March 16 (HealthDay News) -- Implanted defibrillators don't seem to provide any particular benefit to many people with heart failure, a new study finds.
A defibrillator can provide a lifesaving electrical jolt when heart rhythm becomes abnormal enough to be fatal. But it generally does nothing for heart failure, the progressive loss of the heart's ability to pump blood nor does it help any life-threatening illness that might accompany heart failure, such as diabetes, cancer or kidney disease.
These illnesses, or comorbidities, are more common in elderly heart failure patients, said Dr. Soko Setoguchi, an instructor in medicine at Harvard Medical School and lead author of the study, published in the Canadian Medical Association Journal, on the benefits -- or lack of them -- of defibrillators in such cases.
There are guidelines on implanted defibrillators, based on the results of controlled trials, "but the guidelines do not say anything about which population of heart failure patients should get them," she said. "Most trials exclude older patients and patients with comorbidities, but heart failure patients usually are very old and have comorbidities."
To study what happens in real-life medical practice, Setoguchi and her colleagues analyzed data on 14,374 people hospitalized for heart failure, looking specifically at cardiac deaths that occurred outside of a hospital.
The potential benefit of an implanted defibrillator was assessed by assuming that all of those deaths -- involving 13.7 percent of the people in the study -- were caused by cardiac emergency situations that defibrillators are supposed to prevent.
That assumption gives defibrillators the benefit of the doubt because not all deaths are sudden and from cardiac causes. Yet the net potential benefit based on that assumption was an extra seven months. It dropped to about three months for those who had three hospitalizations for heart failure.
Survival time was extended by more than two years for heart failure patients who were younger than 65 and did not have kidney disease, cancer or dementia, the study found. But the average age of the people in the study was 77, and 21 percent had chronic kidney disease.
So, should the guidelines for implanting defibrillators in people with heart failure be changed?
"I wouldn't make such a recommendation based on our study," Setoguchi said. "I think we need more evidence. But our study is in line with other studies showing limited benefit in older people and those with comorbidities."
Data to make such a judgment might soon be available, said Dr. Paul Dorian, a professor of medicine at the University of Toronto and the author of an accompanying commentary on the journal report. Registries in the United States and Canada are tracking the results for people given implanted defibrillators, he said.
"That data is only just beginning to be analyzed," Dorian said. "When it is, we will then have a better feeling on whether patients getting defibrillators have results similar to those of the patients in the clinical trials that established their efficacy."
But the registry data might not allow a judgment because it covers only people given defibrillators, Setoguchi said. "We need concurrent information on patients with the same background and same comorbidities who didn't get defibrillators."
Meanwhile, cardiologists must make decisions every day on whether to give someone a defibrillator. And there's no easy way to make such a decision, both Setoguchi and Dorian said.
"What I do with patients is to try to talk as accurately and dispassionately as I can about their condition, the benefits and risks of defibrillators, and help them make their own conclusion," Dorian said. "I never say, 'You need a defibrillator.' It is language I never use. I say, 'Lets talk awhile, and you see if it's worthwhile.' "
For Setoguchi, who no longer has a clinical practice, the decision "depends on your perspective," she said. "What do you consider a benefit? Suppose we say it can extend life for three months or six months. Is that worthwhile? It is a question that is hard to answer, one that depends on your perspective."
The study comes on the heels of a report this week indicating that many elderly people with heart failure also do not benefit from the most commonly prescribed heart medications.
That report, in the American Journal of Cardiology applied to people over 80 who have the form of heart failure in which the left ventricle fails to relax after a beat.
Cardiologists from Cedars-Sinai Heart Institute in Los Angeles, who conducted the study, also urged doctors to be more cautious in their prescriptions, keeping the possibility of side effects in mind, because elderly people often take many medications.
SOURCES: Soko Setoguchi, M.D., instructor, medicine, Harvard Medical School, Boston; Paul Dorian, M.D., professor, medicine, University of Toronto; March 17, 2009, Canadian Medical Association Journal; March 13, 2009, American Journal of Cardiology