The histopathologic evolution of myocardial infarction.

The histologic criteria for determining the age of a myocardial infarct were established by Mallory et al in 1939. The present study was undertaken to reexamine more quantitatively the evolution of myocardial infarction and to determine the prevalence of two recently described pathologic findings: wavy fibers and myocytolysis. The medical records of 1,155 patients dying of myocardial infarction from 1964 to 1973 were reviewed, and 192 cases in which the age of the infarct could be determined accurately were studied. As in the study by Mallory et al, acute inflammatory changes predominated during the first week, chronic inflammatory changes peaked during the second week, and proliferation of