Implantable cardioverter defibrillator therapy in paediatric patients for primary vs. secondary prevention

Aims The decisions about placing an ICD in a child are more difficult than in an adult due to longer expected lifespan and the complication risk. Young patients gain the most years from ICDs, despite higher risk of device-related complications. The secondary prevention ICD indication is clear, and device is implanted regardless of potential complications. For primary prevention, risk of sudden cardiac death and complications need to be evaluated. We aimed to compare outcomes for primary and secondary prevention ICDs.Methods and results Retrospective nationwide cohort study including paediatric patients identified from the Danish ICD registry with ICD implanted at an age <= 15 from 1982-21. Demographics, complications (composite of device-related infections or lead-failure requiring re-operation, mortality because of arrhythmia, or unknown cause), and mortality were retrieved from medical charts. Endpoint was appropriate therapy (shock or anti-tachycardia pacing for ventricular tachycardia or fibrillation). Of 72 receiving an ICD, the majority had channelopathies (n = 34) or structural heart diseases (n = 28). ICDs were implanted in 23 patients for primary prevention and 49 for secondary prevention, at median ages of 13.8 and 11.6 years (P-value 0.01), respectively. Median follow-up was 9.0 (interquartile ranges: 4.7-13.5) years. The 10-year cumulative incidence of first appropriate therapy was 70%, with complication and inappropriate therapy rates at 41% and 15%, respectively. No difference was observed between prevention groups for all outcomes. Six patients died during follow-up.Conclusion In children, two-thirds are secondary prevention ICDs. Children have higher appropriate therapy and complication rates than adults, while the inappropriate therapy rate was low. Graphical Abstract