St. Jude Medical‘s (NYSE:STJ) troubled Riata defibrillator leads were tied to 22 deaths related to short-circuits between high-voltage components, according to study conducted by the Minneapolis Heart Institute.
Among 133 deaths reported to the FDA’s MAUDE database of adverse events involving medical devices, 22 were caused by failures in the Riata or Riata ST leads, according to the study. By comparison, the authors noted that 5 deaths were caused by Medtronic’s (NYSE:MDT) Quattro Secure leads, which rely on a different coating material.
None of the Riata deaths were tied to "externalized conductors," which occurs when the leads’ wires poke through their insulation and was the prime reason for the Class I recall that began in December 2011.
"Riata and Riata ST ICD leads appear to be prone to high-voltage failures that have resulted in multiple deaths," the study’s authors concluded. "These failures often occurred abruptly, without warning, and they appeared to be caused by insulation defects that caused short-circuiting between high-voltage components."
The authors added that the study, accepted but not yet published by the Heart Rhythm Journal, was limited by the amount and nature of the information provided to the MAUDE database and by the absence of clinical data.
"Post-market surveillance in the United States relies on a passive reporting system, and thus adverse events are under-reported, particularly by physicians and hospitals," they wrote. "Therefore, the number of deaths in this study likely underestimates the actual number of deaths that have occurred."
St. Jude took exception to the study, finding fault with several of its factual conclusions, especially with the 22 deaths figure.
"As the manuscript noted, the MAUDE database often contains incomplete reports that do not fully reflect the conclusions following testing and review of the reported device malfunction. For this reason, it is often not possible to draw conclusions on the root cause of a failure mode based on a review of this source," chief medical officer Dr. Mark Carlson wrote in a response posted on the company’s site today. "Given this understanding of the lack of information and reliability of the MAUDE database, it is not surprising that the manuscript published this week is not entirely accurate."
According to St. Jude, 2 of the 22 deaths in the study were duplicates, 9 were the result of abrasions and another 9 can’t be assigned to specific failures because the failed leads were not returned to the company, leaving 2 that were definitively the result of electrical shorts.
Lead author Dr. Robert Hauser, who was 1 of the physicians who helped uncover problems with Guidant Corp.’s pacemakers after a patient he was treating died , is a vocal critic of the FDA’s policies regarding post-market surveillance and considers the high-profile Riata recall a defect that should have been caught sooner.
"Patients in the U.S. continue to be exposed to under-performing and potentially hazardous medical devices after they have been approved by the FDA, despite multiple recalls and some tragic adverse events," Hauser wrote in an article published in the New England Journal of Medicine earlier this month. "We are confronted once more with a critical clinical situation in which we have no scientifically valid information to guide us."
"St. Jude Medical has the most active post-market surveillance program in the industry for these leads," Carlson said at the time. "St. Jude Medical has a strong history of product safety and reliability, and we remain dedicated to developing technology and products that save and improve the lives of patients."
The new study could be bad news for the med-tech titan’s Durata leads, which the company has forwarded as a replacement for the recalled devices. The Riata leads use a silicone rubber coating that St. Jude said is "the industry’s most commonly used defibrillator lead insulation material over the past 20 years," but is also vulnerable to abrasion. The Durata leads rely on a new Optim insulation material that the company says is thicker and less prone to wear, potentially excluding them from the insulation issues highlighted in the study.
Durata seemed to be gaining ground with doctors, according to analysts for Leerink Swann, who wrote from the American College of Cardiology conference in Chicago this week.
"Our sense from speaking to physicians is that though still cautious, some physicians now seem a bit more comfortable that Durata will likely not have the externalized cable issue that Riata has had," the analysts wrote.
A turnaround in physician attitudes is good new for St. Paul, Minn.-based St. Jude. At the end of a 1-day summit on the Riata recall held in January, 44% of the 61 health care professionals in attendance said that they were concerned enough about Riata that they would not opt for the Durata lead in its stead.
STJ shares were down .45% to $44.11 as of about 1:15 p.m. today.