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High-STEACS: Troponin assay fails to reduce subsequent MI, CV death
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MUNICH — The use of a high-sensitivity cardiac troponin I assay with a 99th centile diagnostic threshold failed to reduce subsequent MI or CV death at 1 year in patients with suspected ACS, according to findings from the High-STEACS study presented at the European Society of Cardiology Congress.
Implementation of the high-sensitivity troponin assay and the recommended MI diagnostic threshold reclassified one in six patients as having evidence of myocardial injury; however, only a third had a diagnosis of MI, Nicholas Mills, reader and consultant cardiologist at the Centre for Cardiovascular Disease, University of Edinburgh, Scotland, said during a press conference here.
“And the rate of subsequent myocardial infarction or cardiovascular death at 1 year was unchanged; there was no benefit,” Mills said. “However, length of stay was reduced by a third, with potential benefits for both patients and health care providers, and reassuringly for me, there was no evidence of excess treatment, misdiagnosis or harm.”
In a step-wedged, cluster-randomized controlled trial, Mills and colleagues analyzed data from 48,282 consecutive patients admitted to one of 10 secondary or tertiary care hospitals across Scotland for suspected ACS between June 2013 and March 2016 (mean age, 61 years; 47% women). Included patients had paired cardiac troponin measurements from both the standard care and high-sensitivity trial assays. During a validation phase, results from the high-sensitivity assay were concealed from the attending clinicians and a contemporary assay was used to guide care. Hospitals were randomly allocated to early (n = 5) or late (n = 5) implementation, in which the high-sensitivity assay and the sex-specific 99th centile diagnostic threshold was introduced immediately after the validation phase or was deferred for 6 more months.
Patients reclassified by the high-sensitivity assay were defined as those with an increased troponin I concentration in whom traditional assay measurements were below the diagnostic threshold level, Mills said. The primary outcome was subsequent MI or CV death at 1 year after initial presentation, using registry data. The researchers used an adjusted generalized linear mixed model to compare outcomes in patients reclassified by the high-sensitivity assay before and after its implementation.
The findings represent the first randomized trial testing the criteria used to diagnose MI and were simultaneously published in The Lancet.
Within the cohort, 10,360 patients (21%) had troponin measurements greater than those of the 99th centile of the normal range values, identified by either the standard or high-sensitivity assay.
The high-sensitivity assay reclassified 17% of patients with myocardial injury or infarction who were not identified by the contemporary assay, Mills said. Among those reclassified, subsequent MI or CV death within 1 year occurred in 15% of 720 patients in the validation phase and 12% of 1,051 patients in the implementation phase. The adjusted OR for the implementation vs. the validation phase was 1.1 (95% CI, 0.75-1.61).
“This suggests that, although we’re not better at ruling in a heart attack, we’re much more confident about ruling it out,” Mills said.
The trial also raises a fundamental question for clinical practice, Mills said during the press conference.
“The question is whether we should continue to base the diagnosis of a heart attack on a statistical threshold in a reference population, or if we need to accept the continuum of disease and use a diagnostic approach that is optimized for performance,” Mills said.
Mills noted that the trial was embedded within routine clinical assessment with hospitals as the unit of randomization, thereby avoiding selection bias and ensuring that the findings are generalizable to all patients. – by Regina Schaffer
References:
Mills N. Hot Line Session 5. Presented at: European Society of Cardiology Congress; Aug. 25-29, 2018; Munich.
Shah ASV, et al. Lancet. 2018; doi:10.1016/S0140-6736(18)31923-8.
Disclosures: The trial was funded by the British Heart Foundation. Abbott Laboratories provided cardiac troponin assay reagents, calibrators, and controls without charge. Mills reports he has received honoraria and consultant fees from Abbott Diagnostics, Roche Diagnostics and Singulex. Please see the study for the other authors’ relevant financial disclosures.