ICD´s efficiency in a single centre paediatric population: rates of discharge, prevention of SCD and bridge to heart transplantation

BACKGROUND Despite sudden cardiac death is a rare phenomenon, the use of the implantable defibrillator (ICD) in pediatric age progressively increased in consideration of its life-saving role both in primary and secondary prevention for several cardiac conditions. There are recent validated recommendations for implantation in primary prevention in paediatric and CHD patients. Further, multiparametric arrhythmic risk calculators have been developed and are often inserted in new Guidelines to help physician during decision-making process. The HCM Risk-Kids score and PRIMaCY are the new two models to apply for considering an implantation in primary prevention for hypertrophic cardiomyopathy (HCM). The effectiveness of the ICD in terms of correct detection and treatment in well known, but few paediatric studies demonstrated its protective role as bridge to heart transplantation. In any case acute and chronic complications are not absent. The efforts to reduce the burden of paediatric inappropriate shocks (IS) led to the customizing of device programming, encouraging antiarrhythmic medications and considering SVT ablation. SVT and lead failure are the main causes of IS. AIMS The study aims to define our paediatric population in term of indications for implantation, device efficacy in preventing sudden cardiac death and bridge to heart transplantation, and ICD-related complications. METHODS 69 patients were enrolled (mean age: 14.27 years; range: 2.8-18; 78.3% male) in a time period between March 2000 and August 2024. All data about underlying cardiac disease, age at implantation, implant technique, burden of appropriate (AS) and inappropriate shocks, acute and chronic complications, transplanted patients and each device customizing programming were collected. The “primary” and “secondary” HCM group was analyzed. RESULTS Mostly patients suffered from cardiomyopathies (56.52%) and one third was HCM. The others are primary electrical disease(24.64%) and congenital heart disease (18.84%). 55% of patients were implanted in primary prevention, primarly those with CM and CHD. The majority of patients received endocardial ICDs (85%). 53.6% of patients experienced ventricular events, with 70.3% receiving appropriate therapy. 24.6% of patients were listed for OHT, with 94% successfully transplanted. The majority (65%) of OHT-listed patients experienced life-threatening ventricular arrhythmias that were effectively treated by ICDs, underscoring their role as a bridge to transplantation. All transplanted HCM patients carried sarcomeric gene mutations, potential genetic predictor for transplant decisions. 11.6% experienced IS, primarily due to misinterpreted supraventricular tachycardias or T-wave oversensing. Despite prolonged detection intervals and faster detection rates, SVTs still cause IS because of their fast heart rate fallen into shock windows. No difference in IS rates between single- and dual-chamber devices, supporting the evidence that an atrial lead does not necessarily improve SVT-VF/VT discrimination. The type of SCD prevention was a significant factor for IS (p=0.03). All HCMs presented non-syndromic disease exclusively and 73% experienced appropriate therapies, with 57% of these patients receiving ICDs for primary prevention. The HCM Risk-Kids score estimated a 5-year SCD risk of 6-15%,. MRI findings, particularly late gadolinium enhancement (LGE) and edema, correlated with acute phases of disease and arrhythmic risk and this is the first to suggest a role for edema in risk assessment. The “secondary” HCM cohort exhibited exclusively sarcomeric.mutations. CONCLUSIONS ICDs effectively prevent SCD and play a role of bridge to heart transplantation, with a low incidence of complications, including IS. Further research is needed to evaluate the role of cardiac ablation and the use of genetic and imaging data, particularly edema, in risk stratification for HCM pediatric patients.