Home AEDs and CPR Equally Helpful for Sudden Cardiac Arrest
The first study of automated external defibrillators used in homes found they are effective for certain types of cardiac arrest but are underused. The Home Automated External Defibrillator Trial, a randomized international clinical trial, was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health. Researchers presented the results Tuesday at the 2008 American College of Cardiology Scientific Sessions in Chicago and online in the New England Journal of Medicine, which will print them April 24.
The research involved 7,001 heart attack patients at moderate risk of sudden cardiac arrest whose spouse or other live-in companion agreed to take conventional steps to respond to an SCA -- calling EMS and performing CPR -- and compared them with households that were asked to use an AED before taking conventional steps. After an average of three years of follow-up, survival rates were about the same between those who had an AED in the home and those who did not. However, there were relatively few sudden cardiac arrests, and only 39 percent of these events were witnessed at home.
The study was conducted in 178 clinical sites in the United States, Canada, Britain, New Zealand, Australia, Germany, and the Netherlands. "Cardiac arrest is a top killer of Americans, and this study shows that the strategies of placing an AED in the home and of being prepared to give CPR are equally effective at saving lives in a population at risk for sudden cardiac arrest," said Dr. Elizabeth G. Nabel, NHLBI's director. "The important message here is that every minute counts, and quick action is key. Use an AED if one is handy or perform CPR, and always call for help by emergency medical professionals, such as by dialing 911." Three out of four sudden cardiac arrests occur at home.
"The long-term survival rates of all of the [study] participants who went into cardiac arrest were significantly higher than what is typically found in the general population, and fewer of the participants than expected had sudden cardiac arrest," said lead author Dr. Gust H. Bardy of the Seattle Institute for Cardiac Research. "We believe that this is because of the optimal medical therapy and coronary revascularization that all [study] participants received following heart attack. Moreover, although the control arm mortality rates in [the study] were equal to the AED group, it is not routine practice to train spouses or other companions following a patient's heart attack on why and how to call emergency medical services for help and how to perform CPR. I believe this should be routine practice following a patient's heart attack, regardless of whether they have an AED in the home."
Overall, 450 participants died during the study -- about as many participants in the control group (228) as in the AED treatment group (222). "We knew that the vast majority of sudden cardiac arrests would happen at home, but we didn't expect that so few would be witnessed by a spouse or other member of the household," Bardy said. "This, of course, dramatically limits the chance that someone would be there to use an AED or to perform CPR. However, when the AEDs were used, they were safe and effective."
Philips Medical Systems and Laerdal Medical donated HeartStart Home Defibrillators for use by participants in the AED group; this unit is the only FDA-approved home defibrillator available without a prescription.