9-Year Follow-Up of a Pediatric LQTS Patient With a Subcutaneous ICD: Considerations for ILR Monitoring

Long QT syndrome (LQTS) is a congenital arrhythmic disorder associated with sudden cardiac death. In patients at low to intermediate risk, implantable loop recorders (ILRs) are sometimes used for arrhythmic surveillance. Subcutaneous implantable cardioverter-defibrillators (S-ICDs) are considered in children, but long-term follow-up data remain limited.

A 9-year-old patient with genetically confirmed LQT1 initially received an ILR. After a syncopal event, an S-ICD was implanted using a 2-incision intermuscular and C-curve technique to accommodate anticipated growth. The S-ICD recorded a short episode of torsades de pointes (TdP) that was not detected by the ILR. After reprogramming with more permissive settings, both devices successfully detected subsequent TdP episodes. Over 9 years of follow-up, the S-ICD maintained stable sensing and function.

This case illustrates the diagnostic limitations of ILRs and demonstrates the feasibility and durability of growth-conscious S-ICD implantation in pediatric patients with LQTS.