Mortality from hypertrophic cardiomyopathy in England and Wales: clinical and screening implications.

OBJECTIVES: Hypertrophic cardiomyopathy is considered a relatively common cause of death in the young. Screening for the disorder has been advocated, but its potential value cannot be assessed because the number of deaths in asymptomatic cases in the general population has not been investigated. We determined the annual number of deaths (and death rates) from hypertrophic cardiomyopathy in England and Wales according to age, sex and the presence or absence of symptoms so that an affected individual's risk of dying from the disorder and the implications of screening could be assessed.
METHODS: Ascertainment of all deaths from hypertrophic cardiomyopathy over a 3-year period (1996-1998), using death certification data from the Office of National Statistics. Deaths in people without symptoms were identified from coroner's reports and correspondence with pathologists who conducted the necropsies.
RESULTS: There were 184 deaths per year from hypertrophic cardiomyopathy in England and Wales (about 15% of all deaths from cardiomyopathy) of which one third (65) were in people without symptoms. Most (110) of the 184 deaths each year were in people over age 55. Under age 55 there were only 37 deaths each year in asymptomatic people, out of an estimated 60,000 people with the disorder in the population. Of the 37 deaths, 14 (20%) occurred in relation to physical activity and 2 after competitive sport.
CONCLUSIONS: In young people without symptoms hypertrophic cardiomyopathy is fairly common (1 in 500) but it rarely causes death; the case-fatality rate is about 6 per 10,000 per year. Current risk estimates from the study of patients in tertiary referral centers or general hospital clinics (420 and 110 deaths per 10,000 per year, respectively) are not applicable to asymptomatic people in the general population; such people, if incidentally identified can be reassured of their low risk of death. Screening would not be worthwhile unless a satisfactory test becomes available that can detect those few cases likely to die.