Review
The Epidemic of the 20th Century: Coronary Heart Disease

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Abstract

Heart disease was an uncommon cause of death in the US at the beginning of the 20th century. By mid-century it had become the commonest cause. After peaking in the mid-1960s, the number of heart disease deaths began a marked decline that has persisted to the present. The increase in heart disease deaths from the early 20th century until the 1960s was due to an increase in the prevalence of coronary atherosclerosis with resultant coronary heart disease, as documented by autopsy studies. This increase was associated with an increase in smoking and dietary changes leading to an increase in serum cholesterol levels. In addition, the ability to diagnose acute myocardial infarction with the aid of the electrocardiogram increased the recognition of coronary heart disease before death. The substantial decrease in coronary heart disease deaths after the mid-1960s is best explained by the decreased incidence, and case fatality rate, of acute myocardial infarction and a decrease in out-of-hospital sudden coronary heart disease deaths. These decreases are very likely explained by a decrease in coronary atherosclerosis due to primary prevention, and a decrease in the progression of nonobstructive coronary atherosclerosis to obstructive coronary heart disease due to efforts of primary and secondary prevention. In addition, more effective treatment of patients hospitalized with acute myocardial infarction has led to a substantial decrease in deaths due to acute myocardial infarction. It is very likely that the 20th century was the only century in which heart disease was the most common cause of death in America.

Section snippets

Decreasing Incidence of Coronary Atherosclerosis

The continuing decline in coronary heart disease deaths could be due to a decreasing prevalence of coronary atherosclerosis, which would lead to a decrease in the prevalence of coronary heart disease.

The Pathobiological Determinants of Atherosclerosis in Youth Study was a multi-institutional study of atherosclerosis in 15- to 34 year-old American men.9 Investigators from this study reported the results of 2876 autopsies performed in this population between 1987 and 1994. They demonstrated that

Decreasing Prevalence of Coronary Heart Disease?

The total prevalence of obstructive (symptomatic and asymptomatic) coronary heart disease in the US is unknown.

The Centers for Disease Control and Prevention (CDC) estimates the prevalence of coronary heart disease by compiling data from the Behavioral Risk Factor Surveillance System, which carries out telephone surveys of the noninstitutionalized US civilian population aged 18 years and older. They ask each survey respondent if a doctor, nurse, or other health professional has ever told them

Effective Secondary Prevention in Patients with Coronary Heart Disease

If secondary prevention in patients with symptomatic or asymptomatic coronary heart disease has been effective, it would cause a decrease in the frequency of myocardial infarction and sudden cardiac death.

Declines in Hospitalizations for Acute Myocardial Infarction

Based on US hospital discharge diagnoses, there has been a striking reduction in the frequency of patients hospitalized with acute myocardial infarction, as shown in Figure 3.

The hospitalization rate for acute myocardial infarction decreased from 175/10,000 in 1970 to 125/10,000 in 2010; a 29% relative decrease. Most of the decrease (32%) occurred between 2000 and 2010.8

The universal definition of acute myocardial infarction changed in 2000 from one based on creatine kinase-MB levels to one

Decreased Mortality in Patients with Acute Myocardial Infarction

In addition to the decreasing frequency of acute myocardial infarction in the US population, there has been a striking decrease in the case fatality rate of patients hospitalized with acute myocardial infarction, as shown in Figure 4. The hospital case fatality rate of patients younger than 65 years decreased from 16% in 1970 to <2% in 2010: an 88% relative decrease. In those aged 65 years and older, the decrease was from 38% in 1970 to 7% in 2010: an 82% relative decrease.8

The increased

Decreased Deaths Due to Myocardial Infarction

The decreased incidence of acute myocardial infarction and the decreased case fatality rate of patients hospitalized with acute myocardial infarction have resulted in a very significant decrease in deaths from it in the US. Deaths from acute myocardial infarction decreased from 672,769 in 1970 to 412,364 in 2010: a 39% decrease.8 These decreased deaths from acute myocardial infarction account for a significant portion of the decrease in deaths due to coronary heart disease.

Decreased Incidence of Sudden Death due to Coronary Heart Disease

More than half of the deaths from coronary heart disease in the US occur as cardiac arrest outside of hospitals or in emergency departments within 1 hour of the onset of symptoms27 and are termed sudden cardiac deaths. Zheng et al28 reported that 63% of all coronary heart disease deaths in 1998 were due to sudden cardiac death.

Sudden cardiac death is frequently the first evidence of the presence of coronary heart disease. Kuller et al23 reported that only 50% of patients with sudden cardiac

Conclusions

Most of the decline in coronary heart disease deaths is due to a decrease in deaths due to acute myocardial infarction and to a reduction in sudden cardiac deaths. These deaths have been reduced by primary prevention, which has decreased the incidence of coronary atherosclerosis, and primary and secondary prevention, which have reduced the progression of coronary atherosclerosis to obstructive coronary heart disease.

In addition, the remarkable reduction in the case fatality rate of acute

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    Funding: None.

    Conflicts of Interest: None.

    Authorship: All authors had access to the data and played a role in writing this manuscript.

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