Alert on St. Jude Heart Device
Published date : 22 August 2012
Article date : 22 August 2012
Cardiologist, Dr. Robert G. Hauser of Abbott Northwestern Hospital in Minneapolis, has called for surgeons to stop using the Durata defibrillator lead until more is known about its long term safety. He made his comments as study he conducted, anticipated by analysts and industry-watchers, was published in the online journal Europace.
Dr. Hauser's research suggests that a coating used on wires that connect an implanted defibrillator to a patient’s heart is breaking down prematurely and, in some cases, leading to failure of the device. The study was published by EP Europace, a British cardiology journal.
Dr. Hauser had previously connected at least 20 deaths to an earlier generation of defibrillator leads, the wiring that runs from the device into the heart. St. Jude has pulled those products from the market but Hauser now says his work indicates that newer products are not immune to the underlying problem in which the coating of the wires wears away.
St. Jude began using the coating, known as Optim, several years ago as a means of better protecting its leads from abrasion. However, Dr. Hauser said a troubling number of cases had been reported to the FDA in which the Optim coating appeared to fail. The company has defended the safety of Optim and its Durata device which has been implanted in an estimated 278,000 patients worldwide. St. Jude has said defibrillators with its coating, which insulates wires on the company's Durata and Riata ST Optim defibrillator leads, are among the most wear-resistant and safest on the market. The company says the Optim coating is 50 times more abrasion-resistant than standard silicone-only leads.
While Hauser found that the Optim-coated leads are not immune to abrasion, he did not find instances of wires working their way outside the insulation of the Durata leads. Such "inside-out" abrasion has plagued St. Jude's now-recalled Riata defibrillator leads. In some cases the abrasions to the Optim-coated leads resulted in high-voltage failures and one death. What isunknown and requires more study, according to Hauser, is how often Optim leads fail because of damaged insulation.
Last week, the FDA announced that it is requiring studies of the Riata and other recalled St. Jude leads. It recommended patients with Riata leads get flouroscopic X-rays to check for abnormalities, and, it required that St. Jude studys its Durata leads. In May, the company noted that its study of Optim-coated leads showed no instances of externalised conductors caused by inside-out abrasion. In addition, the leads had a "99.96 percent rate of freedom from all-cause insulation abrasion" and "99.84 percent rate of freedom from all-cause mechanical failure."
Hauser gathered data from the FDA's Manufacturers and User Device Experience (MAUDE) database on April 13, searching for reports of lead abrasion. He said he found 15 reports for Riata ST Optim and 37 reports for Durata leads. The reports had been submitted by St. Jude Medical between December 2007 and January 2012 based on its analysis of returned leads.
Eight of 15 Riata ST Optim leads had "can" abrasions from rubbing against the defibrillator itself and three abrasions were most likely caused by friction with another lead. Four of these abrasions resulted in high-voltage failures and one death, Hauser said. In the Durata reports, 12 had "can" abrasions and six had abrasions caused by friction with another device. Of these 18 abrasions, Hauser said, 13 had electrical abnormalities.
Source: Batty Meier & Katie Thomas, New York Times, 21 August 2012. Read the NYT article here
Source: James Walsh, Star Tribune, 21 August 2012. Read the Star Tribune article here
UPDATE: St. Jude Medical has issued a detailed statement as follows:
There are a number of ways a lead may fail, including dislodgement, fracture (breaking of the lead), and abrasion (e.g. wear on the lead due to friction against another object). These failures can result in impedance changes, noise, under- and oversensing, an inappropriate shock, an electrical short or, in the most serious cases, a failure to provide therapy. As part of our commitment to communicating with the clinical community about device performance, lead failures are reported in our biannual product performance report, including in the Focus on Clinical Performance section. Failures are associated to some degree with leads from all manufacturers and may also be the result of the harsh environment that these leads must endure.
While no lead is perfect, bench testing has demonstrated that the Optim material is 50 times more abrasion resistant than silicone insulation. Although not mentioned in the manuscript, St. Jude Medical also has the largest prospective, actively monitored lead registries in the industry, including our OPTIMUM registry of Optim insulated leads. Additionally, we announced in March that we have appointed Population Health Research Institute (PHRI), an academic health science research institute, to analyze data from three combined prospective, actively monitored registries involving approximately 11,000 patients enrolled at 292 sites, with more than 5 years and 27,000 patient-years of data, which are documenting the performance of our current-generation leads. In fact, we recently announced that we are expanding our OPTIMUM study follow-up duration to follow patients enrolled in the registry indefinitely.
St. Jude Medical is committed to continuing to make significant investments in technologies and post-market surveillance studies to further advance our insight into the performance of our leads, and to improve patient safety.
Update extracted from medcitynews.com article by Arundhati Parmar, 21 August 2012
Full article here
