Early Defibrillator After Heart Attack May Not Pay Off
WEDNESDAY Oct. 7, 2009 -- Implanting a defibrillator in the first weeks after a heart attack does not improve survival, a major European study shows.
Fewer deaths from sudden cardiac arrest occurred among those given the devices, which shock the heart into beating again. But, the overall death rate was about the same as for those who did not get defibrillators in the 40 days after a heart attack, the researchers reported.
The study results parallel those of a smaller American trial, said Dr. Gerhard Steinbeck, professor of medicine and chairman of internal medicine at Ludwig-Maximilians University in Munich and lead author of a report in the Oct. 8 issue of the New England Journal of Medicine.
One reason for a second study was that the American trial "might have been a false-negative trial signaled by a relatively small sample size and design flaws," Steinberg said.
But the European study was not done to prove or disprove the earlier trial, which was reported on in 2004, he said. "For many years, these two studies were running parallel," Steinbeck said.
The European trial enrolled 898 of 62,944 people treated for heart attacks. About half had defibrillators implanted, while the other half were given standard treatment, without defibrillators.
In an average follow-up of 37 months, 116 of the defibrillator recipients and 117 of those given standard treatment died. Though there were 27 deaths from sudden cardiac arrest in the defibrillator group, compared with 60 in the standard-treatment group, the overall mortality rate was about the same because of the higher incidence of non-sudden cardiac deaths in the defibrillator group -- 68, versus 39 in the standard-treatment group.
The new results are more firmly based than the earlier findings, Steinbeck said. "We can state that we have included more patients and have done a longer mean [average] follow-up," he said. "Our statistical power is based on [about] 230 deaths, while there were only 120 deaths in the other trial."
Also, the treatment of heart attacks has changed since the earlier trial was done, with artery-opening angioplasty much more common now, Steinbeck said. "In the other trial, 27 percent of patients underwent PCI [percutaneous coronary intervention, the medical term for angioplasty], while in our study it was much higher, more than 70 percent," he said.
The newly reported study results are not at all unexpected, said Dr. Arthur J. Moss, a professor of medicine and cardiology at the University of Rochester in New York and leader of a study reported in 2002 that led to guidelines against early installation of defibrillators after a heart attack.
"We thought they should not be implanted for at least three months, for a variety of reasons," Moss said. "We thought that putting one in early could contribute to heart failure, which is what this study found."
Indeed, analysis of Moss's earlier study had found that longer delays worked best, he said. "We looked at it by quartile, one to 18 months, 18 to 36 months," he said. "The only group that did not benefit got defibrillators in the first 18 months."
The new European study does not rule out later use of defibrillators for people who have had heart attacks, Steinbeck said. Defibrillators can save lives, he said, if implanted when someone develops a sustained abnormal heartbeat, such as ventricular fibrillation.
"If after 48 hours the arrhythmia is sustained, such a patient is a candidate for a defibrillator," Steinbeck said.
The American Heart Association has more on implantable defibrillators.
Posted: October 2009