A public access defibrillator is to be installed in Asda Watford and store staff trained in CPR.
Asda, with partner the British Heart Foundation, is rolling out defibrillators in a bid to give its customers the best chance of survival in the case of a cardiac arrest.
The public access defibrillators in the Asda stores can be used by any member of the public to deliver an electric shock to the heart when someone is having a cardiac arrest.
Asda's Kate Naub said: "We’re really proud of our relationship with the BHF and want the people in the Hertfordshire to have the best chance of survival if cardiac arrest strikes.
"It can take a number of minutes for an ambulance to reach one of our stores in response to an emergency like a cardiac arrest.
"Asda’s investment of over half a million pounds in providing life-saving defibrillators for all of the communities we operate in could significantly cut the amount of time a cardiac arrest sufferer has to wait for life-saving CPR and defibrillation, giving them the best possible chance of survival."
Amit Aggarwal, head of Corporate Fundraising at the British Heart Foundation, added: "Cardiac arrest survival rates in the UK are astonishingly low.
But Asda’s bold commitment to become the first large retailer to have CPR trained colleagues and public access defibrillators in every store will be instrumental in helping communities up and down the country access the life-saving support they need in an emergency.
"This really could mean the difference between life and death for someone having a cardiac arrest while doing something as ordinary as shopping."
The British Heart Foundation is also working with local ambulance trusts to run familiarisation training for Asda staff on how to use the defibrillator.