Study: Riata wires have additional risky defects

There may be more risky defects with St. Jude Medical's ($STJ) recalled Riata wires, which are still in roughly 79,000 patients, that have led to electrical abnormalities and multiple conductors.

As Bloomberg reports, failed wires can produce noise--akin to TV static--that can result in unnecessary shocks and other problems, according to study results reported at the American College of Cardiology meeting. The data came from a study of 105 reports on failed wires that found that two-thirds had multiple defects.

The company stopped selling the leads in December 2010 and sent a voluntary medical device advisory letter to doctors late last year, advising them of a higher rate of insulation failures than initially reported. The FDA subsequently deemed the physician alert a Class I recall--the most serious category.

Unfortunately for patients, it's often difficult to detect a defect until an event occurs. Still, they shouldn't necessarily panic. As St. Jude CMO Mark Carlson explained to Bloomberg, of the devices returned to the company because of electrical abnormalities that had protruding wires, the cables still functioned normally 85% of the time.

However, there is some risk for the company, as doctors may shy away from using Durata leads because of Riata concerns, Jefferies & Co. analyst Raj Denhoy said. "This thesis doesn't require a smoking gun on Durata, and as the mechanism of failure is likely time dependent, it may take a year or more to see a higher failure rate in this newer lead," he told investors in a note, as quoted by Bloomberg. "We believe clinicians will increasingly become unwilling to take the chance that the Durata could fail at a higher rate over time."

St. Jude said over the weekend it has tapped the Population Health Research Institute (PHRI) to analyze data from three combined registries on the Riata ST Optim and Durata implantable cardioverter defibrillator leads.

PHRI will gather together a committee of independent physicians chaired by Dr. John Cairns, former dean of Medicine at University of British Columbia. The committee will meet on an ongoing basis for at least two years to review data as it is collected.

- check out the St. Jude release
- get more from Bloomberg

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Doctors in limbo over recalled St. Jude defib lead
Does Riata recall indicate subpar device surveillance?
FDA classifies St. Jude's Riata lead recall as Class I