AEDs did not improve survival among hospitalized patients with cardiac arrest

**Chan P. JAMA. 2010;304:2129-2136.**

Patients hospitalized for cardiac arrest experienced no improvement in survival with the use of automated external defibrillators and, in some cases, had lower rates of survival when compared with those who were not treated with the device.

The study, published in the Journal of the American Medical Association, featured 11,695 patients, 9,616 (82.2%) with non-shockable rhythms such as asystole and pulseless electrical activity, and 2,079 (17.8%) with shockable rhythms, including ventricular fibrillation and pulseless ventricular tachycardia.

Of the study population, AEDs were used in 4,515 patients (38.6%), with 2,117 (18.1%) surviving to hospital discharge. Researchers reported AED use was significantly associated with a lower rate of survival after in-hospital cardiac arrest vs. no AED use (16.3% vs. 19.3%; adjusted rate ratio=0.85; 95% CI, 0.78-0.92).

Further, AED use among cardiac arrests due to non-shockable rhythms was associated with lower survival (10.4% vs. 15.4%; adjusted rate ratio=0.74; 95% CI, 0.65-0.83), whereas AED use for cardiac arrests due to shockable rhythms was not associated with survival (38.4% vs. 39.8%; adjusted rate ratio=1.00; 95% CI, 0.88-1.13).

“We found that use of AEDs among hospitalized patients with cardiac arrests was not associated with improved survival,” the researchers wrote. “While randomized controlled trials are needed to confirm these findings, current use of AEDs in hospitalized patients may warrant reconsideration.”

This is an interesting study that shows how a seemingly good idea can have unexpected negative consequences. In the in-hospital setting, delay to defibrillation is not, or should not be, nearly as great a problem as it is in the out-of-hospital setting. Out-of-hospital, highly trained rescuers must be called to the scene from a distance. The AED greatly increases the pool of potential rescuers and that's why they are effective in that setting. In-hospital, trained rescuers should be readily available. The time advantage gained by having an AED available is probably measured in seconds not minutes. Therefore, the gain that's accrued in ventricular tachycardia/ventricular fibrillation cases is small. In contrast, the potential for delays or interruptions in providing recommended therapy for pulseless electrical activity cases or other types of bradyasystolic arrests seems to have deleterious effects and negates any chance for overall benefit. .

– John Philip DiMarco, MD

Cardiology Today Editorial Board member

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