Immunohistochemical study of fibronectin for postmortem diagnosis of early myocardial infarction.

The postmortem diagnosis of early myocardial infarction has been a puzzling problem in forensic practice. In the present study, an immunohistochemical study of fibronectin (FN) was performed for the first time on 34 autopsy hearts to determine early myocardial infarction with streptavidin/biotin/peroxidase technique. Five cases of definite myocardial infarction showed positive FN staining of cardiomyocytes; of 18 cases where early myocardial infarction was suspected, positive FN staining of cardiomyocytes was found in 15 cases, but no such staining was seen in 11 non-cardiac death controls. The results led to the conclusion that positive FN staining in cardiomyocytes is a reliable marker of acute myocardial infarction and could be used as a new, sensitive method for the postmortem diagnosis of early myocardial infarction. It is worth noting that all cases in this study were autopsied between 8 h and 4 days after death and 5 cases had been fixed in 10% formalin for over 10 years. FN immunohistochemistry still gave satisfactory results in those cases. It seemed that FN was not affected by postmortem autolysis and formalin-fixation and could be used in routine forensic practice, especially for retrospective analysis of cases.