July 19, 2012 — A report submitted to the U.S. Food and Drug Administration (FDA) on April 18 suggests that the St. Jude Durata defibrillator lead could fail in the same was as the St. Jude Riata defibrillator lead. The Riata was recalled in November 2011 after being linked to at least 20 deaths.
The problem with the St. Jude Riata defibrillator lead was that the metal cables could wear through the silicon insulation, and pop out (known as externalization). The cables can become damaged, causing the defibrillator to malfunction — it can deliver an unnecessary electrical shock or fail to shock when the heart has an irregular rhythm. Studies of the Riata, including one released earlier this week, suggest that as many as 30% of the Riata leads become externalized prematurely.
St. Jude replaced the Riata with the Durata, hoping that extra insulation on the thin-diameter defibrillator lead would fix the problem. Preliminary results show lower rates of failure. However, this recent adverse event report suggests that externalization can still occur with the Durata lead.
The doctor who submitted the report first became aware of the externalized wires after reviewing X-rays of the patient. The patient underwent surgery to remove the defective device, and the doctor confirmed that the lead wires had become externalized.
St. Jude responded to the report by conducting their own investigation. The company determined that the externalization occurred because the device was abrading against other structures in the body.
St. Jude defends the safety and effectiveness of the Durata defibrillator lead. Dr. Mark Carlson, the Chief Medical Officer of St. Jude Medical, said that “my only comment is that 2.4 years in my view is an early experience, not a mid-term experience. The event-free survival was >99%. Excluding dislogment and and perforations, namely conductor fractures, in over 8400 implant years. Now this is truly spectacular.”