New Defibrillators Riskier, Study SaysDec 20, 2002 | Washington Post
Heart patients with newer, more sophisticated defibrillators implanted in their chests appear to be more likely to suffer heart failure or die than those with an earlier generation of simpler devices, researchers reported yesterday.
Based on the surprising findings, tens of thousands of Americans implanted with defibrillators to shock their hearts back into normal rhythms, including Vice President Dick Cheney, should consult their doctors to see if they should have their devices reprogrammed to operate in the simpler, safer mode, researchers said.
The study is the latest of several to conclude that newer, more complicated medical treatments and technologies aren't necessarily the most effective. Earlier this week, researchers reported that an old class of blood-pressure medications, known as diuretics, appeared to be superior to newer, more expensive drugs.
''Just because we can do something, doesn't necessarily mean we should do it,'' said David Kass of the Johns Hopkins Medical Institutions in Baltimore. ''In my mind, that's the big message.''
Each year, about 50,000 Americans who are at risk for heart failure because of irregular heart rhythms get cardiac defibrillators surgically implanted in their chests to monitor their heartbeats. If the device detects an abnormal rhythm, it zaps the heart with an electric shock to restore a normal beat.
The devices also have pacemakers built into them to keep the heart beating at the right rate. About 75 percent of the defibrillators now in use have more sophisticated pacemakers, known as dual-chamber devices because they stimulate both the right atrial chamber at the top of the heart and the right ventricle at the bottom. That was thought to be superior, because it could synchronize both parts of the heart. But the older and newer approaches had never been tested against one another.
The new study involved 506 defibrillator patients at 37 hospitals around the country. Half the patients had the pacemakers programmed to stimulate both chambers, while the other half were programmed only to stimulate the ventricle.
On Sept. 30, about two years into the study, researchers halted the research early, after it became clear that patients with the dual-chamber devices were more likely to suffer ill effects. About 26 percent of them were hospitalized for heart failure or died, compared to only about 16 percent of the second group.
''It was a big surprise,'' said Bruce Wilkoff of the Cleveland Clinic Foundation, who led the study, which will be published in Wednesday's issue of the Journal of the American Medical Association.
It's not entirely clear why the dual approach is more dangerous, but Wilkoff said it may be that stimulating both parts of the heart causes the beating to become dangerously uncoordinated.
Based on the findings, Wilkoff recommended that patients with a defibrillator consult with their doctor. Wilkoff stressed that patients with certain heartbeat problems clearly do benefit from the dual-chamber approach. Those who don't have a condition requiring the dual version can easily get their devices reprogrammed, he said.
Patients getting defibrillators for the first time, or replacement devices, might also opt for the less sophisticated versions, which cost about $5,000 less, Wilkoff said.
St. Jude Medical Inc. of St. Paul, the defibrillator maker that funded the study, praised the findings and said they should help guide doctors in deciding whether to reprogram the devices.
But Marshall Stanton of Medtronic Inc. of Minneapolis, which made the defibrillator that Vice President Cheney received, questioned the findings, saying the design of the study may have been faulty.