The long cTnT assay demonstrated superior discriminative ability compared to total cTnT in identifying type 1 myocardial infarction (AUC 0.879 vs. 0.783; p<0.001).
Observational (n=709)
Does measuring long cTnT improve the discrimination between myocardial infarction and atrial fibrillation in emergency department patients with elevated total cTnT compared to the standard total cTnT assay?
A novel assay measuring long forms of cardiac troponin T provides superior diagnostic discrimination between acute myocardial infarction and atrial fibrillation compared to standard high-sensitivity cTnT in emergency department patients.
Absolute Event Rate: 0.879% vs 0.783%
p-value: p=<0.001
Abstract Background Elevated cardiac troponin levels are a frequent finding in patients presenting with atrial fibrillation or atrial flutter (AF) at emergency departments, but only a minority are caused by acute myocardial infarction (MI). Purpose This study investigated whether measuring intact and minimally fragmented cTnT (long cTnT) could discriminate the troponin elevations in AF from those caused by MI better than the current commercial high-sensitivity cardiac troponin T (total cTnT) assay. Methods We recruited consecutive emergency department patients with standard high-sensitivity cTnT levels above the 99th percentile upper reference limit (≥14 ng/L, cobas e801, Roche Diagnostics). Long cTnT levels were measured using a novel immunoassay from leftover lithium heparin plasma samples collected during routine diagnostics. The diagnostic performance of long cTnT was compared to total cTnT in separating patients with AF (either atrial fibrillation or atrial flutter) from those with type 1 MI or any MI (type 1 or 2 MI). Results A total of 709 patients with a total cTnT value ≥14 ng/L were included in the study, 521 patients with AF and 188 patients with MI (139 type 1 MI). Additionally, 17 patients had both AF and MI at presentation. Compared to patients with AF, both total and long cTnT values were higher in those with type 1 MI or any MI (Figure 1; p0.001 for all). The discriminative ability of long cTnT was superior to total cTnT in identifying patients with MI (Figure 2; area under the curve for type 1 MI: 0.879 vs. 0.783 and for any MI: 0.833 vs. 0.782, both p-values 0.001). Results were similar when only patients with chest pain or dyspnea were included in the analysis, as well as when the 17 patients with both AF and MI were included. Long cTnT outperformed total cTnT in identifying type 1 MI and any MI, regardless of sex, age (under or over 70), or estimated glomerular filtration rate (under or over 60 mL/min/1.73 m²), and also in patients with smaller troponin elevations (total cTnT 200 ng/L). The superior ability to discriminate was most notable in patients presenting within 12 hours of symptom onset. Correspondingly, reclassification and decision curve analyses showed superior ability of long cTnT in identifying particularly type 1 MI. Conclusions The long cTnT assay demonstrated good diagnostic performance in correctly discriminating between MI and AF in emergency department patients with elevated total cTnT levels. This novel test has the potential to improve the accuracy of MI diagnosis, particularly for type 1 MI.Distribution of total and long cTnT ROC curves for total and long cTnT
Teppo et al. (2025) conducted an observational in Elevated cardiac troponin levels in atrial fibrillation, atrial flutter, or acute myocardial infarction (n=709). Long cTnT assay vs. Total cTnT assay was evaluated on Discriminative ability (area under the curve) for type 1 myocardial infarction (p=<0.001). The long cTnT assay demonstrated superior discriminative ability compared to total cTnT in identifying type 1 myocardial infarction (AUC 0.879 vs. 0.783; p<0.001).