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

Determination of Clinically Acceptable Analytical Variation of Cardiac Troponin at Decision Thresholds

BACKGROUND

Clinical decision-making for risk stratification for possible myocardial infarction (MI) uses high-sensitivity cardiac troponin (hs-cTn) thresholds that range from the limit of detection to several-fold higher than the upper reference limit (URL). To establish a minimum analytical variation standard, we can quantify the effect of variation on the population clinical measures of safety (sensitivity) and effectiveness [proportion below threshold, or positive predictive value (PPV)].

METHODS

From large datasets of patients investigated for possible MI with the Abbott hs-cTnI and Roche hs-cTnT assays, we synthesized datasets of 1 000 000 simulated patients. Troponin concentrations were randomly varied several times based on absolute deviations of 0.5 to 3 ng/L and relative changes of 2% to 20% around the low-risk threshold (5 ng/L) and URLs, respectively.

RESULTS

For both assays at the low-risk thresholds, there were negligible differences in sensitivity (<0.3%) with increasing analytical variation. The proportion of patients characterized as low risk reduced by 30% to 29% (Roche) and 53% to 44% (Abbott). At the URL, increasing analytical variation also did not change sensitivity; the PPV fell by less than 3%. For risk stratification, increased delta thresholds (change between serial troponin concentrations) increased sensitivity at the cost of a decreased percentage of patients below the delta threshold, with the largest changes at the greatest analytical variation.

CONCLUSIONS

At the low-risk threshold, analytical variation up to 3 ng/L minimally impacted the safety metric (sensitivity) but marginally reduced effectiveness. Similarly, at the URL even relative variation up to 25% minimally impacted safety metrics and effectiveness. Analytical variation for delta thresholds did not negatively impact sensitivity but decreased effectiveness.

Complications in Emergency Department Patients with Acute Coronary Syndrome with Contemporary Care

INTRODUCTION

With the implementation of early reperfusion therapy, the number of complications in patients with acute coronary syndrome (ACS) has diminished significantly. However, ACS patients are still routinely admitted to units with high-level monitoring such as the coronary or intensive care unit (CCU/ICU). The cost of these admissions is high and there is often a shortage of beds. The aim of this study was to analyze the complications in contemporary emergency department (ED) patients with ACS and to map patient management.

METHODS

This observational study was a secondary analysis of data collected in the ESC-TROP trial (NCT03421873) that included 26,545 consecutive chest pain patients ≥18 years at five Swedish EDs. Complications were defined as the following within 30 days: death, cardiac arrest, cardiogenic shock, pulmonary edema, severe ventricular arrhythmia, high-degree atrioventricular (AV) block that required a pacemaker, and mechanical complications such as papillary muscle rupture, cardiac tamponade, or ventricular septum defects (VSDs). Complications were identified via diagnosis and/or intervention codes in the database, and manual chart review was performed in cases with complications.

RESULTS

Of all 26,545 patients, 2,463 (9.3%) were diagnosed with ACS, and 151 of these (6.1%) suffered any complication within 30 days. Mean age was higher in patients with (79.2 years) than without (69.4 years) complications, and more were female (39.7% vs. 33.0%). Eighty-four (3.4% of all ACS patients) patients died, 33 (1.3%) had cardiac arrest, 22 (0.9%) respiratory failure, 13 (0.5%) high-degree AV block, 10 (0.4%) cardiogenic shock, 12 (0.5%) severe ventricular arrhythmia, and 2 each (<0.1%) had VSD or cardiac tamponade. Almost 30% of the complications were present already at the ED, and 40% of patients with complications were not admitted to the CCU/ICU. Only 80 (53%) of the patients with complications underwent coronary angiography and 62 (41%) were revascularized with percutaneous coronary intervention or coronary artery bypass grafting.

CONCLUSION

With current care, serious complications occurred in only 6 out of 100 ACS patients, and 2 of these complications were present already at the ED. Four out of 10 ACS patients with complications were not admitted to the CCU/ICU and about half did not undergo coronary angiography. Further research is needed to improve risk assessment in ED ACS patients, which may allow more effective use of cardiac monitoring and hospital resources.

Validation of Becton Dickinson Barricor™ tubes for use with Abbott Alinity™ and Siemens Atellica® highly sensitive cardiac troponin I measuring systems

BACKGROUND

BD Barricor™ tubes have been proposed to decrease laboratory turnaround time (TAT). We analytically validated and then clinically verified these tubes for use with Abbott Alinity™ and Siemens Atellica® highly sensitive cardiac troponin I (hs-cTnI) assays.

METHODS

hs-cTnI measurements were undertaken in paired Barricor™ and in-use PSTII™ tubes on both systems. 359 matched samples with hs-cTnI levels between 3 and 15,000 ng/L (Atellica® values) were used to assess the hemolysis rate and make method comparisons. 599 paired patient samples were collected on emergency department (ED) admission to compare the performance of the rapid acute myocardial infarction (AMI) rule-out strategy based on hs-cTnI concentrations lower than recommended thresholds (<4 ng/L Alinity™; <5 ng/L Atellica®) when different tubes and systems were employed.

RESULTS

No between-tube differences in hemolysis rate were seen when free hemoglobin concentrations in plasma samples were ≥0.25 g/L, even if PSTII™ showed a significant increase of hemolysis rate vs. Barricor™ (31% vs. 22%, p=0.007) when a lower cut-off for hemolysis (≥0.11 g/L) was employed on the Atellica® detection system. The alternate use of these tubes did not influence the hs-cTnI results obtained from either of the two assays, which remained markedly biased (~40%) irrespective of the tube used. The expected optimal ability of very low hs-cTnI values on ED admission for ruling out AMI was confirmed by using both systems regardless of the tube type.

CONCLUSIONS

Barricor™ and PSTII™ tubes can provide analytically equivalent hs-cTnI results when used on either Alinity™ or Atellica® hs-cTnI assays.

A Single High-Sensitivity Cardiac Troponin T Strategy for Ruling Out Myocardial Infarction

Background

Ruling out acute myocardial infarction (AMI) in the emergency department (ED) is challenging. Studies have shown that a high-sensitivity cardiac troponin T (hs-cTnT) <5 ng/L or <6 ng/L at presentation (0 h) can be used to rule out AMI. The objective of this study was to identify whether an even higher hs-cTnT threshold can be used for a safe rule out of AMI in the ED.

Methods

The derivation cohort consisted of 24,973 ED patients with a primary complaint of chest pain. In this cohort, we identified the highest concentration of 0 h hs-cTnT that corresponded to a negative predictive value (NPV) of ≥99.5% for the primary endpoint of AMI/all-cause death within 30 days and the secondary endpoint of all-cause death within one year. The results were validated in two cohorts consisting of 132,021 and 1167 ED chest pain patients.

Results

The 0 h hs-cTnT threshold corresponding to a NPV of ≥99.5% for the primary endpoint was <9 ng/L (NPV: 99.6% and 95% CI: 99.5-99.7). This cutoff provided a sensitivity of 96.2% (95% CI: 95.2-97.1) and identified 59.7% of the patients as low risk compared to 35.8% and 43.9% with a 0 h hs-cTnT <5 ng/L and <6 ng/L, respectively. The results were similar in the validation cohorts and seemed to perform even better in patients where the 0 h hs-cTnT was measured >3 h after symptom onset and in those with a nonischemic ECG and nonhigh risk history.

Conclusions

A 0 h hs-cTnT cutoff of <9 ng/L safely rules out AMI/death within 30 days in a majority of chest pain patients and is a more effective strategy than the currently recommended <5 ng/L and <6 ng/L cutoffs. This trial is registered with NCT03421873.

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.

Independent Predictors of Repeat Emergency Room Presentations: Insights from a Cohort of 1066 Consecutive Patients with Non-Cardiac Chest Pain Generating 4770 Repeat Presentations

BACKGROUND AND IMPORTANCE

Chest pain (CP) is one of the most frequent presentations to the emergency department (ED), a large proportion of which is non-cardiac chest pain (NCCP). Repeat attendances to ED are common and impose considerable burden to overstretched departments.

OBJECTIVE

Our aim was to determine drivers for repeat ED presentations using NCCP as the primary cause of index presentation.

DESIGN, SETTING AND PARTICIPANTS

This was a retrospective cohort study of 1066 consecutive presentations with NCCP to a major urban hospital ED in North England. Index of Multiple Deprivation (IMD), a postcode-derived validated index of deprivation, was computed. Charlson comorbidity index (CCI) was determined by reference to known comorbidity variables. Repeat presentation to ED to any national hospital was determined by a national linked database (population 53.5 million). Independent predictors of ED representation were computed using logistic regression analysis.

RESULTS

Median age was 43 (IQR 28-59), and 50.8% were male. Furthermore, 27.8%, 8.1% and 3.8% suffered from chronic obstructive pulmonary disease (COPD), hypertension and diabetes mellitus, respectively. The most frequent diagnoses, using ICD-10 coding, were non-cardiac chest pain (55.1%), followed by respiratory conditions (14.7%). One-year incidence of adjudicated myocardial infarction, urgent or emergency coronary revascularisation and all-cause death was 0.6%, 2% and 5.3%, respectively. There was a total of 4770 ED repeat presentations 1 year prior to or following index presentation with NCCP in this cohort. Independent (multivariate) predictors for frequent re-presentation (defined as ≥2 representations) were a history of COPD (OR [odds ratio] 2.06, p = 0.001), previous MI (OR3.6, p = 0.020) and a Charlson comorbidity index ≥1 (OR 1.51, p = 0.030). The frequency of previous MI was low as only 3% had sustained a previous MI.

CONCLUSIONS

This analysis indicates that COPD and complex health care needs (represented by high CCI), but not socio-economic deprivation, should be health policy targets for lessening repeat ED presentations. What is already known on this topic: Repeat presentations with non-ischaemic chest pain are common, placing a considerable burden on emergency departments.

WHAT THIS STUDY ADDS

COPD and complex health care needs, denoted by Charlson comorbidity index, are implicated as drivers for repeat presentation to accident and emergency department. Socio-economic deprivation was not an independent predictor of re-presentation. How might this study affect research, practice, or policy: Community-based support for COPD and complex health care needs may reduce frequency of ED attendance.

Troponin in early presenters to rule out myocardial infarction

AIMS

Whether a single cardiac troponin measurement can safely rule out myocardial infarction in patients presenting within a few hours of symptom onset is uncertain. The study aim was to assess the performance of troponin in early presenters.

METHODS AND RESULTS

In patients with possible myocardial infarction, the diagnostic performance of a single measurement of high-sensitivity cardiac troponin I at presentation was evaluated and externally validated in those tested ≤3, 4-12, and >12 h from symptom onset. The limit-of-detection (2 ng/L), rule-out (5 ng/L), and sex-specific 99th centile (16 ng/L in women; 34 ng/L in men) thresholds were compared. In 41 103 consecutive patients [60 (17) years, 46% women], 12 595 (31%) presented within 3 h, and 3728 (9%) had myocardial infarction. In those presenting ≤3 h, a threshold of 2 ng/L had greater sensitivity and negative predictive value [99.4% (95% confidence interval 99.2%-99.5%) and 99.7% (99.6%-99.8%)] compared with 5 ng/L [96.5% (96.2%-96.8%) and 99.3% (99.1%-99.4%)]. In those presenting ≥3 h, the sensitivity and negative predictive value were similar for both thresholds. The sensitivity of the 99th centile was low in early and late presenters at 71.4% (70.6%-72.2%) and 92.5% (92.0%-93.0%), respectively. Findings were consistent in an external validation cohort of 7088 patients.

CONCLUSION

In early presenters, a single measurement of high-sensitivity cardiac troponin I below the limit of detection may facilitate the safe rule out of myocardial infarction. The 99th centile should not be used to rule out myocardial infarction at presentation even in those presenting later following symptom onset.

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.

Machine learning for diagnosis of myocardial infarction using cardiac troponin concentrations

Although guidelines recommend fixed cardiac troponin thresholds for the diagnosis of myocardial infarction, troponin concentrations are influenced by age, sex, comorbidities and time from symptom onset. To improve diagnosis, we developed machine learning models that integrate cardiac troponin concentrations at presentation or on serial testing with clinical features and compute the Collaboration for the Diagnosis and Evaluation of Acute Coronary Syndrome (CoDE-ACS) score (0-100) that corresponds to an individual's probability of myocardial infarction. The models were trained on data from 10,038 patients (48% women), and their performance was externally validated using data from 10,286 patients (35% women) from seven cohorts. CoDE-ACS had excellent discrimination for myocardial infarction (area under curve, 0.953; 95% confidence interval, 0.947-0.958), performed well across subgroups and identified more patients at presentation as low probability of having myocardial infarction than fixed cardiac troponin thresholds (61 versus 27%) with a similar negative predictive value and fewer as high probability of having myocardial infarction (10 versus 16%) with a greater positive predictive value. Patients identified as having a low probability of myocardial infarction had a lower rate of cardiac death than those with intermediate or high probability 30 days (0.1 versus 0.5 and 1.8%) and 1 year (0.3 versus 2.8 and 4.2%; P < 0.001 for both) from patient presentation. CoDE-ACS used as a clinical decision support system has the potential to reduce hospital admissions and have major benefits for patients and health care providers.

Cross-cultural adaptation and its impact on research in emergency care

The perspective of patients is increasingly recognised as important to care improvement and innovation. Patient questionnaires such as patient-reported outcome measures may often require cross-cultural adaptation (CCA) to gather their intended information most effectively when used in cultures and languages different to those in which they were developed. The use of CCA could be seen as a practical step in addressing the known problems of inclusion, diversity and access in medical research.An example of the recent adaptation of a patient-reported outcome measure for use with ED patients is used to explore some key features of CCA, introduce the importance of CCA to emergency care practitioners and highlight the limitations of CCA.

Cardiac troponin measurement at the point of care: educational recommendations on analytical and clinical aspects by the IFCC Committee on Clinical Applications of Cardiac Bio-Markers (IFCC C-CB)

The International Federation of Clinical Chemistry and Laboarator Medicine (IFCC) Committee on Clinical Applications of Cardiac Bio-Markers (C-CB) has provided evidence-based educational resources to aid and improve the understanding of important analytical and clinical aspects of cardiac biomarkers. The present IFCC C-CB educational report focuses on recommendations for appropriate use, analytical performance, and gaps in clinical studies related to the use of cardiac troponin (cTn) by point of care (POC) measurement, often referred to as a point of care testing (POCT). The use of high-sensitivity (hs)-cTn POC devices in accelerated diagnostic protocols used in emergency departments or outpatient clinics investigating acute coronary syndrome has the potential for improved efficacy, reduction of length of stay and reduced costs in the health care system. POCT workflow integration includes location of the instrument, assignment of collection and testing responsibility to (non-lab) staff, instrument maintenance, in-service and recurrent training, quality control, proficiency assessments, discrepant result trapping, and troubleshooting and inventory management.

Rapid diagnostic strategies using high sensitivity troponin assays: what is the evidence and how should they be implemented?

The introduction of high sensitivity measurement of cardiac troponin T (hs cTnT) and cardiac troponin I (hs cTnI) has given the laboratory the ability to measure very low levels of cardiac troponin. The limit of detection of these assays is well below the 99th percentile. These low levels can also be measured with small values of imprecision. A range of algorithms combining presentation measurement with repeat sample intervals of as little as one to 2 hours have been developed. These are able to predict with acceptable accuracy the diagnosis that would be achieved with continued repeat sampling out to six to 12 hours from presentation. In this article, we review the evidence for the diagnostic accuracy of these approaches and the practical aspects of implementation into routine clinical practice.

An international, stepped wedge, cluster-randomized trial investigating the 0/1-h algorithm in suspected acute coronary syndrome in Asia: the rational of the DROP-Asian ACS study

BACKGROUND

More than half of the world's population lives in Asia. With current life expectancies in Asian countries, the burden of cardiovascular disease is increasing exponentially. Overcrowding in the emergency departments (ED) has become a public health problem. Since 2015, the European Society of Cardiology recommends the use of a 0/1-h algorithm based on high-sensitivity cardiac troponin (hs-cTn) for rapid triage of patients with suspected non-ST elevation acute coronary syndrome (NSTE-ACS). However, these algorithms are currently not recommended by Asian guidelines due to the lack of suitable data.

METHODS

The DROP-Asian ACS is a prospective, stepped wedge, cluster-randomized trial enrolling 4260 participants presenting with chest pain to the ED of 12 acute care hospitals in five Asian countries (UMIN; 000042461). Consecutive patients presenting with suspected acute coronary syndrome between July 2022 and Apr 2024 were included. Initially, all clusters will apply "usual care" according to local standard operating procedures including hs-cTnT but not the 0/1-h algorithm. The primary outcome is the incidence of major adverse cardiac events (MACE), the composite of all-cause death, myocardial infarction, unstable angina, or unplanned revascularization within 30 days. The difference in MACE (with one-sided 95% CI) was estimated to evaluate non-inferiority. The non-inferiority margin was prespecified at 1.5%. Secondary efficacy outcomes include costs for healthcare resources and duration of stay in ED.

CONCLUSIONS

This study provides important evidence concerning the safety and efficacy of the 0/1-h algorithm in Asian countries and may help to reduce congestion of the ED as well as medical costs.

High-Sensitivity Cardiac Troponin and the 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guidelines for the Evaluation and Diagnosis of Acute Chest Pain

The 2021 American Heart Association/American College of Cardiology/American Society of Echocardiography/American College of Chest Physicians/Society for Academic Emergency Medicine/Society of Cardiovascular Computed Tomography/Society for Cardiovascular Magnetic Resonance guidelines for the evaluation and diagnosis of acute chest pain make important recommendations that include the recognition of high-sensitivity cardiac troponin (hs-cTn) as the preferred biomarker, endorsement of 99th percentile upper reference limits to define myocardial injury, and the use of clinical decision pathways, as well as acknowledgment of the uniqueness of women and other patient subsets. Details on how to integrate hs-cTn into clinical practice are less extensively addressed. Clinicians should be aware of some of the analytical aspects related to hs-cTn assays regarding the limit of detection and the limit of quantitation and how they are used clinically, especially for the single sample strategy to rule out acute myocardial infarction. Likewise, it is important for clinicians to understand issues related to the derivation of the 99th percentile upper reference limit; the value of sex-specific 99th percentile upper reference limits; how to use changing concentrations (deltas) to facilitate diagnosis and risk stratification of patients with suspected acute coronary syndrome, including the differentiation of acute from chronic myocardial injury; and how to best integrate the use of hs-cTn with clinical decision pathways. With the use of hs-cTn, conditions such as type 2 myocardial infarction become more common, whereas others such as unstable angina become less frequent but still occur. Sections relating to these issues are included.

High-sensitivity troponin I with or without ultra-sensitive copeptin for the instant rule-out of acute myocardial infarction

Background

The instant, single-sampling rule-out of acute myocardial infarction (AMI) is still an unmet clinical need. We aimed at testing and comparing diagnostic performance and prognostic value of two different single-sampling biomarker strategies for the instant rule-out of AMI.

Methods

From the Biomarkers in Acute Cardiac Care (BACC) cohort, we recruited consecutive patients with acute chest pain and suspected AMI presenting to the Emergency Department of the University Medical Center Hamburg-Eppendorf, Hamburg, Germany. We compared safety, effectiveness and 12-month incidence of the composite endpoint of all-cause death and myocardial infarction between (i) a single-sampling, dual-marker pathway combining high-sensitivity cardiac troponin I (hs-cTnI) and ultra-sensitive copeptin (us-Cop) at presentation (hs-cTnI ≤ 27 ng/L, us-Cop < 10 pmol/L and low-risk ECG) and (ii) a single-sampling pathway based on one-off hs-cTnI determination at presentation (hs-cTnI < 5 ng/L and low-risk ECG). As a comparator, we used the European Society of Cardiology (ESC) 0/1-h dual-sampling algorithm.

Results

We enrolled 1,136 patients (male gender 65%) with median age of 64 years (interquartile range, 51–75). Overall, 228 (20%) patients received a final diagnosis of AMI. The two single-sampling instant rule-out pathways yielded similar negative predictive value (NPV): 97.4% (95%CI: 95.4–98.7) and 98.7% (95%CI: 96.9–99.6) for dual-marker and single hs-cTnI algorithms, respectively (P = 0.11). Both strategies were comparably safe as the ESC 0/1-h dual-sampling algorithm and this was consistent across subgroups of early-comers, low-intermediate risk (GRACE-score < 140) and renal dysfunction. Despite a numerically higher rate of false-negative results, the dual-marker strategy ruled-out a slightly but significantly higher percentage of patients compared with single hs-cTnI determination (37.4% versus 32.9%; P < 0.001). There were no significant between-group differences in 12-month composite outcome.

Conclusions

Instant rule-out pathways based on one-off determination of hs-cTnI alone or in combination with us-Cop are comparably safe as the ESC 0/1 h algorithm for the instant rule-out of AMI, yielding similar prognostic information. Instant rule-out strategies are safe alternatives to the ESC 0/1 h algorithm and allow the rapid and effective triage of suspected AMI in patients with low-risk ECG. However, adding copeptin to hs-cTn does not improve the safety of instant rule-out compared with the single rule-out hs-cTn at very low cut-off concentrations.

Rapid Exclusion of Acute Myocardial Injury and Infarction with a Single High Sensitivity Cardiac Troponin T in the Emergency Department: a Multicenter United States Evaluation

BACKGROUND

There are good data to support using a single high-sensitivity cardiac troponin T (hs-cTnT) below the limit of detection (LoD) of 5 ng/L to exclude acute myocardial infarction. Per the United States (US) Food and Drug Administration (FDA), hs-cTnT can only report to the limit of quantitation (LoQ) of 6 ng/L, a threshold for which there is limited data. Our goal was to determine whether a single hs-cTnT below the LoQ of 6 ng/L is a safe strategy to identify patients at low-risk for acute myocardial injury and infarction.

METHODS

The efficacy (proportion identified as low-risk based on baseline hs-cTnT<6 ng/L) of identifying low-risk patients was examined in a multicenter (n=22 sites) US cohort study of emergency department patients undergoing at least one hs-cTnT (CV Data Mart Biomarker cohort). We then determined the performance of a single hs-cTnT<6 ng/L (biomarker alone) to exclude acute myocardial injury (subsequent hs-cTnT >99^th percentile in those with an initial hs-cTnT<6 ng/L). The clinically intended rule-out strategy combining a nonischemic electrocardiogram with a baseline hs-cTnT<6 ng/L was subsequently tested in an adjudicated cohort in which the diagnostic performance for ruling-out acute myocardial infarction and safety (myocardial infarction or death at 30-days) were evaluated.

RESULTS

A total of 85,610 patients were evaluated in the CV Data Mart Biomarker cohort, amongst which 24,646 (29%) had a baseline hs-cTnT<6 ng/L. Women were more likely than men to have hs-cTnT<6 ng/L (38% vs. 20%, p<0.0001). Among 11,962 patients with baseline hs-cTnT<6 ng/L and serial measurements, only 1.2% developed acute myocardial injury, resulting in a negative predictive value of 98.8% (95% CI 98.6, 99.0) and sensitivity of 99.6% (95% CI 99.5, 99.6). In the adjudicated cohort, a nonischemic electrocardiogram with hs-cTnT<6 ng/L identified 33% of patients (610 of 1849) as low-risk and resulted in a negative predictive value and sensitivity of 100% and a 30-day rate of 0.2% for 30-day myocardial infarction or death.

CONCLUSIONS

A single hs-cTnT below the LoQ of 6 ng/L is a safe and rapid method to identify a substantial number of patients at very low risk for acute myocardial injury and infarction.

Electroanalytical point-of-care detection of gold standard and emerging cardiac biomarkers for stratification and monitoring in intensive care medicine - a review

Determination of specific cardiac biomarkers (CBs) during the diagnosis and management of adverse cardiovascular events such as acute myocardial infarction (AMI) has become commonplace in emergency department (ED), cardiology and many other ward settings. Cardiac troponins (cTnT and cTnI) and natriuretic peptides (BNP and NT-pro-BNP) are the preferred biomarkers in clinical practice for the diagnostic workup of AMI, acute coronary syndrome (ACS) and other types of myocardial ischaemia and heart failure (HF), while the roles and possible clinical applications of several other potential biomarkers continue to be evaluated and are the subject of several comprehensive reviews. The requirement for rapid, repeated testing of a small number of CBs in ED and cardiology patients has led to the development of point-of-care (PoC) technology to circumvent the need for remote and lengthy testing procedures in the hospital pathology laboratories. Electroanalytical sensing platforms have the potential to meet these requirements. This review aims firstly to reflect on the potential benefits of rapid CB testing in critically ill patients, a very distinct cohort of patients with deranged baseline levels of CBs. We summarise their source and clinical relevance and are the first to report the required analytical ranges for such technology to be of value in this patient cohort. Secondly, we review the current electrochemical approaches, including its sub-variants such as photoelectrochemical and electrochemiluminescence, for the determination  of important CBs highlighting the various strategies used, namely the use of micro- and nanomaterials, to maximise the sensitivities and selectivities of such approaches. Finally, we consider the challenges that must be overcome to allow for the commercialisation of this technology and transition into intensive care medicine.

Early discharging patients with chest pain using EDACS-ADP and COMPASS-MI risk predictors

Deciding on the early discharge of low-risk patients with chest pain is still controversial in emergency care. Beyond the validated tools for risk assessment, high sensitive troponin levels on admission, whether to take the next serial sampling or when to take are the main issues affecting the unnecessary follow-ups that lead to the emergency crowd. We aimed to investigate the prediction performance of emergency department assessment of chest pain score and accelerated diagnostic protocol (EDACS-ADP) and calculation of MI risk probabilities to manage patients with suspicion of myocardial infarction (COMPASS-MI). We conducted a prospective cross-sectional study that included patients with chest pain followed-up in the emergency department with a serial troponin sampling. We calculated the performance tests of the risk scores after recording the patients' risk factors, chest pain types, troponin levels as defined in the risk assessment tools. Nine hundred eleven patients were included in the study. Thirty-eight patients had significant adverse cardiovascular events (MACE) within 30 days. Patients with a not-low-risk score at EDACS-ADP had a 3.975 (95% CI 2.136–7.396) fold higher risk of MACE than the patients with low-risk EDACS-ADP, and the absolute risk increase was 7.3%. Patients with high-risk late-stage risk in COMPASS-MI had a 3.581 (95% CI 1.660–7.726) fold higher risk of MACE than those with low-risk late-stage risk in COMPASS-MI, and absolute risk increase was 4.6%. We found EDACS-ADP and COMPASS-MI at a late time point (2 h hsTnI) with a high negative predictive value as a risk assessment tool for discharging chest pain patients.

Rapid Rule-Out of Myocardial Infarction After 30 Minutes as an Alternative to 1 Hour: The RACING-MI Cohort Study

STUDY OBJECTIVE

The aim of this study was to investigate whether myocardial infarction can be safely ruled in or out after 30 minutes as an alternative to 1 hour.

METHODS

This was a prospective, single-center clinical study enrolling patients admitted to the emergency department. Patients with chest pain suggestive of myocardial infarction were eligible for inclusion. There was no walk-in to the emergency department, and patients with highly elevated out-of-hospital troponin were transferred directly to an invasive heart center. High-sensitivity troponin I was measured at admission (0 hour), 30 minutes, 1 hour, and 3 hours. Diagnostic performance was assessed using the sensitivity and negative predictive value (primary endpoints) as measures of ability to rule out myocardial infarction. Specificity and positive predictive value of myocardial infarction were used as measures for the ability to rule in myocardial infarction (secondary endpoints).

RESULTS

In total, 1,003 patients qualified for analysis. Median age was 64 (interquartile range 52 to 74) years, and 42% were women. Myocardial infarction was confirmed in 9% of patients. In the validation cohort (n=503), the 0-h/30-min algorithm assigned 242 (48%) patients to rule out, 54 (11%) to rule in, and 207 (41%) to the observational zone. This resulted in a sensitivity of 100% (92.0% to 100%), negative predictive value of 100% (95% confidence interval 98.5% to 100%), specificity of 96.7% (94.7% to 98.2%), and positive predictive value of 72.2% (58.4% to 83.5%). In comparison, the 0-h/1-h algorithm performed with a sensitivity of 100% (92.0% to 100%), negative predictive value of 100% (98.5% to 100%), specificity of 97.2% (95.2% to 98.5%), and positive predictive value of 75.5% (61.7% to 86.2%).

CONCLUSION

The accelerated 0-h/30-min algorithm allowed for safe rule-out of myocardial infarction 30 minutes after admission. The rule-in ability of the 0-h/30-min algorithm was comparable to that of the 0-h/1h algorithm.

Identifying low-risk chest pain in the emergency department without troponin testing: a validation study of the HE-MACS and HEAR risk scores

INTRODUCTION

Patients presenting to EDs with chest pain of possible cardiac origin represent a substantial and challenging cohort to risk stratify. Scores such as HE-MACS (History and Electrocardiogram-only Manchester Acute Coronary Syndromes decision aid) and HEAR (History, ECG, Age, Risk factors) have been developed to stratify risk without the need for troponin testing. Validation of these scores remains limited.

METHODS

We performed a post hoc analysis of the Limit of Detection and ECG discharge strategy randomised-controlled trial dataset (n=629; June 2018 to March 2019; 8 UK hospitals) to calculate HEAR and HE-MACS scores. A <4% risk of major adverse cardiac events (MACE) at 30 days using HE-MACS and a score of <2 calculated using HEAR defined 'very low risk' patients suitable for discharge. The primary outcome of MACE at 30 days was used to assess diagnostic accuracy.

RESULTS

MACE within 30 days occurred in 42/629 (7%) of the cohort. HE-MACS and HEAR scores identified 85/629 and 181/629 patients as 'very low risk', with MACE occurring in 0/85 and 1/181 patients, respectively. The sensitivities of each score for ruling out MACE were 100% (95% CI: 91.6% to 100%) for HE-MACS and 97.6% (95% CI: 87.7% to 99.9%) for HEAR. Presenting symptoms within these scores were poorly predictive, with only diaphoresis reaching statistical significance (OR: 4.99 (2.33 to 10.67)). Conventional cardiovascular risk factors and clinician suspicion were related to the presence of MACE at 30 days.

CONCLUSION

HEAR and HE-MACS show potential as rule out tools for acute myocardial infarction without the need for troponin testing. However, prospective studies are required to further validate these scores.

Implementation of an early rule-out pathway for myocardial infarction using a high-sensitivity cardiac troponin T assay

OBJECTIVES

Patients with suspected acute coronary syndrome and high-sensitivity cardiac troponin (hs-cTn) concentrations below the limit of detection at presentation are low risk. We aim to determine whether implementing this approach facilitates the safe early discharge of patients.

METHODS

In a prospective single-centre cohort study, consecutive patients with suspected acute coronary syndrome were included before (standard care) and after (intervention) implementation of an early rule-out pathway. During standard care, myocardial infarction was ruled out if hs-cTnT concentrations were <99th centile (14 ng/L) at presentation and at 6-12 hours after symptom onset. In the intervention, patients were ruled out if hs-cTnT concentrations were <5 ng/L at presentation and symptoms present for ≥3 hours or were ≥5 ng/L and unchanged within the reference range at 3 hours. We compared duration of stay (efficacy) and all-cause death at 1 year (safety) before and after implementation.

RESULTS

We included 10 315 consecutive patients (64±16 years, 46% women) with 6642 (64%) and 3673 (36%) in the standard care and intervention groups, respectively. Duration of stay was reduced from 534 (IQR, 220-2279) to 390 (IQR, 218-1910) min (p<0.001) after implementation. At 1 year, all-cause death occurred in 10.9% (721 of 6642) and 10.4% (381 of 3673) of patients in the standard care group (referent) and intervention group, respectively (adjusted OR 1.02, 95% CI 0.88 to 1.18).

CONCLUSION

In patients with suspected acute coronary syndrome, implementing an early rule-out pathway using hs-cTnT concentrations <5 ng/L at presentation reduced the duration of stay in hospital without compromising safety.

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.

Diagnostic accuracy of the HEART Pathway and EDACS-ADP when combined with a 0-hour/1-hour hs-cTnT protocol for assessment of acute chest pain patients

BACKGROUND/AIM

In ED chest pain patients, a 0-hour/1-hour protocol based on high sensitivity cardiac troponin T (hs-cTnT) tests combined with clinical risk stratification in diagnosing acute coronary syndrome is recommended. Two of the most promising risk stratification tools are the History, ECG, Age, Risk Factors and Troponin (HEART) and Emergency Department Assessment of Chest Pain (EDAC) scores. Few studies have assessed the diagnostic accuracy of the 0-hour/1-hour hs-cTnT protocol when combined with HEART score, and none with EDACS. In ED chest pain patients, we aimed to evaluate the diagnostic accuracy of a 0-hour/1-hour hs-cTnT protocol combined the HEART Pathway, or the EDACS accelerated diagnostic pathway (EDACS-ADP).

METHODS

This was a secondary analysis of data from a prospective observational study enrolling 1167 ED chest pain patients who visited the ED at Skåne University Hospital in Lund, Sweden in the period between February 2013 and April 2014. HEART and EDAC scores were assessed together with hs-cTnT at 0 and 1 hour and compared with HEART score alone. Sensitivity, specificity, negative predictive value (NPV) and likelihood ratios were evaluated. The primary outcome was major adverse cardiac events (MACE) including unstable angina within 30 days. The secondary outcome was index visit acute myocardial infarction (AMI).

RESULTS

A total of 939 patients were included in the final analysis. When combined with 0-hour/1-hour hs-cTnT testing, the HEART Pathway and EDACS-ADP identified 49.8% and 49.6% of the patients for rule-out, with NPVs for 30-day MACE of 99.8% and 99.1%, compared with the HEART score alone that identified 53.4% of the patients for rule-out with NPV of 99.2%. The NPV for index visit AMI were 100%, 99.8% and 99.2%, respectively.

CONCLUSION

The combination of the HEART Pathway or the EDACS-ADP with a 0-hour/1-hour hs-cTnT protocol allows safe and early rule-out in a large proportion of ED chest pain patients.

Impact of high-sensitivity cardiac troponin implementation on emergency department length of stay, testing, admissions, and diagnoses

OBJECTIVE

While high-sensitivity (hs) troponin (cTn) has been associated with shorter emergency department (ED) length of stay (LOS) and decreased hospital admissions outside the United States (US), concerns have been raised that it will have opposite effects in the US. In this study, we aimed to compare ED LOS, admissions, and acute coronary syndrome (ACS) diagnoses before and after the implementation of hs-cTn.

METHODS

We conducted a single-institution, retrospective study of two temporally matched six-month study periods before and after the implementation of hs-cTn. We included consecutive adults presenting with chest pain. The primary outcome was ED LOS, which was log transformed and analyzed using multiple linear regression. Binary secondary outcomes of admissions, cardiac testing, cardiology consultation, and ACS diagnoses were analyzed using multiple logistic regression.

RESULTS

We studied 1589 visits before and 1616 visits after implementation of hs-cTn. Median age and sex ratios were similar between study periods. Median ED LOS was longer in the post-implementation period [post: 384 (interquartile range, IQR 260-577) minutes; pre: 374 (IQR 250-564) minutes; adjusted geometric mean ratio 1.05; 95% confidence interval, CI 1.01-1.10)]. Admissions were lower in the post-implementation period [post: 24% (385/1616) vs. pre: 28% (447/1589); adjusted odds ratio, aOR 0.75 (95% CI 0.64-0.88)]. Cardiac risk stratification testing [pre: 9% (142/1589) vs post: 9% (144/1616); aOR 0.95 (95% CI 0.74-1.22)], cardiology consultation [pre: 13% (208/1589) vs post: 13% (207/1616); aOR 0.91 (95% CI 0.73-1.12)], and ACS diagnoses [pre: 7% (116/1589) vs post: 7% (120/1616); aOR 0.94 (95% CI 0.72-1.24)] were similar between the two study periods.

CONCLUSION

In this single-center study, transition to hs-cTn was associated with an increased ED LOS, decreased admissions, and no substantial change in cardiac risk stratification testing, cardiology consultation, or ACS diagnoses.

Single high-sensitivity troponin levels to assess patients with potential acute coronary syndromes

OBJECTIVE

We tested the hypothesis that patients with a potential acute coronary syndrome (ACS) and very low levels of high-sensitivity cardiac troponin I can be efficiently and safely discharged from the emergency department after a single troponin measurement.

METHODS

This prospective cohort study recruited 2255 consecutive patients aged ≥18 years presenting to the Emergency Department, Royal Perth Hospital, Western Australia, with chest pain without high-risk features but requiring the exclusion of ACS. Patients were managed using a guideline-recommended pathway or our novel Single Troponin Accelerated Triage (STAT) pathway. The primary outcome was the percentage of patients discharged in <3 hours. Secondary outcomes included the duration of observation and death or acute myocardial infarction in the next 30 days.

RESULTS

The study enrolled 1131 patients to the standard cohort and 1124 to the STAT cohort. Thirty-eight per cent of the standard cohort were discharged directly from emergency department compared with 63% of the STAT cohort (p<0.001). The median duration of observation was 4.3 (IQR 3.3-7.1) hours in the standard cohort and 3.6 (2.6-5.4) hours in the STAT cohort (p<0.001), with 21% and 38% discharged in <3 hours, respectively (p<0.001). No patients discharged directly from the emergency department died or suffered an acute myocardial infarction within 30 days in either cohort.

CONCLUSIONS

Among low-risk patients with a potential ACS, a pathway which incorporates early discharge based on a single very low level of high-sensitivity cardiac troponin increases the proportion of patients discharged directly from the emergency department, reduces length of stay and is safe.

TRIAL REGISTRATION NUMBER

ACTRN12618000797279.

Optimizing the Use of High-Sensitivity Troponin Assays for the Early Rule-out of Myocardial Infarction in Patients Presenting with Chest Pain: A Systematic Review

BACKGROUND

We assessed the accuracy and clinical effectiveness of high-sensitivity cardiac troponin (hs-cTn) assays for early rule-out of non-ST-segment elevation myocardial infarction (NSTEMI) in adults presenting with acute chest pain.

METHODS

Sixteen databases were searched to September 2019. Review methods followed published guidelines. The bivariate model was used to estimate summary sensitivity and specificity with 95% confidence intervals for meta-analyses involving 4 or more studies, otherwise random-effects logistic regression was used.

RESULTS

Thirty-seven studies (124 publications) were included in the review. The hs-cTn test strategies evaluated in the included studies were defined by the combination of 4 factors (assay, number of tests, timing of tests, and threshold concentration or change in concentration between tests). Clinical opinion indicated a minimum acceptable sensitivity of 97%. A single test at presentation using a threshold at or near the assay limit of detection could reliably rule-out NSTEMI for a range of hs-cTn assays. Serial testing strategies, which include an immediate rule-out step, increased the proportion ruled out without loss of sensitivity. Finally, serial testing strategies without an immediate rule-out step had excellent sensitivity and specificity, but at the expense of the option for immediate patient discharge.

CONCLUSION

Test strategies that comprise an initial rule-out step, based on low hs-cTn concentrations at presentation and a minimum symptom duration, and a second step for those not ruled-out that incorporates a small absolute change in hs-cTn at 1, 2, or 3 hours, produce the highest rule-out rates with a very low risk of missed NSTEMI.

PROSPERO REGISTRATION

CRD42019154716.

Patients' and health professionals' perceptions of the LoDED (limit of detection and ECG discharge) strategy for low-risk chest pain management: a qualitative study

Background

Rapid discharge strategies for patients with low-risk chest pain using high-sensitivity troponin assays have been extensively evaluated. The adherence to, and acceptability of such strategies, has largely been explored using quantitative data. The aims of this integrated qualitative study were to explore the acceptability of the limit of detection and ECG discharge strategy (LoDED) to patients and health professionals, and to refine a discharge information leaflet for patients with low-risk chest pain.

Methods

Patients with low-risk chest pain who consented to a semi-structured interview were purposively sampled for maximum variation from four of the participating National Health Service sites between October 2018 and May 2019. Two focus groups with ED health professionals at two of the participating sites were completed in April and June 2019.

Results

A discharge strategy based on a single undetectable hs-cTn test (LoDED) was acceptable to patients. They trusted the health professionals who were treating them and felt reassured by other tests, (ECG) alongside blood test(s), even when the clinical assessment did not provide a firm diagnosis. In contrast, health professionals had reservations about the LoDED strategy, including concern about identifying low-risk patients and a shortened patient observation period. Findings from 11 patient interviews and 2 staff focus groups (with 20 clinicians) centred around three overarching themes: acceptability of the LoDED strategy, perceptions of symptom severity and uncertainty, and patient discharge information.

Conclusion

Rapid discharge for low-risk chest pain is acceptable to patients, but clinicians reported some reticence in implementing the LoDED strategy. Further work is required to optimise discharge discussions and information provision for patients.

Effects of crowding in the emergency department on the diagnosis and management of suspected acute coronary syndrome using rapid algorithms: an observational study

OBJECTIVES

Fast diagnostic algorithms using high-sensitivity troponin (hsTn) in suspected acute coronary syndrome (ACS) are regarded as beneficial to expedite diagnosis and safe discharge of patients in crowded emergency departments (ED). This study investigates the effects of crowding on process times related to the diagnostic protocol itself or other time delays, and outcomes.

DESIGN

Prospective single-centre observational study.

SETTING

ED (Germany).

PARTICIPANTS

Final study population of 2525 consecutive patients with suspected ACS within 12 months, after exclusion of patients with ST-elevation myocardial infarction, missing blood samples, referral from other hospitals or repeated visits.

INTERVENTIONS

Use of fast algorithms as per 2015 European Society of Cardiology guidelines.

MAIN OUTCOME MEASURES

Crowding was defined as mismatch between patient numbers and monitoring capacities, or mean physician time per case, categorised as normal, high and very high crowding. Outcome measures were length of ED stay, direct discharge from ED, laboratory turn around times (TAT), utilisation of fast algorithms, absolute and relative non-laboratory time, as well as mortality.

RESULTS

Crowding was associated with increased length of ED stay (3.75-4.89 hours, p<0.001). While median TAT of the first hsTnT increased (53-57 min, p<0.001), total TAT of serial hsTnT did not increase significantly with higher crowding (p=0.170). Lower utilisation of fast algorithms (p=0.009) and increase of additional hsTnT measurements after diagnosis (p=0.001) were observed in higher crowding. Most importantly, crowding was significantly associated with prolonged absolute (p<0.001), and particularly relative non-laboratory time (63.3%-71.3%, p<0.001). However, there was no significant effect of crowding on mortality, even after adjustment for relevant clinical variables.

CONCLUSIONS

Process times, and particularly non-laboratory times, are prolonged in a crowded ED diminishing some positive effects of fast diagnostic algorithms in suspected ACS. Higher crowding levels were not significantly associated with higher all-cause mortality rates.

TRIAL REGISTRATION NUMBER

NCT03111862.