A lack of validated clinical protocols for new high sensitivity troponin testing (hs-TnT) in hospital emergency departments has left doctors in the dark about how to use the diagnostic tool to improve practice, Australian researchers claim.
Speaking to the limbic, interventional cardiologist Professor Derek Chew said the test allowed for a much greater discrimination of MI and ACS risk.
“ If [the test] can tell that someone is at high risk and someone is at low risk with greater certainty and greater clarity shouldn’t that change the way you treat that patient?” said Professor Chew who is chairman of the National Acute Coronary Syndromes Data Definitions working group,
“You would think that it should but we found, on the whole, [it doesn’t].”
A recent study by Professor Chew and colleagues showed high-sensitivity troponin reporting alone was associated with only modest changes in practice.
According to Professor Chew, the findings highlight the “inertia of clinical decision-making in response to the adoption of new diagnostic and therapeutic innovations”.
“If you’re going to develop innovation – which we all want to see – those innovations have to be built hand-in-hand with the clinical service consideration so that the promise of these new diagnostic tools are realised.”
While the test has been incorporated into decision pathways Professor Chew says the question now is whether or not those decision pathways also need to be validated.
“Sure, you can tell people how to use these tests and you can therefore change decision making but whether or not those changes are associated with safe care has to be validated in a randomised trial so that’s what we tested – whether or not routine testing improved outcomes. There are a lot of people who will argue that they do but that’s not case.”
In the prospective study, Professor Chew and colleagues evaluated the impact of hs-TnT reporting on care and outcomes among 1937 chest pain patients presenting to five emergency departments in Adelaide between July 2011 and March 2013.
Patients were randomised to either troponin testing reported to standard TnT levels (>30 ng/L n=964) or high-sensitivity TnT levels (>3 ng/L, n=973).
According to the investigators the type of reporting used had little impact on either admission rate (hs-report: 57.7% versus std-report: 58.0%; P=0.069) or angiography (hs-report: 11.9% versus std-report: 10.9%; P=0.479).
What’s more, hs-reporting did not significantly reduce death at 12 months or the amount of new or recurrent acute coronary syndrome in the overall population (hs-report: 9.7% versus std-report: 7.2%; P=0.362)
While the researchers found no between-group differences overall in discharge to home directly from the emergency department, they did observe a higher rate of discharge from the emergency department among low- or no-risk patients in the high-sensitivity group compared with the standard group (168 vs 148, P=0.010).
There was also a significant interaction between use of hs-TnT and the prescription of aspirin among patients with peak troponin of 14 to 29 mg/L within 24 hours (55.4% vs 34.0%, P=0.006) and statins (hs-report: 65.6% versus std-report 5.0%, P=0.017; interaction P value=0.005) at discharge.
However, Professor Chew and colleagues described the clinical impact of hs-TnT as “modest” considering the greater degree of information offered by the test compared to standard troponin reporting.
Professor Chew said that further research will help to validate some of the emerging protocols that have been promoted without randomised evidence of safety and efficacy.
He has already commenced a randomised study to validate a one-hour protocol.