Annals of clinical research
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The association of meterological factors with acute myocardial infarction was studied within a one-year period in Helsinki. Seasonal variation was found with the lowest incidence in summer and the highest in late autumn. Environmental temperature was not significantly correlated with the incidence of myocardial infarction but the case fatality rate was higher on coldest days. ⋯ The incidence of infarction did not increase on typical cold and dry winter days. The most favourable weather was warm, dry and stable summer weather. The difference in incidences between most and least favourable weather types was three-fold.