St. Jude Medical will conduct a prospective study to evaluate the incidence and long-term performance of leads with externalized conductors that do not show electrical abnormalities to determine if there is a need to update recommendations, the company announced Nov. 28. The study, with enrollment set to begin this month, follows a reported increase in the estimated incidence rate for all-cause insulation failure on silicone endocardial defibrillation leads.
Sylmar, Calif.-based St Jude Medical released a medical device advisory detailing estimates of failures related to its Riata (8Fr) and Riata ST (7Fr) silicone endocardial defibrillation leads, noting that the estimated worldwide rate of all-cause abrasion increased from 0.47 percent in December 2010 to 0.63 percent as of this November. It stated that about 15 percent exhibited externalized conductors. The incidence rate was based on complaint and return reports.
“New peer-reviewed literature from one center site in Belfast, Northern Ireland, has indicated a 15 percent incidence rate of externalized conductors in Riata silicone leads (25 out of 165 patients) during fluoroscopic screening, including five leads (3 percent) that were associated with an electrical abnormality,” the advisory stated. “One significant finding [from] the Belfast experience is that a large percentage (35 percent) of the patients with Riata leads at the site had Riata (8Fr) single shock coil models.
“Analysis of worldwide complaint and returns information has identified that Riata (8Fr) single shock coil models exhibit a significantly higher incidence rate of externalized conductors than all other Riata (8Fr) and Riata ST (7Fr) models, which helps explain why the Belfast experience has shown such a high incidence rate.”
The company stated that the Riata ST 7Fr silicone leads, which feature design changes, have a lower externalized conductor incidence rate than the Riata 8Fr. “Although the Riata 8Fr and Riata ST 7Fr leads have the same insulation wall thicknesses, the 7Fr size was achieved by reducing the diameter of the inner coil and the diameter of the central lumen of the multi-lumen tubing,” they explained. “As a result, the conductor cables in Riata ST 7Fr are closer to the center of the lead body which reduces cable tension and the risk of externalized conductors.”
They added that the clinical implication of externalized conductors without electrical anomalies is not well understood.
St. Jude Medical’s medical advisory board recommended the study and is reviewing data.
The advisory addresses Riata (8Fr) models 1560, 1561, 1562, 1570, 1571, 1572, 1580, 1581, 1582, 1590, 1591, 1592; and Riata ST (7Fr) models 7000, 7001, 7002, 7010, 7011, 7040, 7041 and 7042. To view the November product performance report, click here.