A small study presented at the HRS 2013 meeting this week in Denver found wire externalization in nearly half of the 60 QuickSite or QuickFlex cardiac rhythm therapy leads made by St. Jude Medical (NYSE:STJ), but no indication of worsening heart failure symptoms, according to heartwire.
Dr. Umashankar Lakshmanadoss of the Guthrie Clinic in Sayre, Pa., told the website that his clinic found evidence of externalized wires – the same issue that’s been a pox on St. Jude since the 2010 recall of its Riata leads – in 27 of the 60 patients with either QuickSite or QuickFlex leads, or 45.0%. Of those leads with externalized wires, electrical problems developed in about 26% of cases, with the externalized wires showed changes including drops in impedance, increased pacing thresholds and intermittent loss of capture, according to heartwire.
But patients with and without externalized wires showed similar signs of heart failure, meaning that the compromised leads weren’t, in turn, further compromising the patients’ heart failure, the website reported.
St. Jude has pegged the incidence of wire externalization for the QuickSite/QuickFlex leads at 3%-4%. The St. Paul, Minn.-based medical device company pulled the leads after receiving reports of exposed wires in 39 patients.
Unlike the Riata leads, which St. Jude pulled in late 2010 because of the incidence of wire externalization, with the QuickSite/QuickFlex leads only the ends are coated with the silicon insulation believed to be the culprit, Lakshmanadoss told the website.
In his center’s study, the rates of wire externalization were 63% for the QuickSite 1056T, 29% for QuickSite 1058T and 36% for QuickFlex 1158T. The 7 externalized wires that showed electrical problems were all from QuickSite 1056T leads, according to heartwire.
Health and regulatory agencies have been keeping a close eye on St. Jude and its Riata leads since late last year when the medical device company yanked the Riata leads off the market, a move the FDA later slapped with Class I recall status.
Reports later emerged that the devices may be prone to internal short circuits that were more rare than the incidence of exposed wires but potentially more dangerous.
St. Jude has been busy ever since calming fears about its next-generation Durata leads. The company hosted several events at the Heart Rhythm Society meeting in Boston in May 2012, distancing Durata from its troubled forebears.