Understanding the circulating forms of cardiac troponin: insights for clinical practice

Abstract Ischemic heart disease remains the leading cause of death globally, with acute coronary syndrome (ACS) being the main reason for emergency hospital admissions and thus representing a significant health care issue worldwide. Cardiac troponin I (cTnI) and cardiac troponin T (cTnT) are widely recognized biomarkers of cardiomyocyte injury and the gold-standard biomarkers for diagnosing myocardial infarction (MI). High-sensitivity cardiac troponin (hs-cTn) assays have the ability to accurately detect low cTn concentrations and document minor increases. However, in addition to MI, various other pathophysiological states can trigger elevated cardiac troponin levels, thus creating potential challenges in the diagnostic process. As cTn released into the bloodstream exists in heterogeneous forms, improving our understanding and accurately characterizing these forms across various etiologies might hold clinical significance. In this review, we add to the field by offering an overview of research on possible circulating forms of cTn, the mechanisms of cTn elevation, and the clinical significance of cTn following conditions such as MI, endurance exercise, and chronic kidney disease, thus highlighting the importance and challenge of understanding of the circulating forms of cTn and possible strategies for cTn immunodetection.