Variability in High-Sensitivity Cardiac Troponin T Testing in Stable Patients With and Without Coronary Artery Disease.

BACKGROUND

High-sensitivity cardiac troponin T (hs-cTnT) is used to diagnosis acute myocardial infarction, often based on values exceeding the 99th percentile threshold (14 ng/L) of normal populations. The short- and long-term variability of hs-cTnT in stable patients with or without coronary artery disease (CAD) is unknown.

METHODS

Prospective cohort study of 75 stable patients with CAD and 3 differing clinical profiles (stable angina [SA]; remote myocardial infarction [MI]; repetitive acute coronary syndrome [ACS]) and 25 controls without angiographic CAD, each with 15 hs-cTnT measurements over 1 year.

RESULTS

Individual results (1491 measurements) did not vary over within-day, daily, weekly, monthly, seasonal, or yearly time windows. The overall median was 2.8 ng/L (interquartile range [IQR] 5.2 ng/L) with the highest median (6.3 ng/L) and variability (IQR 6. 9 ng/L) in the repetitive ACS group. Diabetes, impaired renal function, and raised C-reactive protein were independent predictors of higher hs-cTnT values (average increase by 8.5 ng/L [95% CI, 5.0-11.9], 5.0 ng/L [95% CI, 2.0-8.1] and 4.0 ng/L (95% CI, 1.0-7.0), respectively). The 99th percentile value of all hs-cTnT measurements in the combined stable patients with CAD was 39 ng/L compared with 14 ng/L in the non-CAD patients.

CONCLUSIONS

Individual hs-cTnT readings in both patients with and without CAD were stable over hours, days, weeks, and months. Diabetes, poor renal function, and elevated C-reactive protein were independent predictors of higher median and IQR hs-cTnT values, often exceeding conventional thresholds. These findings highlight the need for caution and clinical contextualization in the interpretation of hs-cTnT results.