Paediatric experience with an extravascular implantable cardioverter defibrillator system

Abstract Background/Introduction Extravascular implantable cardioverter defibrillator (EV-ICD) systems have been developed to avoid transvenous leads while preserving pacing and defibrillation capabilities. Evidence in paediatric patients remains limited. Purpose To describe feasibility, acute performance, and short-term outcomes of EV-ICD implantation in paediatric patients. Methods We conducted a prospective observational case series including all consecutive paediatric patients who underwent EV-ICD implantation in 2025 at a tertiary centre. Demographics, underlying disease, procedural characteristics, sensing and pacing parameters, defibrillation testing, and follow-up outcomes were collected. Results Three patients (2 males) with a median age of 15 years (range 14–17) and body weight 38–65 kg underwent EV-ICD implantation for primary prevention: two with hypertrophic cardiomyopathy and one with Brugada syndrome, all carrying pathogenic sarcomeric or sodium channel variants. Devices were implanted using a subxiphoid midline substernal tunnelling approach under general plus regional anaesthesia with adjunctive cross-sectional imaging. Median procedure time was 94 minutes (range 61–130), with low fluoroscopy exposure (2.1, 6.0 and 2.4 minutes). Substernal tunnelling was successful at the first attempt in two patients and required three passes in one to optimise sensing. Acute R-wave amplitudes were 3.9, 1.3 and 1.5 mV; pacing thresholds 3.5–6.0 V; and high-voltage impedance 59–77 Ω. Defibrillation testing at 30 J was successful in all cases. No acute complications occurred. At a median follow-up of 5.0 months (range 4.5–8.0), R-wave amplitudes increased in all patients, electrical parameters remained within recommended ranges, and no appropriate or inappropriate therapies, infections, lead dislodgements or pocket complications were observed. Conclusion In this small prospective paediatric series, EV-ICD implantation was feasible and acutely safe, with stable or improving sensing and adequate defibrillation thresholds during early follow-up. EV-ICD systems may represent a valuable alternative to transvenous and subcutaneous defibrillators in selected paediatric patients and warrant confirmation in larger cohorts.Figure 1