Fibronectin as an Immunohistochemical Marker for Postmortem Diagnosis of Myocardial Infarction

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Acute myocardial infarction is sometimes a diagnostic dilemma in forensic pathology. Our aim is to evaluate the efficacy of fibronectin by immunohistochemical methods for diagnosis of early myocardial infarction in heart autopsies.Three groups of cases selected from autopsied hearts submitted to the pathology department of legal medicine organization of Iran during years 2004-2007 which included 15 cases of definite myocardial infarction (positive control group), 18 cases of noncardiac death (negative control group) and 26 cases suspicious of myocardial infarction based on clinical presentation just before death, presence of marked stenosis in at least one major coronary artery and exclusion of other causes of death (suspicious group). Fibronectin staining was performed on sections prepared from all of the cases. With our proposed cut off value for fibronectin staining the sensitivity and specificity of this marker are 93.3% and 94.4%, respectively. This marker could also support the occurrence of myocardial infarction in 42% of our suspicious cases.We conclude that in spite of usefulness of this marker for detection of myocardial infarction, the results should be interpreted with caution.

Diagnosis of acute myocardial infarction is a challenging issue in forensic pathology. In autopsied hearts macroscopic findings of myocardial infarction accompanied by microscopic confirmation are the gold standards for diagnosis. However, the development of these changes requires time and in real practice we rarely are fortunate enough to see the typical cases. In most instances nothing other than significant narrowing of coronary arteries is found in favor of myocardial infarction. Use of an ancillary method is highly advocated in these situations. Application of triphenyltetrazolium chloride to the fresh myocardium, electron microscopy and some immunohistochemical markers including myoglobin, fatty acid binding protein (FABP), troponin, desmin, fibronectin, fibrinogen, C5b-9 and vascular endothelial growth factor (VEGF) are among many different diagnostic methods which have been used to address this diagnostic dilemma. The electron microscopy is not available in every pathology laboratory and requires comprehensive expertise. The triphenyltetrazolium chloride method requires fresh tissue and a great deal of suspicion at the time of autopsy. The immunohistochemical studies are, however, promising alternatives. The aim of the current study is to evaluate the diagnostic power of one of these immunohistochemical markers, the fibronectin, in suspicious cases of myocardial infarction.