Abstract 1204: Incidence of Myocardial Infarction: Impact of the Universal Definition in the Community
Background: The new definition of myocardial infarction (MI) based on troponin, was expected to modify incidence and outcomes by a degree to be determined.
Methods and results: MIs occurring in Olmsted County from 1987–2006 were validated by standardized criteria. CKMB was measured in all cases and troponin T in those from August 2000 onward. During this time, 2816 incident MIs (mean age 68±15 years, 43% women) occurred, including 1127 after introducing troponin; 25% of these met only the troponin-based definition. When including only cases meeting CKMB criteria, the incidence of MI declined by 1.1%/year (p=0.020; Figure⇓) and compared to 1987, the age and sex adjusted relative risk of experiencing an MI in 2006 was 0.80 (0.67, 0.97), indicating a 20% decline in incidence over 20 years. When cases defined only by troponin were included, the decline in incidence was no longer detectable (age and sex-adjusted incidence rate (95% CI) 186/100,000 (149–222) in 1987 vs 180/100,000 (151–129) in 2006). The 30-day fatality rate was higher in women and older persons but decreased over time (p=0.001). Compared to 1987, the age and sex-adjusted relative risk of death within 30 days for an MI occurring in 2006 was 0.42 (0.28, 0.63). Among 30-day survivors, survival did not improve (p=0.72), and cause of death shifted over time (p=0.04) from cardiovascular (CV) to non-CV. The outcomes were similar irrespective of the inclusion of cases meeting only troponin criteria.
Conclusion: The universal definition of MI masked the temporal decline in incidence without a detectable change in outcomes. While 30-day case fatality improved, long term survival did not change and more deaths were related to non-CV causes.