By Melodie Warner
St. Jude Medical Inc. (STJ) said early results from the Riata lead evaluation study indicate externalized conductors occur less frequently in thinner leads and the rates were consistent with other published studies.
The medical-device company voluntarily stopped selling its Riata and Riata ST silicone defibrillation leads in December 2010 following reports of wires wearing through their silicone covering.
The latest study's Phase 1 results found that externalized conductors--or the appearance on x-ray or fluoroscopy of conductors outside of the lead body--occurred in 9.3% of the smaller-diameter Riata ST 7F leads in the study, and in 24% of the larger-diameter Riata 8F leads.
The study enrolled 724 patients at 20 sites in the U.S. and Canada. An additional 51 patients were enrolled at three sites in Japan and those results are awaiting final adjudication and will be reported at a later date.
"The rates of externalized conductors in this study are consistent with other published studies involving fluoroscopic screening of patients with Riata leads," said Mark Carlson, chief medical officer and senior vice president of clinical affairs for the St. Jude Medical Cardiac Rhythm Management Division. "This study also reinforces that externalized conductors are more prevalent in larger-diameter Riata leads."
The study will continue to evaluate the performance of Riata leads over the next two years to determine how they function over time.
The company said in other clinical studies, the majority of leads with an externalized conductor continued to function normally.
St. Jude Medical said its independent leads medical advisory board has reviewed the results and recommends no changes to existing patient management recommendations.
The company said it will now focus on collecting longer-term data in the second phase of this study in order to provide physicians "timely and relevant clinical data to best support their patient management decisions."
In April, St. Jude said it was seeking a retraction of a study published in the February edition of the Heart Rhythm Journal medical periodical that found heart-defibrillator wires made by the company were responsible for at least 20 deaths, citing inaccurate facts and biased analysis. The study also purported the deaths allegedly caused by Riata malfunctions were about nine times greater than a competing lead called the Quattro Secure made by Medtronic Inc. (MDT).
Write to Melodie Warner at firstname.lastname@example.org