Implications of Introducing High-Sensitivity Cardiac Troponin T Into Clinical Practice: Data From the SWEDEHEART Registry.

BACKGROUND

Cardiac troponin is the preferred biomarker for diagnosing myocardial infarction (MI).

OBJECTIVES

The aim of this study was to examine the implications of introducing high-sensitivity cardiac troponin T (hs-cTnT) into clinical practice and to define at what hs-cTnT level risk starts to increase.

METHODS

We analyzed data from 48,594 patients admitted because of symptoms suggesting an acute coronary syndrome and who were entered into a large national registry. Patients were divided into Group 1, those with hs-cTnT<6 ng/l; Group 2, those with hs-cTnT 6 to 13 ng/l; Group 3, those with hs-cTnT 14 to 49 ng/l (i.e., a group in which most patients would have had a negative cardiac troponin T with older assays); and Group 4, those with hs-cTnT≥50 ng/l.

RESULTS

There were 5,790 (11.9%), 6,491 (13.4%), 10,476 (21.6%), and 25,837 (53.2%) patients in Groups 1, 2, 3, and 4, respectively. In Groups 1 to 4, the proportions with MI were 2.2%, 2.6%, 18.2%, and 81.2%. There was a stepwise increase in the proportion of patients with significant coronary stenoses, left ventricular systolic dysfunction, and death during follow-up. When dividing patients into 20 groups according to hs-cTnT level, the adjusted mortality started to increase at an hs-cTnT level of 14 ng/l.

CONCLUSIONS

Introducing hs-cTnT into clinical practice has led to the recognition of a large proportion of patients with minor cardiac troponin increases (14 to 49 ng/l), the majority of whom do not have MI. Although a heterogeneous group, these patients remain at high risk, and the adjusted mortality rate started to increase at the level of the 99th percentile in healthy controls.