Population trends in the incidence and outcomes of acute myocardial infarction.

BACKGROUND: Few studies have characterized recent population trends in the incidence and outcomes of myocardial infarction.

METHODS: We identified patients 30 years of age or older in a large, diverse, community-based population who were hospitalized for incident myocardial infarction between 1999 and 2008. Age- and sex-adjusted incidence rates were calculated for myocardial infarction overall and separately for ST-segment elevation and non-ST-segment elevation myocardial infarction. Patient characteristics, outpatient medications, and cardiac biomarker levels during hospitalization were identified from health plan databases, and 30-day mortality was ascertained from administrative databases, state death data, and Social Security Administration files.

RESULTS: We identified 46,086 hospitalizations for myocardial infarctions during 18,691,131 person-years of follow-up from 1999 to 2008. The age- and sex-adjusted incidence of myocardial infarction increased from 274 cases per 100,000 person-years in 1999 to 287 cases per 100,000 person-years in 2000, and it decreased each year thereafter, to 208 cases per 100,000 person-years in 2008, representing a 24% relative decrease over the study period. The age- and sex-adjusted incidence of ST-segment elevation myocardial infarction decreased throughout the study period (from 133 cases per 100,000 person-years in 1999 to 50 cases per 100,000 person-years in 2008, P<0.001 for linear trend). Thirty-day mortality was significantly lower in 2008 than in 1999 (adjusted odds ratio, 0.76; 95% confidence interval, 0.65 to 0.89).

CONCLUSIONS: Within a large community-based population, the incidence of myocardial infarction decreased significantly after 2000, and the incidence of ST-segment elevation myocardial infarction decreased markedly after 1999. Reductions in short-term case fatality rates for myocardial infarction appear to be driven, in part, by a decrease in the incidence of ST-segment elevation myocardial infarction and a lower rate of death after non-ST-segment elevation myocardial infarction.