Another factor militating against the reality of an “epidemic” was an increased likelihood that a death would be classified on a death certificate as coronary heart disease. Here the difficulty of correctly diagnosing cause of death is the crucial point. Most of us probably have some atherosclerotic lesions at this moment, although we may never feel symptoms. Confronted with the remains of someone who expired unexpectedly, medical examiners would likely write “(unexplained) sudden death” on the death certificate. Such a death could well have been caused by atherosclerosis, but, as Levy suggested, physicians often go with the prevailing fashions when deciding on their ultimate diagnosis.

The proper identification of cause on death certificates is determined by the International Classification of Diseases, which has gone through numerous revisions since its introduction in 1893. In 1949, the ICD added a new category for arteriosclerotic heart disease.*4 That made a “great difference,” as was pointed out in a 1957 report by the American Heart Association:

The clinical diagnosis of coronary arterial heart disease dates substantially from the first decade of this century. No one questions the remarkable increase in the reported number of cases of this condition. Undoubtedly the wide use of the electrocardiogram in confirming clinical diagnosis and the inclusion in 1949 of Arteriosclerotic Heart Disease in the International List of Causes of Death play a role in what is often believed to be an actual increased “prevalence” of this disease. Further, in one year, 1948 to 1949, the effect of this revision was to raise coronary disease death rates by about 20 percent for white males and about 35 percent for white females.

In 1965, the ICD added another category for coronary heart disease—ischemic heart disease (IHD). Between 1949 and 1968, the proportion of heart-disease deaths attributed to either of these two new categories rose from 22 percent to 90 percent, while the percentage of deaths attributed to the other types of heart disease dropped from 78 percent to 10 percent. The proportion of deaths classified under all “diseases of the heart” has been steadily dropping since the late 1940s, contrary to the public perception. As a World Health Organization committee said in 2001 about reports of a worldwide “epidemic” of heart disease that followed on the heels of the apparent American epidemic, “much of the apparent increase in [coronary heart disease] mortality may simply be due to improvements in the quality of certification and more accurate diagnosis….”