The Rise of Cardiac Diseases
Changes in disease classification reflect both social and biological events. Even after accounting for changes in definitions, it seems clear that there has been a significant change in the types of disease from which people die.
During the twentieth century, our methods of classification have helped to make heart disease an increasingly important cause of death and disability. The predominant causes of sickness and death were once infectious diseases. In the mid-nineteenth century, for example, tuberculosis accounted for an estimated one-seventh of all deaths in western Europe. Yet the impact of infectious diseases has subsequently decreased in many parts of the world, partly because of improved living conditions and partly because of improved treatment with antibiotics.Two major forms of heart disease related to infectious agents have undergone a dramatic shift in pattern. Rheumatic fever, a disease related to infection with a specific streptococcus that can cause heart disease, was once a major cause of heart disease in Western countries. In industrialized countries, it has now become a relatively minor cause of heart disease, with a prevalence as low as 0.6 per 1,000 school-aged children in the United States and 0.7 per 1,000 in Japan. In other parts of the world, however, rheumatic heart disease remains a serious problem; the prevalence per 1,000 school-aged children has been reported to be in the range of 15 to 20 for Algeria, Bolivia, and Thailand.
Endocarditis, an infection of the heart valves, carried an almost certain death sentence before the advent of antibiotics. At one time, endocarditis in the United States primarily afflicted people with valvular disease caused by rheumatic heart disease. The changing pattern of this illness reflects changes not only in treatment but also in life-style. Now endocarditis is far more often a disease of intravenous drug abusers.
Another result of the decline of infectious diseases has been an increase in the average life expectancy. People now live long enough to succumb to diseases that take time to develop, which is the case with many cardiac diseases, particularly coronary heart disease. And again life-styles have changed. A lack of physical activity and a change in diet may contribute to the increased incidence of coronary heart disease.
Finally, the development of cardiology as a major field of specialization in the United States is indebted in large part to the earlier campaign against tuberculosis, which prompted the development of the voluntary health movement. The first U.S. cardiology organization, the American Heart Association, drew substantial intellectual, organizational, and financial support from the antituberculosis movement, primarily the National Tuberculosis Association.