Boston Scientific has issued a letter notifying affected customers that certain Endotak Reliance Defibrillation leads with expanded polytetrafluoroethylene (ePTFE) coated coils may impact shock efficacy and/or require early replacement, according to an FDA alert.
According to the FDA, 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 due to high impedance.
Per the FDA alert, Boston Scientific has reported 386 serious injuries and 16 patient deaths associated with this issue, as of July 24.
Boston Scientific Endotak Reliance leads are intended for pacing, rate-sensing, and delivery of cardioversion and defibrillation shocks when used with a compatible pulse generator, the FDA says.
The FDA says findings of a Boston Scientific investigation the devices include:
- While cracking of calcified ePTFE coating has been observed, calcification of the shock coil(s) does not compromise the physical or electrical integrity of the lead.
- A trend of gradually rising LVSI is correlated with shock coil calcification and is more prevalent with BSC RELIANCE ePTFE defibrillation leads compared to non-ePTFE defibrillation leads from BSC and other manufacturers; leads may be implanted for eight or more years prior to manifestation of this trend.
- The shock coil encapsulant material may exhibit a polarity bias with Reversed (RV+) polarity having an elevated high voltage shock impedance (HVSI) relative to Initial (RV-) polarity7. Reversed (RV+) polarity shocks are 4.5 times more likely to initiate a high, delivered shock impedance alert (Code-1005), and defibrillation systems programmed to Reversed (RV+) polarity exhibiting a gradual rising LVSI have a lower defibrillator-determined shock success rate.
- When managing leads with calcified coil(s), delivery of commanded shocks is neither effective at permanently mitigating rising impedance risk nor predictive of future impedance as LVSI may initially decrease but typically returns to pre-shock values in less than six months.
