The alphabet mantra of CPR is changing.

Instead of performing the A-B-C checks first -- airway, breaths, circulation -- new guidelines out Monday call for chest compressions to come first.

The guidelines, released by the Heart and Stroke Foundation of Canada and other international heart groups, call for bystanders to first call 911 when they come across someone who appears to have gone into cardiac arrest.

The next step is to start compressing the victim's chest hard and fast.

Earlier guidelines called for looking, listening and feeling for normal breathing before starting CPR, then checking that the airway was clear and then giving quick breaths into the victim through mouth-to-mouth respiration.

Now, compressions should be started immediately on anyone who is unresponsive and not breathing normally, because taking the time to perform the other steps first can mean the difference between life and death, the guidelines advise.

Many bystanders balked or panicked about having to perform those preparatory steps. So in recent years, heart groups began recommending that untrained bystanders should simply start hands-only CPR until paramedics arrive or a defibrillator is used to restore a normal heart beat.

These newest guidelines say everyone -- from professionals to bystanders -- who use standard CPR should begin first with chest compressions.

"We've switched the components of CPR, they are all very important . . . but the sequence of them has changed, we now teach C-A-B, compressions first, then airway, then breathing," Dr. Andrew Travers, chair of the Heart and Stroke Foundation of Canada's policy advisory committee on resuscitation and one of the co-authors of the guidelines, told CTV News Channel Monday.

The guidelines stress that even those who have never taken a CPR course can do chest compressions.

"The best evidence right now says if you are not trained in CPR . . . if you come across someone who is in cardiac arrest, you should call 911, ask for a defibrillator, and push hard and fast in the centre of the patient's chest," Dr. Travers said.

The key is to do them fast, at a rate of at least 100 compressions per minute – about the same tempo as the Bee Gees' song "Stayin' Alive".

It's also important to do the compression firmly, the guidelines stress, so that there is complete recoil when the hands lift off the chest between compressions. The adult sternum should be depressed at least five centimetres. For infants, it should be about four centimetres.

"Think about moving the heel of your hands up and down about two inches into the chest - or the height of your pinky finger," Dr. Travers said in an earlier news release.

For those who are trained in CPR, the new guidelines still call for 30 compressions, then opening the victim's airway and delivering two breaths.

These are the first updates to the guidelines in Canada in five years, and experts from 29 countries contributed to them. The 356 authors took into account research about the reluctance of some bystanders to do mouth-to-mouth resuscitation.

A national survey conducted Sept. 2-10 by Environics for the Heart and Stroke Foundation that polled more than 2,000 people found 62 per cent of respondents had taken a CPR course, but it was more than a year ago for three-quarters of them.

Most worryingly, only 40 per cent of those who had taken a CPR class said that nothing would prevent them from trying to revive a person.

A full 15 per cent said they had a lack of confidence in their skills and training, while eight per cent saying they'd prefer to wait for qualified help to arrive; seven per cent mentioned fears of contracting a disease.

"You can't hurt someone if they don't live to see another day, and the reality is . . . the actual number of incidents of injury (from doing proper CPR) is very, very low," Dr. Travers said. "The benefit of doing chest compressions far outweighs any risk associated with it."

The guidelines also take into account the fact that in the first few minutes of a cardiac arrest, victims still have oxygen remaining in their lungs and bloodstream. So starting CPR with chest compressions can pump that blood to the victim's brain and heart sooner.

Research has shown that rescuers who started CPR with opening the airway took 30 critical seconds longer to begin chest compressions than rescuers who began CPR with chest compressions.

The odds of surviving a heart attack (cardiac arrest) are almost four times greater if someone performs CPR right away. When CPR is combined with an Automated External Defibrillator (AED), survival rates soar to 50 per cent or higher, according to the Heart and Stroke Foundation.

Without CPR and defibrillation, fewer than five per cent of people who have a cardiac arrest outside of a hospital survive.

First aid and CPR service provider, St. John Ambulance Canada, said Monday that it supports the new guidelines and will continue to teach all aspects of CPR in its classes.

"It is important to note that if you have had CPR training, the skills you were taught are still okay to use and by immediately beginning CPR you can make a valuable difference in helping to save a life," the organization said in a news release.