Trends in severity of hospitalized myocardial infarction: The Atherosclerosis Risk in Communities (ARIC) Study, 1987-1994

Background Declining mortality rates of coronary heart disease in the United States could be attributable to declining incidence, declining severity, and/or improvements in treatment. Methods We examined trends in severity of patients hospitalized for myocardial infarction to characterize its contribution to this decline by using data from the Atherosclerosis Risk in Communities (ARIC) study. Results No significant change in the proportion having systolic blood pressure <100 mm Hg or an abnormal pulse at presentation was noted. The proportion with ST-segment elevation on the initial electracardiogram increased 10% per year (P <.001), and the proportion with a diagnostic or evolving diagnostic electrocardiogram abnormality increased 4% per year (P <.01); the proportion that had a new Q-wave infarction develop remained unchanged. The mean peak creatine kinase level decreased 5% per year (P <.001), the proportion with abnormal enzyme levels decreased 10% per year (P <.001), and the proportion that met criteria for definite myocardial infarction decreased 4% per year (P <.05). The proportion that had cardiogenic shock decreased 10.9% per year (P <.01), but the proportion that had an acute episode of congestive heart failure was stable. Conclusions With stable hemodynamic indicators, worsening electrocardiographic indicators, and improving enzymatic indicators, these results provide mixed support for decreases in the severity of myocardial infarction.