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Performing high-sensitivity troponin (hs-TnT) tests, in the absence of an explicit management protocol incorporating the results, did not alter treatment or outcomes of patients with acute coronary syndrome in a prospective multi-center trial.

Patients who had serum troponin levels reported with the hs-TnT test were just as likely as their peers who underwent a standard assay to be admitted (57.7% versus 58.0%, P=0.069) and to have angiography (11.9% versus 10.9%, P=0.479), , of Flinders Medical Centre in Australia, and colleagues reported online in Circulation: Cardiovascular Quality and Outcomes.

Clinical outcomes were at 12 months, either, with hs-TnT reporting versus standard reporting in terms of:

• Death or acute coronary syndrome (5.86% versus 7.05%, HR 0.83, 95% CI 0.57 to 1.22)
• MI (2.06% versus 2.18%, HR 0.94, 95% CI 0.64 to 1.40)
• Readmission for chest pain (13.46% versus 13.28%, HR 0.98, 95% CI 0.78 to 1.25)
• Any cardiovascular event (24.67% versus 24.07%, HR 1.04, 95% CI 0.87 to 1.25)

The exception was the group with troponin levels below 30 ng/L, which saw a modest reduction in the combination of mortality and acute coronary syndrome when the highly sensitive test was used (2.6% versus 4.4%, HR 0.58, 95% CI 0.34 to 1.00).

"We observed only modest impact on clinical practice considering the greater degree of information offered by the hs-TnT result, with only minor reduction in the rate of discharge from hospital, and a nonsignificant increases in hospital admissions and revascularization overall," Chew and co-authors wrote.

Thus, "hs-TnT reporting alone is associated with only modest changes in practice. Clinical effectiveness in the adoption of hs-TnT may require close coupling with protocols that guide interpretation and care," they continued, adding that a real shift towards a notable impact would require a change in clinical decision-making.

"High-sensitivity troponin provides useful risk information, but routine reporting without integration within protocols is associated with only modest changes in practice. Nevertheless, beyond the diagnostic process, routine use may improve late outcomes. Adoption of high-sensitivity troponin testing is likely to require coupling with management protocols that guide interpretation and care if the benefits of greater diagnostic discrimination are to be harnessed."

The multicenter trial included 1,937 patients presenting to emergency departments from 2011 through 2013 who had chest pain but no ST-segment elevation. They were randomized to hs-TnT reporting or a standard troponin T assay.

At the index hospitalization, 75.7% had a maximal troponin level below 30 ng/L within 24 hours.

The investigators noted a previous observational study had come up with different results, which they suggested could be attributable to "a greater difference in the information being provided to the clinician resulting from a much greater difference in assay performance between the two troponin I tests assessed; the post hoc exclusion of patients with an alternate noncardiac diagnosis; and the impact of secular changes in clinical practice that is difficult to control for when conducting a before and after comparisons of healthcare innovations."

"Of significance is that hs-TnT assays are yet to be approved by the Food and Drug Administration for routine use in the United States, whereas HealthPACT (Australian Health Technology Assessment Agency) and the Canadian Agency for Drug and Technologies in Heath currently recommend against routine use as recently as in 2011 and 2013, respectively," Chew's group commented.

In those other countries, they added, "The routine use of hs-TnT assays incorporated into protocols of care is currently advocated in acute coronary syndrome guidelines, particularly for identifying patients suitable to early discharge."

"This study highlights the inertia of clinical decision making in response to the adoption of new diagnostic and therapeutic innovations. Availability of troponin results with greater diagnostic precision alone did not substantially improve the effectiveness or efficiency of care, particularly among patients with low or no detectable troponin T," they concluded.

"The modest change in practice may reflect many factors, including a lack of clinical appreciation of the increased risk for future events associated with low-level elevations in troponin or the lack of mature decision making and established investigative/management pathways for the care of patients with and without evidence of low-grade myocardial injury."

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