March 26 (Bloomberg) -- St. Jude Medical Inc.’s recalled Riata wires, used to connect life-saving defibrillators to the heart, can short circuit, a defect that may have led to 22 deaths, researchers said.
An analysis of the U.S. Food and Drug Administration’s safety database turned up 133 deaths linked to St. Jude’s Riata or Medtronic Inc.’s Quattro Secure leads, according to the report from Robert Hauser, a cardiologist at the Minneapolis Heart Institute. The 22 deaths that stemmed from failures of the wires used to connect Riata and Riata ST to the heart were typically caused by short circuits between high-voltage components, the study found.
St. Jude, based in St. Paul, Minnesota, stopped selling the wires, known as leads, in December 2010 and recalled them a year later amid reports that they could break through the insulation coating and fail to work properly. The deaths weren’t caused by the flaw, known as externalized conductors, Hauser said. The wires remain in about 79,000 patients.
Riata and Riata ST wires “are prone to high-voltage failures that have resulted in death,” according to the study to be published in the journal Heart Rhythm that was obtained by Bloomberg News and confirmed by Hauser. “These failures appear to be caused by insulation defects that resulted in short-circuiting between high-voltage components.”
Failures and Harm
Abrasion-related issues with defibrillator wires like Riata that are insulated with silicone are known to cause failure and patient harm, said Amy Jo Meyer, a St. Jude spokeswoman, in an e-mail. The risk is documented in medical literature and is tied to a failure rate ranging from 3 percent to 10 percent, she said. The information was included in a December 2010 letter the company sent to physicians, she said.
The risk is why St. Jude stopped selling silicone-only defibrillator leads and started using a novel insulation known as Optim, she said. Medtronic’s Quattro, which was compared with Riata in the study, uses a polyurethane insulation.
“We continue to study the performance of our older generation silicone leads through the Riata Lead Evaluation Study that was initiated at the end of last year and will communicate the findings from this study as soon as they become available,” Meyer said.
The company announced yesterday it had appointed Population Health Research Institute, an academic health science research institute, to analyze data from three registries of the newer Riata ST Optim and Durata leads to determine their performance.
“We take our responsibilities as a leading manufacturer of cardiac rhythm management devices very seriously and recognize our primary responsibility as a global medical device manufacturer is to ensure that our devices are of the highest quality and that they function safely and properly,” said Mark Carlson, chief medical officer of St. Jude. “We are pleased to enlist PHRI to perform an independent analysis and validation of the Optim insulated defibrillation lead data from these three very large, long-term registries.”
St. Jude gained less than 1 percent to $43.80 at the close in New York. The shares have fallen 14 percent in the past year.
The analysis is a further look at a review by Hauser released yesterday that found the failed leads had multiple defects. Surgery to remove the wires still in use may present higher risks than keeping them in, U.S. regulators have said.
There were five deaths tied to Medtronic’s Quattro Secure lead, with the remainder stemming from other causes, according to the report.
The study compares what is one of the best-performing defibrillator leads, the Quattro, to an average or below average lead, said Bruce Wilkoff, director of cardiac pacing and defibrillation at the Cleveland Clinic and president of the Heart Rhythm Society. The risk was already known, and the fact that it happens more often with the silicone-coated lead isn’t surprising, he said.
“This raises the visibility of the issue,” he said in a telephone interview. “People will ask more questions and try to work out what is the best way of a approaching these patients. But the failure rate of this lead is not that much different than other leads.”
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