INCIDENCE AND PREVALENCE OF RECOGNIZED AND UNRECOGNIZED MYOCARDIAL-INFARCTION IN WOMEN - THE REYKJAVIK STUDY

Aims The incidence and prevalence of recognised and unrecognised myoca rdial infarction were determined in the Icelandic cohort study of 13 0 00 women (the Reykjavik Study), followed for up to 29 years (mean 15 y ears). Methods and Results Women attending the Reykjavik Study, born b etween 1908 and 1935, were examined in five stages from 1968 to 1991. A health survey included history and ECG manifestations of coronary he art disease. Data retrieved from hospitals, autopsy records and death certificates identified 596 fatal and non-fatal myocardial infarctions to the end of 1992 (61 prior to examination, 320 non-fatal and 215 fa tal). The incidence of recognised myocardial infarction ranged from 22 cases/100 000/year at 35-39 years to 1800 cases/100 000/year at 75-79 years. The incidence of unrecognised myocardial infarction ranged fro m 1800 cases/100 000/year at 35 years to 219 cases/100 000/year at 75 years. Thirty-three percent of non-fatal myocardial infarctions were u nrecognised. More occurred in the younger age groups (40%) than in the older (27%). The prevalence of recognised myocardial infarction was i nfluenced by age and calendar year. In 1990, it was 1.3/1000 at 35 yea rs and 60/1000 at 75 years. Prevalence showed a time trend, tripling i n all age groups from 1968-1992. For unrecognised myocardial infarctio n, prevalence rose from 0.9/1000 at 35 years to 19.2/1000 at 75 years, although there was no evident time trend. Conclusion Myocardial infar ction in women is very age-dependent, with both incidence and prevalen ce increasing continuously and steeply with age. There was a significa nt trend for an increase in prevalence of recognised myocardial infarc tion from 1968 to 1992. The proportion of unrecognised non-fatal infar ctions ranged from 27% in the oldest age group to 40% in the youngest. On average, this form of coronary heart disease is as common as in me n.