The following is the summary of “Diagnostic discrimination of a novel high-sensitivity cardiac troponin I assay and derivation/validation of an assay-specific 0/1h-algorithm” published in the January 2023 issue of Heart by Koechlin, et al.
It was their intention to evaluate the diagnostic value of the Dimension EXL LOCI High-Sensitivity Troponin I (hs-cTnI-EXL) assay. Participants in this international trial had presented to the emergency room complaining of chest pain. 2 cardiologists reviewed all relevant clinical data and made final diagnoses at a central location. High-sensitivity cardiac troponin (hs-cTn) I-Architect (primary analysis) and high-sensitivity cardiac troponin (hs-cTn)T-Elecsys (secondary analysis) serial readings were taken to determine a final verdict. The main goal of this study was to evaluate and contrast the diagnostic accuracy of hs-cTnI-EXL, hs-cTnI-Architect, and hs-cTnT-Elecsys in detecting acute myocardial infarction (MI). In addition, researchers developed and verified a 0/1h-algorithm tailored to hs-cTnI-EXL.
Only 204 out of 1454 (14.3%) patients were diagnosed with MI. Comparable to hs-cTnI-Architect (0.95; 95% CI, 0.93-0.96) and hs-cTnT-Elecsys (0.93; 95% CI, 0.91-0.95), hs-cTnI-EXL had an area under the receiver operating characteristics curve of 0.94 (95%CI, 0.93-0.96). Rule-out criteria of MI were 9ng/L at presentation (if chest pain onset >3h) or 9ng/L and 0h-1h-change 5ng/L in the derivation cohort (n = 813), while rule-in criteria were 160ng/L at presentation or 0h-1h-change 100ng/L. Positive predictive value was 83.3% (95% CI, 66.4-92.7), specificity was 98.3% (95% CI, 96.1-99.3), and negative predictive value was 99.5% (95% CI, 97.1-99.9) in the validation cohort (n=345).
The results were validated in follow-up analyses where adjudication was based on hs-cTnT readings. An assay-specific 0/1h-algorithm reliably rules out and accurately rules in acute MI using hs-cTnI-EXL, and the assay’s overall performance was comparable to that of the best-validated hs-cTnT/I assays.