Comparison of cardiac troponin assays reveals assay-specific sensitivities in a clinical model of very acute myocardial injury

AIMS: High-sensitivity cardiac troponin (hs-cTn) assays indicating myocardial injury are critical for the diagnosis of acute myocardial infarction (AMI), but their use to differentiate between acute and chronic myocardial injury is limited. This study aimed to assess the differential utility of three hs-cTn assays, targeting different troponin epitopes (proximal and/or central), to detect myocardial injury in a clinical model of acute myocardial injury by left-atrial ablation. METHODS AND RESULTS: First, pre- and post-procedural serum samples were prospectively collected from 158 patients undergoing pulmonary vein isolation in a standardised setting. cTn-concentrations were measured using the high-sensitive Architect-cardiac troponin I (cTnI)-, Atellica-IM-cTnI-, and Elecsys-cTnT assays. Cardiac troponin I/T-concentrations and -ratios were compared, also to established AMI rule-in-thresholds. Second, 48 patients in which hs-cTn measurements were performed in clinical routine after ablation with a clinical indication were assessed for correlations between hs-cTn-levels, symptoms and electrocardiogram changes. The Atellica-assessed cTnI showed a doubled relative pre-to-post-procedural concentration increase compared to Architect-cTnI (39.6-fold vs. 20.5-fold; P = 0.0036). The Atellica-hs-cTnI/T-ratio had a 2.5 (95% confidence intervals (CI) 1.1,5.2) relative increase, while the Architect-cTnI-to-Elecsys-cTnT-ratio showed a 6.9 (95% CI 2.3,11.8) relative increase (P < 0.0001). In 78% of patients, at least one post-procedural cTn-concentration exceeded AMI rule-in-thresholds. Chronic kidney disease predicted higher pre-to-post-increases. In retrospectively analysed routine cTn-assessments after ablation, cTn-levels after ablation did not correlate with neither symptoms, electrocardiogram changes nor angiography findings. CONCLUSION: The Atellica assay demonstrated enhanced sensitivity for very acute myocardial injury, likely via its additional recognition of the proximally located cTnI epitope. This suggests its potential to improve differentiation of acute from chronic myocardial injury, warranting further investigation to confirm its clinical utility in that setting.