The device, Medtronic's InSync pacemaker, has been implanted in more than 3,000 people in the United States since its approval by the Food and Drug Administration in August.
It is intended for people with a particular form of heart failure, a debilitating illness in which people suffer shortness of breath because their hearts do not beat strongly enough. Overall, an estimated 5 million Americans have heart failure, and it is considered to be the only major form of heart trouble that is growing in prevalence.
Dr. David Meyerson of Johns Hopkins University, a spokesman for the American Heart Association, estimates that 10 percent of heart failure patients whose symptoms are not relieved by medicines could benefit from the new pacemakers.
"For those patients, this is a potentially exciting adjunct to our current therapies," he said.
The latest data on the pacemaker were released Monday by Dr. William Abraham of the University of Kentucky at a meeting in Atlanta of the American College of Cardiology.
In one-quarter to one-half of all heart failure victims, the heart fails to beat in a uniform way. The walls of their left and right ventricles - the main pumping chambers - do not squeeze at precisely the same moment. This sloppy motion robs the heart of its pumping power.
The new pacemakers deliver an electrical impulse that synchronizes the ventricles so their walls pump in unison.
In research sponsored by Medtronic, doctors followed 524 patients who received the InSync pacemakers. The devices were randomly turned on in half and left off in the rest. After the study's finish, all the pacemakers were switched on.
During six months of follow-up, the researchers found that people with the pacemakers were only half as likely to be admitted to the hospital for worsening heart failure. They spent an average of 3.4 days in the hospital, compared with seven for the comparison group.
The study was too small to assess whether the devices helped people live longer.
Installing the pacemaker, which requires attaching three wires, can be tricky. "As with most technical procedures, there is a learning curve," Abraham said.
On their first tries, doctors often take three to five hours to hook them up. But after they get more skilled, this falls to about an hour and a half. The procedure is successful in about 97 percent of cases, Abraham said.
Among other reports at the meeting Monday:
By Daniel Q. Haney