Cardiac Troponin Assay Compared with Existing Tests

Efficient rule-out of acute myocardial infarction (MI) in patients presenting with symptoms of cardiac ischemia facilitates early disposition of the patient to outpatient care, and helps to relieve the increasing crowding of the emergency departments (ED) in most hospitals.

Sensitive cardiac troponin (cTn) assays support such a decision based on results at admission and three hours after admission, according to current guidelines. The time needed for results to become available from the hospital central laboratory often delays the disposition decision for another one or two hours.

An international team of scientists collaborating with those at the University of Uppsala compared a novel point-of-care assay (POC) for cardiac troponin I with a high-sensitivity cardiac troponin I laboratory assay. They enrolled 450 prospectively patients admitted with suspected MI at EDs or coronary care units/chest pain units of seven hospitals in Germany, France, Austria and the Netherlands. Patients eligible for enrolment were adults (age ≥ 18 years) who had presented with symptoms suggestive of MI. Only patients who presented for the first time and less than 12 hours from onset of symptom onset were included.

The novel cTnI POC test, the Minicare cTnI, provides a cTnI result within 10 minutes. The test was compared with two widely used cTnI assays: the Abbott Architect hs-cTnI and the POC Abbott I-Stat cTnI. The concentrations of cTnT in lithium-heparin plasma were measured at the local hospital laboratories using a hs-cTnT assay.

The team observed significant correlations for cTnI concentrations measured on the Minicare cTnI, either as whole blood or plasma, compared with the Architect hs-cTnI and I-Stat cTnI. There was evidence of bias for both comparisons: 0.59 (whole blood) and 0.48 (plasma) for the Architect hs-cTnI and 0.48 (whole blood) and 0.43 (plasma) for the I-Stat cTnI. The 8% discordant results among MI patients between Minicare cTnI and Architect hs-cTnI were almost equally distributed with 3% showing elevated concentrations with Minicare cTnI and 5% showing elevated results with Architect hs-cTnI, but non-elevated results with the other.

The authors concluded that that the novel Minicare cTnI POC assay equals the clinical performance in their patient cohort of a hs-cTnI assay. The Minicare cTnI assay, with a very high negative predictive value, may become suitable for prompt and safe rule-out of MI for patients with symptoms suggestive of MI in the emergency setting using a 0/3 hour sampling protocol. The study was published online on March 25, 2017, in the journal Clinica Chimica Acta.