More than 79,000 people in the United States and 49,000 abroad still have the implants with the faulty wires
Implantable cardioverter defibrillators (ICDs): they’re lifesaving devices. Implanted in the chest to correct risky heart rhythms that can be fatal, they work by triggering electrical shocks to correct irregular heartbeats. Thin wires — known as leads — attach the defibrillator to the heart and are responsible for monitoring irregular beats, then triggering shocks to correct the irregularities when these occur.
But can defibrillators themselves be deadly? Yes, according to a new study by a prominent Minneapolis Heart Institute cardiologist published in a leading cardiology journal.
Defective wires or leads made by St. Jude Medical Inc. to connect defibrillators to hearts caused at least 20 patient deaths when they short-circuited, Dr. Robert Hauser says in an analysis published in the March 26 issue of the online journal, Heart Rhythm.
Dr. Robert Hauser and colleagues at the Minneapolis Heart Institute searched the Food and Drug Administration’s MAUDE database of reported device malfunctions, and found:
• 133 total deaths;
• Of these, five were caused by Quattro Secure failure;
• Twenty-two were caused by Riata or Riata ST ICD lead failure.
• Riata and Riata ST deaths were caused by short-circuits between high voltage components.
• No death was due to externalized conductors.
• The deaths occurred over the past five years.
About 79,000 of the Riata and Riata ST defibrillator “leads” are still implanted in patients in the United States — and 49,000 in patients abroad — although St. Jude stopped selling the devices in December 2010.
A year later, the manufacturer sent a letter to physicians warning that the devices could be faulty because of a tendency for the metal wires to wear through their silicone insulation covering. The company didn’t issue a recall, but the FDA later classified the letter as a recall. St. Jude introduced the Riata in 2002 and the Riata ST in 2005.
The company said the malfunctioning was caused by the coating over the wires — or externalized conductors — wearing and breaking down over time. It also claimed the issue had been fixed in its new devices — the Durata leads, which are insulated with polyurethane, instead of silicone.
But in their report, the authors say that the ICD Riata deaths “were typically caused by short-circuits between high voltage components” — which is tougher to detect than thinning insulation. “No death was due to externalized conductors,” they say.
“Electrical shorts are particularly lethal because they may occur abruptly during shock delivery, and thus failure to defibrillate may be the first and only sign of lead failure,” Dr. Hauser writes in his report in the Heart Rhythm.
The leads are prone to high-voltage failures that have resulted in death, Dr. Hauser explains. Insulation defects that resulted in short-circuiting between high-voltage components appeared to cause these failures.
Dr. Hauser, a practicing cardiologist at the Minneapolis Heart Institute, had previously played a major role in gathering and publicizing information about the defective ICD Riata leads, which led to the 2010 halt of their sale on the market.
In the new study, Dr. Hauser recorded 9.7 deaths caused by ICD Riata leads for every 100,000 devices implanted. But Dr. Hauser warns that since many reports don’t give enough detail to determine the cause of the malfunction, the figure could be even higher.
“The deaths are rare, but more frequent than you would expect. It’s another example of our flawed regulatory system,” Hauser told the Wall Street Journal.
“For the tens of thousands of patients worldwide who have Riata and Riata ST leads, there’s an urgent need for test methods that are capable of identifying life-threatening defects,” Dr. Hauser writes in Heart Rhythm.
The Minneapolis Heart Institute analysis was undertaken specifically to assess the deaths of heart patients using Riata and Riata ST that had been reported to the FDA in order to determine if they were due to lead malfunction. Dr. Hauser’s team also performed a similar study for leads of Quattro Secure defibrillators made by Minneapolis, Minnesota-based Medtronic, Inc.
It isn’t the first time that faulty leads have caused serious adverse effects and deaths. Leads have long been the biggest safety issue linked to implantable pacemakers and heart defibrillators. In 2007, Medtronic estimated that at least 13 patients died from receiving its heart defibrillators with faulty leads that could crack over time. In 2010, the company paid US$268 million to settle lawsuits brought by patients who had received the defective leads.
FDA system ‘flawed’
The Riata brand ICD leads underwent successful human clinical testing before they were approved in 2002 and 2005. Since then, about Riata and Riata ST leads 141,000 have been sold in the U.S. and 227,000 worldwide.
The FDA — the federal agency responsible for medical device safety — says it now requires more pre- and post-approval clinical data than it did when Riata leads were approved.
But “the problem is that our current passive postmarketing surveillance system fails to detect significant device defects before large patient populations have been exposed,” Dr. Hauser wrote in a commentary March 8 in the New England Journal of Medicine.
St. Jude takes action
St. Paul, Minnesota-based St. Jude challenged the accuracy of the analysis, including the number of patient deaths linked to its devices.
Dr. Mark Carlson, the company’s chief medical officer, said that because of duplicated paperwork, two additional deaths were reported, but the actual number was 20. The company also disputes the alleged cause of the malfunction.
St. Jude also announced on March 27 that it had appointed Population Health Research Institute, an academic health science research institute, to analyze data from three large, long-term registries of the newer Riata ST Optim and Durata leads to determine their performance.
“We are pleased to enlist PHRI to perform an independent analysis and validation of the Optim insulated defibrillation lead data from these three very large, long-term registries,” St. Jude says in a statement.
“We take our responsibilities as a leading manufacturer of cardiac rhythm management devices very seriously and recognize our primary responsibility as a global medical device manufacturer is to ensure that our devices are of the highest quality and that they function safely and properly,” says Dr. Carlson.
In December, the company had also launched its own 500-patient study to determine the failure rate for Riata leads and track them over time.
“The evidence we have at the moment indicates very few have electrical abnormalities and that they continue to perform normally,” Carlson tells the Associated Press. “But physicians and patients need to know whether that will continue to be the case.”
If you have a defibrillator from St. Jude, should you have it removed?
St. Jude — and the FDA — don’t recommend that. As surgery is more likely to trigger a malfunction than leaving the wires alone, doctors recommend regularly monitor patients, instead.
Dr. Hauser doesn’t advise surgical extraction as well — especially if no problems have arisen. Extraction can create infection or even torn tissue in a vein or the heart that can — although rarely — lead to fatal bleeding.
St. Jude Medical, Inc. is a US$16 billion global medical device company that sells into 100 countries and has over 20 operations and manufacturing facilities worldwide. Aside from artificial pacemakers and defibrillators for treating cardiac rhythm disorders, St. Jude develops and manufactures cardiac resynchronization therapy devices for heart failure; diagnostic and therapeutic electrophysiology catheters; introducers, catheters, and vascular closure devices for cardiology and vascular access; mechanical and tissue heart valves plus valve repair products; and spinal cord stimulators for intractable pain.
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