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Single-Measurement Risk Stratification Using hs-cTnI
Study Questions:
What is the diagnostic performance, safety, and efficiency of a single high-sensitivity cardiac troponin I (hs-cTnI) measurement strategy to identify patients at low and high risk for acute myocardial infarction (AMI)?
Methods:
The investigators conducted a prospective, multicenter, observational study of patients with suspected AMI enrolled across 29 US sites with hs-cTnI measured using the Atellica IM TnIH and ADVIA Centaur TNIH (Siemens Healthineers) assays. To identify low-risk patients, sensitivities and negative predictive values (NPVs) for AMI and MI or death at 30 days were examined across baseline hs-cTnI concentrations. To identify high-risk patients, positive predictive values and specificities for AMI were evaluated. NPVs and diagnostic sensitivities with corresponding 95% confidence intervals (CIs) were calculated to examine the diagnostic performance and safety of rule-out strategies across baseline hs-cTnI concentrations for both the Atellica IM and ADVIA Centaur assays.
Results:
Among 2,212 patients, AMI occurred in 12%. The limits of detection or quantitation resulted in excellent sensitivities (range 98.6% to 99.6%) and NPVs (range 99.5% to 99.8%) for AMI or death at 30 days across both assays. An optimized threshold of <5 ng/L identified almost one-half of all patients as low risk, with sensitivities of 98.6% (95% CI, 97.2%-100%) and NPVs of 99.6% (95% CI, 99.2%-99.9%) for AMI or death at 30 days across both assays. For high-risk patients, hs-cTnI ≥120 ng/L resulted in positive predictive values for AMI of ≥70%.
Conclusions:
The authors concluded that an optimized threshold of <5 ng/L safely identified almost one-half of all patients as low risk at presentation, with hs-cTnI ≥120 ng/L identifying high-risk patients.
Perspective:
This study reports that a uniform, optimized hs-cTnI concentration of <5 ng/L is the preferred concentration that balanced safety, as demonstrated by the excellent sensitivities for AMI or death at 30 days, and efficiency, identifying almost 50% of patients as low risk. Furthermore, a single measurement at presentation can also facilitate the triage of patients at high risk, with concentrations ≥120 ng/L identifying a subset of patients at high risk for AMI at presentation in whom prompt evaluation and/or management is needed in the appropriate clinical context. Additional randomized studies are indicated to confirm the efficiency and safety of risk stratification strategies based on single hs-cTn measurements.
Keywords: Acute Coronary Syndrome, Biomarkers, Myocardial Infarction, Predictive Value of Tests, Primary Prevention, Risk, Sensitivity and Specificity, Troponin I
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