Sudden cardiac death in a child with low-risk hypertrophic cardiomyopathy: limitations of current pediatric risk stratification-a case report.

Background: Hypertrophic cardiomyopathy (HCM) is characterized by marked phenotypic heterogeneity and remains a leading cause of sudden cardiac death (SCD) in young individuals. Risk stratification in children is particularly challenging, and current predictive models may underestimate arrhythmic risk in certain patients. Case summary: We report a familial case of sarcomeric HCM. A 41-year-old man presented with sustained ventricular tachycardia revealing asymmetric HCM, requiring implantable cardioverter-defibrillator (ICD) implantation, and later died from end-stage heart failure. His 12-year-old son was diagnosed with asymmetric HCM and was classified as low risk according to the HCM Risk-Kids score. At the time of evaluation, the child did not meet current guideline based criteria for ICD implantation. Nevertheless, SCD occurred during moderate physical exertion 2 months after diagnosis. Discussion: This familial case highlights the limitations of paediatric risk stratification scores at the individual level and underscores the need for a more individualized approach integrating family history, early phenotypic expression, advanced imaging findings, and genetic context beyond risk scores alone.