BACKGROUND
The prompt and accurate diagnosis of acute myocardial infarction (MI) is crucial in reducing morbidity and mortality rates. Point-of-care high-sensitivity cardiac troponin (POC hs-cTn) assays offer rapid results and potential benefits in decision-making and emergency facility management. This study aimed to validate the diagnostic performance of a POC-hs-cTnI measurement for early rule-out of non-ST-segment MI (NSTEMI) and assess the assay's safety in relation to adverse cardiac events or death within 30 days.

METHODS
A prospective study was conducted at the emergency department (ED) of Slagelse Hospital, Denmark, between October 2022 and January 2023. Eligible participants included patients aged ≥18 years with suspected NSTEMI and symptom onset > 3 hours prior to arrival. Alongside standard laboratory hsTnI measurements at arrival and after 3 hours, POC hs-cTnI testing using the Siemens Atellica® VTLi POC hs-cTnI immunoassay (8–10 min turnaround time) was performed. A POC-hs-cTnI cutoff level of < 4 ng/L was considered a rule-out result. The final diagnosis of MI was determined by journal audit by two independent physicians using the universal definition of MI. Sensitivity, specificity, negative predictive values, and positive predictive values were calculated for POC hs-cTnI.

RESULTS
Out of 250 screened patients, 64 were included in the study. The prevalence of MI was 9.4% (6 cases). Using a POC hs-cTnI cutoff level of < 4 ng/L, three patients were classified as rule-out, and 61 as rule-in for acute MI. The rule-out group exhibited 100% sensitivity and negative predictive value for acute MI. In the rule-in group, the specificity and positive predictive value for acute MI were 5.2% and 9.8%, respectively. No adverse cardiac events or deaths occurred within 30 days among patients with a negative POC hs-cTnI result.

CONCLUSIONS
The POC hs-cTnI assay demonstrated the ability to safely rule out NSTEMI. However, a considerable number of false-positive results were observed, potentially leading to unnecessary patient concern and further investigations. Incorporating a second POC hs-cTnI test and analyzing troponin trajectories could enhance the ability to safely rule out more patients. Further research is needed to optimize the diagnostic algorithm and enhance the clinical utility of the POC hs-cTnI assay.