A third troponin T blood sample is not cost-effective in patients with suspected non-ST segment elevation acute coronary syndrome.

Background: The diagnosis of acute myocardial infarction requires troponin assessment in at least two blood samples 6-9 hours apart, with an optional third sample 12-24 hours after admission if suspicion is high. Yet, in many institutions, this third sample is routinely drawn. This study aimed to evaluate cost-effectiveness of this third sample of troponin.

Methods: A total of 534 patients with possible Non ST-Elevation Acute Coronary Syndrome (NSTE-ACS) were included. Blood samples for cardiac TroponinT (cTnT) were obtained on arrival, after 6-9 hours, and 12-24 hours after admission. The costs of cTnT analysis, and hospital stay were calculated.

Results: Of the 534 patients, 124 had at least one elevated cTnT value. Among these, four patients (3.2%) had cTnT values increased only in the third sample. Based on their risk profile and/or ECG changes, these four patients were eligible for referral to coronary angiography even before the result of the third sample became available. The number of patients whose length of stay was extended solely because of the third sample was 275. Incremental cost of the third blood sample: [534 patients × Euro (EUR) 12 per cTnT analysis] + [275 patients × 0.5 day × EUR 1,550] = EUR 219,533. Approximately 1400 patients with suspected NSTE-ACS are admitted to our department each year. Thus, the total cost per year is: (1,400/534) × EUR 219,533 = EUR 575,555.

Conclusion: A third troponin sample adds no vital information regarding patients' treatment or investigations plan. On the contrary, it may lead to an unnecessary extension of the admission period and increased costs.