Immunohistochemical detection of very recent myocardial infarctions in humans with antibodies against heart-type fatty acid-binding protein.

Depletion of human heart-type fatty acid-binding protein (H-FABP) from cardiomyocytes in infarcted areas with varying postinfarction intervals was studied in 25 autopsy cases. In 23 autopsy cases myocardial infarction was the clinical diagnosis; 2 cases were noncardiac deaths and served as controls. Formaldehyde-fixed and paraffin-embedded myocardial tissue sections were stained immunohistochemically with antibodies to human H-FABP. H-FABP immunohistochemical findings were compared with those from conventional nitroblue tetrazolium (NBT) macroenzyme staining and conventional histochemical hematoxylin-eosin staining of sections of the same infarctions. In all cases of infarction confirmed by NBT staining, decreased or absent H-FABP immunostaining was observed. In 12 cases of clinically diagnosed infarction, H-FABP depletion could be demonstrated in areas that showed normal NBT staining. These findings strongly suggest that immunohistochemical staining with antibodies to H-FABP can confirm the clinical diagnosis or suspicion of early myocardial infarction. In both control cases no depletion of H-FABP was observed in cardiomyocytes in different myocardial tissue sections, and macroenzyme staining with NBT was normal. We conclude that H-FABP immunostaining may detect very recent ischemia/ infarction in human myocardium and can be applied in routine autopsy pathology.