ATLANTA (AP) - Routinely implanting pager-size defibrillators in heart attack survivors to stop cardiac arrest reduces their chance of dying by a surprising one-third and could benefit millions of Americans, a major study found.
The devices, like the one given to Vice President Dick Cheney last summer, constantly check for abnormal beats and zap the heart back to normal in case of cardiac arrest. About 250,000 people collapse with cardiac arrest outside hospitals in the United States each year, and 95 percent of them die.
``We are talking about preventing the sudden death of people who are active and functioning,' said Dr. Arthur J. Moss of the University of Rochester ``The opportunity here is quite profound.'
His study, released Tuesday, suggests the implanted defibrillators should be much more widely used and considered for all who meet just two simple criteria: a history of heart attack and evidence of resulting heart weakness.
Heart specialists called the results important, but some wondered whether fine-tuning the criteria might better target their use so that fewer people will need them.
Until now, the devices have been reserved for the rare few who survive cardiac arrest or are found to be at high risk through electrophysiological testing, which involves deliberately trying to trigger heart rhythm problems with a catheter that is snaked into the heart.
Moss presented the results at a meeting of the American College of Cardiology in Atlanta, and they will also be published in Thursday's issue of the New England Journal of Medicine. The $7 million study was financed by Indianapolis-based Guidant Corp., which makes the defibrillators.
Moss said at least 2 million Americans - and perhaps more - could benefit from the defibrillators, and there will be 300,000 more every year.
``Electricity saves lives. That's what we've heard today,' said Dr. Douglas Zipes of Indiana University, president of the cardiology college, who nonetheless worried about ``the profound economic implications' of implanting so many defibrillators.
The devices cost about $20,000, though higher demand could eventually drive that down. With surgery and a one-night hospital stay to install them, the total cost is $40,000 to $60,000. In addition to Guidant, they are made by St. Jude Medical and Medtronic.
Dr. Sidney Smith, research director of the American Heart Association, called the findings ``very impressive' but added, ``We are talking about a lot of people who would receive defibrillators. We need to identify a subset who would benefit the most.'
Moss's study involved 1,232 heart attack survivors who also had diminished heart pumping power, a common consequence of the damage caused by a heart attack.
The doctors studied people whose ejection fractions were 30 percent or less. Ejection fraction is the amount of blood pumped from the heart with each beat. It is measured with a routine echocardiogram. Normal is 50 percent or more.
The volunteers were randomly assigned to get an implanted defibrillator or standard drug treatment. The study was stopped in November when it became clear that those getting the devices were doing much better.
After an average of 20 months, the death rate from any cause was 14 percent in those who received defibrillators and 20 percent in people who did not. The difference translates into a 31 percent reduction in risk of death.
Moss said this improvement in survival is the biggest since the introduction of beta blocker drugs for heart disease in the 1970s.
The implanted devices work the same as the external defibrillators that are now becoming standard equipment in sports arenas, airport terminals and other public places.
Cardiac arrest happens most often after age 60. Doctors estimate that half of all cases result from electrical disturbances that send the heart into chaotic quivering. Defibrillators are designed to correct these. The rest occur after heart attacks, when sudden blockages cut off the heart's blood supply.