Utility of routine follow‐up defibrillation safety margin testing in young patients with epicardial implantable cardioverter‐defibrillators.

Background: Routine defibrillation threshold testing (DFT) of transvenous implantable defibrillators (ICDs) has largely been in decline. In patients with non‐transvenous ICDs that utilize subcutaneous and pleural ICD leads, serial DFT testing can detect a significant number of failures. Data about the utility of follow‐up defibrillation safety margin testing (DSM) testing in pediatric patients and young adults with an epicardial ICD are lacking. Methods: Patients aged < 25 years old who underwent epicardial ICD placement at Mayo Clinic from 2014 to 2023 with at least one follow‐up DSM test were included. The patients were divided into a "routine" (R) and "clinically indicated" (CI) group based on the index of clinical concern. Inadequate DSM was defined as unsuccessful defibrillation at an output of less than 10 J below the maximum output of the device. The purpose of this study was to assess the utility of follow‐up DSM testing. Results: An epicardial ICD system was placed in 122 patients. A total of 26 patients met inclusion criteria and underwent a total of 47 DSM follow up tests. Inadequate DSM occurred in 1/33 (3%) in the R group and 2/14 (14%) DSM tests in the CI group. The median follow‐up period was 54 and 36 months for the R and CI group, respectively. Conclusions: Our data suggest that epicardial ICDs are reliable and routine follow‐up DSM testing may not be necessary for all patients. DSM testing should be performed in individuals with epicardial ICD systems when there is clinical concern about lead or coil performance. [ABSTRACT FROM AUTHOR]