Cardiac Troponin Assays With Improved Analytical Quality: A Trade-Off Between Enhanced Diagnostic Performance and Reduced Long-Term Prognostic Value

Prognostic Implications of N-Terminal Pro-B-Type Natriuretic Peptide in Patients With Non-ST-Elevation Myocardial Infarction

BACKGROUND

Limited data exist regarding the prognostic implications of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients with non-ST-elevation myocardial infarction (NSTEMI) who undergo percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Of 13,104 patients in the nationwide Korea Acute Myocardial Infarction Registry-National Institutes of Health, 3,083 patients with NSTEMI who underwent PCI were included in the present study. The primary endpoint was major adverse cardiovascular events (MACE) at 3 years, a composite of all-cause death, recurrent myocardial infarction, unplanned repeat revascularization, and admission for heart failure. NT-proBNP was measured at the time of initial presentation for the management of NSTEMI, and patients were divided into a low (<700 pg/mL; n=1,813) and high (≥700 pg/mL; n=1,270) NT-proBNP group. The high NT-proBNP group had a significantly higher risk of MACE, driven primarily by a higher risk of cardiac death or admission for heart failure. These results were consistent after confounder adjustment by propensity score matching and inverse probability weighting analysis.

CONCLUSIONS

In patients with NSTEMI who underwent PCI, an initial elevated NT-proBNP concentration was associated with higher risk of MACE at 3 years, driven primarily by higher risks of cardiac death or admission for heart failure. These results suggest that the initial NT-proBNP concentration may have a clinically significant prognostic value in NSTEMI patients undergoing PCI.

Aiming toWards Evidence baSed inTerpretation of Cardiac biOmarkers in patients pResenting with chest pain using Point of Care Testing (WESTCOR-POC): study design

OBJECTIVES

Patients presenting with symptoms suggestive of acute coronary syndrome (ACS) contribute to a high workload and overcrowding in the Emergency Department (ED). Accelerated diagnostic protocols for non-ST-elevation myocardial infarction have proved challenging to implement. One obstacle is the turnaround time for analyzing high-sensitivity cardiac troponin (hs-cTn). In the WESTCOR-POC study (Clinical Trials number NCT05354804) we aim to evaluate safety and efficiency of a 0/1 h hs-cTn algorithm utilizing a hs-cTnI point of care (POC) instrument in comparison to central laboratory hs-cTnT measurements.

DESIGN

This is a prospective single-center randomized clinical trial aiming to include 1500 patients admitted to the ED with symptoms suggestive of ACS. Patients will receive standard investigations following the European Society of Cardiology 0/1h protocols for centralized hs-cTnT measurements or the intervention using a 0/1h POC hs-cTnI algorithm. Primary end-points are 1) Safety; death, myocardial infarction or acute revascularization within 30 days 2) Efficiency; length of stay in the ED, 3) Cost- effectiveness; total episode cost, 4) Patient satisfaction, 5) Patient symptom burden and 6) Patients quality of life. Secondary outcomes are 12-months death, myocardial infarction or acute revascularization, percentage discharged after 3 and 6 h, total length of hospital stay and all costs related to hospital contact within 12 months.

CONCLUSION

Results from this study may facilitate implementation of POC hs-cTn testing assays and accelerated diagnostic protocols in EDs, and may serve as a valuable resource for guiding future investigations for the use of POC high sensitivity troponin assays in outpatient clinics and prehospital settings.

Diagnostic Performance of Novel Troponin Algorithms for the Rule-Out of Non-ST-Elevation Acute Coronary Syndrome

BACKGROUND

The European Society of Cardiology (ESC) rule-out algorithms use cutoffs optimized for exclusion of non-ST elevation myocardial infarction (NSTEMI). We investigated these and several novel algorithms for the rule-out of non-ST elevation acute coronary syndrome (NSTE-ACS) including less urgent coronary ischemia.

METHOD

A total of 1504 unselected patients with suspected NSTE-ACS were included and divided into a derivation cohort (n = 988) and validation cohort (n = 516). The primary endpoint was the diagnostic performance to rule-out NSTEMI and unstable angina pectoris during index hospitalization. The secondary endpoint was combined MI, all-cause mortality (within 30 days) and urgent (24 h) revascularization. The ESC algorithms for high-sensitivity cardiac troponin T (hs-cTnT) and I (hs-cTnI) were compared to different novel low-baseline (limit of detection), low-delta (based on the assay analytical and biological variation), and 0-1-h and 0-3-h algorithms.

RESULTS

The prevalence of NSTE-ACS was 24.8%, 60.0% had noncardiac chest pain, and 15.2% other diseases. The 0-1/0-3-h algorithms had superior clinical sensitivity for the primary endpoint compared to the ESC algorithm (validation cohort); hs-cTnT: 95% vs 63%, and hs-cTnI: 87% vs 64%, respectively. Regarding the secondary endpoint, the algorithms had similar clinical sensitivity (100% vs 94%-96%) but lower clinical specificity (41%-19%) compared to the ESC algorithms (77%-74%). The rule-out rates decreased by a factor of 2-4.

CONCLUSION

Low concentration/low-delta troponin algorithms improve the clinical sensitivity for a combined endpoint of NSTEMI and unstable angina pectoris, with the cost of a substantial reduction in total rule-out rate. There was no clear benefit compared to ESC for diagnosing high-risk events.

Development of a novel ssDNA aptamer targeting cardiac troponin I and its clinical applications

Cardiac troponin I (cTnI) is a specific biomarker of acute myocardial infarction (AMI). However, cTnI detection kits prepared with antibodies have many defects. Nucleic acid aptamers are sequences of single-strand DNA or RNA that can overcome the deficiency of antibodies. Herein, sandwich ELONA methods were established based on aptamers. Two selected ssDNA aptamers (Apt3 and Apt6) showed high binding affinity and sensibility (Apt3: Kd = 1.01 ± 0.07 nM, Apt6: k = 0.68 ± 0.05) and did not bind to the same domain of cTnI. Therefore, these two aptamers can be applied to the ELONA methods. The detection range of cTnI using the dual-aptamer sandwich ELONA method was 0.05-200 ng/mL, and the bioanalytical method verification results can meet the national standard of Chinese Pharmacopoeia (2020 Edition). There was no difference between results of the dual-aptamer sandwich ELONA method and the diagnostic results of serum obtained from 243 people (P = 0.39, P ˃ 0.05). The sensitivity and specificity of the ELONA with cTnI in serum were 96.46% and 93.85%, respectively. Compared with the FICA kit, which is clinically used, the consequences of ELONA method are closer to the diagnostic results. This study suggests that the aptamers Apt3 and Apt6 have high affinity and strong specificity and that the dual-aptamer sandwich ELONA method has a wide detection range and can be used to determine cTnI in serum, with potential applications in the diagnosis of AMIs.

Cardiac Troponin Assays With Improved Analytical Quality: A Trade-Off Between Enhanced Diagnostic Performance and Reduced Long-Term Prognostic Value

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 cTnT_ESC (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.