Evaluation of new predictive scores for sudden cardiac death in childhood hypertrophic cardiomyopathy in a French cohort

Background. – Hypertrophic cardiomyopathy (HCM) is rare in children, and sudden cardiac death (SCD) is difficult to predict. Two prognostic scores – HCM Risk-Kids and Precision Medicine for Cardiomyopathy (PRIMaCY) – were developed to assess the risk of SCD in the next 5 years in children with HCM.Aims. – To test the ability of these scores to predict SCD in children with HCM. Also, to identify factors associated with a severe cardiac rhythmic event (SCRE) (ventricular fibrillation, sustained ventricular tachycardia, heart transplant for rhythmic reasons or SCD).Methods. – Retrospective, multicentre, observational study at 10 medical centres in the Nord-Pas-de-Calais region, France.Results. – This study included 72 paediatric patients with HCM during 2009–2019 who were followed for a median (interquartile range [IQR]) of 8.5 (5.0–16.2) years. Eleven patients (15.3%) presented with SCRE. HCM Risk-Kids was high, with a median (IQR) score of 6.2% (2.1–12.8%; significant threshold ≥ 6.0%) and the PRIMaCY median (IQR) score was 7.1% (2.6–15.0%; significant threshold ≥ 8.3%). The positive predictive value was only 27.1% (95% confidence interval [CI] 21.5–32.5%) for HCM Risk-Kids (with a threshold of ≥ 6.0%) and 33.2% (95% CI 27.1–38.9%) for the PRIMaCY score (with a threshold of ≥ 8.3%). The negative predictive values were 95.4% (95% CI 92.3–97.7%) and 93.0% (95% CI 89.8–96.2%), respectively. Three of 28 patients with an implantable cardioverter defibrillator (ICD) experienced complications (including inappropriate shocks).Conclusion. – HCM Risk-Kids and the PRIMaCY score have low positive predictive values to predict SCD in paediatric patients. If used alone, they could increase the rate of ICD implantation and thus ICD complications. Therefore, the scores should be used in combination with other data (genetic and magnetic resonance imaging results).