If you're going to suffer cardiac arrest, you had best hope it occurs in a public place such as a hockey arena or shopping mall rather than at home.
New research shows that a person whose heart stops is three times more likely to survive if the incident occurs in a public venue than in a private residence – especially if an automated external defibrillator (AED) is available.
"Our research clearly shows that the chances of surviving a shockable cardiac arrest are best when someone publicly witnesses it happening," said Myron Weisfeldt, a cardiologist at Johns Hopkins Hospital in Baltimore, Md.
The key, he said, is that bystanders do three things: Start cardiopulmonary resuscitation, use the AED to "shock" the heart and call 911 so that emergency responders can be on the scene promptly.
The study, published in Thursday's edition of the New England Journal of Medicine, evaluated 12,930 out-of-hospital cardiac arrests that occurred in 10 Canadian and U.S. cities from 2005 to 2007. Of the total, 2,042 cardiac arrests occurred in public places and 9,564 in the home.
Among people who suffered cardiac arrest in a public place and were shocked by bystanders using an AED the survival rate was 34 per cent. By contrast, when people suffered cardiac arrest at home (where AEDs are rare and CPR is the only option), the survival rate was 12 per cent.
The researchers noted, however, that about 80 per cent of people who suffered cardiac arrest in public had a condition that was "shockable," compared with 36 per cent of those who arrested at home. The reason is that people who are out and about are healthier and more likely to have heart-rhythm problems as opposed to heart failure.
Still, in both cases, those numbers were markedly better than the overall survival rate from cardiac arrest in North America – 7.9 per cent.
"What's important is that bystanders do something – CPR or the defibrillate – and do it quickly," said Laurie Morrison, a clinician-scientist at the Li Ka Shing Knowledge Institute of St. Michael's Hospital in Toronto and co-author of the research.
"When you do nothing, people die."
Dr. Morrison said the study underscores that having AEDs in public places saves lives. But she is dismayed that defibrillators are not mandatory in Canada, as they are in most U.S. states. "Every public building must have fire extinguishers. It should be the same for AEDs," she said.
Cardiac arrest is when the heart stops beating and a person loses consciousness. The research focused on "shockable" forms – ventricular fibrillation (unco-ordinated contraction of the heart) or pulseless ventricular tachycardia (excessively fast heart rhythm that fails to produce a pulse).
Cardiac arrest is not the same as a heart attack, which occurs when there is a blockage in the arteries and a conscious person suffers pain and/or dizziness.
About 330,000 people a year suffer cardiac arrest outside the hospital setting in North America and more than 300,000 die as a result.
Even in big cities such as Toronto and Vancouver, EADs are used on less than 3 per cent of people who suffer cardiac arrest.
The new study is one in a landmark series of research projects known as the Resuscitation Outcomes Consortium, designed to reveal the best life-saving techniques for cardiac emergencies.