A Medtronic Inc. DF4 defibrillator wire used to connect the lifesaving device to the heart inexplicably fractured after 18 months in a 52-year-old man, raising questions about how quickly doctors should embrace new technology, researchers said.
The man with Brugada syndrome, a potentially life-threatening heart rhythm disorder, hadn't engaged in any high-risk sports or activities that would have increased the fracture risk, according to a report to be published in the journal Heart Rhythm. The device's alert system activated and prevented inappropriate shocks. The wire was removed two days later.
Flaws with the wires, known as leads, are a potential complication with defibrillators and resynchronization devices, which can shock an erratic heart back into a normal rhythm. St. Jude Medical Inc., based in Little Canada, pulled its Riata wire off the market in 2010 because the wires could protrude from their insulation, while Fridley-based Medtronic's Sprint Fidelis leads were recalled in 2007.
"Given the proven long-term reliability of existing DF-1 ICD leads, switching to new technology may be accompanied with unexpected risks," the researchers from Grenoble Hospital and Saint-Loup Hospital in France wrote in the report. "The lessons learned from prior lead recalls should temper our enthusiasm in regards to novel lead technology."
Medtronic shares fell 1.6 percent to close Wednesday at $52.05. The shares have gained 36 percent in the past 12 months.
The researchers said the wire has been redesigned to make it easier to implant. The changes, with three different splices located in the lead, may increase the risk of connector failure, they said.
"This first report of a DF4 ICD lead fracture highlights its potential early vulnerability," they wrote. "Although no conclusions can be drawn from this single report, the risks and benefits of this new connector should be considered carefully before adopting it as a new standard of care."
The problem was detected and physicians alerted by the device itself before the man was aware there was an issue that needed attention, said Kathleen Janasz, a Medtronic spokeswoman. Every manufacturer of DF4 leads has experienced cases of fractures that are disclosed in the U.S. Food and Drug Administration's Maude database, she said in a statement.
Medtronic's device, the 6947M DF4, has a 99.5 percent survival rate at six months and the company has the industry's most rigorous lead surveillance program, she said. It was approved in January 2012 for use in the United States.