Shah ASV, et al. - In patients with suspected acute coronary syndrome, researchers ascertained if the introduction of a high-sensitivity cardiac troponin I (hs-cTnI) assay with a sex-specific 99th centile diagnostic threshold would decrease subsequent myocardial infarction or cardiovascular death. Use of a high-sensitivity assay triggered reclassification of 1,771 (17%) of 10,360 subjects with myocardial injury or infarction. However, the incidence of subsequent myocardial infarction or death from cardiovascular causes within 1 year was not affected.

Methods

• Researchers assessed the implementation of an hs-cTnI assay in consecutive patients who had been admitted to the hospitals' emergency departments with suspected acute coronary syndrome in this stepped-wedge, cluster-randomized controlled trial across 10 secondary or tertiary care hospitals in Scotland.
• Study participants were eligible for inclusion if they presented with suspected acute coronary syndrome and had paired cardiac troponin measurements from the standard care and trial assays.
• Results from the hs-cTnI assay were concealed from the attending clinician during a validation phase of 6–12 months.
• A contemporary cardiac troponin I (cTnI) assay was used to guide care.
• After that, hospitals were randomly allocated to early (n=5 hospitals) or late (n=5 hospitals) implementation, in which the high-sensitivity assay and sex-specific 99th centile diagnostic threshold was introduced immediately after the 6-month validation phase or was deferred for a further 6 months.
• Patients reclassified by the high-sensitivity assay were characterized as those with an increased hs-cTnI concentration in whom cTnI concentrations were below the diagnostic threshold on the contemporary assay.
• Subsequent myocardial infarction or death from cardiovascular causes at 1 year after initial presentation was the primary outcome.
• They compared outcomes in patients reclassified by the high-sensitivity assay before and after its implementation by use of an adjusted generalized linear mixed model.

Results

• Forty-eight thousand, two hundred eighty-two consecutive patients (61 [SD 17] years, 47% women) were enrolled, of whom 10,360 (21%) patients had cTnI concentrations greater than those of the 99th centile of the normal range of values, who were identified by the contemporary assay or the high-sensitivity assay between June 10, 2013, and March 3, 2016.
• Findings revealed that the high-sensitivity assay reclassified 1,771 (17%) of 10,360 subjects with myocardial injury or infarction who were not identified by the contemporary assay.
• Subsequent myocardial infarction or cardiovascular death within 1 year occurred in 105 (15%) of 720 patients in the validation phase and 131 (12%) of 1,051 patients in the implementation phase (adjusted odds ratio for implementation vs validation phase 1.10, 95% CI 0.75 to 1.61; p=0.620) in those reclassified.