Published on July 14, 2005 at 4:49 AM
British researchers say that for people over 70, pacemakers that stimulate only one part of the heart are just as effective as newer and more expensive devices that apply electricity to two of the heart's four chambers.
According to the team, led by William Toff of Britain's Leicester University, this finding suggests that the benefits of two-chamber pacemakers had been overestimated in older people with a heart condition known as atrioventricular block.
Apparently atrioventricular blocks occur when electrical impulses fail to reach the ventricles or are conducted with a delay, and they are a common reason for implanting a pacemaker.
The research team examined 2,021 volunteers who suffered from a slowed heartbeat and they found that after almost five years the annual death rate was 7.2 percent among those with pacemakers that stimulated one chamber, versus 7.4 percent for the people who got so-called dual-chamber pacing.
The research team found when they looked at deaths directly caused by heart disease, that the rate was 3.9 percent with single-chamber devices and 4.5 percent for double-chamber pacemakers.
Also similar in the two groups were the rates of stroke and heart failure.
The researchers say that earlier studies that were not as well controlled had shown that the dual-chamber devices were better.
The research is published in the current edition of the New England Journal of Medicine.