Autopsy Cardiac Troponin I Plasma Levels Can Be Elevated in Myocardial Infarction Type 3: A Proposal to Modify the Definition of Myocardial Infarction Type 3.

AIMS: The definition of myocardial infarction (MI) type 3 does not include the possible elevation of postmortem biomarkers if measured at autopsy. We determined postmortem cardiac troponin I (cTnI) levels in plasma samples obtained at autopsy in patients who died from MI type 3 to determine whether cTnI plasma levels may be elevated. METHODS AND RESULTS: Using a chemiluminescent microparticle immunoassay system, we determined postmortem cTnI plasma levels at autopsy performed within 24 hours of death in every decedent who died from MI type 3, confirmed by an autopsy. Over 2 years, autopsy confirmed 52 decedents who died from MI type 3 due to coronary atherosclerotic disease. The age range and mean age were 40 to 78 and 60.6 years, respectively, 38 (73%) men and 14 (27%) women. Ten percent of the decedents exhibited postmortem cTnI plasma levels that were within the normal reference levels (0.01-0.30 ng/mL). Ninety percent of the decedents exhibited elevated cTnI plasma levels at autopsy, which ranged from 0.31 to greater than 4400 ng/mL. Sixty-nine percent of our decedents showed severe/significant (75%-100%) luminal occlusion in 2 or 3 major coronary arteries. CONCLUSIONS: If cTnI plasma levels are measured in autopsy blood samples after sudden and unexpected death due to MI type 3, highly elevated cTnI plasma levels may be detected. We propose that the current MI type 3 definition be slightly modified to include the possible elevation of cTnI plasma levels if measured at autopsy in the immediate postmortem period.