Defining Chronic Myocyte Injury With hs-cTnT: The Importance of Serial Measurements and the Value of hs-cTnI

Abstract

Background: There is increasing awareness of the differing characteristics of troponin subunits.

Case summary: We present a case where an elevation of high-sensitivity troponin T (hs-cTnT) (>6× 99th percentile) beyond the single-sample rule-in threshold led to an erroneous diagnosis of acute coronary syndrome (ACS). After exhaustive biochemical tests proving chronic myocardial injury, we also determined that 4 different high sensitivity assays for troponin I revealed values well below their respective 99th percentiles. This uniquely highlights the difference in troponin subunit characteristics in chronic myocyte injury and dispels any notion that the difference relates to assay characteristics.

Discussion: Chronic elevations of hs-cTnT can be sufficiently large to surpass single rule-in thresholds in some ACS pathways, but this case stresses the importance of the delta value regardless of the degree of elevation of the presentation sample. In cases of diagnostic doubt for ACS, clinicians should consider measuring hs-cTnI as an alternative troponin.

Keywords: chronic myocyte injury; high-sensitivity troponin subtypes; suspected acute coronary syndromes.