Boston Scientific has issued a letter to customers warning that certain ENDOTAK RELIANCE defibrillation leads with expanded polytetrafluoroethylene (ePTFE) coated coils may impact shock efficacy and/or require early replacement, and have been linked to injuries and death.
The manufacturer told healthcare providers that device leads coated with ePTFE are showing signs of calcification, resulting in a pattern of gradually rising low-voltage shock impedance (LVSI) measurements, reports Medpage Today.
Calcification is therefore potentially making some defibrillation lead coils electrically insulated, impacting shock efficacy and/or requiring early replacement.
The most common harm is early lead replacement, and the most serious harm is death or need for cardiac resuscitation due to non-conversion of a sustained ventricular arrhythmia from a reduced shock energy caused by high impedance.
An early FDA alert warned that as of 24 July, there had been 386 reported serious injuries and 16 patient deaths associated with this issue.
Implicated are several models of Endotak Reliance, Reliance 4-Site, and Reliance 4-Front leads, all used for pacing, rate-sensing, and delivery of cardioversion and defibrillation shocks when connected to a compatible pulse generator.
Boston Scientific is recommending continued follow-up of defibrillation systems with ePTFE leads via in-person or remote monitoring.
During these routine checks, healthcare providers should determine the most recent approximate 28-day average LVSI that has not been influenced by the delivery of a shock, and should review high-voltage shock impedance (HVSI) for all shocks from the most recent episode since the last system check.
If lead replacement is planned, it is possible that the calcified leads may pose an increased risk of extraction-related complications.
An internal investigation by the company showed that ePTFE defibrillation leads are more prone to this shock coil calcification than other leads. Typically, the rise in LVSI can be observed roughly eight or more years after placement, according to the manufacturer.
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