(April 2, 2008 - Insidermedicine) Using an at-home device that can “shock” the heart back into a normal rhythm does not improve the survival chances for individuals who have experienced a type of heart attack that places them at moderately high risk for experiencing sudden cardiac arrest or fatal heart rhythm disturbances, according to research published in the latest issue of the New England Journal of Medicine.

Here are some facts about automated external defibrillators:
•    They are portable automatic devices that a person can use to restore normal heart rhythm to someone whose heart has stopped or is beating irregularly.

•    In general, anyone can operate an automated external defibrillator, but it is better if a trained person uses it, as there are cases when it should not be used, and operators can risk receiving an electric shock themselves if they touch the patient at the wrong time.

•    These devices are available in several public areas, such as airports, airplanes, and casinos, and there is evidence that making these devices widely available can save lives.

Researchers out of the Seattle Institute for Cardiac Research and the University of Washington randomly divided over 7,000 individuals who had survived a type of heart attack that placed them at risk for experiencing cardiac arrest or a fatal arrhythmia but who were not candidates for an implantable device that would automatically shock their heart as needed into one of two groups: The first group received an automated external defibrillator to use at home, and their loved ones were instructed to use it first in the case of a cardiac emergency, before calling emergency services or using cardiopulmonary resuscitation (CPR). The second group did not receive a device, and their loved ones were instructed to first call emergency services, then use CPR.

After an average of over three years, 160 deaths occurred that were believed to be due to cardiac arrest or arrhythmia. Of these, only 58 were witnessed, and only 32 patients received treatment with an automated external defibrillator. The death rates among the two groups of patients were virtually identical – about 6.5%.

Today’s research demonstrates that providing survivors of heart attacks that increase their risk of cardiac arrest or arrhythmia with an automated external defibrillator to use at home does not increase their chances of survival.

For Insidermedicine in Depth, I'm Dr. Susan Sharma.