Boston, MA - Recalls and safety alerts issued by the Food and Drug Administration, collectively known as advisories, occur frequently for automated external defibrillators (AEDs), a new study has shown [1]. The report found that, overall, 21.2% of AEDs were affected by the advisories, which were most often issued for electrical or software problems.

From 1996 to 2005, "the annual number of AED advisories and the annual number of AEDs affected by the advisories increased, and numerous confirmed AED malfunctions occurred," write Drs Jignesh Shah and William Maisel (Beth Israel Deaconess Medical Center, Boston, MA) in the August 9, 2006 issue of the Journal of the American Medical Association.

Maisel, who first presented the data at the Heart Rhythm Society 2006 Scientific Sessions in Boston, MA, told heartwire at the time, "One in five recalls is a high number for any product, let alone a life-saving product. These advisories occur frequently, they affect a lot of AEDs, and the mechanisms in place to notify AED users are poor. . . . Potentially, there are a lot of recalled AEDs that have not been replaced or repaired."

In an editorial accompanying the published study, Dr Mark Estes (Tufts University School of Medicine, Boston, MA), like Shah and Maisel, notes that the advisory rate did not increase significantly during the 10-year period and that an increase in advisories would be expected considering the increase in the number of AEDs marketed and sold [2]. However, Estes points out that the study focuses attention on salient issues regarding monitoring and reporting of device performance.

"The report by Shah and Maisel serves a major purpose of highlighting the inadequacies of manufacturer and FDA postmarketing device tracking, performance assessment, and notification mechanisms," he writes. "Preclinical testing and clinical trials are not designed to identify device reliability with relatively small numbers of devices followed for short periods of time."

The market for AEDs, often found in many public places, including airports, casinos, sports arenas, and shopping malls, has increased tremendously. From 1996 to 2005, more than 775 000 AEDs were marketed, with the annual number of units sold increasing 10-fold during the study, or approximately 30% per year. In 2005, 192 400 devices were sold in the US. Despite this, there are few data concerning the technical performance of the devices, note the authors

To address the issue, Shah and Maisel analyzed weekly safety alerts and recalls affecting AEDs and AED accessories from FDA Enforcement Reports. The authors also reviewed all AED-related adverse events reported to the FDA to assess confirmed device malfunctions.

From January 1996 to December 2005, there were 52 advisories issued by the FDA. Of the 37 AED advisories, 10.8% were categorized as class I, meaning there was "reasonable probability that use of the product will cause serious adverse health consequences," while 83.7% were categorized as class II (possibly causing temporary or reversible adverse health consequences). Electrical or software-related issues were the most often cited reason for the advisory, while failure to detect the arrhythmia, failure to shock, and battery-related issues accounted for the other advisories. Most of the advisories issues for AED accessories were judged to be class II recalls.

As noted in the paper, advisories from the FDA indicate only the potential for the device to malfunction and as such are a surrogate marker. An analysis of malfunction reports, taken from the FDA Manufacturer and User Facility Device Experience (MAUDE) database, revealed a total of 801 AED or AED-accessory adverse event reports involving a death. Of these, 46.1% were classified as confirmed device malfunctions.

The authors write that although malfunctions do occur occasionally, the number "is small compared with the number of lives saved." Shah and Maisel note that as the prevalence of the devices continues to increase, the number of AEDs affected by the advisories is likely to increase also. "Efforts should be directed at developing a reliable system to locate and repair potentially defective devices in a timely fashion," they conclude.

Estes agrees, noting that postmarketing surveillance with rigorous mechanisms to accurately monitor device performance might be costly, but such efforts are essential to achieve the best possible clinical outcomes.

"The same standards of evidence-based medicine used to define the benefits of AEDs should be the foundation of postmarketing surveillance for AEDs," writes Estes. "These devices, like all electronic medical devices, will always fall short of perfection, but there is a shared responsibility to make AEDs as reliable as possible."