Subcutaneous-implantable cardiac defibrillators (S-ICDs) are used increasingly to prevent sudden cardiac death in young patients. This study was set up to gain insight in the indications for S-ICD, possible complications, and their predictors and follow-up results. A multicentre, observational, retrospective, non-randomized, standard-of-care registry on S-ICD outcome in young patients with congenital heart diseases (CHDs), inherited arrhythmias (IAs), idiopathic ventricular fibrillation (IVF), and cardiomyopathies (CMPs). Anthropometry was registered as well as implantation technique, mid-term device-related complications, and incidence of appropriate/inappropriate shocks (IASs). Data are reported as median (interquartile range) or mean ± standard deviation. Eighty-one patients (47% CMPs, 20% CHD, 21% IVF, and 12% IA), aged 15 (14–17) years, with body mass index (BMI) 21.8 ± 3.8 kg/m², underwent S-ICD implantation (primary prevention in 59%). This was performed with two-incision technique in 81% and with a subcutaneous pocket in 59%. Shock and conditional zones were programmed at 250 (200–250) and 210 (180–240) b.p.m., respectively. No intraoperative complications occurred. Follow up was 19 (6–35) months: no defibrillation failure occurred, 17% of patients received appropriate shocks, 13% of patients received IAS (supraventricular tachycardias 40%, T-wave oversensing 40%, and non-cardiac oversensing 20%). Reprogramming, proper drug therapy, and surgical revision avoided further IAS. Complications requiring surgical revision occurred in 9% of patients, with higher risks in patients with three-incision procedures [hazard ratio (HR) 4.3, 95% confidence interval (95% CI) 0.5–34, P = 0.038] and BMI < 20 (HR 5.1, 95% CI 1–24, P = 0.031). This multicentre European paediatric registry showed good S-ICD efficacy and safety in young patients. Newer implantation techniques and BMI > 20 showed better outcome.

Aims: Premature ventricular contractions (PVCs) in paediatric patients often present a benign course. However, a minority of patients may develop left ventricular (LV) dysfunction, and risk factors are still under debate. The aim of this systematic review and meta-analysis was to analyse the prevalence of PVC-induced cardiomyopathy (CMP) and understand the risk factors in paediatric patients with PVCs and structurally normal hearts. Methods and results: A systematic search strategy was performed to identify original reports published between 1 January 2000 and 31 August 2024. Studies including adult patients and patients with cardiomyopathies, congenital heart diseases, or channelopathies were excluded. Seventeen studies were included and comprised 1.701 patients, with a mean age of 11.4 years. The mean burden of PVCs across the included studies was 16% (12.2–19.7). Left ventricular systolic dysfunction occurred in 40 patients, and they showed older age at presentation. Premature ventricular contraction burden emerged as significant risk factor for PVC-induced CMP (mean burden among patients with and without LV dysfunction 32.5 and 15.47%, respectively). Shorter coupling intervals and longer QRS duration were predictors in a few studies. No major adverse cardiovascular events occurred. Left ventricular dysfunction recovered in all but one patient after spontaneous or pharmacologically induced PVC reduction. Class IC drugs showed greater efficacy than other drugs. Conclusion: Premature ventricular contraction–induced CMP is rare in children, and PVC burden is the key determinant of risk. The threshold burden associated with LV dysfunction is higher in paediatric patients than in adults. Most patients with PVC-induced CMP experience normalization of LV function during follow-up.

Background: Right free wall (RFW) accessory pathways (APs) represent a relatively rare form of AP, and transcatheter (TC) ablation of these APs carries high procedural failure rates, both with radiofrequency (RF) and cryoenergy. The aim of this study was to report the outcomes of a minimally invasive approach in non-fluoroscopic 3D TC ablation of RFW APs, comparing cryoenergy and RF. Methods: Between March 2010 and March 2024, 62 consecutive patients with RFW APs underwent transcatheter ablation at our institution with a minimally invasive approach. The ablation results were analyzed and compared. Results: The overall acute success rate was 83.9% [52/62 patients; 25/28 (89.3%) for right lateral (RL) APs, 18/19 (94.7%) for right anterior–lateral (RAL) APs, and 9/15 (60.0%) for right posterior–lateral (RPL) APs, p = 0.014], with very limited fluoroscopy use and no complications. There were no significant differences in the acute success rates between the RF and cryoablation groups (32/37 vs. 20/25, p = 0.506). The median follow-up was 24.8 months (IQR 12.5–49.8), and 16 recurrences (30.8%) were observed (3 in the cryoablation group and 13 in the RF group, p = 0.068). The RAL localization of the AP and age > 12 years were predictors of ablation success in multivariate regression analysis. Conclusions: In children, a minimally invasive 3D TC ablation of RFW APs is a completely safe and quite effective approach, with better results for RAL and RL APs, poorer results for RPL APs, and no significant differences between cryoenergy and RF.

Background/Objectives: Transcatheter ablation assisted by three-dimensional (3D) electroanatomical mapping (EAM) is the elective treatment for atrioventricular nodal reentrant tachycardia (AVNRT) in children and adolescents. In this population of patients, the most frequently employed EAM strategies are the low-voltage bridge (LVB) strategy and sinus rhythm propagation mapping (SRPM). However, the exact pathophysiology and anatomy of the AVNRT reentrant circuits are still poorly understood. The aim of this study was to investigate the relationship between SRPM and LVB and to shed light on nodal physiology in children and adolescents affected by AVNRT. Methods: We retrospectively collected data on pediatric patients who underwent cryoablation for AVNRT assisted by high-density 3D EAM by using the LVB strategy; maps were reviewed by two independent electrophysiologists and the SRPM was described. SRPM was defined as typical when only one collision area was identified and atypical whenever either no or ≥ two collision areas were localized. Results: Twenty-eight consecutive patients (11.3 ± 3.3 years) were enrolled. All procedures were acutely successful. Overall, atypical SRPM was present in 10 patients (35.7%), and it did not correlate with the presence of multiple SPs or electrophysiological data. Moreover, we observed an imperfect concordance between SRPM and LVB (only in 10/18 patients). When SRPM and LVB were assessed in different locations, the LVB identified the effective cryoablation site in more cases than SRPM (4/8 vs. 1/8). Lastly, in cases of double collision, one collision area co-localized with the LVB and the effective cryoablation spot, whereas the other was located superiorly, closer to the His bundle. Conclusions: Atypical sinus rhythm propagation in the Koch’s triangle is a frequent finding in pediatric AVNRT patients. In this series, LVB showed closer concordance with the successful cryolesion site than retrospectively reconstructed SRPM.