Appropriateness of troponin testing in the emergency department

Cardiac troponin (cTn) - preferably high-sensitivity cardiac troponin (hs-cTn) - plays a central role in evaluating patients with suspected acute coronary syndrome (ACS) in any Emergency Department (ED). According to the Fourth Universal Definition of Myocardial Infarction (MI), if the clinical presentation is consistent with myocardial ischemia, a rise and/or fall in cTn above the 99th percentile of healthy individuals supports the diagnosis of MI. However, daily clinical practice and several studies suggest that this biomarker is frequently ordered inappropriately, leading to overdiagnosis, unnecessary treatment, and avoidable financial costs.

To assess the appropriateness of troponin testing in the Emergency Department.

We performed a retrospective analysis of ED admissions over eight consecutive days in February 2023. Patients with an order for Troponin I were included. Testing was considered appropriate when requested for chest pain, chest pain–equivalent symptoms (dyspnea, epigastric pain, or pain in the left or right arm, neck, or jaw), or syncope with high-risk features. The presence of an electrocardiogram (ECG) request was also analyzed.

The primary outcome was the proportion of patients undergoing troponin testing that met appropriateness criteria. Secondary outcomes included the diagnosis of ACS and the estimated annual financial burden of inappropriate testing.

During the study period, 2,367 patients were admitted to the ED. Of these, 425 had a Troponin I test ordered. Overall, 51.6% (n=220) were female and 48.2% (n=205) male, with a median age of 69 years (interquartile range [IQR]: 36–102). Of all Troponin I orders, 47.1% (n=200) were deemed appropriate, while 52.9% (n=225) were inappropriate (Graph 1). Among appropriate requests, 47% (n=94) were due to chest pain, 43% (n=86) to chest pain–equivalent symptoms, and 10% (n=20) to syncope with high-risk features (Graph 2). Among patients with appropriate Troponin I orders, 14% (n=28) did not have an ECG requested. Nevertheless, patients with appropriate Troponin I orders were 3.46 times more likely than those with inappropriate orders to have an ECG requested (odds ratio [OR] 3.46; p<0.001).

Only 1.2% (n=5) of the 425 patients - all with appropriate Troponin I orders - were diagnosed and treated for ACS (1 with ST-segment elevation MI [STEMI] and 4 with non-ST-segment elevation ACS [NSTE-ACS]). Based on the proportion of inappropriate orders, the estimated avoidable annual financial cost of unnecessary Troponin I testing in the ED was €40,000–50,000.

More than half (52.9%) of Troponin I orders in the ED were considered inappropriate. These findings highlight the need for developing a clinical guideline with clear indications for troponin testing to minimize overdiagnosis, unnecessary interventions, and healthcare costs.