NEW YORK – Test makers that have taken the lead on bringing high-sensitivity cardiac troponin testing to the point of care have said that bringing testing into the emergency room can help doctors to more quickly focus their attention on the patients who are having a heart attack and de-escalate care for those at low risk.
But according to doctors, while high-sensitivity cardiac troponin testing has clear benefits for the evaluation of patients with chest pains for suspected acute myocardial infarction, it is not yet clear how much of a difference implementing point-of-care testing could make compared to lab-based testing in terms of patient outcomes and emergency department efficiency.
High-sensitivity cardiac troponin is the preferred biomarker for the detection of myocardial injury during the evaluation of patients with acute chest pain, and multiple assays have gained US Food and Drug Administration 510(k) clearance since 2017 for clinical use. The results of a single test can be used to help identify patients who are at low risk of acute myocardial infarction, although most patients are tested at least twice with one, two, or three hours between the first and second tests.
PHC Holdings' Pathfast hs-cTnI-II test, marketed in the US by Polymedco, became this spring the first POC high-sensitivity cardiac troponin (hs-cTn) test to gain FDA marketing approval. The test is also available in other markets globally from other distributors.
QuidelOrtho, meanwhile, has been marketing its own hs-cTn assay in several markets including Canada, Australia, India, Italy, and France, and company officials said last year they planned to soon launch the test in the US. Siemens Healthineers, meanwhile, began rolling out its Atellica-based test in Europe several years ago, and company officials said recently they were working with the FDA toward securing marking clearance.
Dennis Dalangin, VP and head of QuidelOrtho's point of care business, said lab-based hs-cTn testing typically has a turnaround time of about one hour while the company's TriageTrue test provides results in about 20 minutes. Delivering faster test results helps doctors to more quickly manage emergency department patients who are presenting with chest pains while reducing ER overcrowding.
The TriageTrue test is a fluorescence immunoassay that is used for the quantitative determination of troponin I in EDTA anticoagulated whole-blood and plasma samples. It is designed for use on the Quidel Triage MeterPro instrument. Dalangin said that the firm will introduce the test in the US as soon as possible, but he did not disclose an expected timeline.
Todd Kelley, VP of medical affairs for Polymedco, said that more muscle dies the longer a patient has blockage in a coronary artery, and having POC testing available in the emergency department can help reduce or eliminate delays resulting from lab-based testing such as the times to transport samples and enter test results into the medical record.
He acknowledged there haven't been many peer-reviewed studies that bear out the benefits of high-sensitivity troponin testing at the point of care, but "we're looking forward to supporting those kinds of studies as we get Pathfast into the market here."
The Pathfast test is a chemiluminescent enzyme assay that is used for the quantitative measurement of cardiac troponin I in heparinized or EDTA whole blood and plasma samples, with results in 17 minutes. It is designed for use on PHC's Pathfast instrument.
Siemens Healthineers, meanwhile, declined an interview for this article because the company was engaging with the FDA as it pursues marketing clearance for a test in the US, but the company said in a statement that the firm's POC Atellica VTLi immunoassay for the quantitative measurement of cardiac troponin I is gaining adoption and support from opinion leaders in the Europe, Middle East, and Asia-Pacific regions. The firm noted that recent study results published in the European Heart Journal validate the use of the test with an algorithm-based two-hour serial testing strategy using whole-blood samples, with results in eight minutes.
While the Pathfast, TriageTrue, and Atellica POC tests all are used for the detection of cardiac troponin I, the hs-cTn tests that are on the market for use in laboratories are used for the detection of either the high-sensitivity troponin T or I subunits of the troponin protein. The biomarkers provide similar performance in acute care settings, and which test hospitals select sometimes depends on whom they use as device suppliers.
Sean-Xavier Neath, an emergency services physician and researcher who recently retired from the University of California, San Diego, said that most of the country has adopted hs-cTn testing for its faster turnaround times and improved ability to detect heart attack earlier, although those advantages can be reduced in emergency departments that have to wait upward of several hours to receive answers from a central lab or an affiliate hospital's lab. Neath, who is a consultant for Polymedco among other diagnostic companies, said that POC testing can speed the time to results, especially in emergency rooms that are unable to get results quickly enough to reliably meet a one-hour goal of time-to-decision on whether patients with chest pain should be admitted, transferred, or discharged.
"If you cannot get a high-sensitivity troponin [result] reliably within an hour from your central lab, the point-of-care troponin will help you identify patients who are at risk for cardiac events a lot earlier, a lot more sensitively, and [they'll] help manage patients more effectively," he said. "That is a very important thing in the ED because every time that bed is occupied by someone waiting for a serial test, you are not treating someone else."
Neath said that healthcare providers who are considering adopting POC hs-cTn testing need to evaluate their lab turnaround times to determine whether they should add instruments to the emergency department's lab bench and deploy nurses to run the tests.
Joy Gelbman, a cardiologist at NewYork-Presbyterian Weill Cornell Medicine, similarly said by email that point-of-care testing can lead to increased efficiency and improved patient care if the assays have similar performance to central lab-based testing. In general, hs-cTn testing allows doctors to differentiate between high- and low-risk chest pain far more quickly than conventional troponin, make faster triage decisions, and facilitate quicker discharge from the emergency department the patients who are at low risk of cardiovascular events.
Worth adopting?
But along with the benefits, such tests carry potential drawbacks, according to some healthcare providers. Bram Geller, member of the American College of Cardiology Critical Care Cardiology Council and director of the cardiac intensive care unit at MaineHealth, said that while implementing high-sensitivity troponin testing at the point of care could reduce the time to get results by eliminating the 20 minutes or so of delivering samples to a lab, he is not convinced that those benefits would outweigh the added burdens of training staff and maintaining the precision of testing instruments as well as the costs associated with the tests.
"From my standpoint, the advantages are quite minimal," he said, adding that maintaining quality and standardization in many point-of-care tests has been a challenge historically.
Allan Jaffe, cardiologist and professor of cardiology and cardiovascular research at the Mayo Clinic, said that a shorter time to results for POC hs-cTn testing could help to reduce emergency department overcrowding.
"Our EDs are terribly overcrowded, and when there are too many patients in the emergency room, everybody suffers because ED staff can't take care of everybody ideally," he said.
The Mayo Clinic typically turns around its troponin tests within 40 minutes, Jaffe said. Taking advantage of the faster turnaround time of a POC test would require reconfiguring care pathways in the emergency department.
He also noted that a central lab likely has greater ability to troubleshoot tests with results that look incorrect, and he said it is uncertain how many instruments and emergency department personnel would be needed to perform timely testing. At any given time, an emergency department may have 50 chest pain patients, he noted. Would an ED need to be stocked with 50 POC instruments, for example?
Researchers from Australia, the UK, and Germany similarly said in a 2022 Emergency Medicine Journal article the potential for rapid rule-out of acute myocardial infarction is attractive and it could improve clinical efficiency, but the impact of POC testing is uncertain without further study and implementation into the overall patient assessment pathways.
"For example, without additional investigation results, such as hemoglobin, electrolytes, and creatinine being readily available, POC hs-cTn assays may not have a significant impact on ED efficiency," the authors said. "The literature to date illustrates that it is not the provision of rapid cTn results alone that is important but their inclusion within a clinical decision-making pathway."
Dalangin of QuidelOrtho noted that ongoing studies are being performed to examine the use of high-sensitivity cardiac troponin tests by EMS staff to determine whether a patient should be transported by an ambulance or what level of care should be given upon arrival at a hospital.
"Those are efficiencies that can be gained, and there's definite interest, specifically, in France, Scandinavian countries, the US, of course, as well as the UK," he said.
Polymedco's Kelley said the company is gradually rolling out its test, and implementing POC hs-cTn testing requires some training for clinical staff on the differences in the test results and parameters for interpretation across testing platforms. It also requires communication across the lab, cardiology, emergency department, and nursing staff, he said.
"Once the clinicians are educated, they understand what it means to look at a POC test result versus a central lab test result," he said. "And after that initial education is performed, it works very, very well."