St. Jude warns of possible glitch in CRT bipolar leads

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St. Jude Medical has issued a medical device advisory for its QuickSite and QuickFlex left ventricular cardiac resynchronization therapy (CRT) bipolar leads after the company said that the coated cable conductors have the potential for externalization. St. Jude said that it will discontinue these leads.

While there have been no reports of death of serious injury linked to the externalized conductors, St. Jude issued the advisory to inform clinicians of the possible externalized conductors on the leads. The company said that the externalized conductors are caused by the abrasion of the silicone insulation within the distal portion of the QuickSite and QuickFlex leads.

St. Jude estimated that between 3 percent and 4 percent of the QuickSite and QuickFlex leads may exhibit this anomaly. St. Jude decided to discontinue these leads starting April 3; nearly 101,000 QuickSite and QuickFlex leads are currently in service.

Thirty-nine cases of externalized conductors in the QuickSite and QuickFlex leads have been confirmed. However, St. Jude said that the unipolar version of the QuickSite lead (model 1056K), the QuickFlex (model 1258T) and Quartet (1458Q) leads are not included in this advisory.

“The root failure mechanism of externalized conductors observed on QuickSite and QuickFlex leads has been identified as mechanical stress at the distal silicone insulation portion of the lead leading to the insulation abrasion,” St. Jude said in a statement.

Additionally, the company said that the reported rate of externalized conductors in the QuickSite and QuickFlex leads is 2.3 per 10,000 leads.

“In the event that a QuickSite or QuickFlex LV CRT lead experiences an externalized conductor, the likelihood of an electrical anomaly or adverse clinical event is low,” according to St. Jude. “There are no known risk factors for cable externalization."

The company, along with the Medical Advisory Board, has recommended physicians continue to monitor patients implanted with these devices.