Coronary Disease Morbidity and Mortality in a Population

BACKGROUND:

Cardiovascular disease remains the leading cause of death in the U.S. Despite an encouraging
decline in age-adjusted coronary heart disease (CHD) mortality, prevalent CHD continues to
represent a major health burden, particularly in the elderly population. Most community
surveillance programs, however, cannot fully characterize this problem because they are
restricted to an upper age limit of 74 years and thus do not include the events occurring in
an increasingly growing part of the population. Observational studies have questioned the
existence of a change over time in the prevalence of anatomic coronary disease either at
post-mortem examination or at coronary angiography. This remains to be further examined in
a population-based setting. In addition, the natural history of myocardial infarction (MI)
in the reperfusion area is unknown; in particular, there are no population-based data on the
incidence of post-MI heart failure.

DESIGN NARRATIVE:

The records of all Olmsted County residents with a hospital discharge diagnosis of MI
between 1979 and 1999 were reviewed, and standard epidemiologic MI validation criteria were
applied; post-MI outcome over time was determined, including post-MI heart failure, angina,
30 day case fatality and long-term survival. In parallel with the analysis of time trends
in CHD mortality, the autopsy reports were reviewed to examine whether the prevalence of
coronary disease at autopsy has changed over time. These studies provided an assessment of
the clinical and anatomical manifestations of CHD, including the outcome of acute MI, over a
time period characterized by intensified primary prevention efforts and major changes in the
treatment of acute CHD.

The study was renewed in July 2002 to continue surveillance of acute coronary heart disease
events in order to address issues surrounding the diagnostic precision and risk
stratification potential of troponin and high sensitivity C reactive protein (CRP) and to
monitor secular trends in severity and treatment modalities. Novel approaches to the
procurement of carefully timed blood samples allow direct measurement of the increase in
number of cases of myocardial infarction using the new biomarker, troponin. An examination
will be made of the prognostic value of quantitative peak troponin measured at 24 to 36
hours and high sensitivity C reactive protein measured early after symptom onset in the
myocardial infarction cohort.

All residents of Olmsted County, MN who are hospitalized and have an elevated Troponin
level.