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Cardiac Troponin Assays With Improved Analytical Quality: A Trade-Off Between Enhanced Diagnostic Performance and
Hilde L Tjora1, Ole-Thomas Steiro2, Jørund Langørgen2
1Emergency Care Clinic Haukeland University Hospital Bergen Norway.
Insights
A new cardiac troponin I (cTnI) algorithm improves early rule-out/rule-in for myocardial infarction. This novel cTnI assay offers better diagnostic performance and classifies more patients compared to existing protocols.
Area of Science:
- Cardiology
- Biomarker Analysis
- Diagnostic Algorithms
Background:
- Cardiac troponin (cTn) is crucial for diagnosing non-ST-segment-elevation myocardial infarction (NSTEMI).
- Existing protocols have limitations in early rule-out/rule-in of NSTEMI.
- Highly sensitive troponin assays are needed for improved patient management.
Purpose of the Study:
- To develop and evaluate a novel 0/1-hour rule-out/rule-in algorithm for a highly sensitive cardiac troponin I (cTnI) assay (cTnIsgx).
- To compare the diagnostic and prognostic performance of the new algorithm against existing troponin protocols.
- To assess the impact of the algorithm on patient classification and long-term outcomes.
Main Methods:
- Developed novel admission and 0/1-hour rule-out/rule-in algorithms for the cTnIsgx assay.
- Measured cTnT, cTnI(Abbott), and cTnI(sgx) in 971 admission and 465 1-hour samples from suspected NSTEMI patients.
- Compared diagnostic properties with established ESC and prior cTnIsgx algorithms; assessed long-term prognosis (mortality, MI) over 723 days.
Main Results:
- The novel cTnIsgx algorithms demonstrated superior diagnostic performance (higher area under the curve) compared to other assays.
- The cTnIsgx 0/1-hour algorithm achieved rule-in or rule-out for 92% of patients, significantly higher than comparators (≤78%).
- Patients ruled out by prior algorithms had better long-term outcomes, but the novel algorithm did not allow for prognostication.
Conclusions:
- The novel cTnIsgx 0/1-hour algorithm significantly improves early NSTEMI diagnosis and patient classification.
- Highly sensitive troponin assays can enhance NSTEMI identification but may identify subclinical myocardial injury.
- Separate protocols for diagnosis and risk prediction are recommended for troponin-based management.
Abstract:
Background Cardiac troponin (cTn) permits early rule-out/rule-in of patients admitted with possible non-ST-segment-elevation myocardial infarction. In this study, we developed an admission and a 0/1 hour rule-out/rule-in algorithm for a troponin assay with measurable results in >99% of healthy individuals. We then compared its diagnostic and long-term prognostic properties with other protocols. Methods and Results Blood samples were collected at 0, 1, 3, and 8 to 12 hours from patients admitted with possible non-ST-segment-elevation myocardial infarction. cTnT (Roche Diagnostics), cTnI(Abbott) (Abbott Diagnostics), and cTnI(sgx) (Singulex Clarity System) were measured in 971 admission and 465 1-hour samples. An admission and a 0/1 hour rule-out/rule-in algorithm were developed for the cTnI(sgx) assay and its diagnostic properties were compared with cTnTESC (European Society of Cardiology), cTnI(Abbott)ESC, and 2 earlier cTnI(sgx) algorithms. The prognostic composite end point was all-cause mortality and future nonfatal myocardial infarction during a median follow-up of 723 days. non-ST-segment-elevation myocardial infarction prevalence was 13%. The novel cTnI(sgx) algorithms showed similar performance regardless of time from symptom onset, and area under the curve was significantly better than comparators. The cTnI(sgx)0/1 hour algorithm classified 92% of patients to rule-in or rule-out compared with ≤78% of comparators. Patients allocated to rule-out by the prior published 0/1 hour algorithms had significantly fewer long-term events compared with the rule-in and observation groups. The novel cTnI(sgx)0/1 hour algorithm used a higher troponin baseline concentration for rule-out and did not allow for prognostication. Conclusions Increasingly sensitive troponin assays may improve identification of non-ST-segment-elevation myocardial infarction but could rule-out patients with subclinical chronic myocardial injury. Separate protocols for diagnosis and risk prediction seem appropriate.
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