Do clinical features and natural history differ between preadolescent and later childhood presentation of nonsyndromic hypertrophic cardiomyopathy?
Early-onset childhood HCM has similar long-term mortality to later childhood onset, but adverse events occur at a younger age.
Early-onset childhood HCM is associated with a comparable symptom burden and cardiac phenotype as in patients presenting later in childhood. Long-term outcomes including mortality did not differ by age of presentation, but patients presenting at younger than 12 years experienced adverse events at younger ages.
Norrish et al. (Sun,) studied this question.