Cardiac arrest: Do you know what to do to help save a life?

After three runners went into cardiac arrest at the Montreal Marathon last weekend, the head of the medical response team is urging all Quebecers to learn what to do should someone's heart stop beating.

Medics acted quickly at the time and all three are recovering in hospital.

Marathon runner Marion Artaud knows how fortunate they are. She was participating in last year's event in Montreal when at the 20 km mark it all went wrong.

"I don't remember the moment it happened," Artaud said, or much about anything surrounding the medical emergency, but when she woke up in the hospital doctors told her she had suffered a cardiac arrest.

"Yes, I'm very lucky," she said, lucky to be alive and lucky that people around her acted quickly.

First responders used a defibrillator. It delivers a shock, only if the machine indicates it's needed.

The Montreal Marathon's medical director Francois de Champlain, an emergency room doctor, says cardiac arrests during runs are rare but not unheard of.

The three who were stricken this year were transported to the hospital from the finish line.

But cardiac arrest can happen anywhere and at any time and de Champlain says the general population should be prepared to react because a person's chance of survival is greater than 50 percent if a defibrillator is used within the first five minutes.

And, emergency responders usually take at least six minutes to arrive, he says.

"For each minute that passes, the chance of survival actually decreases by about 10 per cent," says de Champlain, and with each minute that passes the chance of permanent brain damage increases.

Since the machines are easy to use and guide people through the process, de Champlain has been working tirelessly over the years to have them installed in as many public places as possible.

"It’s so simple, a child, without any prior knowledge, can use an AED almost as fast as a paramedic, just by listening to the voice," de Champlain explained.

Artaud has been forced to cut back on exercise but she did get trained to use a defibrillator.

Now she knows if she's called upon, she'll be able to keep someone else's heart safe and get them back in the race.