A life-saving app, that prevented four deaths in a six-week pilot, will be rolled out across NSW.

The free GoodSAM app closes the gap between triple-zero calls and the start of CPR for cadiac arrest victims by alerting registered community members to nearby incidents.

A responding member of the public receives guidance over the phone from an ambulance staffer until paramedics arrive and take over.

Research shows the first minutes after someone suffers a cardiac arrest are the most crucial to survival, NSW Ambulance Acting Commissioner David Dutton said.

He said the more people who registered, the better as it would increase the chance someone was available to respond.

NSW Ambulance responds to about 200 cardiac arrests a week.

"When someone goes into cardiac arrest outside of hospital, they only have an 11 per cent chance of surviving, but the survival rate improves significantly if chest compressions begin in the first few minutes," Mr Dutton said.

"For every minute that a patient is in cardiac arrest and does not receive CPR, their chance of survival drops by seven to 10 per cent."

After its success in Victoria and South Australia, NSW struck a four-year deal with GoodSAM in 2022.

A six-week pilot that began in May involving 1600 NSW Ambulance clinical and corporate staff was credited with saving four lives, impressing Health Minister Ryan Park.

The pilot has continued, but on Thursday will expand to the wider community.

Any adult who feels able to provide chest compressions can register as a GoodSAM responder.

Formal first aid or CPR training is not required.

Responders can opt whether or not to accept the alert and respond - with an ambulance dispatched regardless.

"This is an internationally-recognised program which has improved survival rates for people who have a cardiac arrest outside of hospital," Mr Park said.

"As we all know, every minute counts when someone is in cardiac arrest."

Registrations can be made on the NSW Ambulance website