Evaluation of agonal artifacts in the myocardium using a combination of histological stains and immunohistochemistry

The problem of discrimination between agonal artifacts and intravital ischemic myocardial lesions was studied with four histochemical stains [hematoxylin-eosin, Mallory's phosphotungstic acid hematoxylin (PTAH), modified luxol fast blue, and Lie's hematoxylin basic fuchsin picric acid (HBFP)] and with immunohistochemistry using two antibodies (antimyoglobin and anti-C5b-9). Seventy-five forensic autopsy cases were divided into six groups designed to represent successively shorter periods of agonal myocardial ischemia: (a) sudden deaths with coronary artery disease, macroscopically visible myocardial infarction, and/or fresh coronary thrombus; (b) unexplained sudden deaths without coronary artery disease; (c) accidental CO poisoning; (d) suicidal CO poisoning in cars; (e) suicidal hangings; and (f) instant traumatic deaths, i.e., total brainstem laceration or rupture of the thoracic aorta. From each heart, five pieces were removed from standardized locations, and six parallel sections were stained with each method (i.e., 30 sections from each heart). Hematoxylin-eosin and anti-C5b-9 were only positive in the first three groups, thus indicating specificity for intravital necrotic changes. The other staining methods were "positive" in one or more cases in all six groups, thus implicating a high degree of sensitivity for artifactual, agonal ischemic changes. The latter methods cannot be used alone in the diagnosis of myocardial infarction. By staining parallel sections with different stains and antibodies, it seems possible to estimate the relative length of the agonal period in cardiac and noncardiac deaths.