OVERLAND PARK, KS -- Installing automated external defibrillators (AEDs) in schools and public places could increase survival rates for sudden cardiac arrest (SCA), according to two studies published earlier this week in the American Heart Association (AHA) journal Circulation.

However, for AEDs to be effective, plans for emergency response should be initiated and practiced annually, and public AED installation should be guided to avoid excess cost and promote the best coverage, the studies also found.

In one study, researchers examined 1,710 American high schools with AED programs in place. It found that school AEDs promoted a high rate of survival for both students and adults who suffered SCA on school grounds.

Of 36 cases of SCA between December 2006 and July 2007, the study found that 30 of the victims received an AED shock and 23 of them survived to hospital discharge — this included 9 of 14 student-athletes and 14 of 22 adults.

However, although 83 percent of the schools studied had an emergency AED plan in place, only 40 percent practiced the plan annually.

“It is not just about the AEDs. Schools must have a comprehensive emergency response plan for sudden cardiac arrest that includes training anticipated responders in CPR and AED use, access to an AED, and practice and review of the response plan,” wrote Jonathan A. Drezner, M.D., lead author of the study and associate professor and team physician in the Department of Family Medicine at the University of Washington.

In a separate Danish study, researchers found that almost 70 percent of cardiac arrests in public places could be covered by AEDs placed strategically within a city’s center with acceptable costs.

Scientists digitally marked locations in Copenhagen, Denmark, where 1,274 SCA incidences occurred in public from 1994 through 2005. Then they analyzed the locations of 104 public AEDs in relation to the sites.

Danish researchers also looked at effectiveness of both European and American guidelines for public AED placement. The American AHA guidelines recommend adding AEDs to public places in which one cardiac arrest has happened within five years while European guidelines recommend AEDs for public areas in which one cardiac arrest occurred every two years.

The researchers found that AHA guidelines would have helped 67 percent of the cases studied, while European guidelines only would have covered 20 percent.

The cost of the recommended AED installations was estimated to be $33,100-$41,000 per additional quality-adjusted life year, whereas unguided AED placement covering the entire city had an estimated cost of $108,700 per quality-adjusted life year, researchers noted.

“If AED deployment in the community is driven by local or political initiatives and not on strategic AED placement, there is a high risk of AEDs being placed primarily in low-incidence areas of cardiac arrest and hence low likelihood of the AEDs ever being used,” wrote Fredrik Folke, M.D., lead author of the study and a cardiology research fellow at Gentofte University Hospital in Hellerup, Denmark.