It has been proposed that the reduction in the severity of acute myocardial infarction (MI) could explain the declining death rates for coronary heart disease in the United States. This hypothesis was tested in the Atherosclerotic Risk in Communities Study, which followed men and women 35 to 74 years of age from 1987 to 2002. Overall, the MI severity indicators suggested a significant reduction in the severity of MI during the follow-up. The proportion of MI cases with major ECG abnormalities decreased (declines in the proportion of patients with initial ST-segment elevation, with subsequent Q-waves and with any major Q wave). Maximum creatine kinase and creatine kinase-MB concentrations also declined during the 15-year follow-up, although maximum troponin I values remained stable in the later years. Moreover, a combined severity score (PREDICT) also declined over the years. The sex- and race-specific models paralleled the overall results of the study. The reduction in the severity of MI may therefore help explain the decline in death rates for coronary heart disease in the United States.
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