Premature battery depletion of EMBLEM subcutaneous implantable cardioverter-defibrillators

The EMBLEM subcutaneous implantable cardioverter defibrillator (S-ICD) has an expected longevity of 7 years. In August 2019, Boston Scientific released an advisory regarding a limited subset of similar to 400 S-ICDs that exhibited an increased likelihood of an electrical component malfunction causing accelerated battery depletion. We observed several cases of nonadvisory S-ICD early battery depletion and sought to systematically evaluate the cohort of EMBLEM devices implanted and followed in our medical center. Out of 118 nonadvisory EMBLEM S-ICDs with a median time to most recent follow-up after implant of 735 days (interquartile range 375-1219 days), there were four premature battery failures identified. Serial device interrogations showed a sudden reduction in battery life at 1 195, 1 205, 1 300, and 678 days after implant. The number of shocks delivered during the lifetime of the devices did not explain the premature depletion. There was a sudden departure from the gradual linear decrease in battery longevity observed over time. We are the first to report a signal of premature battery depletion among S-ICD EMBLEM devices that were not among the initial advisory devices. The prevalence of premature battery failure in our cohort was 3.4%, occurring at an average of 1 095 days. Following these reports, Boston Scientific issued an advisory on EMBLEM devices in December 2020 extending beyond the initial advisory subset. The current projected occurrence rate for hydrogen-induced accelerated battery depletion is 3.7% at 5 years. Increased surveillance of this potential device issue and mitigation to identify patients at risk for this is warranted.