The researchers did see better long-term cardiac functional status in patients with dual chamber pacemakers, but this observation, they say, demonstrates the complexities inherent in measuring quality of life in the elderly. "While it is clear from our results that dual chamber pacing is associated with long-term improvements in cardiovascular function of over time," said Goldman, "aging and the development or worsening of other diseases may overwhelm the modest improvements in cardiovascular functional class and minimize the long-term effect on generic quality of life."
The pacemakers have traditionally been associated with different advantages. The single chamber ventricular pacemaker is less expensive, easier to implant, and has a longer service life than the dual chamber pacemaker; most important, there often are fewer complications associated with the pacemaker itself. Dual chamber pacemakers, on the other hand, offer the theoretical benefit of mimicking the normal electrical sequence of the heart, pacing the atrium first and the ventricular chamber second.
"The question," said Goldman, "has been whether the benefit of the dual chamber pacemaker in terms of heart function and other complications warrants the extra difficulty in placement, shorter battery life and potential risk of complications for the pacemaker itself, as well as the extra cost. The answer seems to be that in many cases it is not."
The 29-center study, called the Pacemaker Selection in the Elderly Trial,
involved patients diagnosed with either sinus node dysfunction, a condition in
which the heart beat is not initiated at the appropriate rate, or
atrial-ventricular block, in which the heart beat is initiated at the
appropriate rate but does not make it through the electrical system. Patients
were assessed at three, nine and 18 months after enrollment in the study.
Contact: Jennifer O'Brien
University of California - San Francisco