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 Unite d States could be attributable to declining incidence, declining severity, and/or improvements in treatment. Methods We examined trends in severity of patients hospitalized for myocard ial infarction to characterize its contribution to this decline by using da ta from the Atherosclerosis Risk in Communities (ARIC) study. Results No significant change in the proportion having systolic blood press ure <100 mm Hg or an abnormal pulse at presentation was noted. The proporti on with ST-segment elevation on the initial electracardiogram increased 10% per year (P <.001), and the proportion with a diagnostic or evolving diagn ostic electrocardiogram abnormality increased 4% per year (P <.01); the pro portion that had a new Q-wave infarction develop remained unchanged. The me an peak creatine kinase level decreased 5% per year (P <.001), the proporti on with abnormal enzyme levels decreased 10% per year (P <.001), and the pr oportion 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 conges tive heart failure was stable. Conclusions With stable hemodynamic indicators, worsening electrocardiograp hic indicators, and improving enzymatic indicators, these results provide m ixed support for decreases in the severity of myocardial infarction.