WEDNESDAY, July 13, 2005 (HealthDay News) -- A new British study has produced a sharp difference of opinion about the value of pacemakers that deliver electrical shocks to two chambers of the heart.
Some previous studies have found that two-chamber pacemakers, which act on both a ventricle and an atrial heart chamber to keep the heart beating regularly, do better at improving survival and quality of life than pacemakers that act only on a ventricle.
But British cardiologists are reporting in the July 14 issue of the New England Journal of Medicine that they found no improved survival associated with two-chamber pacemakers.
Their study, the United Kingdom Pacing and CardiovascularEvents (UKPACE) trial, included more than 2,000 elderly patients who had either a one-chamber or a two-chamber device implanted because of atrioventricular block, a failure of electrical signals to be transmitted in the heart.
The researchers reported that the death rates from all causes during the first five years after implantation and the incidence of cardiovascular events during the first three years were unaffected by the choice of device.
"What the study shows is that it doesn't make a great deal of difference as to which sort of pacemaker is implanted," said study author Dr. William D. Toff, a senior lecturer in cardiology at the University of Leicester.
That assertion drew an immediate rebuttal from Dr. Kenneth A. Ellenbogen, a professor of medicine at the Virginia Commonwealth University School of Medicine, who wrote an accompanying editorial in the journal.
Ellenbogen's major criticism was that the study only included information on survival, with no data on whether patients who got two-chamber pacemakers had a better quality of life, with fewer symptoms and more ability to do everyday tasks.
"Earlier studies have shown that you do have a higher quality of life with a two-chamber pacemaker," Ellenbogen said. "Quality of life is as important as length of life."
Because of that lack of information and because the study included only patients 70 or older, Ellenbogen said the study would not change his clinical practice, which emphasizes two-chamber pacemakers.
"If the patient were extremely old and had a poor quality of life to begin with, with a limited lifespan, a single-chamber pacemaker would be acceptable," he said. "But the vast majority of patients would get dual-chamber pacemakers."
But Toff maintained that "the value of two-chamber pacemaking has been overrated." He leans toward implanting single-chamber devices in his patients with atrioventricular block.
The study did include an assessment of quality of life, Toff added, but that information will be published in a future paper. He gave some indication of what those results might be when he said past studies "haven't found very impressive, if at all, differences in quality of life."
Ellenbogen expressed concern that the study "may have some impact on governments that have limited finances for health care." Dual-chamber pacemakers are more expensive than the single-chamber version.
Toff said, "these hard endpoints [of the study] are pretty irrefutable." But he added, "We feel the choice should be made on an individual basis."
For more on pacemakers, visit the American Heart Association.