Fifth Generation Cardiac Troponin-T (cTnT) Assays in Emergency Department (ED) Evaluation of Possible Acute Coronary Syndromes (ACS)

The workup of patients for acute coronary syndrome (ACS) is one of the most common diagnostic considerations in medicine today. Chest pain is the cause of over 7 million annual emergency visits in the United States alone, representing over $10 billion in annual healthcare costs. Because of the significant morbidity and mortality associated with ACS, as well as the perception that there is a greater degree of professional liability associated with its misdiagnosis, a disproportionate amount of clinical energy and resources are currently employed to either make ("rule-in") or exclude ("rule-out") the diagnoses. Yet only a small fraction of these patients are eventually diagnosed with ACS. The combination of high importance paired with significant clinical heterogeneity makes it a diagnosis that is made with great difficulty and at great expense.

For the past several decades serial measurements of cardiac biomarkers over a period of several hours have been the mainstay of ACS evaluation. More recently, "high sensitivity" assays for the troponin enzyme, the most widely followed marker of cardiac injury, have been introduced for clinical use outside of the United States.

These high-sensitivity cardiac troponin (hs-cTn) assays have been shown to be more sensitive for detecting injury to cardiac myocytes and have been employed in protocols that allow for a more rapid rule-in and rule-out of ACS in European, Canadian, and Australasian settings. In 2017, the FDA approved the Roche Elecsys Troponin T Gen 5 Stat (5th Gen Tn) assay for clinical use in the United States.

The American medical community has responded to this with both eagerness and trepidation. Despite large clinical trials demonstrating the utility of these new assays in study populations, it is unclear what the impact will be on clinical practice. There is an understandable concern among providers that this highly sensitive assay will identify many patients with elevated levels of troponin from non-ACS causes and with uncertain clinical significance. There is also uncertainty because studies performed in European populations may not be applicable to the multi-ethnic populations that present to US emergency departments.

While there is much literature that attests to the performance of the test in study settings, there is less understanding of the impact of this assay on real-world practice settings. Therefore, it is critically important that we track and study how the new assay affects provider practice and clinical outcomes in our diverse population of patients in our quaternary medical system which includes a largely inner city, lower income, multi-ethnic population with a high proportion of Hispanic and black patients.