Updated June 15, 2012, at 1:15 p.m. with comments from Medtronic.
A common procedure in which surgeons swap out a patient’s implantable cardioverter defibrillator may significantly increase the risk of failure for Medtronic’s (NYSE:MDT) already fracture-prone Sprint Fidelis defibrillator leads, according to a new study.
Researchers found that 1 in 5 Fidelis leads failed after an ICD swap, most of them within 3 months, raising questions about the need for lead replacement at the time of ICD replacement.
"The replacement procedure itself seems to be the cause, since most of the failures occur within 3 months of the procedure," according to the study.
Researchers observed 72 patients whose Fidelis leads were functioning and who underwent ICD exchange without lead replacement. The Fidelis leads failed in 15 patients after the swap, 60% within 3 months.
The failure rate for swapped patients was 20.8%, compared with 2.5% for patients who didn’t have a recent swap.
The Fidelis devices, which Medtronic recalled in 2007, are still active in an estimated 100,000 patients out of the 268,000 originally implanted, according to the study, published in the June issue of Heart Rhythm.
Medtronic pulled the leads in October 2007 amid concerns that they were prone to fracture – meaning they could either fail to deliver the shock needed to regulate a haywire heartbeat or else send unneeded shocks. The wires are implicated in more than 100 deaths, although Medtronic has said that only 13 fatalities had the Fidelis leads as a "possible or likely contributing factor."
Medtronic has said that "Sprint Fidelis performance after device change-out is similar to lead performance without device change-out," but the researchers warned that published data supporting the statement was limited.
"There are no clinical parameters that predict lead failure after ICD exchange, suggesting that all Fidelis patients should be considered at risk after a generator replacement," according to the researchers.
"Medtronic is aware of the study you referenced and will share these findings with Medtronic’s Independent Physician Quality Panel," company spokesman Chris Garland told MassDevice.com in an email today. "At this time, there is no change to our patient management recommendations."
Medtronic’s physician guidelines, last updated in April 2011, recommend that surgeons take no action on functioning leads in normal circumstances. In the event of a device change-out or upgrade procedure, however, the Minneapolis-based med-tech giant recommends that surgeons consider patient factors and device model failure rates in determining whether to leave the functioning leads intact or replace them.
"This study adds to the body of scientific data available on the Sprint Fidelis lead that, along with Medtronic’s data, are taken into consideration by the IPQP as it considers patient management recommendations," Garland added.
Earlier this year, a separate study warned that the Fidelis recall wasn’t aging well. Researchers warned that failure rates were climbing and that some physicians were opting to replace the leads before they showed signs of failure.
"The rate of Fidelis failure continues to increase over time, with failures approaching 17% at 5 years," the researchers wrote in the January issue of Circulation. "Our data suggests that Fidelis replacement should be strongly considered, at the time of generator replacement."
