Assessment of cardiac biomarker "point-of-care" testing as postmortem diagnostic tool.

Abstract

In cardiac death, some entities, such as arrhythmia or nonocclusive myocardial ischemia, are not associated with clear and certain macroscopic surrogates of cardiac death. Cardiac biomarker point-of-care testing (POCT) seems suitable for further improving postmortem diagnostics in legal medicine casework. Considering the preanalytic phase, the present study aims to define criteria for blood samples suitable for POCT and assess the diagnostic performance of postmortem cardiac biomarker POCT. A fluorescent immunoassay device was used. The biomarkers assessed were myoglobin, brain-type natriuretic peptide (BNP), N-terminal proBNP, creatine kinase muscle-brain type, and cardiac troponin I. Blood was obtained from the intrapericardial inferior vena cava. In a prestudy, criteria for the selection of blood samples were established and the biomarker stability over time, test reliability and reproducibility of postmortem cardiac biomarker analyses were assessed. Afterward, blood samples from 150 autopsied individuals were evaluated for their diagnostic performance and compared with findings from autopsy as the postmortem diagnostic gold standard. In doing so, the assessed biomarkers provided valid and reproducible results. Cardiac troponin I yielded the highest sensitivity for detecting cardiac death, whereas BNP had the highest specificity and positive predictive value for detecting cardiac death. Markers of myocardial damage had better negative than positive predictive value. NT-proBNP and BNP POCT seem applicable to support diagnosis of death associated with congestive heart failure. Postmortem cardiac biomarker POCT results need to be interpreted in conjunction with all available information, i.e., autopsy findings, medical history, investigatory results, and other test results.