Clinical presentation and long-term outcomes of infantile hypertrophic cardiomyopathy: a European multicentre study

Aims: Children presenting with hypertrophic cardiomyopathy (HCM) in infancy are reported to have a poor prognosis, but this heterogeneous group has not been systematically characterized. This study aimed to describe the aetiology, phenotype, and outcomes of infantile HCM in a well-characterized multicentre European cohort. Methods and results: Of 301 children diagnosed with infantile HCM between 1987 and 2019 presenting to 17 European centres [male n=187 (62.1%)], underlying aetiology was non-syndromic (n=138, 45.6%), RASopathy (n=101, 33.6%), or inborn error of metabolism (IEM) (n=49, 16.3%). The most common reasons for presentation were symptoms (n=77, 29.3%), which were more prevalent in those with syndromic disease (n=62, 61.4%, P&nbsp