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, British researchers report.

The finding suggested that the benefits of two-chamber pacemakers had been overestimated in older people with a heart condition known as atrioventricular block, according to the team led by William Toff of Britain’s Leicester University.

The finding was published in Thursday’s issue of The New England Journal of Medicine.

Atrioventricular blocks, which occur when electrical impulses fail to reach the ventricles or are conducted with a delay, are a common reason for implanting a pacemaker.

The test of 2,021 volunteers who suffered from a slowed heartbeat found that after nearly 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.

When the research team looked at deaths directly caused by Heart disease, the rate was 3.9 percent with single-chamber devices and 4.5 percent for double-chamber pacemakers.

The rates of Stroke and heart failure were also similar in the two groups.

Earlier studies that were not as well controlled had shown that the dual-chamber devices were better, the researchers said.