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hsTnT Identifies Low-Risk Patients for ACS
Study Questions:
Does high-sensitivity troponin T (hsTnT) identify patients at low risk for 30-day adverse cardiac events who present to the emergency department (ED) with possible acute coronary syndrome (ACS)?
Methods:
This was a prospective observational study, which enrolled patients at 15 EDs in the United States between 2011 and 2015. Adults over the age of 21 years who presented to the ED with possible ACS were eligible. For this analysis, those with no cardiac TnT measurement or missing results for 0 or 3 hours were excluded. Serial hsTnT measurements (using fifth-generation Roche Elecsys hsTnT assay) were collected at 3 hours, 6-9 hours, and 12-24 hours later. The primary outcome of interest was adverse cardiac events, defined as myocardial infarction (MI), urgent revascularization, or death. The upper reference level for the hsTnT assay, defined as the 99th percentile, was established as 19 ng/L in a separate healthy US cohort. Patients were considered ruled out for acute MI (AMI) if their hsTnT level at 0 and 3 hours was less than the upper reference level.
Results:
A total of 1,301 healthy volunteers (50.4% women; median age, 48 years), were used to define the upper reference level of 19 ng/L. In 1,600 patients with suspected ACS (48.4% women; median age, 55 years), a single hsTnT level <6 ng/L at baseline had a negative predictive value for AMI of 99.4%. In 974 patients (77.1%) with both 0- and 3-hour hsTnT levels of ≤19 ng/L, the negative predictive value for 30-day adverse cardiac events was 99.3% (95% confidence interval, 99.1-99.6). Using sex-specific cut-points, C statistics for women (0.952) and men (0.962) were similar for AMI.
Conclusions:
The authors concluded that a single hsTnT level ≤6 ng/L was associated with a markedly decreased risk of AMI, while serial levels at ≤19 ng/L identified patients at <1% risk of 30-day adverse cardiac events.
Perspective:
These data support the use of hsTnT for identification of low-risk patients presenting with possible ACS. This would potentially lead to reduced hospital admissions for such patients. However, clinicians were blinded to the results in this study. Ultimately how hsTnT changes clinical management remains to be seen. Prospective observational cohorts and pragmatic trials will help us determine how hsTnT is best used for care of the cardiac patient.
Keywords: Acute Coronary Syndrome, Biomarkers, Emergency Service, Hospital, Myocardial Infarction, Myocardial Revascularization, Risk Assessment, Secondary Prevention, Troponin T
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