Altitude and arteriosclerotic heart disease mortality in white residents of 99 of the 100 largest cities in the United States

Geographical differences in cardiovascular mortality within the United States have not yet been adequately explained. Age-adjusted rates of mortality due to arteriosclerotic heart disease in the white residents of 99 of the 100 largest cities in the United States were compared with the hardness of the finished drinking water of the municipal supplies and with the altitude of residence above sea level. This mortality showed a higher negative correlation with the latter variable than with the former for white residents. These findings are coherent with results from other epidemiological studies showing decreased cardiovascular disease mortality at high altitude. Animal experiments and pathological observations in the literature make it likely that hypoxia causes an increase of collateral circulation in the coronary arteries. However, alternative explanations of the presently observed relationship have not been excluded by our study.