Rapid Biochemical Analysis of Postmortem Serum and Myocardial Homogenates—An Exploratory Study

Postmortem diagnosis of sudden cardiac death (SCD) may escape detection due to the absence of thrombi and slow development of structural and immunohistochemical changes. Therefore, this study explores the possibility of analyzing relevant clinical chemistry biomarkers in myocardial homogenates and serum. Following an initial pilot study, myocardial samples from 113 autopsy cases were homogenized with distilled water, T-PER or 2 M urea. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK-MB), lactate dehydrogenase (LDH), orosomucoid and total protein were analyzed with an IndikoPlus and a subset was also analyzed with a Roche Cobas 8000 c701 analyzer, which also provided results for cardiac Troponin T, myoglobin and NT-proBNP. Although the yields varied with different extraction buffers depending on the analyte, distilled water was often as effective as T-PER and 2 M urea extraction for most analytes. Biomarker levels were consistently higher in the myocardial homogenates than in serum. Proteomic profiling on a subset confirmed higher concentrations of the cardiac markers in the tissue samples than in serum. Finally, we investigated whether selected markers could support the diagnosis of acute cardiac disease by classifying cases as sudden cardiac death (SCD) or controls. There was no significant difference in serum concentrations of the selected biomarkers between SCD cases and controls, whereas a significant loss of several markers was observed in SCD myocardial samples as compared to controls. Hence, our results suggest that analysis of tissue homogenates is likely better for detecting early ischemia, and we show that an in-house benchtop multi-analyzer can provide rapid results to assist the pathologist's decision-making during autopsy.