Evaluating Rapid Rule-out of Acute Myocardial Infarction Using a High-Sensitivity Cardiac Troponin I Assay at Presentation

Diagnostic accuracy of a machine learning algorithm using point-of-care high-sensitivity cardiac troponin I for rapid rule-out of myocardial infarction: a retrospective study

BACKGROUND

Point-of-care (POC) high-sensitivity cardiac troponin (hs-cTn) assays have been shown to provide similar analytical precision despite substantially shorter turnaround times compared with laboratory-based hs-cTn assays. We applied the previously developed machine learning based personalised Artificial Intelligence in Suspected Myocardial Infarction Study (ARTEMIS) algorithm, which can predict the individual probability of myocardial infarction, with a single POC hs-cTn measurement, and compared its diagnostic performance with standard-of-care pathways for rapid rule-out of myocardial infarction.

METHODS

We retrospectively analysed pooled data from consecutive patients of two prospective observational cohorts in geographically distinct regions (the Safe Emergency Department Discharge Rate cohort from the USA and the Suspected Acute Myocardial Infarction in Emergency cohort from Australia) who presented to the emergency department with suspected myocardial infarction. Patients with ST-segment elevation myocardial infarction were excluded. Safety and efficacy of direct rule-out of myocardial infarction by the ARTEMIS algorithm (at a pre-specified probability threshold of <0·5%) were compared with the European Society of Cardiology (ESC)-recommended and the American College of Cardiology (ACC)-recommended 0 h pathways using a single POC high-sensitivity cardiac troponin I (hs-cTnI) measurement (Siemens Atellica VTLi as investigational assay). The primary diagnostic outcome was an adjudicated index diagnosis of type 1 or type 2 myocardial infarction according to the Fourth Universal Definition of Myocardial Infarction. The safety outcome was a composite of incident myocardial infarction and cardiovascular death (follow-up events) at 30 days. Additional analyses were performed for type I myocardial infarction only (secondary diagnostic outcome), and for each cohort separately. Subgroup analyses were performed for age (<65 years vs ≥65 years), sex, symptom onset (≤3 h vs >3 h), estimated glomerular filtration rate (<60 mL/min per 1·73 m2vs ≥60 mL/min per 1·73 m2), and absence or presence of arterial hypertension, diabetes, a history of coronary artery disease, myocardial infarction, or heart failure, smoking, and ischaemic electrocardiogram signs.

FINDINGS

Among 2560 patients (1075 [42%] women, median age 58 years [IQR 48·0-69·0]), prevalence of myocardial infarction was 6·5% (166/2560). The ARTEMIS-POC algorithm classified 899 patients (35·1%) as suitable for rapid rule-out with a negative predictive value of 99·96% (95% CI 99·64-99·96) and a sensitivity of 99·68% (97·21-99·70). For type I myocardial infarction only, negative predictive value and sensitivity were both 100%. Proportions of missed index myocardial infarction (0·05% [0·04-0·42]) and follow-up events at 30 days (0·07% [95% CI 0·06-0·59]) were low. While maintaining high safety, the ARTEMIS-POC algorithm identified more than twice as many patients as eligible for direct rule-out compared with guideline-recommended ESC 0 h (15·2%) and ACC 0 h (13·8%) pathways. Superior efficacy persisted across all clinically relevant subgroups.

INTERPRETATION

The patient-tailored, medical decision support ARTEMIS-POC algorithm applied with a single POC hs-cTnI measurement allows for very rapid, safe, and more efficient direct rule-out of myocardial infarction than guideline-recommended pathways. It has the potential to expedite the safe discharge of low-risk patients from the emergency department including early presenters with symptom onset less than 3 h at the time of admission and might open new opportunities for the triage of patients with suspected myocardial infarction even in ambulatory, preclinical, or geographically isolated care settings.

FUNDING

The German Center for Cardiovascular Research (DZHK).

Uniform or Sex-Specific Cardiac Troponin Thresholds to Rule Out Myocardial Infarction at Presentation

BACKGROUND

Myocardial infarction can be ruled out in patients with a single cardiac troponin measurement. Whether use of a uniform rule-out threshold has resulted in sex differences in care remains unclear.

OBJECTIVES

The purpose of this study was to evaluate implementation of a uniform rule-out threshold in females and males with possible myocardial infarction, and to derive and validate sex-specific thresholds.

METHODS

The implementation of a uniform rule-out threshold (<5 ng/L) with a high-sensitivity cardiac troponin I assay was evaluated in consecutive patients presenting with possible myocardial infarction. The proportion of low-risk patients discharged from the emergency department and incidence of myocardial infarction or cardiac death at 30 days were determined. Sex-specific thresholds were derived and validated, and proportion of female and male patients were stratified as low-risk compared with uniform threshold.

RESULTS

In 16,792 patients (age 58 ± 17 years; 46% female) care was guided using a uniform threshold. This identified more female than male patients as low risk (73% vs 62%), but a similar proportion of low-risk patients were discharged from the emergency department (81% for both) with fewer than 5 (<0.1%) patients having a subsequent myocardial infarction or cardiac death at 30 days. Compared with a uniform threshold of <5 ng/L, use of sex-specific thresholds would increase the proportion of female (61.8% vs 65.9%) and reduce the proportion of male (54.8% vs 47.8%) patients identified as low risk.

CONCLUSIONS

Implementation of a uniform rule-out threshold for myocardial infarction was safe and effective in both sexes. Sex-specific rule-out thresholds should be considered, but their impact on effectiveness and safety may be limited.

Safety and Effectiveness of the High-Sensitivity Cardiac Troponin HEART Pathway in Patients With Possible Acute Coronary Syndrome

BACKGROUND

The HEART Pathway (History, Electrocardiogram, Age, Risk factors, Troponin) can be used with high-sensitivity cardiac troponin to risk stratify emergency department patients with possible acute coronary syndrome. However, data on whether a high-sensitivity HEART Pathway (hs-HP) are safe and effective is lacking.

METHODS

An interrupted time series study was conducted at 5 North Carolina sites in 26 126 adult emergency department patients being investigated for possible acute coronary syndrome and without ST-segment-elevation myocardial infarction. Patients were accrued into 16-month preimplementation and postimplementation cohorts with a 6-month wash-in phase. Preimplementation (January 2019 to April 2020), the traditional HEART Pathway was used with 0- and 3-hour contemporary troponin measures (Siemens). In the postimplementation period (November 2020 to February 2022), a modified hs-HP was used with 0- and 2-hour high-sensitivity cardiac troponin (Beckman Coulter) measures. The primary safety and effectiveness outcomes were 30-day all-cause death or myocardial infarction and 30-day hospitalizations. These outcomes and early discharge rate (emergency department discharge without stress testing or coronary angiography) were determined from health records and death index data. Outcomes were compared preimplementation versus postimplementation using χ2 tests and multivariable logistic regression to adjust for potential confounders.

RESULTS

Preimplementation and postimplementation cohorts included 12 317 and 13 809 patients, respectively, of them 52.7% (13 767/26 126) were female with a median age of 54 years (interquartile range, 42-66). Rates of 30-day death or MI were 6.8% (945/13 809) postimplementation and 7.7% (948/12 317) preimplementation (adjusted odds ratio, 1.00 [95% CI, 0.90-1.11]). hs-HP implementation was associated with 19.9% (95% CI, 18.7%-21.1%) higher early discharges (post versus pre: 63.6% versus 43.7%; adjusted odds ratio, 2.22 [95% CI, 2.10-2.35]). The hs-HP was also associated with 16.1% (95% CI, 14.9%-17.3%) lower 30-day hospitalizations (postimplementation versus preimplementation, 31.4% versus 47.5%; adjusted odds ratio, 0.51 [95% CI, 0.48-0.54]). Among early discharge patients, death or myocardial infarction occurred in 0.5% (41/8780) postimplementation versus 0.4% (22/5383) preimplementation (P=0.61).

CONCLUSIONS

hs-HP implementation is associated with increased early discharges without increasing adverse events. These findings support the use of a modified hs-HP to improve chest pain care.

Establishing optimal cutoff values for high-sensitivity cardiac troponin algorithms in risk stratification of acute myocardial infarction

Acute myocardial infarction (AMI) is a leading cause of mortality globally, highlighting the need for timely and accurate diagnostic strategies. Cardiac troponin has been the biomarker of choice for detecting myocardial injury. A dynamic change in concentrations supports the diagnosis of AMI in the setting of evidence of acute myocardial ischemia. The new generation of high-sensitivity cardiac troponin (hs-cTn) assays has significantly improved analytical sensitivity but at the expense of decreased clinical specificity. As a result, sophisticated algorithms are required to differentiate AMI from non-AMI patients. Establishing optimal hs-cTn cutoffs for these algorithms to rule out and rule in AMI has been the subject of intensive investigations. These efforts have evolved from examining the utility of the hs-cTn 99th percentile upper reference limit, comparing the percentage versus absolute delta thresholds, and evaluating the performance of an early European Society of Cardiology-recommended 3 h algorithm, to the development of accelerated 1 h and 2 h algorithms that combine the admission hs-cTn concentrations and absolute delta cutoffs to rule out and rule in AMI. Specific cutoffs for individual confounding factors such as sex, age, and renal insufficiency have also been investigated. At the same time, concerns such as whether the small delta thresholds exceed the analytical and biological variations of hs-cTn assays and whether the algorithms developed in European study populations fit all other patient cohorts have been raised. In addition, the accelerated algorithms leave a substantial number of patients in a non-diagnostic observation zone. How to properly diagnose patients falling in this zone and those presenting with elevated baseline hs-cTn concentrations due to the presence of confounding factors or comorbidities remain open questions. Here we discuss the developments described above, focusing on criteria and underlying considerations for establishing optimal cutoffs. In-depth analyses are provided on the influence of biological variation, analytical imprecision, local AMI rate, and the timing of presentation on the performance metrics of the accelerated hs-cTn algorithms. Developing diagnostic strategies for patients who remain in the observation zone and those presenting with confounding factors are also reviewed.

Suspected myocardial infarction in the emergency department: An evaluation of clinical thresholds for the Beckman Coulter Access hsTnI high-sensitivity cardiac troponin I assay

OBJECTIVE

The primary objective was to determine rapid rule-out (RRO) criteria for the outcome of myocardial infarction (MI) using the Beckman Coulter Access high-sensitivity cardiac troponin I (hs-cTnI) assay. Secondary objectives were to explore cut-points for rapid rule-in (RRI) and amount of change at 3-h (3-h delta) indicative of MI.

METHODS

A retrospective study included ED patients with suspected MI between June and September 2019. hs-cTnI levels were performed at baseline and after 3 h. The performance benchmark for RRO criteria was a negative predictive value (NPV) for MI with a lower 95% confidence limit >99%, and for RRI and 3-h delta cut-points was a positive predictive value (PPV) for MI >70%. Delta calculation required rising hs-cTnI levels, with at least one above the 99th percentile of the upper reference limit. Analyses utilised receiver operating characteristic (ROC) curves and contingency tables.

RESULTS

Baseline hs-cTnI levels from 935 patients were available for RRO analyses. Of tested criteria, baseline hs-cTnI <6 ng/L (females) or <11 ng/L (males) plus symptom onset >2 h met the performance benchmark (NPV: 100% [95% confidence interval 99-100]). hs-cTnI levels were available for RRI and 3-h delta analyses from 935 and 52 patients, respectively. A 3-h delta cut-point >35 ng/L met the performance benchmark (PPV: 81% [95% confidence interval 58-95]) but no RRI cut-point did so.

CONCLUSIONS

For the Beckman Coulter Access hs-cTnI assay, RRO criteria of baseline hs-cTnI <6 ng/L (females) or <11 ng/L (males) plus symptom onset >2 h met our performance benchmark. A 3-h delta cut-point >35 ng/L met the performance benchmark, but poor precision means further adequately powered research is required.

Effect of a High-Sensitivity Troponin I and Associated Diagnostic Protocol on Emergency Department Length of Stay: A Retrospective Cohort Study

Background

The objective of this study was to assess the introduction of a high-sensitivity troponin I (hs-TnI) assay and its associated accelerated protocol on emergency department (ED) length of stay (LOS) for patients presenting with chest pain, compared to an accelerated diagnostic protocol using conventional troponin (TnI) testing.

Methods

We conducted a retrospective cohort study of all adults with a primary presenting complaint of chest pain of cardiac origin and a Canadian Triage and Acuity Scale score of 2 or 3, between November 8, 2019 and November 9, 2021, to a tertiary-care urban Canadian ED. The primary outcome was ED LOS. Secondary outcomes included consultation proportions and major adverse cardiac events within 30 days of the index ED visit.

Results

A total of 2640 patients presenting with chest pain were included, with 1333 in the TnI group and 1307 in the hs-TnI group. Median ED LOS decreased significantly, from 392 minutes for the TnI group, and 371 minutes for the hs-TnI group (median difference = 21 minutes; 95% confidence interval: 5.3, 36.7). The numbers of consultations and admissions were not statistically different between study periods. The major adverse cardiac events outcomes did not change following the implementation of the hs-TnI test (13.6% vs 13.1%; P = 0.71).

Conclusions

The implementation of an accelerated chest pain protocol using an hs-TnI assay in a tertiary-care Canadian ED was associated with a modest reduction of LOS for all patients, and a substantial reduction of LOS for patients undergoing serial troponin testing. This strategy was safe, with no increase in adverse outcomes.

Single Troponin Measurement to Rule Out Myocardial Infarction: JACC Review Topic of the Week

The term "single-sample rule-out" refers to the ability of very low concentrations of high-sensitivity cardiac troponin (hs-cTn) on presentation to exclude acute myocardial infarction with high clinical sensitivity and negative predictive value. Observational and randomized studies have confirmed this ability. Some guidelines endorse use of a concentration of hs-cTn at the assay's limit of detection, while other studies have validated the use of higher concentrations, allowing this approach to identify a greater proportion of patients at low risk. In most studies, at least 30% of patients can be triaged with this approach. The concentration of hs-cTn varies according to the assay used and sometimes how regulations permit reporting. It is clear that patients need to be at least 2 hours from the onset of symptoms being evaluated. Caution is warranted, particularly with older patients, women, and patients with underlying cardiac comorbidities.

Analytical performance comparing siemens whole blood point of care Atellica VTLi to the central laboratory plasma Atellica IM high-sensitivity cardiac troponin I assays

INTRODUCTION

This study examined the analytical performance of a whole blood (WB) point of care (POC) hs-cTnI assay compared to a plasma central laboratory hs-cTnI assay in patients presenting with ischemic symptoms to a US emergency department.

METHODS

Fresh WB specimens collected at 0 and 2 h from 1089 consecutive patients (2152 total from 1076 matched specimens) were analyzed for hs-cTnI using WB on POC Siemens Atellica VTLi assay and plasma on central laboratory Siemens Atellica IM assay. Concordances were determined based on concentrations ranging from < limit of detection (LoD), LoD to overall and sex specific 99th percentiles from both the IFCC manufacturer package inserts and Universal Sample Bank (USB) data, and > 99th percentiles. Method comparisons were calculated using Passing Bablok regression and Bland Altmann plots, and linear regression determined by Pearson correlation coefficient.

RESULTS

Baseline concentration comparisons showed: POC VTLi < LoD 4-5 %, ≥ LoD 95 %; Atellica IM < LoD 5-7 %, and ≥ LoD 94-95 %. From the 2152 paired 0 and 2-hour samples, based on 99th percentiles, overall concordance was 91-92 % (kappa 0.72-0.77) and discordance 8 %. Passing Bablok regression analysis using 1924 specimens between LoD to 500 ng/L showed: slopes 0.469-0.490; y-intercepts 1.753-2.028; r values 0.631-0.817. Pearson correlation coefficient showed moderate to strong correlation strength, even with up to 53 % cTnI concentrations variance (Passing Bablok slopes) vs 27.0-40.1 % (Bland-Altmann plots).

CONCLUSIONS

Up to 95 % of measured samples were > LoD for both the POC (Atellica VTLi) and central laboratory (Atellica IM) hs-cTnI assays. Moderate to strong concordance and correlation were observed between assays, despite up to 53 % variances in cTnI concentration.

Derivation and validation of a high sensitivity troponin-T HEART pathway

BACKGROUND

The HEART Pathway is widely used for chest pain risk stratification but has yet to be optimized for high sensitivity troponin T (hs-cTnT) assays.

METHODS

We conducted a secondary analysis of STOP-CP, a prospective cohort study enrolling adult ED patients with symptoms suggestive of acute coronary syndrome at 8 sites in the United States (US). Patients had a 0- and 1-hour hs-cTnT measured and a HEAR score completed. A derivation set consisting of 729 randomly selected participants was used to derive a hs-cTnT HEART Pathway with rule-out, observation, and rule-in groups for 30-day cardiac death or myocardial infarction (MI). Optimal baseline and 1-hour troponin cutoffs were selected using generalized cross validation to achieve a negative predictive value (NPV) >99% for rule out and positive predictive value (PPV) >60% or maximum Youden index for rule-in. Optimal 0-1-hour delta values were derived using generalized cross validation to maximize the NPV for the rule-out group and PPV for the rule-in group. The hs-cTnT HEART Pathway performance was validated in the remaining cohort (n = 723).

RESULTS

Among the 1452 patients, 30-day cardiac death or MI occurred in 12.7% (184/1452). Within the derivation cohort the optimal hs-cTnT HEART Pathway classified 36.5% (266/729) into the rule-out group, yielding a NPV of 99.2% (95% CI: 98.2-100) for 30-day cardiac death or MI. The rule-in group included 15.4% (112/729) with a PPV of 55.4% (95% CI: 46.2-64.6). In the validation cohort, the hs-cTnT HEART Pathway ruled-out 37.6% (272/723), of which 2 had 30-day cardiac death or MI, yielding a NPV of 99.3% (95% CI: 98.3-100). The rule-in group included 14.5% (105/723), yielding a PPV of 57.1% (95% CI: 47.7-66.6).

CONCLUSIONS

A novel hs-cTnT HEART Pathway with serial 0- and 1-hour hs-cTnT measures has high NPV and moderate PPV for 30-day cardiac death or MI.

Implementation of the ESC 0 h/1 h high-sensitivity troponin algorithm for decision-making in the emergency department

Diagnosis of non-ST-segment elevation acute coronary syndromes (NSTEACS) is based on 3 cornerstones: clinical presentation, 12-lead electrocardiogram, and cardiac troponin measurement. Advances in the development of high-sensitivity cardiac troponin (hs-cTn) assays have substantially improved the detection of cardiomyocyte injury in a shorter time period, and hs-cTn has consequently been established as the gold-standard biomarker for the assessment of patients with suspected NSTEACS. The implementation of these assays in clinical practice allows a faster "rule-out", especially among low-risk patients, as well as a safer and more rapid "rule-in", with its therapeutic consequences. Current guidelines for the diagnosis of NSTEACS recommend the use of hs-cTn applied in rapid diagnostic algorithms based on serial hs-cTn sampling within the first few hours. The current work provides an overview of the use of hs-cTn for the early detection of NSTEACS.

Single High-Sensitivity Point-of-Care Whole-Blood Cardiac Troponin I Measurement to Rule Out Acute Myocardial Infarction at Low Risk

BACKGROUND

High-sensitivity cardiac troponin (hs-cTn) laboratory assays are used to rule out myocardial infarction (MI) on presentation, but prolonged result turnaround times can delay patient management. Our primary aim was to identify patients at low risk of index MI using a rapid point-of-care (POC) whole-blood hs-cTnI assay at presentation with potential early patient discharge.

METHODS

Consecutive patients presenting to the emergency department from 2 prospective observational studies with suspected acute coronary syndrome were enrolled. A POC hs-cTnI assay (Atellica VTLi) threshold using whole blood at presentation, which resulted in a negative predictive value of ≥99.5% and sensitivity of >99% for index MI, was derived (SEIGE [Safe Emergency Department Discharge Rate]) and validated with plasma (SAMIE [Suspected Acute Myocardial Infarction in Emergency]). Event adjudications were established with hs-cTnI assay results from routine clinical care. The primary outcome was MI at 30 days.

RESULTS

A total of 1086 patients (8.1% with MI) were enrolled in a US derivation cohort (SEIGE) and 1486 (5.5% MI) in an Australian validation cohort (SAMIE). A derivation whole-blood POC hs-cTnI concentration of <4 ng/L provided a sensitivity of 98.9% (95% CI, 93.8%-100%) and negative predictive value of 99.5% (95% CI, 97.2%-100%) for ruling out MI. In the validation cohort, the sensitivity was 98.8% (95% CI, 93.3%-100%), and negative predictive value was 99.8% (95% CI, 99.1%-100%); 17.8% and 41.8%, respectively, were defined as low risk for discharge. The 30-day adverse cardiac events were 0.1% (n=1) for SEIGE and 0.8% (n=5) for SAMIE.

CONCLUSIONS

A POC whole-blood hs-cTnI assay permits accessible, rapid, and safe exclusion of MI and may expedite discharge from the emergency department.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04772157. URL: https://www.australianclinicaltrials.gov.au/anzctr_feed/form; Unique identifier: 12621000053820.

Evaluation of the Atellica TnIH cardiac troponin I assay and assessment of biological equivalence

OBJECTIVES

We evaluated the analytical performance characteristics and the biological equivalence of the Atellica TnIH assay.

METHODS

Precision, detection capability, linearity, and sex specific 99^th percentiles were determined de novo. Classification of patients relative to the 99^th percentiles was used to assess biological equivalence.

RESULTS

Analytical precision and detection capability of the Atellica TnIH assay is excellent with a limit of blank <1 ng/L and 62.5% of women and 93% of men had results above the limit of detection. The 99th percentiles (90% CI) in women were 49 ng/L (31-67) and 70 ng/L (48-121) in men. An asymmetrical distribution involving 5% of results was notable. Agreement was moderate (Kappa 0.58, 95% CI 0.53-0.63) with 20% of patients discordantly classified with Atellica TnIH below and Access hsTnI above the 99th percentiles. Serial results in 195 patients demonstrated good agreement (Kappa 0.84, 95% CI 0.77-0.90). Differences greater than the assay specific reference change values (z_≥±1.96) occurred in 65% (95% CI 53-76%) of 99th percentile discordant patients compared to 2.7% (p<0.001) and 76% (p=0.17) of the concordant low and high cTnI groups respectively.

CONCLUSIONS

The 99th percentile discordant and the concordantly elevated groups are more alike with respect to their z_≥±1.96 rates. This favours an overestimated Atellica TnIH 99th percentile as more likely, and we hypothesize that antibody interference resulting in asymmetric scatter of nearly 5% samples may be the underlying mechanism. Analytical accuracy and interferences in cardiac troponin assays should be investigated and resolved with high priority.

Inhibition of the lncRNA DANCR attenuates cardiomyocyte injury induced by oxygen-glucose deprivation via the miR-19a-3p/MAPK1 axis

Long noncoding RNAs (lncRNAs) have been considered as crucial regulators of acute myocardial infarction (AMI). In this study, to analyze the effect of differentiation antagonizing nonprotein coding RNA (DANCR) of lncRNA on cardiomyocyte damage in AMI, cardiomyocyte injury was induced by oxygen-glucose deprivation (OGD). Cell counting kit-8 (CCK-8) assay and flow cytometry were used to assess cell viability and apoptosis, respectively. Quantitative real-time PCR was used to measure the expression levels of DANCR and miR-19a-3p. Bioinformatics analysis and luciferase gene reporter assay were utilized to explore the relationship among DANCR, miR-19a-3p, and mitogen-activated protein kinase 1 (MAPK1). CCK-8 and TUNEL assays were used to explore the effects of DANCR alone or plus miR-19a-3p on the viability and apoptosis of OGD/R-exposed HL-1 cells. Western blot analysis was used to detect changes in the MAPK1/ERK1/2 pathway in HL-1 cells. We found that DANCR expression and miR-19a-3p level are negatively correlated as DANCR expression is increased, while miR-19a-3p level is decreased in AMI patients' serum and OGD/R-exposed HL-1 cells. DANCR knockdown increased miR-19a-3p level, and miR-19a-3p inhibition increased DANCR expression. Moreover, DANCR directly binds to miR-19a-3p. DANCR knockdown reduced viability but induced apoptosis in OGD/R-exposed HL-1 cells, while miR-19a-3p inhibition weakens these effects. Furthermore, MAPK1 is a target of miR-19a-3p. miR-19a-3p overexpression decreases MAPK1 and ERK1/2 in HL-1 cells, while miR-19a-3p inhibition increases MAPK1 and ERK1/2 in HL-1 cells. Moreover, DANCR knockdown reduces myocardium apoptosis in mice with the left anterior descending artery ligated. DANCR knockdown effectively restores myocardial cell apoptosis by regulating the miR-19a-3p/MAPK1/ERK1/2 axis.

Single troponin measurement to rule-out acute myocardial infarction in early presenters

BACKGROUND

A single high-sensitive cardiac troponin (hs-cTn) can be used to rule-out acute myocardial infarction (MI) in patients presenting >3 hours (3 h) after chest pain onset to the emergency department. This study aimed to investigate the safety of ruling-out MI in early presenters with chest pain ≤3 h using a single hs-cTnI at admission.

METHODS

We prospectively enrolled patients presenting with chest pain suggestive of MI. Hs-cTnI (Siemens ADVIA Centaur TNIH, Limit of detection: 2.2 ng/L) was measured at admission. Two physicians adjudicated final diagnosis. A diagnostic cut-off value <3 ng/L was used to rule-out MI. Patients were classified as early (chest pain ≤3 h) or late presenters (>3 h).

RESULTS

We included 1370 patients with available admission hs-cTnI results: median (Q1-Q3) age 65 (52-74), female sex: 43%, previous MI: 22%. We confirmed MI in 118 (8.6%) patients. Overall, 470 (34%) patients were classified as early, 770 (56%) as late presenters, and 130 (9%) patients had unknown onset. When applying the diagnostic cut-off value, MI was correctly ruled-out at admission in 370 (27%) patients: 134 (29%) early presenters, 206 (27%) late presenters and 30 (23%) patients with unknown onset. This resulted in an overall negative predictive value of 100% (95% CI: 99.0-100%), with both 100% (97.3-100%) for early and 100% (98.2-100%) for late presenters, respectively. Sensitivity was similarly high in the two groups.

CONCLUSION

MI could be safely ruled-out in all patients presenting with chest pain ≤3 h when using a single hs-cTnI value <3 ng/L as diagnostic cut-off.

TRIAL REGISTRATION NUMBER

NCT03634384.

High-Sensitivity Cardiac Troponin on Presentation to Rule Out Myocardial Infarction: A Stepped-Wedge Cluster Randomized Controlled Trial

BACKGROUND

High-sensitivity cardiac troponin assays enable myocardial infarction to be ruled out earlier, but the safety and efficacy of this approach is uncertain. We investigated whether an early rule-out pathway is safe and effective for patients with suspected acute coronary syndrome.

METHODS

We performed a stepped-wedge cluster randomized controlled trial in the emergency departments of 7 acute care hospitals in Scotland. Consecutive patients presenting with suspected acute coronary syndrome between December 2014 and December 2016 were included. Sites were randomized to implement an early rule-out pathway where myocardial infarction was excluded if high-sensitivity cardiac troponin I concentrations were <5 ng/L at presentation. During a previous validation phase, myocardial infarction was ruled out when troponin concentrations were <99th percentile at 6 to 12 hours after symptom onset. The coprimary outcome was length of stay (efficacy) and myocardial infarction or cardiac death after discharge at 30 days (safety). Patients were followed for 1 year to evaluate safety and other secondary outcomes.

RESULTS

We enrolled 31 492 patients (59±17 years of age [mean±SD]; 45% women) with troponin concentrations <99th percentile at presentation. Length of stay was reduced from 10.1±4.1 to 6.8±3.9 hours (adjusted geometric mean ratio, 0.78 [95% CI, 0.73-0.83]; P<0.001) after implementation and the proportion of patients discharged increased from 50% to 71% (adjusted odds ratio, 1.59 [95% CI, 1.45-1.75]). Noninferiority was not demonstrated for the 30-day safety outcome (upper limit of 1-sided 95% CI for adjusted risk difference, 0.70% [noninferiority margin 0.50%]; P=0.068), but the observed differences favored the early rule-out pathway (0.4% [57/14 700] versus 0.3% [56/16 792]). At 1 year, the safety outcome occurred in 2.7% (396/14 700) and 1.8% (307/16 792) of patients before and after implementation (adjusted odds ratio, 1.02 [95% CI, 0.74-1.40]; P=0.894), and there were no differences in hospital reattendance or all-cause mortality.

CONCLUSIONS

Implementation of an early rule-out pathway for myocardial infarction reduced length of stay and hospital admission. Although noninferiority for the safety outcome was not demonstrated at 30 days, there was no increase in cardiac events at 1 year. Adoption of this pathway would have major benefits for patients and health care providers. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03005158.

Cardiac Troponins: Contemporary Biological Data and New Methods of Determination

Laboratory diagnosis plays one of the key roles in the diagnosis of many diseases, including cardiovascular diseases (CVD). The methods underlying the in vitro study of many CVD biomarkers, including cardiac troponins (cTnI and cTnT), are imperfect and are continually being improved to enhance their analytical performance, with sensitivity and specificity being the most important. Recently developed improved cTnI and cTnT detection methods, referred to as highly sensitive methods (hs-cTnI, hs-cTnT), have changed many of our ideas about the biology of cardiac troponins and opened up a number of additional diagnostic capabilities for practical healthcare. This article systematizes some relevant data on the biology of cardiac troponins as well as on methods for determining cTnI and cTnT with an analysis of the diagnostic value of their analytical characteristics (limit of blank, limit of detection, 99th percentile, coefficient of variation, and others). Data on extracardiac expression of cTnI and cTnT, mechanisms of formation and potential clinical significance of gender, age, and circadian characteristics of hs-cTnI and hs-cTnT content in serum are discussed. Considerable attention is paid to the discussion of new diagnostic capabilities of hs-cTnI, hs-cTnT, including consideration of promising possibilities for their study in biological fluids that can be obtained by non-invasive methods. Also, some possibilities of using hs-cTnI and hs-cTnT as prognostic laboratory biomarkers in healthy people (for example, to assess the risk of developing CVD) and in patients suffering from a number of pathological conditions that cause damage to cardiomyocytes are examined, and the potential mechanisms underlying the increase in hs-cTnI and hs-cTnT are discussed.

Clinical Impact of High-Sensitivity Cardiac Troponin T Implementation in the Community

BACKGROUND

Limited U.S. data exist regarding high-sensitivity cardiac troponin (cTn) implementation.

OBJECTIVES

This study sought to evaluate the impact of high-sensitivity cardiac troponin T (cTnT) implementation.

METHODS

Observational U.S. cohort study of emergency department (ED) patients undergoing measurement of cTnT during the transition from 4th (pre-implementation March 12, 2018, to September 11, 2018) to 5th generation (Gen) cTnT (post-implementation September 12, 2018, to March 11, 2019). Diagnoses were adjudicated following the Fourth Universal Definition of Myocardial Infarction (MI). Resources evaluated included length of stay, hospitalizations, and cardiac testing.

RESULTS

In this study, 3,536 unique patients were evaluated, including 2,069 and 2,491 ED encounters pre- and post-implementation. Compared with 4th Gen cTnT, encounters with ≥1 cTnT >99th percentile increased using 5th Gen cTnT (15% vs. 47%; p < 0.0001). Acute MI (3.3% vs. 8.1%; p < 0.0001) and myocardial injury (11% vs. 38%; p < 0.0001) increased. Although type 1 MIs increased (1.7% vs. 2.9%; p = 0.0097), the overall MI increase was largely due to more type 2 MIs (1.6% vs. 5.2%; p < 0.0001). Women were less likely than men to have MI using 4th Gen cTnT (2.3% vs. 4.4%; p = 0.008) but not 5th Gen cTnT (7.7% vs. 8.5%; p = 0.46). Overall length of stay and stress testing were reduced, and angiography was increased (all p < 0.05). Among those without cTnT increases, there were more ED discharges and a reduction in length of stay, echocardiography, and stress tests (all p < 0.05).

CONCLUSIONS

High-sensitivity cTnT implementation resulted in a marked increase in myocardial injury and MI, particularly in women and patients with type 2 MI. Despite this, except for angiography, overall resource use did not increase. Among those without cTnT increases, there were more ED discharges and fewer cardiac tests.

Pre-coated interface proximity extension reaction assay enables trace protein detection with single-digit accuracy

Advances in trace protein detection contribute to the early diagnosis of diseases and exploration of stem cell development. The pre-coated interface proximity extension reaction (PIPER) assay enables target protein detection at trace levels and was developed based on protein biomarker recognition using sets of three specific antibodies and the extension of antibody-bound nucleic acid chains in proximity, accompanied by amplification and reading of protein signals via real-time quantitative polymerase chain reaction (qPCR). Noise generated in binding reactions and enzymatic steps was decreased by transferring the liquid-liquid reactions onto a liquid-solid interface in glutaraldehyde-treated tubes pre-coated with antibodies. Nucleic acid sequences of oligo-antibody-based probes were designed for extension and qPCR without pre-amplification when binding to a target molecule. As a proof of concept, the PIPER assay was used to profile slight variations in crucial biomarkers, high-sensitivity C-reactive protein, and cardiac troponin I. The detection sensitivity of the assay for the biomarkers was 0.05 pg/mL (1.25 fM) in 10% human serum. In phosphate-buffered saline, the PIPER assay detected fewer than 10 protein molecules per μL. The simple, widely applicable PIPER assay can detect trace protein biomarkers with single-digit accuracy, making it appropriate for the development of clinical hypersensitive protein detection and single-cell protein detection technology.

Independent and combined effects of biotin and hemolysis on high-sensitivity cardiac troponin assays

OBJECTIVES

This study compared the independent and combined effects of hemolysis and biotin on cardiac troponin measurements across nine high-sensitivity cardiac troponin (hs-cTn) assays.

METHODS

Parallel cTn measurements were made in pooled lithium heparin plasma spiked with hemolysate and/or biotin using nine hs-cTn assays: Abbott Alinity, Abbott ARCHITECT i2000, Beckman Access 2, Ortho VITROS XT 7600, Siemens Atellica, Siemens Centaur, Siemens Dimension EXL cTnI, and two Roche Cobas e 411 Elecsys Troponin T-hs cTnT assays (outside US versions, with and without increased biotin tolerance). Absolute and percent cTn recovery relative to two baseline concentrations were determined in spiked samples and compared to manufacturer's claims.

RESULTS

All assays except the Ortho VITROS XT 7600 showed hemolysis and biotin interference thresholds equivalent to or greater than manufacturer's claims. While imprecision confounded analysis of Ortho VITROS XT 7600 data, evidence of biotin interference was lacking. Increasing biotin concentration led to decreasing cTn recovery in three assays, specifically both Roche Cobas e 411 Elecsys Troponin T-hs assays and the Siemens Dimension EXL. While one of the Roche assays was the most susceptible to biotin among the nine studied, a new version showed reduced biotin interference by approximately 100-fold compared to its predecessor. Increasing hemolysis also generally led to decreasing cTn recovery for susceptible assays, specifically the Beckman Access 2, Ortho VITROS XT 7600, and both Roche Cobas e 411 Elecsys assays. Equivalent biotin and hemolysis interference thresholds were observed at the two cTn concentrations considered for all but two assays (Beckman Access 2 and Ortho VITROS XT 7600). When biotin and hemolysis were present in combination, biotin interference thresholds decreased with increasing hemolysis for two susceptible assays (Roche Cobas e 411 Elecsys and Siemens Dimension EXL).

CONCLUSIONS

Both Roche Cobas e 411 Elecsys as well as Ortho VITROS XT assays were susceptible to interference from in vitro hemolysis at levels routinely encountered in clinical laboratory samples (0-3 g/L free hemoglobin), leading to falsely low cTn recovery up to 3 ng/L or 13%. While most assays are not susceptible to biotin at levels expected with over-the-counter supplementation, severely reduced cTn recovery is possible at biotin levels of 10-2000 ng/mL (41-8,180 nmol/L) for some assays. Due to potential additive effects, analytical interferences should not be considered in isolation.

High-sensitivity methods for cardiac troponins: The mission is not over yet

The measurement of cardiac troponin (cTn) is recommended by all guidelines as the gold standard for the differential diagnosis of Acute Coronary Syndromes. The aim of this review is to discuss in details some key issues regarding both analytical and clinical characteristics of the high-sensitivity methods for cTn (hs-cTn), which are still considered controversial or unresolved. In particular, the major clinical concern regarding hs-cTn methods is the difficulty to differentiate the pathophysiological mechanism responsible for biomarker release from cardiomyocytes after reversible or irreversible injury, respectively. Indeed, recent experimental and clinical studies have demonstrated that different circulating forms of cTnI and cTnT can be respectively measured in plasma samples of patients with reversible or irreversible myocardial injury. Accordingly, a new generation of hs-Tn methods should be set up, based on immunometric immunoassays or chromatographic techniques, specific for circulating peptide forms more characteristics for reversible or irreversible myocardial injury. It is conceivable that this new generation of hs-cTn methods will complete the mission regarding the laboratory tests for specific cardiac biomarkers, started more than 20 years ago, which has already revolutionized the diagnosis, prognosis and management of patients with cardiac diseases.

Using the clinical chemistry score in the emergency department to detect adverse cardiac events: a diagnostic accuracy study

BACKGROUND

The ability to rule out or in a major adverse cardiac event (MACE) in patients with suspected acute coronary syndrome at emergency department (ED) presentation would be beneficial to patient care and the health care system. The clinical chemistry score (CCS) was evaluated in this context.

METHODS

This diagnostic accuracy study evaluated 2 different ED cohorts with suspected acute coronary syndrome. For patients in cohort 1, who presented to the ED of 3 hospitals in Hamilton, Ontario, between May and August 2013, retrospective measurements were taken using the Ortho Clinical Diagnostics high-sensitivity cardiac troponin I (hs-cTnI) assay; for patients in cohort 2, who presented to the ED of the same 3 hospitals in Hamilton between November 2012 and February 2013, an ED cardiac presentation blood test panel was performed with the Abbott Diagnostics hs-cTnI assay. The sensitivity and specificity of the CCS (cut-offs of ≥ 1 and 5) and hs-cTnI alone (published cut-offs) were compared for MACE (composite of death, myocardial infarction, unstable angina, revascularization) at 30 days for both cohorts and at 90 days for cohort 2.

RESULTS

The incidence of MACE at 30 days was higher in cohort 1 (n = 1058) (19.4%, 95% confidence interval [CI] 16.8%-22.2%) than in cohort 2 (n = 5974) (14.6%, 95% CI 13.6%-15.6%). In cohort 1, a CCS of 1 or above yielded a sensitivity of 99.5% (95% CI 97.3%-99.9%). The sensitivity with an Ortho hs-cTnI cut-off of 1 ng/L or above was 91.2% (95% CI 86.5%-95.7%). The specificity of a CCS of 5 (97.8%, 95% CI 96.5%-98.7%) was higher than when the overall 99th-percentile cut-off for the Ortho hs-cTnI assay (> 11 ng/L; 90.1%, 95% CI 87.9%-92.0%) was used. A similar pattern was observed in cohort 2 at 30 days and persisted at 90 days with the Abbott hs-cTnI assay.

INTERPRETATION

The CCS derived with 2 different hs-cTnI assays and ED populations yielded higher sensitivity and specificity estimates for MACE than hs-cTnI alone. An intervention study is needed to evaluate the impact of the CCS at both the patient and hospital levels.

TRIAL REGISTRATION

ClinicalTrials.gov, no. NCT01994577.

Myocardial Infarction Can Be Safely Excluded by High-sensitivity Troponin I Testing 3 Hours After Emergency Department Presentation

BACKGROUND

The accuracy and speed by which acute myocardial infarction (AMI) is excluded are an important determinant of emergency department (ED) length of stay and resource utilization. While high-sensitivity troponin I (hsTnI) >99th percentile (upper reference level [URL]) represents a "rule-in" cutpoint, our purpose was to evaluate the ability of the Beckman Coulter hsTnI assay, using various level-of-quantification (LoQ) cutpoints, to rule out AMI within 3 hours of ED presentation in suspected acute coronary syndrome (ACS) patients.

METHODS

This multicenter evaluation enrolled adults with >5 minutes of ACS symptoms and an electrocardiogram obtained per standard care. Exclusions were ST-segment elevation or chronic hemodialysis. After informed consent was obtained, blood samples were collected in heparin at ED admission (baseline), ≥1 to 3, ≥3 to 6, and ≥6 to 9 hours postadmission. Samples were processed and stored at -20°C within 1 hour and were tested at three independent clinical laboratories on an immunoassay system (DxI 800, Beckman Coulter). Analytic cutpoints were the URL of 17.9 ng/L and two LoQ cutpoints, defined as the 10 and 20% coefficient of variation (5.6 and 2.3 ng/L, respectively). A criterion standard MI diagnosis was adjudicated by an independent endpoint committee, blinded to hsTnI, and using the universal definition of MI.

RESULTS

Of 1,049 patients meeting the entry criteria, and with baseline and 1- to 3-hour hsTnI results, 117 (11.2%) had an adjudicated final diagnosis of AMI. AMI patients were typically older, with more cardiovascular risk factors. Median (IQR) presentation time was 4 (1.6-16.0) hours after symptom onset, although AMI patients presented ~0.5 hour earlier than non-AMI. Enrollment and first blood draw occurred at a mean of ~1 hour after arrival. To evaluate the assay's rule-out performance, patients with any hsTnI > URL were considered high risk and were excluded. The remaining population (n = 829) was divided into four LoQ relative categories: both hsTnI < LoQ (Lo-Lo cohort); first hsTnI < LoQ and 2nd > LoQ (Lo-Hi cohort); first > LoQ and second < LoQ (Hi-Lo cohort); or both > LoQ (Hi-Hi cohort). In patients with any hsTnI result <20% CV LoQ (Groups 1-3), n = 231 (23.9% ruled out), AMI negative predictive value (NPV) was 100% (95% confidence interval [CI] = 98.9% to 100%). In patients with any hsTnI below the 10% LoQ, n = 611 (58% rule out), AMI NPV was 100% (95% CI = 99.5% to 100%). Of the Hi-Hi cohort (i.e., no hsTnI below the 10% LoQ, but both < URL), there were four AMI patients, NPV was 98.2% (95% CI = 95.4% to 99.3%), and sensitivity was 96.6.

CONCLUSIONS

Patients presenting >3 hours after the onset of suspected ACS symptoms, with at least two Beckman Coulter Access hsTnI < URL and at least one of which is below either the 10 or the 20% LoQ, had a 100% NPV for AMI. Two hsTnI values 1 to 3 hours apart with both < URL, but also >LoQ had inadequate sensitivity and NPV.

CSANZ Position Statement on the Evaluation of Patients Presenting With Suspected Acute Coronary Syndromes During the COVID-19 Pandemic

A pandemic of Coronavirus-19 disease was declared by the World Health Organization on March 11, 2020. The pandemic is expected to place unprecedented demand on health service delivery. This position statement has been developed by the Cardiac Society of Australia and New Zealand to assist clinicians to continue to deliver rapid and safe evaluation of patients presenting with suspected acute cardiac syndrome at this time. The position statement complements, and should be read in conjunction with, the National Heart Foundation of Australia & Cardiac Society of Australia and New Zealand: Australian Clinical Guidelines for the Management of Acute Coronary Syndromes 2016: Section 2 'Assessment of Possible Cardiac Chest Pain'.

Limit of detection of troponin discharge strategy versus usual care: randomised controlled trial

Introduction

The clinical effectiveness of a ‘rule-out’ acute coronary syndrome (ACS) strategy for emergency department patients with chest pain, incorporating a single undetectable high-sensitivity cardiac troponin (hs-cTn) taken at presentation, together with a non-ischaemic ECG, remains unknown.

Methods

A randomised controlled trial, across eight hospitals in the UK, aimed to establish the clinical effectiveness of an undetectable hs-cTn and ECG (limit of detection and ECG discharge (LoDED)) discharge strategy. Eligible adult patients presented with chest pain; the treating clinician intended to perform investigations to rule out an ACS; the initial ECG was non-ischaemic; and peak symptoms occurred <6 hours previously. Participants were randomised 1:1 to either the LoDED strategy or the usual rule-out strategy. The primary outcome was discharge from the hospital within 4 hours of arrival, without a major adverse cardiac event (MACE) within 30 days.

Results

Between June 2018 and March 2019, 632 patients were randomised; 3 were later withdrawn. Of 629 patients (age 53.8 (SD 16.1) years, 41% women), 7% had a MACE within 30 days. For the LoDED strategy, 141 of 309 (46%) patients were discharged within 4 hours, without MACE within 30 days, and for usual care, 114 of 311 (37%); pooled adjusted OR 1.58 (95% CI 0.84 to 2.98). No patient with an initial undetectable hs-cTn had a MACE within 30 days.

Conclusion

The LoDED strategy facilitates safe early discharge in >40% of patients with chest pain. Clinical effectiveness is variable when compared with existing rule-out strategies and influenced by wider system factors.

Trial registration number

ISRCTN86184521.

Two-Hour Algorithm for Rapid Triage of Suspected Acute Myocardial Infarction Using a High-Sensitivity Cardiac Troponin I Assay

BACKGROUND

We aimed to derive and externally validate a 0/2-h algorithm using the high-sensitivity cardiac troponin I (hs-cTnI)-Access assay.

METHODS

We enrolled patients presenting to the emergency department with symptoms suggestive of acute myocardial infarction (AMI) in 2 prospective diagnostic studies using central adjudication. Two independent cardiologists adjudicated the final diagnosis, including all available medical information including cardiac imaging. hs-cTnI-Access concentrations were measured at presentation and after 2 h in a blinded fashion.

RESULTS

AMI was the adjudicated final diagnosis in 164 of 1131 (14.5%) patients in the derivation cohort. Rule-out by the hs-cTnI-Access 0/2-h algorithm was defined as 0-h hs-cTnI-Access concentration &lt;4 ng/L in patients with an onset of chest pain &gt;3 h (direct rule-out) or a 0-h hs-cTnI-Access concentration &lt;5 ng/L and an absolute change within 2 h &lt;5 ng/L in all other patients. Derived thresholds for rule-in were a 0-h hs-cTnI-Access concentration ≥50 ng/L (direct rule-in) or an absolute change within 2 h ≥20 ng/L. In the derivation cohort, these cutoffs ruled out 55% of patients with a negative predictive value (NPV) of 99.8% (95% CI, 99.3–100) and sensitivity of 99.4% (95% CI, 96.5–99.9), and ruled in 30% of patients with a positive predictive value (PPV) of 73% (95% CI, 66.1–79). In the validation cohort, AMI was the adjudicated final diagnosis in 88 of 1280 (6.9%) patients. These cutoffs ruled out 77.9% of patients with an NPV of 99.8% (95% CI, 99.3–100) and sensitivity of 97.7% (95% CI, 92.0–99.7), and ruled in 5.8% of patients with a PPV of 77% (95% CI, 65.8–86) in the validation cohort.

CONCLUSIONS

Safety and efficacy of the l hs-cTnI-Access 0/2-h algorithm for triage toward rule-out or rule-in of AMI are very high.

TRIAL REGISTRATION

APACE, NCT00470587; ADAPT, ACTRN1261100106994; IMPACT, ACTRN12611000206921.

High-Sensitivity Cardiac Troponin I Assay for Early Diagnosis of Acute Myocardial Infarction

BACKGROUND

The aim of this study was to validate the clinical performance of the Beckman Access high-sensitivity cardiac troponin I (hs-cTnI) assay.

METHODS

We enrolled patients presenting to the emergency department with symptoms suggestive of acute myocardial infarction (AMI). Final diagnoses were centrally adjudicated by 2 independent cardiologists with all clinical information including cardiac imaging twice: first, using serial hs-cTnT (Elecsys, primary analysis), and second, using hs-cTnI (Architect, secondary analysis) measurements in addition to the clinically used hs-cTn. hs-cTnI Access was measured at presentation and at 1 h. The primary objective was a direct comparison of diagnostic accuracy as quantified by the area under the ROC curve (AUC) of hs-cTnI Access vs the hs-cTnT Elecsys and hs-cTnI Architect assays. Secondary objectives included the derivation and validation of an hs-cTnI Access-specific 0/1-h algorithm.

RESULTS

AMI was the adjudicated final diagnosis in 243 of 1579 (15.4%) patients. The AUC at presentation for hs-cTnI Access was 0.95 (95% CI, 0.94–0.96), higher than hs-cTnI Architect [0.92 (95% CI, 0.91–0.94; P &lt; 0.001)] and comparable to hs-cTnT Elecsys [0.94 (95% CI, 0.93–0.95; P = 0.12)]. Applying the derived hs-cTnI Access 0/1-h algorithm (derivation cohort n = 686) to the validation cohort (n = 680), 60% of patients were ruled out [sensitivity, 98.9% (95% CI, 94.3–99.8)], and 15% of patients were ruled in [specificity, 95.9% (95% CI, 94.0–97.2)]. Patients ruled out by the 0/1-h algorithm had a survival rate of 100% at 30 days. Findings were confirmed in the secondary analyses by the adjudication including serial measurements of Architect hs-cTnI.

CONCLUSIONS

Diagnostic accuracy and clinical utility of the Beckman hs-cTnI Access assay are very high and at least comparable to Roche hs-cTnT and Abbott hs-cTnI assays. ClinicalTrials.gov Identifier: NCT00470587.

Recommendations for Institutions Transitioning to High-Sensitivity Troponin Testing: JACC Scientific Expert Panel

High-sensitivity cardiac troponin (hs-cTn) I or T methods have been in use in certain regions for years but are now increasingly globally adopted, including in the United States. Accordingly, inevitable challenges are created for institutions transitioning from conventional cardiac troponin (cTn) assays. hs-cTn assays have higher analytic precision at lower concentrations, yielding greater clinical sensitivity for myocardial injury and allowing accurate recognition of small changes in troponin concentration (rise or fall) within a short time frame. Although much of the knowledge regarding troponin biology that was applicable with older troponin assays still holds true, considerable education regarding the differences between conventional cTn and hs-cTn is needed before medical systems convert to the newer methods. This includes a basic understanding of how hs-cTn testing differs from conventional cTn testing and how it is best deployed in different settings, such as the emergency department and inpatient services. This Expert Panel will review important concepts for institutional transition to hs-cTn methodology, providing recommendations useful for education before implementation.

Clinical use of cardiac troponin for acute cardiac care and emerging opportunities in the outpatient setting

Cardiac troponin (cTn) testing has evolved significantly in recent times. Because of increased sensitivity, its use has shifted from a marker used to help diagnose acute myocardial infarction (MI) to a marker than can be used in the outpatient setting, as well as for both detection of myocardial injury and risk-stratification. Its main role remains in the diagnosis of acute MI and the risk-stratification of patients presenting with suspected acute coronary syndrome. The analytical improvements in assays leading to precise high-sensitivity cTn assays have contributed to the development of numerous strategies to identify patients at both low- and high-risk for acute MI within a few hours. These approaches should reduce overcrowding in the emergency room and expedite triaging. The ability of measuring cTn in most patients using high-sensitivity (hs) assays has allowed for the opportunity to examine its use in the detection of cardiotoxicity in patients undergoing chemotherapy, as well as exploring the application in both primary and secondary prevention of coronary artery disease. This particular field of research has become increasingly complex, partly due to the numerous cTn assays available (I and T; point-of-care, contemporary, hs) and an array of approaches in which one can use the test. The purpose of this document is to summarize the analytical and clinical information relevant to cTn assays, in particular, hs-cTn assays, and describe present and future opportunities for use of cTn in acute cardiac care and in the outpatient setting.

Randomised controlled trial of the Limit of Detection of Troponin and ECG Discharge (LoDED) strategy versus usual care in adult patients with chest pain attending the emergency department: study protocol

INTRODUCTION

Observational data suggest a single high-sensitivity troponin blood test taken at emergency department (ED) presentation could be used to rule out major adverse cardiac events (MACE) in 10%-60% of ED patients with chest pain. This is done using an 'undetectable' cut-off (the Limit of Detection: LoD). We combined the LoD cut-off with ECG findings to create the LoDED strategy. We aim to establish whether the LoDED strategy works under real-life conditions, when compared with existing strategies, in a way that is cost-effective and acceptable to patients.

METHODS AND ANALYSIS

This is a parallel-group pragmatic randomised controlled trial across UK EDs. Adults presenting to ED with suspected cardiac chest pain will be randomised 1:1. Existing rule-out strategies in current use across study centres, using serial high-sensitivity troponin testing, will be compared with the LoDED strategy. The primary outcome is successful early discharge (discharge from hospital within 4 hours of arrival) without MACE occurring within 30 days. Secondary outcomes include initial length of hospital stay; comparative costs; patient satisfaction and acceptability to patients. To detect a 9% difference between the early discharge rates (assuming an 8% rate in the standard care group) with 90% power, 594 patients need to be recruited, assuming a 95% follow-up rate.

ETHICS AND DISSEMINATION

The study has been approved by the Frenchay Research Ethics Committee (reference 18/SW/0038). Results will be published in an international peer-reviewed journal. Lay summaries will be made available to patients.

TRIAL REGISTRATION NUMBER

ISRCTN86184521; Pre-results.

Acute coronary syndromes diagnosis, version 2.0: Tomorrow's approach to diagnosing acute coronary syndromes?

Chest pain accounts for approximately 6% of Emergency Department (ED) attendances and is the most common reason for emergency hospital admission. For many years, our approach to diagnosis has required patients to stay in hospital for at least 6–12 h to undergo serial biomarker testing. As less than one fifth of the patients undergoing investigation actually has an acute coronary syndrome (ACS), there is tremendous potential to reduce unnecessary hospital admissions.

Recent advances in diagnostic technology have improved the efficiency of care pathways. Decision aids such as the Thrombolysis in Myocardial Infarction (TIMI) risk score and the History, Electrocardiogram, Age, Risk factors and Troponin (HEART) score enable rapid ‘rule out’ of ACS within hours of patients arriving in the ED. With high sensitivity cardiac troponin (hs-cTn) assays, approximately one third of patients can have ACS ‘ruled out’ with a single blood test, and up to two thirds could have an acute myocardial infarction ‘ruled out’ with a second sample taken after as little as 1 h.

Building on those recent advances, this paper presents an overview of the principles behind the development of the Troponin-only Manchester Acute Coronary Syndromes (T-MACS) decision aid. This clinical prediction model could be used to ‘rule out’ and ‘rule in’ ACS following a single blood test and to calculate the probability of ACS for every patient. The future potential of this approach is then addressed, including practical applications of artificial intelligence, shared decision making, near-patient testing and personalized medicine.