CHICAGO - Buying an automated external defibrillator - a portable device that can revive a heart-attack victim with electric shock - for use at home appeared to provide no significant life-saving benefit in the first major study in household settings.

The devices, which cost $1,000 or more, did help heart-attack survivors live through a second crisis. But so did CPR, and at much lower cost.

In reporting their findings online in the New England Journal of Medicine and in Chicago at the American College of Cardiology meeting, the researchers noted that the life-saving potential of defibrillators was well established in hospitals, emergency vehicles, and in public settings such as airports and casinos.

In contrast to the typical household, however, such public locations attract thousands, and in some cases millions, of people a year, and there are typically employees close at hand who are trained to use the defibrillators.

While the 7,000-person study found no downside to having a defibrillator, the authors said that any program to get them into homes would be "an inefficient strategy in public-health terms."

David Callans, a professor of cardiovascular medicine at the University of Pennsylvania School of Medicine who wrote an editorial accompanying the journal report, was blunter about consumer investments in the devices:

"It's a great example of what is wrong with American health care," Callans said in a telephone interview. He said home defibrillator kits might make sense in rare cases, such as when children at risk of cardiac arrest who have multiple caregivers and are too small to have an implanted defibrillator.

The National Heart, Lung and Blood Institute paid most of the study's cost. Device-makers Philips Healthcare and Laerdal Medical, a subsidiary in England, provided defibrillators and CPR training mannequins.

The study showed the devices "delivered the shock that was needed, when it was needed," said Mike Miller, head of Philips' defibrillator business.

Whether to buy one is "a personal choice," he said, like having a sprinkler system, a smoke detector or other safety equipment.