Differences in circulating cardiac troponin I and T in acute and chronic cardiac disease

Abstract

Abstract Background Clinical practice and guidelines assume that cardiac troponin I (cTnI) and cTnT are interchangeable, reflecting identical pathophysiological processes. However, it is unknown if cTnI and cTnT really are equivalent measures in different pathophysiological settings. Purpose To highlight potential differences in the release of cTnI and cTnT. Methods Large pooled cohort analysis including extensively characterized individuals, stratified into three groups: no cardiac disease (normal aging), chronic cardiac disease, and acute cardiac disease. Circulating cTnI and cTnT concentrations were measured blinded to clinical data using high-sensitivity assays (hs-cTnI-Architect, hs-cTnT-Elecsys) and their ratio calculated. Findings were validated using a second hs-cTnI assay (hs-cTnI-Clarity). Results Among 8719 individuals, 29% female, 10% had no known cardiac disease, 71% chronic cardiac disease, and 20% acute cardiac disease. Baseline characteristics including renal function were comparable between individuals with chronic and acute cardiac disease. Normal aging (without cardiac disease) was associated with a disproportional increase in cTnT versus cTnI (low cTnI/cTnT ratio, median 0.50, IQR 0.38–0.68). Although older, patients with chronic cardiac disease had a slightly higher cTnI/cTnT ratio (median 0.53, IQR 0.37–0.79, p<0.05). In contrast, in patients with acute cardiac disease, cTnI concentrations were disproportionally elevated compared to cTnT concentrations, resulting in a cTnI/cTnT ratio of 1.96 (IQR 0.93–4.73, p<0.001). Internal validation using a second hs-cTnI assay confirmed these findings. Conclusion These findings suggest relevant differences in the release of cTnI and cTnT with a greater release of cTnT versus cTnI in normal aging and a disproportional increase in cTnI versus cTnT in acute cardiac disease. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Swiss National Science Foundation