How great is the risk of sudden death caused by hypertrophic cardiomyopathy in childhood and adolescence?
The high annual mortality seen in the childhood cohort, peaking at over 9%, needs to be interpreted in the context that 74% of our cases had a clinical presentation of the disease in childhood and therefore likely belonged to the most malignant spectrum of HCM mutations, and only 26% were children diagnosed by routine screening. Overt clinical presentation of HCM in childhood is seen in only 2.9 per 100 000 age-specific population5 as distinct from the prevalence detected in echocardiographic population screening of young adults of 0.2%,1,2 i.e. childhood HCM represents at most only 1.5% of the total number of mutation carriers in the population. Thus among the total population of HCM mutation carriers including asymptomatic and undiagnosed cases the annual mortality is probably around 0.056% in the 8–16 year age range, and 0.028% in the 17–30 year age range as calculated from our cause of death registry figures. Thus, there seems to be no case for general population screening for HCM.
