The smartphone app using good Samaritans to help save lives

An app is encouraging good Samaritans to play a role in improving the survival rates of heart attack sufferers.

GoodSAM alerts app users when someone nearby is having a cardiac arrest, so they can jump into action while the ambulance is on the way.

Valerie knows first-hand how important CPR is, after bystanders helped save her life when she went into cardiac arrest while rock-climbing at a local gym in May last year.

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Thankfully, two off-duty nurses stepped in to provide compressions while waiting for paramedics to arrive.

The 57-year-old mum-of-three credits the women with saving her life.

"I'm incredibly fortunate, and lucky is a good word," she said.

"[I'm lucky] that the bystanders were there and the ambulance arrived and did what they did and the other part is when I got to the hospital and they looked after me.

If a patient doesn't get CPR their chances of survival can fall by up to 10 per cent.

Valerie is one of 8000 volunteers who have already signed up to the app, which is already up and running overseas.

But NSW MP Ryan Park says he wants to see tens of thousands of Aussies signing on to save a life.

Watch the full video in the player above.