[Evaluation of rule out strategy for patients with non-ST-elevation acute coronary syndrome with single measurement of high-sensitivity cardiac troponin I from one sample tested beetween 3 and 6 hours after chest pain onset]

Background: Guidelines recommend to consider excluding non-ST-segment elevation myocardial infarction (NSTEMI) when high-sensitivity cardiac troponin is below the limit of quantification and a single blood sample is taken > 6 h after the onset of chest pain. The aim of our study was to assess such exclusion when a single blood sample was taken 3-6 h after the onset of permanent chest pain.

Methods: This observational study included consecutive patients admitted into the emergency room of our hospital with chest pain and suspected NSTEMI, with non-contributive electrocardiograms and a single high-sensitivity cardiac troponin I (hs-cTnI) blood sample taken 3-6 h after the onset of chest pain and hs-cTnI < 4 ng/l (Abbott Diagnostic). Clinical follow-up was undertaken 1 month after admission.

Results: The mean age of the 432 patients was 48.5 ± 5.6 years and 51% were male. Based on a clinical algorithm, the pre-test probability of NSTEMI was low in 70%, and intermediate in 21% of patients. Among 419 patients with available 1-month follow-up data, there were no myocardial infarctions or deaths. Thirty-eight patients (9%) were admitted into hospital but none for cardiac reasons.

Conclusions: Our results suggest that exclusion of NSTEMI in patients with a non-contributive electrocardiogram and a single "negative" troponin test in a blood sample taken 3-6 h after the onset of symptoms is valid.