Prehospital High-Sensitivity Cardiac Troponin Test can rule out MI
The last decade has seen an increased focus on diagnostic assessment with troponins outside of hospitals. Point-of-care (POC) troponin assays, used in general practice or by emergency medical services (EMS), are useful in identifying high-risk patients.
In a recent study, researchers have found that point-of-care high-sensitivity cardiac troponin (hs-cTn) assays have the potential to safely rule out MI in the prehospital setting, thereby avoiding unnecessary ambulance rides. The study findings were published in the Journal of American College of Cardiology on November 29, 2021.
Patients presenting with acute chest pain outside of hospitals represent a diagnostic challenge. Presently, most hs-cTn assays are conducted in hospital laboratories to help to diagnose and rule out MI, with newer accelerated algorithms enabling patients to be triaged within hours. Dr Jamie G. Cooper and his team postulated a hypothesis what if patients were able to have their blood drawn and assessed before they even reach the hospital, potentially allowing them to stay home?
Therefore, they conducted a prespecified secondary analysis of the ACCESS study, in which patients with suspected ACS were assessed in ambulances fitted with Samsung LABGEOIB10 point-of-care analyzers (Samsung) between 2014 and 2018.
Key Findings of the study:
- Among 966 patients with a prehospital hs-cTn measurement, the researchers identified 44% had known ischemic heart disease and 19% had a subsequent MI or cardiac death within the next 30 days. The median hs-cTnI concentration was 4.0 ng/L.
- Overall, they noted that 28.9% of patients had hs-cTnI concentration below the laboratory assay's limit of detection of < 2 ng/L, with a sensitivity of 97.3% and a negative predictive value of 98.2%.
- They also noted that more than half of patients (55.4%) had levels below the rule out threshold of < 5 ng/L, with a sensitivity of 88.5% and negative predictive value of 96.1%.
- They observed similar findings in subgroups with normal ECG and subgroups stratified by age, sex, and smoking status.
- They noted that the negative predictive value was even higher in patients with a normal ECG without known ischemic heart disease (98.3%) who presented within 3 hours of symptom onset (98.8%).
The authors concluded, "Our findings demonstrate how hs-cTn testing might be applied to risk-stratify patients in the prehospital setting".
For further information:
Cooper JG, Ferguson J, Donaldson LA. Could high-sensitivity cardiac troponin testing rule out acute myocardial infarction in the prehospital setting?_ J Am Coll Cardiol_. 2021;78:2392-1294.
