Phenotypic distribution and clinical burden of pediatric Hypertrophic Cardiomyopathy: insights from a longitudinal US claims database
J Conway, M Butzner, J Godown, E Papademetriou, X Liu, S Shreay, A DalalAbstract
Background
Pediatric hypertrophic cardiomyopathy (HCM) is rare and clinically heterogeneous. Contemporary real-world epidemiology data are severely limited but increasingly important as targeted therapies and clinical trials in pediatric HCM emerge. The aim of this study was to characterize the real-world epidemiology of pediatric HCM in the United States.
Methods
We performed a retrospective cohort study using Symphony medical and pharmacy longitudinal claims data to identify pediatric patients (≤18 years) with HCM (2015–2024). Patients were classified as obstructive (oHCM) or non-obstructive (nHCM) using ICD-10 diagnosis codes and required ≥12 months of continuous follow-up. We describe disease phenotype at presentation and symptomatology within ±3 months of the index encounter.
Results
Among 6,093 children and adolescents with HCM, 1,452 (24%) had obstructive physiology (oHCM) and 4,641 (76%) had non-obstructive disease (nHCM). Age at index diagnosis was slightly higher in oHCM than nHCM (mean 11.0 ± 5.1 vs 10.5 ± 5.3 years, p = 0.001), although median age was similar (both 12 years). Most patients were male (oHCM 66.9% vs nHCM 64.3%), with no meaningful sex difference between obstructive and non-obstructive disease (p = 0.07). Individual extracardiac conditions were uncommon; hypertension (oHCM 4.5% vs nHCM 6.1%), chronic pulmonary disease (oHCM 7.0% vs nHCM 7.5%), obesity (oHCM 6.3% vs nHCM 5.4%), and depression (oHCM 2.1% vs nHCM 3.6%). Most patients were asymptomatic, though symptoms were slightly more frequent in oHCM (symptomatic 28.7% vs 25.4% in nHCM, p = 0.01). The most common symptoms in both groups were chest pain (oHCM 10.7%, nHCM 9.7%), dyspnea (oHCM 8.5% vs nHCM 7.3%), heart-failure symptoms (oHCM 6.1% vs nHCM 5.9%), palpitations (oHCM 6.1% vs nHCM 4.7%), and syncope (oHCM 4.4% vs nHCM 4.6%; Figure).
Conclusions
In this large, real-world US cohort, approximately one in four children with HCM has obstructive disease, and roughly one in four is symptomatic. These findings define the size and characteristics of the pediatric oHCM population most likely to be targeted by emerging disease-modifying therapies and highlight a large, predominantly asymptomatic group in whom earlier intervention strategies may ultimately be evaluated.For image description, please refer to the figure legend and surrounding text.