A combination of different techniques will be used for surveillance. CHD deaths will be obtained from death certificate data from the Minneapolis Department of Public Health. Census data will be used to construct the appropriate denominators. A major focus is based on in-hospital CHD morbidity and mortality. Data from the Minnesota Hospital and Health Care Partnership, which originally receives data from 22 of the 23 area hospitals, will be used to identify and validate acute myocardial infarction (AMI) cases. Census data will again be used to obtain the appropriate denominators. An important issue in assessing time trends in hospitalized AMI attack rate is the changing definitions used to identify cases over time. A specific issue in this regard is the increasing use of troponin levels that are more sensitive than previously used CKMB levels to identify cases. Thus, a validation study will be conducted comparing these two methodologies on the same subjects. The goal of the study is to obtain correction factors so that time trends in AMI attack rates are not influenced by differences in diagnostic criteria.