Validity of a Novel Point-of-Care Troponin Assay for Single-Test Rule-Out of Acute Myocardial Infarction

Abstract

IMPORTANCE Emergency department (ED) investigations of patients with suspected acute myocardial infarction (AMI) are time consuming, partly because of the turnaround time of laboratory tests. Current point-of-care troponin assays shorten test turnaround times but lack precision at lower concentrations. Development of point-of-care troponin assays with greater analytical precision could reduce the decision-making time in EDs for ruling out AMI. OBJECTIVE To determine the clinical accuracy for AMI of a single troponin concentration measured on arrival to ED with a new-generation, higher precision point-of-care assay with a 15-minute turnaround time. DESIGN, SETTING, AND PARTICIPANTS This observational study occurred at a single urban regional ED. Adults presenting acutely from the community to the ED with symptoms suggestive of AMI were included. Troponin concentrations were measured on ED arrival with both a novel point-of-care assay (i-STAT TnI-Nx; Abbott Point of Care) and a high-sensitivity troponin I assay (Architect hs-cTnI; Abbott Diagnostics). MAIN OUTCOMES AND MEASURES The primary outcome was type 1 AMI during index presentation. We compared the discrimination ability of the TnI-Nx assay with the hs-cTnI assay using the area under receiver operator characteristic curve (AUC) and sensitivity, negative predictive value, and the proportion of negative test results at thresholds with 100% sensitivity. RESULTS Of 354 patients (255 [72.0%] men; mean [SD] age, 62 [12] years), 57 (16.1%) experienced an AMI. Eighty-five patients (24.0%) presented to the ED less than 3 hours after symptom onset. No difference was found 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 to 0.990]; P = .46). A TnI-Nx assay result of less than 11 ng/L identified 201 patients (56.7%) as low risk, with a sensitivity of 100% (95% CI, 93.7%-100%) and a negative predictive value of 100% (95% CI, 98.2%-100%). In comparison, an hs-cTnI assay result of less than 3 ng/L identified 154 patients (43.5%) as low risk, with a sensitivity of 100% (95% CI, 93.7%-100%) and a negative predictive value of 100% (95% CI, 97.6%-100%). CONCLUSIONS AND RELEVANCE A novel point-of-care troponin assay that can produce a result 15 minutes after blood sampling had comparable discrimination ability to an hs-cTnI assay for ruling out AMI after a single blood test. Use in the ED may facilitate earlier decision making and could expedite the safe discharge of a large proportion of low-risk patients.

Challenges in Managing Acute Cardiovascular Diseases and Follow Up Care in Rural Areas: A Narrative Review

“…However, lower specificity accompanies the increasing sensitivity of such tests results [46], so a clear understanding is required of the need for serial troponins in conjunction with interpretable ECGs for the accurate diagnosis of AMI. Point-of-care testing for troponins has made the rapid assessment of patients in remote areas easier, with the accuracy of these tests so improved in recent years that even single test troponin has comparable discrimination ability to a high sensitivity cardiac troponin assay for ruling out AMI after a single blood test [47].…”

Preoperative cardiac troponin below the 99th-percentile upper reference limit and 30-day mortality after noncardiac surgery

“…Based on clinical relevance shown in previous studies 3 – 5 , 20 , the Fourth Universal Definition of Myocardial Infarction also recommended using the 99th-percentile URL of any assay to define myocardial injury, but at the same time it specifically highlighted myocardial injury as discrete from myocardial infarction 5 . Moreover, some investigators recently argued that a lower cut-off should be applied even for ruling out acute myocardial infarction 21 . In addition, the 99th-percentile URLs provided by immunoassay manufacturers are derived from a limited number of apparently healthy individuals 22 , and several factors such as age, sex, kidney and heart function, and the presence of inflammation that are known to affect troponin level are not considered 17 , 23 .…”

Effect of Long-Duration Adventure Races on Cardiac Damage Biomarker Release and Muscular Function in Young Athletes

“…Capillary arterialized blood samples (100 µl) were drawn from the earlobe and collected in heparinized tubes before (Pre), immediately after (Post) and on days 1 (D + 1) and 2 (D + 2) following each race to determine the time course of cTnI and CK-MB. The myocardial damage biomarkers concentrations were analyzed using the i-STAT R handheld analyzer (Abbott Point of Care, Inc., Princeton, NJ, United States), which was clinically validated (Pickering et al, 2018). The measurements were immediately made after collection using i-STAT cTnI and CK-MB cartridges.…”