‘Demystifying’ High-Sensitivity Troponin to Ease US Adoption

Centers thinking about making the transition to high-sensitivity cardiac (hs-c) troponin testing have some new guidance in the form recommendations from an expert panel.

High-sensitivity assays have been available in the United States for about 2 years now, but many institutions have yet to make the switch from conventional troponin tests, James Januzzi Jr, MD (Massachusetts General Hospital, Boston), who led the scientific expert panel that crafted the guidance, told TCTMD. It could be that centers that haven’t made the transition are using troponin tests that are not yet available in a high-sensitivity form or are taking the time to learn more about the newer assays before changing, he explained.

“This is not an insignificant change,” Januzzi said. “Going from a conventional troponin to a high-sensitivity assay really requires a substantial bit of education—understanding how to think about these tests, how to use them, how to interpret them, and how to manage patients when the tests are abnormal.”

The new recommendations, published in the March 12, 2019, issue of the Journal of the American College of Cardiology, aim to address some of the questions and apprehensiveness clinicians and hospital administrators might have about moving away from the older troponin assays and to provide practical tips about how to implement high-sensitivity testing when ready.

As another member of the expert panel, L. Kristin Newby, MD (Duke University Medical Center, Durham, NC), explained it, “It kind of demystifies high-sensitivity troponin and takes away, I hope, some of the concern and angst around bringing these assays into practice in the US.”

One Way or Another, Change Is Coming

It’s reasonable to expect, Januzzi said, that all companies that currently make troponin assays will ultimately switch to high-sensitivity methods, which are thought to be superior to conventional tests due to the ability to more rapidly identify or exclude acute myocardial injury. Indeed, he said, adoption of high-sensitivity troponin testing at his center has allowed patients to be discharged earlier from the emergency department after having acute MI ruled out.

“Therefore, it’s not really a question of why [centers would switch], but when,” Januzzi said.

This is not an insignificant change. James Januzzi Jr

But despite the advantages of the newer tests, moving away from conventional tests should not be done hastily because of differences in how the assays are used and interpreted. Januzzi said, for example, that clinicians often find it challenging to switch because high-sensitivity tests report results in ng/L and conventional assays report results in ng/mL.

“It would be a major mistake to simply convert from a conventional assay to a high-sensitivity assay without considering these differences and implementing the strategies we suggest with respect to education and preparation for the change,” Januzzi said.

The authors first tackle considerations for hospital laboratories, covering definitions for various analytic terms, common questions about high-sensitivity assays, and issues that should be thought about before adopting the newer testing.

They then delve into clinical considerations, addressing topics important for clinician education before implementation, such as assay use in patients with suspected MI; testing in the emergency department; the utility of accelerated diagnostic protocols; combining troponin testing with risk scores or decision aids; use of high-sensitivity assays to guide noninvasive testing; and the impact of testing on clinical outcomes (which remains uncertain). The paper includes a table and a figure to aid in the differential diagnosis of an elevated troponin level on a high-sensitivity test.

Because of the nature of high-sensitivity assays, Januzzi said, they are now detecting cardiac injury in patients who do not have an MI. “Keeping in mind that these assays are able to detect injury to the heart from a broad range of medical conditions besides a myocardial infarction,” he added, “clinicians need to be educated about what to expect when shifting to high-sensitivity so they don’t misinterpret abnormal high-sensitivity results as being a myocardial infarction without considering the other variables in the universal definition [of MI].”

The document also has sections covering testing outside of the emergency department, managing patients with evidence of chronic myocardial injury, and testing in the outpatient setting (no guidance can be offered there yet).

Preparation is Key

Both Januzzi and Newby stressed the importance of adequate preparation, which can take several months, before implementing high-sensitivity troponin testing. At Duke, for example, it took 6 to 9 months of planning involving representatives from all areas of the hospital before the transition was made, Newby said.

“The more time one invests in engaging all the stakeholder groups and setting up your systems and kind of beta testing them . . . I think the more you do that, the easier the transition is and the fewer speed bumps you run into along the way,” she said. She added that at Duke, aside from “a couple little programming hiccups that we’ve had to fix, in terms of acceptance and how patients are managed and triaged, it’s gone extremely smoothly.”

This new document contains overall recommendations for implementing high-sensitivity troponin testing accompanied by checklists that institutions can use to get ready for the move.

“The most important element to transition,” Januzzi said, “is preparation—collaborative efforts between the laboratory and other stakeholders, education, and communication among all who will be measuring the test so that people are not caught unaware of the change and then get confused. It is not an insignificant change. However, our own experience at the Mass General heart center would suggest that with good education, preparation, and some time the change can go actually very smoothly.”