Performance of the novel high-sensitivity cardiac troponin T- Generation 6 assay in the early diagnosis of myocardial infarction in patients with prior coronary artery bypass grafting

Background The new high-sensitivity cardiac troponin (hs-cTn) T-Generation (gen) 6 assay has higher analytical sensitivity than the current hs-cTnT-gen5 assay and performs excellently when embedded in a guideline-recommended early triage algorithm, such as the European Society of Cardiology (ESC) 0/1h- or 0/2h-algorithm. However, its performance in the vulnerable cohort of patients with prior coronary artery bypass grafting (CABG) presenting to the Emergency Department (ED) with chest pain is unclear. Purpose Therefore, we aimed to directly compare the performance of the hs-cTnT-gen6 assay with that of the established hs-cTnT-gen5 assay in patients who underwent CABG. Methods In this secondary analysis of an international, prospective, diagnostic study with central adjudication, patients with prior CABG who presented with suspected myocardial infarction (MI) to the emergency department (ED) were enrolled. hs-cTnT-gen6 and gen5 were measured at the same timepoints. The diagnostic performance of hs-cTnT-gen6 was compared with that of hs-cTnT-gen5. Results Among 191 patients, MI was the final diagnosis in 74 (38.8%) patients. The proportion of patients with concentrations above the upper reference limit and therefore myocardial injury was lower for hs-cTnT-gen6 (64.4%) than for hs-cTnT-gen5 (76.4%; P<0.001). Diagnostic accuracy at ED presentation, expressed as AUC, was 0.864 (95%CI: 0.812–0.916) for hs-cTnT-gen6 and 0.867 (95% CI: 0.816–0.919) for hs-cTnT-gen5 (P=0.542). Applying the previously derived cutoffs for the ESC 0/1h- and 0/2h-hs-cTnT-gen6-algorithms triaged patients with 100% negative predictive value and sensitivity to rule-out MI. When hs-cTnT-gen6 was used within guideline-recommended early triage algorithms (ESC 0/1h or ESC 0/2h), the efficacy (defined as the proportion of patients receiving a definitive triage decision and not remaining in the observe zone) was comparable between hs-cTnT-gen6 and hs-cTnT-gen5. (e.g., 47% remaining in the observe zone when using the ESC 0/1h- hs-cTnT-gen6 algorithm versus 51% when using the ESC 0/1h- hs-cTnT-gen5 algorithm; P=0.289). Conclusions In patients with prior CABG surgery presenting with chest discomfort in the ED, the novel hs-cTnT-gen6 assay demonstrated excellent and comparable diagnostic performance to the established hs-cTnT-gen5 assay with fewer patients identified as having myocardial injury. Use-optimized, assay-specific cut-offs for the ESC 0/1h- and 0/2h-algorithms provided very high sensitivity.