TORONTO – The odds of surviving a cardiac arrest are higher for people who are in a public place like a mall or a sports arena than for those who are at home when they receive electrical shocks, a new study indicates.
That’s because people whose hearts stop in public are more likely to be experiencing a type of heart disruption that is responsive to shocks, the researchers suggest.
Large public venues are also more likely to have automated external defibrillators, or AEDs, as well as bystanders who are able to use the device and perform CPR.
But some critics argue that the study’s conclusions are premature.
Researchers monitored 14,000 cardiac arrest calls on 911 emergency lines in 10 North American regions, including Vancouver, Ottawa and southern Ontario.
The resulting paper, published Thursday in the New England Journal of Medicine, is the largest and most comprehensive analysis of its kind in Canada and the United States.
It found that 34 per cent of cardiac arrest victims who received electrical shocks from a defibrillator in public venues survived, versus only 11.6 per cent of those shocked at home.
Senior author Dr. Laurie Morrison, an emergency medicine specialist at St. Michael’s Hospital in Toronto, says that those who are out and about when their hearts stop are more likely to be experiencing an unusual heart rhythm called ventricular fibrillation.
Ventricular fibrillation is an electrical problem in the heart that can be caused by anything from poor circulation to drug use, says Morrison.
In contrast, those whose hearts stop at home are more likely to be suffering from an ongoing illness that leads to heart failure.
Morrison concludes that defibrillators should be made more widely available in public spaces, whereas those caring for cardiac arrest victims at home perhaps would do best to call 911 promptly and administer CPR.
This is because there is little difference in the success rates of using a defibrillator versus administering CPR for those whose hearts stop beating while at home, she explains.
But Dr. Gust Bardy, the founding president of the Seattle Institute for Cardiac Research, says the study does not prove that ventricular fibrillation occurs more often in public than in private.
“Without electrocardiographic (ECG) data regarding the onset of the event, we cannot know for certain,” Bardy writes in a commentary published by the journal.
He suggests the findings may be due to a delay in how long it takes a loved one, stricken with panic and grief, to call 911.
“The dismissal of home AEDs is premature, and other than the personal expense, there is no known downside to such a purchase,” he writes.
“It is time to reassess the value of CPR, not dismiss definitive therapy with defibrillation.”
Regardless of whether CPR or defibrillators produce greater benefits, bystanders in Canada are less likely to use either than their American counterparts, says Morrison.
The bystander CPR rate has flatlined at about 30 per cent over the last decade, while defibrillator use is only around three per cent.
Morrison attributes the difference to the greater amount of public research, CPR training in schools and defibrillators available in the United States.
Morrison is an advocate of Bill C41, which, if passed, will make Ontario the first province to mandate defibrillators in all public buildings.
Dubbed the Defibrillator Access Act, the bill is currently in its third reading.
“We want people to realize that they can save a person’s life, and to have the courage to reach up and grab that little AED that you see in all the subway stations, airports and gyms,” says Morrison.
“I would encourage each province to push their legislation to make AEDs mandatory, like fire extinguishers, in all public buildings.”
Don Marentette, manager of national first aid for the Red Cross, says the main barrier to bystander CPR is that people are afraid they might do it wrong.
“Our mission is to share with Canadians that they’re not doing it wrong, that anything is helpful,” says Marentette, adding that effective CPR and defibrillation doubles the chance of survival.
The Red Cross trained 600,000 people in CPR and defibrillation last year.
“The more Canadians that get trained the better. That’s our biggest message.”
Bystanders should never be afraid of using an AED. Researchers have discovered even a Grade six child has the skill to use the AED. Although it maybe hard for them to do CPR, early defibrillation is always a priorty in the Chain of Survival of Sudden Cardiac Arrest. We hope BC and other province will follow Ontario, and legislate the province to make AEDs mandatory in all public places. In addition, proper training is also needed.