Cardiac arrest survival rates vary widely by geography, study finds

There is a huge variation in survival rates among people who receive emergency treatment after suffering cardiac arrest — and the overall prognosis is poor at best, a study of 10 Canadian and U.S. cities and regions has found.

A team of researchers from the two countries found that overall, less than eight per cent of people who were treated by paramedics or firefighters for cardiac arrests in the home or elsewhere outside hospital were successfully resuscitated.

Seattle had the best survival rate at 16 per cent, while Alabama had the lowest at three per cent. In Toronto and the Ottawa region, just over five per cent of treated victims lived, while in Vancouver, the third Canadian city in the study, 10 per cent survived.

"The regional differences in our study are huge — 500 per cent — much greater than the regional differences in survival for patients who are hospitalized with stroke or heart attack," lead author Dr. Graham Nichol of the University of Washington said Tuesday from Seattle.

Cardiac arrest is different from — but may be caused by — a heart attack. It occurs when the heart suddenly stops beating and the person is no longer breathing. One major cause is disruption of normal heart contractions, such as that caused by ventricular fibrillation.

Nichol said the key to saving lives is a quick response by bystanders, who need to perform immediate and continuous CPR until paramedics or firefighters arrive to treat and transport the patient to hospital. But in far too many cases, CPR is not performed and by the time EMS personnel arrive with defibrillators to shock the heart and restore circulation, it is too late.

In the study, published in this week's Journal of the American Medical Association, researchers looked at more than 20,000 cardiac arrest cases between May 2006 and April 2007. Resuscitation was attempted in fewer than 12,000 cases — and only 954 of those felled by a cardiac arrest lived to be discharged from hospital. About 80 per cent of arrests occurred in the home.

And although CPR is known to save lives, the study found that in less than a third of cases did a bystander — whether a family member, friend or stranger — jump in to perform the procedure.

Nichol isn't sure why that figure is so low, but he speculated that people untrained in CPR — which involves chest compressions to move oxygenated blood to the brain and, in some cases, assisting breathing — may be fearful of doing more harm than good to the patient. 

"But people need to remember that when they're unconscious and not breathing, they're already dead," he said bluntly. "So you can't hurt them. You'll only hurt them by not doing something."

'Treatable condition'

In Seattle, community efforts to increase awareness of cardiac arrest, support of CPR training for city residents and strong emergency services appear to have paid off in higher survival rates, proving that "cardiac arrest is a treatable condition." 

Cardiac arrest strikes an estimated 200,000 to 300,000 Americans and Canadians each year outside of hospital. Co-author Dr. Ian Stiell of the University of Ottawa said about 30,000 Canadians die each year from the condition.   

Saving more lives means more Canadians need to be trained in and willing to perform CPR, Stiell said, noting that an earlier study showed that in Ontario, for instance, bystanders performed CPR in only about 15 per cent of cases.

"It's the whole community response, and that speaks to the chain of survival," he said from Ottawa. "It's not just the paramedics, it's how fast you can access 911, were there bystanders to do CPR, did fire get there first with a defibrillator and then finally the paramedics?" 

Stiell said there are no national bodies in either Canada or the U.S. taking the lead on CPR training of community residents. Most CPR education is done at the community level, but that can be hit and miss, he said.

"There needs to be a higher awareness and perhaps some government agency to take responsibility, whether it be the city public health or the provincial government or federal government, to take responsibility as a goal to improve bystander CPR training strategies."