Medical device maker St. Jude Medical Inc. says a new study finds that most the reported Riata defibrillator lead erosion incidents were among its larger-diameter wires.
The Riata and Riata ST leads were recalled last year after they were associated with a high rate of failure caused by the conductive ends of the leads that connected an implanted cardiac defibrillator to the heart. The protective housing on the conductive ends was made of an inferior material and the lead ends were prone to break out of that protection and cause serious injuries or death to patients relying on them to provide shocks to keep a heart beating or to regulate the heart’s rhythm.
The Food and Drug Administration issued a Class I recall on St. Jude Riata and Riata ST leads in December 2011. They’ve been linked to more than 20 unexpected and preventable deaths due to the conductive ends breaking free from the silicone housing.
While St. Jude has taken some odd steps in reacting to research that highlights the dangers of these leads, new research from the company suggests it may be at least somewhat interested in providing information on those people who still face a risk using the Riata model of leads.
According to a Reuters report this week, St. Jude released initial results of an international study finding that larger-diameter Riata leads were more likely to fail due to “inside-out erosion” than those of a smaller diameter. The study was conducted mostly in the U.S. and Canada, involving nearly 800 patients. A group of 50 patients from Japan were also included.
On average, 24 percent of the large diameter Riata 8F leads failed due to inside-out erosion of the connective ends. Just 9.3 percent of the smaller Riata ST7F leads had failed during the “Phase One” portion of the study. The company said it is now focusing on long term effects of the Riata model of leads. Its research will continue for the next two years.
When the Riata leads fail due to erosion, they can fail to deliver the necessary shocks or deliver an unnecessary shock. The exposed wires can also cause abrasion of the heart and nearby tissue and muscles or other internal injuries.
Tens of thousands of people who need an implanted cardiac defibrillator still rely on the Riata model leads. More than 227,000 leads were implanted worldwide.
Since the recall, many wonder if they are prone to these leads suffering the same malfunctions that have resulted in unexpected deaths to more than 20 patients. In that time, several studies have attempted to find those at the highest risk of suffering a failure from a Riata lead.
A previous study suggested that leads not replaced at the same time the defibrillator generator was replaced are also prone to malfunction.
The decision to replace the leads also poses risks. At least two patients have died during surgeries to replace the Riata leads so determining who is most at risk appears to be paramount.