Background and Aim: Cardiac troponins are well-known risk predictors in patients with coronary artery disease as well as in the general population. Currently, high sensitivity assays are the gold standard. Lately, super sensitivity assays have been established that might provide additional information especially in patients with less cardiovascular risk burden. Aim of the present study was to compare the predictive value of a novel super sensitivity cardiac Troponin I (ss-cTnI) assay with a conventional high sensitivity cardiac Troponin I (hs-cTnI) assay in patients younger than 60 years with suspected chronic coronary syndrome.

Methods: We investigated patients with suspected chronic coronary syndrome who were enrolled in a multi-center, prospective biomarker registry. To reflect a low-risk population, the investigated cohort only included patients under the age of 60 years (n=428, mean age 54.3 years, n=124 [29.0%] females). The primary endpoint overall mortality was reached in n=37 (9%) patients. Mean follow up time was of 9.8 years. Ss-cTnI and hs-cTnI were measuredbatchwise in frozen samples obtained at baseline. To compare the predictive value of hs-cTnI and ss-cTnI regarding the primary endpoint we carried out a receiver operating characteristic (ROC) analysis. We furthermore performed Kaplan-Meier analysis (stratified by median hs-cTnI and ss-cTnI level) as well as cox regression analysis to compare the predictive information given by ss-cTnI and hs-cTnI. 

Results: In our cohort, patients with higher ss-cTnI were older (p=0.024) and had a higher rate of arterial hypertension (p=0.034). The ROC analysis showed an area under the curve (AUC) of 0.708 (Confidence interval [CI] 0.610-0.805) for hs-cTnI with respect to the primary endpoint of death and a slightly higher AUC of 0.723 (CI 0.628-0.819) for ss-cTnI without reaching a statistical significance (p_AUCdiff=0.504). The Kaplan-Meier-analysis showed  a slightly better discriminatory information regarding survival using ss-cTnI levels (median as cut-off of 1.3 pg/mL; p=0.086) compared to the use of hs-cTnI levels (median as cut-off  of 2.1 pg/mL; p=0.11) without reaching statistical significance. In cox regression analyses both, hs-cTnI as well as ss-cTnI, were significantly associated with death. Here a hazard ratio (HR) of 1.71 (CI 1.18-2.48, p=0.0045) for hs-cTnI and a HR of 1.78 (CI 1.24-2.54, p=0.0016) for ss-cTnI was observed. 

Conclusion: Cardiac troponin I measured using a high sensitivity or a super sensitivity assay is associated with mortality in younger, therefore low-risk patients with suspected chronic coronary syndrome. However, ss-cTnI compared to hs-cTnI might provide additional prognostic information in cardiovascular patients with low risk burden as it detects even very low concentrations of cardiac troponin I with high precision. However, further research with larger cohorts is needed to investigate this hypothesis.