Mild myocardial infarction-A classification problem in epidemiologic studies

摘要: In studies assessing the trends in coronary events, such as the World Health Organization (WHO) MONICA Project (multinational MONltoring of trends and determinants of CArdiovascular disease), the main emphasis has been on coronary deaths and non-fatal definite myocardial infarctions (Ml). It is, however, possible that the proportion of milder MIS may be increasing because of improvements in treatment and reductions in levels of risk factors. We used the Ml register data of the WHO MONICA Project to investigate several definitions for mild non-fatal MIS that would be applicable in various settings and could be used to assess trends in milder coronary events. Of 38 populations participating in the WHO MONICA Ml register study, more than half registered a sufficiently wide spectrum of events that it was possible to identify subsets of milder cases. The event rates and case-fatality rates of Ml are clearly dependent on the spectrum of non-fatal MIS, which are included. On clinical grounds we propose that the original MONICA category “non-fatal possible Ml” could be divided into two groups:“non-fatal probable Ml” and “prolonged chest pain.” Non-fatal probable MIS are cases, which in addition to “typical symptoms” have electrocardiogram(ECG) or enzyme changes suggesting cardiac ischemia, but not severe enough to fulli the criteria for non-fatal definite Ml. In more than half of the MONICA Collaborating Centers, the registration of Ml covers these milder events reasonably well. Proportions of non-fatal probable MIS vary less between populations than do proportions of non-fatal possible MIS. Also rates of non-fatal probable Ml are somewhat more …