MASSDEVICE ON CALL — The defibrillator leads developed and subsequently recalled by medical device makers Medtronic (NYSE:MDT) and St. Jude Medical (NYSE:STJ) may have been doomed by their design, according to a new study.
The slimmer profiles boasted by Medtronic’s Fidelis lead and St. Jude’s Riata and Riata ST leads may have made them more prone to impedance changes and electrical noise, researchers reported.
"The crucial point is whether a small-diameter lead can be robust enough to last over time," the authors of a study published this month in the journal Heart Rhythm wrote. "Indeed, in our study, a small lead diameter proved to be a significant predictor of lead failure, accounting for the cumulative incidence of events in the Riata and Sprint Fidelis families."
Other researchers warned that the relationship between the suite of thin leads and their recall history may be more coincidence than evidence of a trend.
""It just happened that those two leads were smaller and they were recalled," Dr. Samir Saba of the University of Pittsburgh Medical Center told Heartwire. "It doesn’t mean that any other lead that is of smaller caliber, if it is appropriately designed, would necessarily have the same issues."
Medtronic pulled the Sprint Fidelis leads from shelves worldwide in October 2007 when it was announced 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 defective leads were implicated in more than 100 deaths, although Medtronic has said that only 13 fatalities listed the leads as a "possible or likely contributing factor."
The FDA in December 2011 slapped St. Jude Medical with a Class I recall on the Riata leads after the company said the devices failed more frequently than previously reported. St. Jude recalled the leads after receiving reports of high rates of "insulation abrasion," which occurs when the leads’ wires poke through their insulation. St. Jude had started pulling the devices off the shelves a year earlier over the same concerns.
St. Jude’s next-generation Durata leads, which the company had taken pains to insulate from the clamour surrounding the recall, also have a smaller diameter but haven’t thus far shown any of the failures associated with Riata, Heartwire noted.
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