There’s only a one in five chance that a potentially life-saving automated external defibrillator (AED) will be nearby when someone experiences cardiac arrest and a 20 to 30 percent chance that the nearby device will be inaccessible because it is inside a building that’s closed, according to a study published Aug. 15 in the special Cardiovascular Health Promotion issue of the Journal of the American College of Cardiology.

Researchers, led by Timothy C.Y. Chan, PhD, examined all public out-of-hospital cardiac arrests occurring between January 2006 and August 2014 in Toronto. Public locations included public buildings, places of recreation, industrial facilities and outdoor public spaces, but not hospitals or nursing homes. Researchers compared that to a list of registered AEDs in Toronto as of March 2015. AED registration is voluntary, but according to researchers, unregistered AEDs are more likely to be privately owned and located in places where a bystander would not be able to access them.

Results showed that Toronto had 2,440 cases of out-of-hospital cardiac arrest during the study period and 767 AED locations. Of the AED locations, 542, or 73.5 percent, were not open 24 hours a day and 211, or 28.6 percent, were closed on weekends. Of the total number of out-of-hospital cardiac arrests, 451 were located near an AED but only 354 were located near an AED when the AED was accessible, resulting in a coverage loss of 21.5 percent. When researchers just looked at cardiac arrests during evenings (4:00 p.m. to 12:00 a.m.), nights (12:00 a.m. to 8:00 a.m.) and weekends, coverage loss increased to 31.6 percent.

The researchers concluded that a significant proportion of out-of-hospital cardiac arrests occur close to a public AED that is inaccessible at the time of the arrest, and a model that accounts for both location and availability when determining AED placement has the potential to significantly increase the likelihood of accessing an AED when needed. Also, government legislation mandating all AEDs must be registered with emergency medical services dispatch centers and accessible to the public 24/7 would improve access to AEDs. The authors add that coverage is only one issue, and AED coverage does not necessarily equal survival because coverage does not mean the AEDs are being used.

In an accompanying editorial comment, Robert J. Myerburg, MD, FACC, says the study is important and should be included in planning strategies for AED locations, but society would benefit more by both achieving better outcomes after out-of-hospital cardiac arrest and reducing the number that occur in the first place. “Now we need a parallel effort to develop a roadmap for improving prediction and prevention of out-of-hospital cardiac arrest,” he concludes.

Keywords: Defibrillators, Emergency Medical Services, Government, Health Promotion, Nursing Homes, Out-of-Hospital Cardiac Arrest, Recreation, Secondary Prevention

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