April 2, 2008 (Chicago) -- If you're a heart attack survivor, having a defibrillator at home won't increase your odds of survival any more than having family members and friends who know what to do in case of emergency, research shows.
The first large-scale study to look at the use of automated external defibrillators, or AEDS, in the home shows that over a three-year period about 6% of heart attack survivors with an AED in the home had died -- about the same rate as those who didn't have an AED in the home.
That's not to say that the devices didn't work: They were extremely effective when used properly, says researcher Gust Bardy, MD, of the Seattle Institute for Cardiac Research.
It's just that intensive training of spouses and caregivers in CPR and the urgency of calling 911, combined with top-notch medical treatment, appeared to work just as well, he tells WebMD.
Not Just for Worried Well
A home defibrillator, which costs about $1,200, is not just the latest gadget for the worried, Bardy says.
"It was safe and it saved a relatively large number of people. There's no downside and it certainly could be of value," he says.
But from a public health point of view, placement of defibrillators in homes appears to be "an inefficient strategy," Bardy says.
Bardy, a self-confessed AED enthusiast who has a device in each of his two homes and each of his two cars, reported the findings here at the annual meeting of American College of Cardiology. They were simultaneously published online by The New England Journal of Medicine.
AEDs Jump-start Arrested Hearts
The study involved more than 7,000 people who had survived a heart attack. That places them at high risk of cardiac arrest, in which the heart suddenly stops beating, blood does not circulate, and victims fall into unconsciousness.
Each year, 166,200 Americans suffer cardiac arrest outside of a hospital. Paramedics, firefighters and, in some communities, police officers are trained to use defibrillators to shock a heart rhythm back to normal.
Several years ago, researchers found that training volunteers to use defibrillators distributed in shopping malls, airports, casinos, and other public places can double the chance that cardiac arrest victims will survive.
But because about three-fourths of sudden cardiac arrests occur in the home, where successful resuscitation is achieved in only about one in 50 cases, the effect of such programs is limited, Bardy says.
Enter the new study, designed to see if placing defibrillators in the homes of heart attack survivors can improve the odds.
Used Properly, AEDs Work
All participants received training in how to respond to a cardiac arrest. They were told to call 911 immediately. And they were taught how to perform CPR.
Then, half were randomly assigned to receive a home AED, which they were to told to use before calling for assistance and performing CPR.
Over the next 37 months, 450 patients died of any cause: 228 who had an AED at home and 222 who did not.
Why Home AEDs Performed Poorly
There are a variety of reasons for home AEDs seemingly dismal performance, Bardy says:
- The majority of patients died from causes other than cardiac arrest, so they would not be helped by an AED to begin with. No one else was home when about half of the cardiac arrest victims collapsed. Of the 117 sudden deaths that occurred at home, only 58 were witnessed. But when researchers looked specifically at deaths due to cardiac arrest, the odds of surviving were three times greater if there was an AED in the house compared with waiting for the normal EMS response. "There was very good survival when cardiac arrest was witnessed," he says.
- The survival rates in the no-AED homes was higher than usual because of the intensive emergency training all participants received. "There's something about making people more aware of their disease that helps patients," he says.
- All the participants received the best available treatments, Bardy says.
Helping a Neighbor
Bardy notes that there were seven known instances when the home AED "was borrowed" to help a cardiac arrest victim who was a neighbor or a visitor to the patient's home.
American College of Cardiology past president Steven E. Nissen, MD, chairman of cardiovascular medicine at Cleveland Clinic, says, "The study is terrific because it answers the question of whether routine home AED use is cost-effective, and it's not.
"But if you have unlimited resources and wanted an added safety measure, why not? Just make sure you're trained," Nissen tells WebMD.
American Heart Association spokesman Gordon Tomaselli, MD, chief of cardiology at Johns Hopkins, says the study shouldn't "dampen our enthusiasm for AEDs in general."
CPR, he tells WebMD, can "just sustain a patient until help arrives. There's only one thing that can reliably treat a patient [who goes into cardiac arrest] and that's treatment with an AED."