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Chances of Surviving Cardiac Arrest Higher in Public Places: Study

A study of more than 14,000 men and women whose hearts stopped suddenly suggests that the chances of survival are high if such cardiac arrests are witnessed in large public venues, including airports, sports arenas or malls.

Toronto, January 27, 2011

by Leslie Shepherd

The reasons, researchers say, are that almost four out of five such cases appear to be due to a survivable type of heart rhythm disruption and that big places with lots of people are more likely to have an automated external defibrillator, or AED, handy, along with those who can apply it as well as start CPR and call 911.

"You’re more likely to be noticed if you have a cardiac arrest in a public place," said Dr. Laurie Morrison, an emergency medicine physician at St. Michael's Hospital and senior author on the research study.

"There are lots of people around and the venue is more likely to have an AED than you are at tome. At least one person will likely know the right thing to do, which is call 911, start CPR and send someone to run and get the AED."

Dr. Myron "Mike" Weisfeldt, the lead author of the study, said the prompt arrival of trained emergency personnel and a trip to the hospital also lead to the best outcomes. Dr. Weisfieldt, a cardiologist, is physician in chief at The Johns Hopkins Hospital in Baltimore, Maryland, and director of the Department of Medicine at Hopkins' School of Medicine.

Among the key findings reported in the January 26 edition of the New England Journal of Medicine, were that 79 percent of people in the study had the kind of disrupted heart rhythm that could be corrected by an electrical shock from an AED device placed on them in public by a bystander. Among those who were actually shocked, 34 percent survived, recovering well enough to be discharged from the hospital.

The frequency of such shockable rhythm disturbances – known by the acronym VT/VF, short for ventricular tachycardia, ventricular fibrillation – was much less among those stricken at home, at 36 percent. And if a relative or bystander witnessed the arrest there and used an AED there, 11.6 percent survived to leave the hospital.

Weisfeldt speculated that patient demographics and severity of their heart disease likely explain why VT/VF rates are different between those whose hearts stop pumping at home and those who suffer an event in public, with people at home being older and more likely to have underlying chronic disease than those who are active and attending major sports events. Weisfeldt emphasized that people at risk of sudden cardiac death and who have an AED at home may still benefit. "But the survival rate is really not that much different than with a bystander practicing CPR without an AED and quickly calling 911," he said.

Dr. Morrison said the study underscores that having AEDs in public places saves lives. She said she was dismayed that defibrillators are not legislated as essential in all public buildings and places of business in Canada as they are in most US states.

"Every public building must have fire extinguishers and it should be the same for AEDs," she said.

The study is believed to be the largest and most comprehensive VT/VF analysis ever done in the United States and Canada. It evaluated 12,930 out-of-hospital cardiac arrests that occurred in 10 Canadian and US cities from 2005 to 2007. Of the total, 2,042 cardiac arrests occurred in public places and 9,564 in the home.

The study is part of a landmark series of research projects known as the Resuscitation Outcomes Consortium (ROC), designed to reveal the best life-saving techniques for cardiac emergencies. Dr. Morrison heads the ROC team in Toronto, known as Rescu.