Prevalence of hypertrophic cardiomyopathy in a population-based sample of American Indians aged 51 to 77 years (the Strong Heart Study).

Recognition of the frequency with which hypertrophic cardiomyopathy (HC) occurs in the general population is critical to understanding its demographics and public health implications. However, few data are available for estimating HC prevalence in large populations of different age strata and ethnic or racial groups. The Strong Heart Study is a prospective, population-based epidemiologic survey of cardiovascular disease in residents of 13 geographically diverse American Indian communities. The study population was comprised of 3,501 subjects with echocardiograms performed in 1993 and 1995 to determine the prevalence of HC in middle-aged and older adult populations. Evidence of the HC phenotype was present in 8 previously undiagnosed patients (0.23%; 2 of 1,000) based on a left ventricular (LV) wall thickness >/=15 mm and a nondilated cavity that was not associated with another cardiac disease and was sufficient to produce the magnitude of hypertrophy evident. Ages were 51 to 77 years (mean 64 +/- 9). Four subjects were men and 4 were women, with prevalences by gender of 0.3% (3 of 1,000) and 0.18% (1.8 of 1,000), respectively. Maximum LV thicknesses were 19 to 29 mm (mean 21 +/- 3). Two subjects had mitral valve systolic anterior motion, which was sufficient to produce LV outflow obstruction at rest in 1 patient. Different electrocardiographic abnormalities were present in 5 subjects. In conclusion, clinically unrecognized HC was present in 1:500 of an aging American Indian cohort. This prevalence was similar to that reported in other general populations comprised of younger subjects of other races, offering evidence that HC is a relatively common genetic disease with widespread occurrence within the United States.