A study concluding that home defibrillators didn't do much to improve the survival rate of cardiac-arrest victims could dampen hopes for the Seattle-area manufacturers trying to create a new market for the devices.

The study, published Tuesday in the New England Journal of Medicine, followed for three years some 7,000 patients at moderate risk for sudden cardiac arrest.

It found that automated external defibrillators (AEDs), devices that can provide an electric shock to an arrhythmic heart to coax it back into proper rhythm, were "underused" at home.

About half the study patients were given a device and a spouse or companion was trained to use it, then told to call emergency medical services (EMS). For the others, family members were trained in CPR and told to call EMS.

The overall survival in both groups was comparable.

AEDs are popular at airports, casinos and other public places, but manufacturers are counting on growing awareness of the risks of cardiac arrest to break into the consumer market.

The top three AED makers — Philips Heartstart, a unit of Royal Philips; Physio-Control, a unit of Medtronic; and Cardiac Science — are all based here.

Consumers still account for less than 10 percent of the $192 million market for AEDs, said Mike Arani, a San Antonio-based analyst with Frost and Sullivan.

But the news "is probably going to put a dent" in that market's growth rate, Arani said.

Philips, whose AED unit is in downtown Seattle, is the only manufacturer to sell its product over the counter, including through Amazon, where it retails for $1,275.99. But it's pretty easy to obtain a doctor's prescription to buy an AED from any company, Arani said.

The study is a setback for Philips, one of the fastest-growing defibrillator makers, which "has been spearheading the home-defibrillator campaign" as others watched from the sidelines, Arani said.

But the company, which provided the AEDs used in the trial, said the study ratified the effectiveness of its product.

"They were very easy to use, very intuitive, and provided the therapy when needed," said Philips' AED general manager Chuck Little.

Home use will increase as advances in technology help lower costs, he said. "We think that will do nothing but improve the survival rate" among owners.

Anne Devine, a spokeswoman for Redmond-based Physio-Control, said the study samples were "really too small to detect a difference between the groups."

"The impact of the article will be minimal on the market for Physio-Control," she said.

Cardiac Science Chief Executive John Hinson said that home sales via prescription constitute "a very small part of our business." But the Bothell company had plans to launch a home defibrillator sold without prescription sometime this year.

"We haven't had time to study and reach the full conclusion" on the issues raised by the Journal paper.

"It's not that home defibrillators didn't work — they saved some lives. It's the cost-effectiveness debate that has been raised," he said.

A cardiac arrest occurs when the heart's beating suddenly — and unexpectedly — stops. More than 95 percent of victims die before reaching the hospital, according to the American Heart Association.

Some 50,000 lives could be saved in the U.S. if AEDs were more broadly deployed in public places and homes, the National Conference of State Legislatures has previously estimated.

Most sudden cardiac arrests occur at home. But the study, led by Dr. Gust Bardy, of the Seattle Institute for Cardiac Research, may prompt policymakers to discard home AEDs as a cost-effective tool to save lives.

An editorial accompanying the New England Journal of Medicine article said the results "suggest that future efforts should turn away from improbable resuscitation efforts and toward education, modification of risk factors, and other methods for primary prevention of heart disease."

Devine said home AEDs also could serve as a bridge for high-risk patients waiting to have an internal defibrillator implanted.

Ángel González: 206-515-5644 or agonzalez@seattletimes.com

Material from The Associated Press was used in this report.