Biochemical analysis and immunohistochemical determination of cardiac troponin for the postmortem diagnosis of myocardial damage.

Cardiac disease is the most common cause of sudden death in Western nations. In forensic practice there is a need for more sensitive diagnostic methods for the postmortem diagnosis of myocardial damage. The aim of this study was to analyse the diagnostic efficacy of biochemical markers in cadaver fluids in conjunction with histological studies and the immunohistochemical determination of cardiac troponin C (cTnC) and cardiac troponin T (cTnT) levels in myocardial tissue fixed in formol and included in paraffin. We studied 50 cadavers (43 males and 7 females) with a mean age of 47.5 years (SD 19.2; range 12 to 87 years). Cases were chosen according to the postmortem interval, cause of death, and circumstances of death. Pericardial fluid and serum were tested in duplicate for cardiac troponin I (cTn I), myoglobin and CKMB by immunoassay system using commercial kits. In myocardial tissue, histological studies were performed with hematoxylin and eosin (HE), Masson's trichrome staining and immunohistochemical techniques involving streptavidin-biotin-peroxidase were performed. The results pointed to statistically significant differences for all the biochemical markers in pericardial fluid. The highest levels were obtained in the group of cadavers who had died from myocardial infarction. The immunohistochemical expression of cTnC was detected in 86% of cases; it was strongly positive and usually diffuse. The expression of cTnT, was much less frequent (46% of cases) and less intense. It was concluded that the immunohistochemical determination of cTnC and cTnT levels in myocardial tissue may be used as an index of myocardium damage.