FRIDAY, May 15, 2015 (HealthDay News) -- A new study of nearly 100,000 people with implantable cardioverter-defibrillators found that more physical activity was tied to living longer.
Implantable cardioverter-defibrillators (ICDs) are battery-powered devices implanted in patients whose hearts cannot maintain a normal rhythm. The devices keep the heart beating normally and can provide a shock to return the heart to a normal rhythm when needed.
Researchers found that patients who were the most active during the first 30 to 60 days after getting their ICD were 40 percent less likely to die within four years compared to patients who were the least active.
"Patients with the highest level of activity had dramatically better long-term survival after four years -- about 90 percent -- than patients with the lowest activity level, whose four-year survival was only about 50 percent," said lead researcher Dr. Matthew Reynolds, a cardiologist at the Lahey Hospital and Medical Center in Burlington, Mass.
Although the researchers found a strong connection between activity and longer life in these patients, they wrote that this study can't prove cause-and-effect. It's possible that those who were more active were in better health, which could also lead to a longer life, they explained.
The report was published May 15 online in the Journal of the American Heart Association, to coincide with presentation of the study results at the annual meeting of the Heart Rhythm Society, in Boston.
For the study, Reynolds and colleagues collected data on more than 98,000 patients with implantable cardioverter-defibrillators from across the United States. ICDs are inserted under the skin and electric wires are attached to the heart. In addition to their lifesaving task, ICDs also record patients' activity levels.
This information can be monitored remotely or in a doctor's office, Reynolds said. For this study, researchers analyzed patient activity in the first 30 to 60 days after implantation. They followed up on the patients' overall health for four years.
People in the study who had the highest activity level were active for about three hours a day. Those with the lowest activity level were active for about 30 minutes a day, he said.
Activity recorded by the ICD includes general activity, such as walking. "We are not talking about exercise," Reynolds said. "The bar is quite low," he added.
Reynolds thinks doctors can use the data on activity to identify patients with ICDs who are at increased risk of premature death. For patients, his advice is: "Get up and move. Fundamentally, people who are more active have better health."
Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles, said, "Physical fitness and engaging in regular physical activity have been associated with lower risk of dying in patients with heart disease."
Guidelines recommend regular physical activity in patients with heart disease and for some patients in cardiac rehabilitation, he said. This new study of men and women who have received an ICD shows that the level of physical activity as recorded by the device is predictive of patient survival, Fonarow said.
"These findings highlight how information that is collected by implanted devices and transmitted through remote monitoring may assist doctors in identifying individuals at higher risk," he said.
"The next step," he added, "is to determine whether a program that targets risk factors, such as physical inactivity, is effective in improving outcomes."
For more on implantable cardioverter-defibrillators, visit the American Heart Association.
SOURCES: Matthew Reynolds, M.D., M.Sc., cardiologist, Lahey Hospital and Medical Center, Burlington, Mass.; Gregg Fonarow, M.D., professor, cardiology, University of California, Los Angeles; May 15, 2015, Journal of the American Heart Association, online; May 15, 2015, presentation, Heart Rhythm Society meeting, Boston
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