Incidence and presentation of myocardial infarction in North Karelia, Finland.

A myocardial infarction (mi) register was started on May 1, 1972 in the county of North Karelia in Eastern Finland as a part of the North Karelia project. Information about all cases with a suspected acute MI among the North Karelian population are collected by the register. The principles of the register follow the recommendations of the WHO expert working group. Altogether 713 cases were registered between May 1, and Dec. 31,1972. The distribution of them into diagnostic categories was: "definite" 57%, "possible" 30%, "no acute MI" 8% and "insufficient information" 5%. Patients with no acute MI have been excluded in the results. About 47% of the male patients below 65 years had a history of previous MI. Most of the patients in the group had been heavy cigarette smokers, eating mainly butter as the fat in their diet. Overweight was rare among the male patients but not among the females. During the years preceding the attack, most of the patients had visited a physician and a pathological ECG had been recorded. The average time delay before hospital treatment was internationally relatively short. The 4 week fatality rate among patients below 65 years was 37% for males and 35% for females. These rates were slightly lower than those in the register material in Helsinki. The annual incidence rate per thousand for the age group 30-64 in North Karelia was 13.8 among males and 2.6 among females. The incidence rate increased continuously with age among males,among females it increased markedly only after the age of 60. The risk ratio between North Karelia and Helsinki for the age standardized incidence rates of males in the age group 30-64 was 1.38, and for respective mortality rates 1.21. Within North Karelia the highest incidence rate for males aged 30-64 was recorded in the rural area of Ilomantsi-Tuupovaara in the East.