Interest of TTC for the Early Diagnosis of Acute Myocardial Infarction at Autopsy

Ischemic heart disease is the leading cause of death worldwide and the leading cause of sudden cardiac death. However, its post-mortem diagnosis is particularly difficult because the gross examination of the heart is usually normal at the autopsy . The diagnosis is therefore often based on a set of indirect arguments, such as the patient's medical and clinical history and the degree of occlusion of the coronary arteries. The formal diagnosis of acute myocardial infarction (AMI) currently relies on standard histological examination. However, histological findings often require a prolonged survival time of several hours to be highlighted. Triphenyltetrazolium chloride (TTC) is a salt that reacts with lactate dehydrogenases contained in still viable myocardial cells, forming a red pigment visible to the naked eye, (1,3,5 triphenylformazan). Ischemia-induced cell death, which occurs within minutes of the causative event, is responsible for the leakage of lactate deshydrogenase into the extracellular medium and thus results in the absence of formazan formation in the infarcted area, which displays an easily identifiable pale unstained color. It has been suggested that the use of TTC would allow the identification of MI as early as one hour of survival in animal models, before the usual macroscopic and microscopic signs are visible. It could therefore represent an attractive forensic tool for the early diagnosis of AMI at the autopsy.