A new point-of-care troponin assay for ruling out acute myocardial infarction (AMI) produces results 15 minutes after collection of a blood sample and could help expedite emergency room (ER) decision-making, according to a study published in JAMA Cardiology.
Researchers assessed a new, high-precision point-of-care troponin I (TnI-Nx) assay that accurately measures very low concentrations of troponin I with a 15-minute turnaround time. This test may reduce the time required to rule out an AMI and may accelerate discharge times for low-risk patients.
Investigators examined a cohort of 354 patients admitted to the ER with symptoms of an acute coronary syndrome for this observational study. Patients were evaluated according to local guidelines, and serial troponin measurements were obtained from all using the Abbott Architect high-sensitivity cardiac troponin I (hs-cTnI) assay.
The TnI-Nx is a new enzyme-linked immunosorbent assay that improves detection of troponin I by leveraging paramagnetic beads and electrochemical detection of the resulting enzyme signal.
Of 354 patients, 57 (16.1%) experienced an AMI. Men comprised 72% of the sample, and the mean age was 62 years. Discrimination for type 1 AMI was assessed under the receiver operator characteristic curve (AUC). Researchers found no difference between the AUC of the TnI-Nx assay (0.975 [95% CI, 0.958-0.993]) and the hs-cTnI assay (0.970 [95% CI, 0.949-0.990]; P =.46).
Identification as low-risk was achieved for 201 patients (56.7%) by a TnI-Nx assay result of less than 11 ng/L. Sensitivity for the assay was 100% (95% CI, 93.7%-100%) with a negative predictive value of 100% (95% CI, 98.2%-100%), compared to the hs-cTnI assay result of 154 patients (43.5%) who identified as low risk (results less than 3 ng/L).
Sensitivity for the hs-cTnI assay was 100% (95% CI, 93.7%-100%) with a negative predictive value of 100% (95% CI, 97.6%-100%).
Limitations for the study include a small sample size, noninclusion of type 2 AMI, and no comparison with turnaround times from a central laboratory assay. Study authors conclude that the I-Stat TnI-Nx assay could be used to rule out myocardial infarction rapidly and safely in a large proportion of patients admitted to ERs with acute coronary syndrome symptoms.
Multiple authors report associations with pharmaceutical companies. See original reference for a full list of authors’ disclosures.
Pickering JW, Young JM, George PM, et al. Validity of a novel point-of-care troponin assay for single-test rule-out of acute myocardial infarction [published online October 17, 2018]. JAMA Cardiol. doi: 10.1001/jamacardio.2018.3368