code.
Lead researcher Dr Chris Wilkinson, a consultant cardiologist and senior lecturer at Hull York Medical School, said this showed that Britain is short of machines.
Presenting the findings at the conference of the European Society of Cardiology in Amsterdam, he said: ‘Our research has clearly shown that defibrillators are too far away and that a few minutes’ delay can make the difference between life and death.
“This is 19 minutes at an average walking pace to pick up a defibrillator. That’s a long time in cardiac arrest.
‘We have to make sure that the average goes down.’ There are about 200 cardiac arrests a day in Britain, with a survival rate of just 8 percent.
About seven in ten occur in the home or workplace, with half being observed by a bystander.
Yet less than one in ten cases of out-of-hospital cardiac arrest report the use of defibrillators.
The device gives a short electric shock to bring the heart back into rhythm and can be used by anyone without training, because an audio command tells the user exactly what to do.
Researchers used data from the national defibrillator network and Britain’s 1.7 million postcodes.
There are around 200 cardiac arrests a day in Britain, half of which are observed, but public defibrillators are used in less than one in ten hospital incidents
For the first time, researchers had access to data on the location and operating hours of defibrillators in England, Scotland and Wales.
They found that the sites that were accessible 24/7 were typically more than half a mile away, while access was limited in poorer areas.
Co-author Prof Chris Gale from the University of Leeds said: ‘Our research shows that community defibrillators are not an option for many people in cardiac arrest, particularly those living in deprived areas.
“This puts lives at risk. Urgent action is needed to give everyone equal access to these devices, preventing unnecessary deaths.”
The maximum distance to an automated external defibrillator (AED) was greatest in Scotland at 30 miles, in England at 18 miles and in Wales at 9 miles.
Judy O’Sullivan, director of health innovation at the British Heart Foundation, said: ‘CPR and bystander defibrillation can double the chance of survival after cardiac arrest, so it is critical that we address unequal access to defibrillators to improve survival rates.’