A heart-device problem that has plagued St. Jude Medical Inc. shows no signs of relenting, according to data in the company's latest performance report, expected to be published Tuesday.
The rate of a key failure for the company's Riata-series "leads," wires that connect a defibrillator to the heart, increased 17% since the company's last performance report in November. Following that report, the company issued an advisory—regulators called it a recall—over concerns that the electrical wires inside the lead have a tendency to wear through their silicone coating, becoming loose in blood vessels near the heart.
The scope of the problem captured in the report is small, just 0.74% of the 79,000 Riatas in use as of the end of December. But even doctors involved in reviewing it acknowledge that St. Jude's report cards undercount incidents.
The reports are based on complaints filed by doctors, and on products returned to St. Jude for inspection after patients die or have the device removed. They don't account for problems that aren't actively relayed to the company. St. Jude stopped selling the Riata leads at the end of 2010.
Outside researchers have found failure rates as high as 33%, though such reports have focused on small groups of patients. An 87-patient study at Vanderbilt University Medical Center in Tennessee found one-third of patients had wires that eroded through their insulation. A Vanderbilt electrophysiologist and author, said he believed the findings roughly reflected the scope of the problem.
Not all insulation problems result in electrical problems, including sometimes-lethal short circuits. St. Jude's report cards don't specifically show the rate of leads with insulation problems that also result in electrical problems.
The variation in measures of failure rates underscores the problems the industry has faced in finding ways to better track defibrillators, devices that zap dangerously irregular heartbeats back to a normal rhythm. In the wake of several high-profile recalls in recent years, the industry has put efforts in place—for instance, independent medical advisory boards and wireless monitoring systems—to better identify problems. But many older devices, such as the Riata leads, predate those efforts.
St. Jude is increasing its investment in patient registries that could help better understand the performance of the devices and detect early on if there is an issue.
St. Jude also launched a 700-patient study in December that is meant to give doctors a clearer picture of the rate of both conductors breaking through coating and electrical problems.
Problems with the Riata-series leads first appeared in 2010, and the company stopped selling the product that December. St. Jude acknowledged more problems with the device a year later, prompting the recall. A series of medical journal articles ignited new scrutiny this spring.
In the new performance report, the company also included, for the first time, data collected from several patient registries detailing the performance of its newer, Durata-series leads. The company has struggled with a spreading perception among doctors that the problems of Riata could also arise in Durata, which shares certain design elements, even though there is so far no evidence of problems in the newer leads.
Durata is coated in an extra layer of polyurethane that the company says protects it from wires eroding through the silicone, and has other design changes. It is implanted in 145,000 Americans, with few reports of problems. St. Jude used its performance report to highlight a 90% lower rate of erosion problems for Durata leads at five years, compared with Riata, according the registries, which consist of data collected every six months by doctors for more than 10,000 patients.
Doctors who are dealing with the Riata problems in the field are frustrated, in part, because they lack data to know the full scope of the problem.
St. Jude has recommended that doctors monitor patients with Riata devices closely, in some cases using wireless devices. Doctors are also advised, at their discretion, to do extra electrical tests and to screen for wires breaking through their silicone sheaths with X-rays. St. Jude says there is no consensus on whether to replace leads found to be faulty, but it will provide a free Durata for patients whose doctors go that route.
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