By Bill Berkrot and Ransdell Pierson
DALLAS (Reuters) - A new generation of Medtronic Inc's EnRhythm pacemaker programmed to kick in only when heart rhythm disturbances are detected led to fewer deaths, hospitalizations and incidences of developing permanent heart problems than traditional versions of the device, according to data from a study.
The enhanced pacing strategy had its most profound effect in cutting the risk of developing permanent atrial fibrillation - a dangerously irregular heartbeat - by 61 percent over the traditional pacemakers.
Researchers conducting the 1,166-patient study, dubbed Minerva, found that the new pacing strategy helped avoid the side effects of continual electrical stimulation from standard pacemakers, which include weakening of the heart's main pumping chamber as well as a progression to permanent atrial fibrillation.
Patients in the study had a condition known as a bradycardia, in which the heart rate is less than 60 beats per minute, below the normal range of 60 to 100 beats per minute. They also suffered occasional bouts of atrial fibrillation, which if it becomes permanent puts a patient at five times the risk of suffering a stroke.
The primary goal of the two-year trial was a reduction in a combination of death, hospitalizations and permanent atrial fibrillation. The more sophisticated pacemaker led to an overall 26 percent risk reduction compared to the traditional model, which researchers said was statistically significant.
"For every 20 patients we treated, we attained saving one patient from permanent atrial fibrillation," said Dr. Giuseppe Boriani, lead author of the Minerva study who presented the findings on Monday at the American Heart Association scientific meeting in Dallas.
The incidence of permanent atrial tachycardia - a type of heart rhythm disturbance - or atrial fibrillation was 3.8 percent with the enhanced pacemaker versus 9.2 percent for those with the traditionally programmed pacemaker, researchers found.
In addition, after two years 15.2 percent of those with smart pacemakers were hospitalized and 4.6 percent died. That compared with hospitalizations of 16.8 percent and deaths of 5.6 percent for those with the older versions of the device.
Patients with the enhanced pacemaker also reported better quality of life and less fatigue, researchers said.
Boriani said he believed the results were definitive enough to change medical practice so that thousands more patients should get pacemakers with the enhanced features, which are also available in newer pacemakers made by Medtronic that followed the EnRhythm devices used in the study.
"This smarter pacemaker does seem to offer benefit for these type of patients," said Dr. Robert Harrington, chairman of Stanford University School of Medicine, who was not involved in the study.
However, he said, "it should not be a reason to put the most advanced pacemaker in everybody."
(Reporting by Bill Berkrot; Editing by Leslie Adler)