Comparison of rapid test for high-sensitivity troponin I with laboratory high-sensitivity troponin T in patients with acute chest pain - a prospective monocentric study

Abstract

Abstract Background and purpose High-sensitivity troponin (hs-Tn) assays are recommended for routine clinical use for diagnosis of acute coronary syndrome (ACS). However, laboratory hs-TnT can be elevated due to non-cardiac conditions, such as pulmonary embolism, skeletal muscle injury or chronic kidney disease. The aim of our study was to compare the diagnostic accuracy of the bed-side rapid hs-troponin I (hs-TnI) assay with hs-TnT measured by routine laboratory. Methods This prospective monocentric study was conducted at a tertiary hospital outpatient cardiac unit with an emergency clinic for patients with acute symptoms. A total of 129 patients were included between May 2021 and August 2022. Hs-TnI was measured via a bed-side test from whole blood directly in the emergency room, while hs-TnT was measured from plasma through the routine laboratory. Definite ACS was confirmed by coronary angiography. Patients were compared by grouping them into definitive diagnosis of ACS or no ACS. Hs-TnI as well as hs-TnT values were compared for accuracy and predictive values. Routine clinical parameters and comorbidities were documented and compared as well. Agreement between hs-TnI and hs-TnT was assessed by likelihood ratios and Bland Altman plot. Results Overall, 129 patients (65.1% male, 61.8 ± 15.6 years) with acute chest pain were analysed. Median hs-TnI was 7.0 ng/L (IQR: 2.7-15.8), while median hs-TnT was 14 ng/L (IQR: 7.0-31.0). Results for TnI were available faster (average: 1:14 h ± 0:54) compared to TnT. Coronary angiography confirmed ACS in 17 patients (13.2%) displaying significant coronary stenoses requiring intervention. The relative risk of ACS patients to have an elevated hs-TnI result was 6.59 compared to that of 2.29 for the hs-TnT test, meaning that a positive hs-TnI test was a better classifier for validated ACS than that of hs-TnT. Hs-TnI exhibited equivalent negative predictive value to hs-TnT (99%) for definite ACS diagnosis, but had comparatively higher positive predictive value (50.0 vs. 25.8%). Bland Altman plot of hs-TnI versus hs-TnT showed an average difference of -4.6 ng/L (95% CI: -12.4 to 3.2) between the tests. In 39 patients with chronic kidney disease (minimum stage 3a CKD) median hs-TnT (27.0 ng/L, IQR: 16.0-55.0) values were higher than hs-TnI (11.2 ng/L, IQR: 7.5-30.7). Conclusion Bed-side hs-TnI is comparable to hs-TnT with a high degree of agreement. Measurement of troponin I using the rapid bed-side hs-TnI assay possesses a shorter blood-draw-to-result-time than routine troponin T measurement.