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Studies Show Remote Monitoring of Implantable Cardioverter Defibrillators May Extend Battery Life
By Charlene Laino
WebMD Health News
Reviewed by Laura J. Martin, MD
Aug. 30, 2011 (Paris) -- Home monitoring of a device that protects the heart is safe, suggest two French studies presented here at the European Society of Cardiology meeting.
Remote monitoring of patients with implantable cardioverter defibrillators (ICDs) also reduced inappropriate shocks and extended battery life, according to one of the reports.
But whether home monitoring of ICDs actually improves patients' heart health and/or saves money are still the big questions, U.S. doctors say.
About 180,000 ICDs are implanted in the U.S. each year. Former Vice President Dick Cheney, who has a long history of heart disease, had one implanted in 2001.
The battery-powered devices are designed to continuously monitor heart rhythms and shock the heart back into its normal rhythm when certain abnormal heart rhythms occur or the heart stops beating altogether.
Patients typically have to come to the clinic every three to six months so doctors can make sure their ICD is working correctly.
"But there are two major drawbacks to the in-clinic follow-up," says researcher Philippe Mabo, MD, of the University Hospital of Rennes in France.
"They are time-consuming for both the patient and the clinic, and there's no link between the time of the appointment and [a heart problem] or device malfunction," he tells WebMD.
Now, remote monitoring of patients at home is available for many ICD models. Information on heart rhythms and shocks is stored and transmitted -- either continuously or at regular intervals -- via telephone lines or the Internet to a doctor's office.
Home ICD Monitoring Studies
One new study, called ECOST, involved 433 patients with ICDs. They were divided into two groups. The usual-care group came to the clinic every six months so doctors could ensure the devices were working correctly. The other group had continuous automatic wireless monitoring of their ICD. They were seen at the clinic only once a year, unless the remote monitoring detected a problem.
By 27 months later, people in the home monitoring group had received 52% fewer inappropriate shocks, compared with the usual-care patients. Eleven patients (5%) in the remote monitoring group had inappropriate shocks vs. 22 (10.4%) in the usual-care group.
Researcher Salem Kacet, MD, of Regional University Hospital of Lille, in France, tells WebMD that overall, home monitoring was associated with a reduction in the number of shocks "with a significant impact on ICD battery longevity."
But information on how long battery life was extended and potential cost savings is still being analyzed, he says. ICD batteries typically last between five and seven years. Replacing them requires surgery, typically with anesthesia and antibiotics to prevent infection.
The second study, dubbed EVATE by Mabo, involved 1,501 patients. They were divided into two groups: the remote follow-up group, whose ICD data were transmitted to the clinic every three months, and the usual-care group, who had office follow-up visits every three months.
Thirty percent of people in the remote monitoring group died or were hospitalized for cardiovascular disease vs. 29% of the usual-care group, a difference so small it could have been due to chance.
There was also no difference in survival rates among the two groups.
However, people in the remote group were less likely to receive heart-rhythm medication they didn't need based on erratic device readings: 5% vs. 8% of the usual-care group.
Cost May Be an Issue
Commenting on the studies, American Heart Association (AHA) spokeswoman Mariell Jessup, MD, of the University of Pennsylvania, says that reducing inappropriate shocks and medication use is "really important, as that's what we as doctors want to avoid."
Still, there may be cost concerns with the routine use of home monitoring, she tells WebMD.
AHA President Gordon Tomaselli, MD, of Johns Hopkins University, says that at least in the short-term, he expects home monitoring to raise costs.
Noting that his practice already remotely monitors patients who live far away, he says, "we get a boatload of data every day, potentially every heartbeat."
As a result, "more staff that can catch and interpret the ICD data and feed it to the doctors is needed," Tomaselli tells WebMD. "And that costs money."
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.