Contemporary Emergency Department Management of Patients with Chest Pain: A Concise Review and Guide for the High-Sensitivity Troponin Era

Not T too! False elevations in high-sensitivity cardiac troponin T (hs-TnT) following specimen transport

Though false elevations attributed to preanalytical specimen handling have been widely reported for Troponin I (TnI), Troponin T (TnT) has appeared more robust to falsely elevated Tn. We describe reproducible false elevations in high sensitivity TnT (hs-TnT) in specimens after courier transport in plasma separator tubes (PST) off-site for testing. Hs-TnT was measured under 5 different conditions: 1) at collection location (N=24); 2) after transport upright in racks (N=66); 3) after transport with no control over tube agitation (N=69); 4) on transported aliquots (N=84); or 5) immediately after transport with no control over tube agitation (N=16), followed by keeping the specimen upright and re-measuring at 1hr, 2hr, 4hr, and 20-24hrs (N=6). To assess the degree of discrepancy, plasma from the original PST was aliquotted, re-centrifuged, potential debris removed, and hs-TnT re-measured. 43% of PST specimens collected offsite and transported with no control over tube agitation had clinically significant false elevations of hs-TnT which subsequently decreased following aliquotting and re-centrifugation (median decrease =9.9ng/L). Onsite testing or transported aliquots demonstrated no discrepancy. After being kept upright, discrepant specimens were not different from re-centrifuged aliquots by 4hrs (p=0.6141, repeated measures ANOVA with Dunn's multiple comparisons). Clinically significant false elevations of hs-TnT occurred in approximately 40% of separated PSTs that were transported in containers where specimens are transported with no control over tube agitation. This interference does not occur if plasma is aliquoted or if hs-TnT is tested at the collection site. In order to prevent these false elevations, and their potential patient impact on the diagnosis of acute myocardial infarction, specimens for hs-TnT measurement should be aliquoted at the collection location prior to transport.

External validation of a low HEAR score to identify emergency department chest pain patients at very low risk of major adverse cardiac events without troponin testing

BACKGROUND

The history, ECG, age, risk factor (HEAR) score has been proposed to identify patients at sufficiently low risk of acute coronary syndrome that they may not require troponin testing. The objective of this study was to externally validate a low HEAR score to identify emergency department (ED) patients with chest pain at very low risk of 30-day major adverse cardiac events (MACE).

METHODS

This was a secondary analysis of a prospective cohort of patients requiring troponin testing to rule out myocardial infarction (MI) in a large urban ED. HEAR scores were calculated in two cohorts: (1) patients with no known history of coronary artery disease (CAD); and (2) all eligible patients. The proportion of patients classified as very low risk, sensitivity, specificity, predictive values and likelihood ratios at each cut-off were quantified for index acute myocardial infarction (AMI) and 30-day MACE at HEAR = 0 and HEAR ≤ 1 thresholds.

RESULTS

Of the 1150 patients included in this study, 820 (71.3%) had no history of CAD, 97 (8.4%) had index AMI and 123 (10.7%) had 30-day MACE. In patients with no prior history of CAD, HEAR ≤ 1 identified 202 (24.6%) of patients as very low risk for 30-day MACE with 98.4% (95% CI 91.6-99.9%) sensitivity. Among all patients, HEAR ≤ 1 identified 202 (17.6%) patients as very low risk for 30-day MACE with 99.2% (95% CI 95.6-99.9%) sensitivity.

CONCLUSIONS

A HEAR score ≤ 1 can identify more than 17% of all patients as very low risk for index AMI and 30-day MACE and unlikely to benefit from troponin testing. Broad implementation of this strategy could lead to significant resource savings.

Prospective comparative evaluation of the European Society of Cardiology (ESC) 1-hour and a 2-hour rapid diagnostic algorithm for myocardial infarction using high-sensitivity troponin-T

OBJECTIVE

Both 1- and 2-hour rapid diagnostic algorithms using high-sensitivity troponin (hs-cTn) have been validated to diagnose acute myocardial infarction (MI), leaving physicians uncertain which algorithm is preferable. The objective of this study was to prospectively evaluate the diagnostic performance of 1- and 2-hour algorithms in clinical practice in a Canadian emergency department (ED).

METHODS

ED patients with chest pain had high-sensitivity cardiac troponin-T (hs-cTnT) collected on presentation and 1- and 2-hours later at a single academic centre over a 2-year period. The primary outcome was index MI, and the secondary outcome was 30-day major adverse cardiac events (MACE). All outcomes were adjudicated.

RESULTS

We enrolled 608 patients undergoing serial hs-cTnT sampling. Of these, 350 had a valid 1-hour and 550 had a 2-hour hs-cTnT sample. Index MI and 30-day MACE prevalence was ~12% and 14%. Sensitivity of the 1- and 2-hour algorithms was similar for index MI 97.3% (95% CI: 85.8-99.9%) and 100% (95% CI: 91.6-100%) and 30-day MACE: 80.9% (95% CI: 66.7-90.9%) and 83.3% (95% CI: 73.2-90.8%), respectively. Both algorithms accurately identified about 10% of patients as high risk.

CONCLUSIONS

Both algorithms were able to classify almost two-thirds of patients as low risk, effectively ruling out MI and conferring a low risk of 30-day MACE for this group, while reliably identifying high-risk patients. While both algorithms had equivalent diagnostic performance, the 2-hour algorithm offers several practical advantages, which may make it preferable to implement. Broad implementation of similar algorithms across Canada can expedite patient disposition and lead to resource savings.

Higher Frequency of Undetected Acute Coronary Syndrome in Elderly Patients with Chest Pain Who Visited the Emergency Department: A Large-Cohort Retrospective Study

Background

Acute coronary syndrome (ACS) is a critical disease encountered in the emergency department (ED). Despite the development of diagnostic tools, it may be difficult to diagnose ACS because of atypical symptoms and equivocal test results. We investigated the difference in the rates of revisit and undetected ACS between adult and elderly patients who visited the ED with chest pain.

Method

Data from 11,323 patients who visited the ED with chest pain at university hospitals in Korea were retrospectively analyzed. The cohort was categorized into two age groups: the adult (30–64 years) and elderly (>65 years). Baseline characteristic data (age, sex, vital signs, triage category, etc.) were obtained. We selected patients who revisited the ED within 30 d and investigated whether ACS was diagnosed.

Result

The revisit rate was higher in the elderly (12%) than in the adult group (8.3%). The rate of undetected ACS among the revisited patients was 2.91% (18/7,186) in adults and 6.08% (16/1,998) in elderly patients.

Conclusion

Elderly patients with chest pain had an increased rate of ED revisits and undetected ACS than adult patients. We recommend that old patients should be hospitalized to observe the progression of cardiac complaints or receive short-term follow-up.

Invasive Coronary Angiography after Chest Pain Presentations to Emergency Departments

We investigated patients presenting to emergency departments (EDs) with chest pain to identify factors that influence the use of invasive coronary angiography (ICA). Using linked ED, hospitalisations, death and cardiac biomarker data, we identified people aged 20 years and over who presented with chest pain to tertiary public hospital EDs in Western Australia from 1 January 2016 to 31 March 2017 (ED chest pain cohort). We report patient characteristics, ED discharge diagnosis, pathways to ICA, ICA within 90 days, troponin test results, and gender differences. Associations were examined with the Pearson Chi-squared test and multivariate logistic regression. There were 16,974 people in the ED chest pain cohort, with a mean age of 55.6 years and 50.7% males, accounting for 20,131 ED presentations. Acute coronary syndrome was the ED discharge diagnosis in 10.4% of presentations. ED pathways were: discharged home (57.5%); hospitalisation (41.7%); interhospital transfer (0.4%); and died in ED (0.03%)/inpatients (0.3%). There were 1546 (9.1%) ICAs performed within 90 days of the first ED chest pain visit, of which 59 visits (3.8%) had no troponin tests and 565 visits (36.6%) had normal troponin. ICAs were performed in more men than women (12.3% vs. 6.1%, p < 0.0001; adjusted OR 1.89, 95% CI 1.65, 2.18), and mostly within 7 days. Equal numbers of males and females present with chest pain to tertiary hospital EDs, but men are twice as likely to get ICA. Over one-third of ICAs occur in those with normal troponin levels, indicating that further investigation is required to determine risk profile, outcomes and cost effectiveness.

High-Sensitivity Cardiac Troponin-Optimizing the Diagnosis of Acute Myocardial Infarction/Injury in Women (CODE-MI): Rationale and design for a multicenter, stepped-wedge, cluster-randomized trial

Despite evidence that high-sensitivity cardiac troponin (hs-cTn) levels in women are lower than in men, a single threshold based on the 99th percentile upper reference limit of the overall reference population is commonly used to diagnose myocardial infarction in clinical practice. This trial aims to determine whether the use of a lower female-specific hs-cTn threshold would improve the diagnosis, treatment, and outcomes of women presenting to the emergency department with symptoms suggestive of myocardial ischemia. METHODS/DESIGN: CODE-MI (hs-cTn-Optimizing the Diagnosis of Acute Myocardial Infarction/Injury in Women) is a multicenter, stepped-wedge, cluster-randomized trial of 30 secondary and tertiary care hospitals across 8 Canadian provinces, with the unit of randomization being the hospital. All adults (≥20 years of age) presenting to the emergency department with symptoms suggestive of myocardial ischemia and at least 1 hs-cTn test are eligible for inclusion. Over five, 5-month intervals, hospitals will be randomized to implement lower female hs-cTn thresholds according to the assay being used at each site. Men will continue to be assessed using the overall thresholds throughout. Women with a peak hs-cTn value between the female-specific and the overall thresholds will form our primary cohort. The primary outcome, a 1-year composite of all-cause mortality or readmission for nonfatal myocardial infarction, incident heart failure, or emergent/urgent coronary revascularization, will be compared before and after the implementation of female thresholds using mixed-effects logistic regression models. The cohort and outcomes will be obtained from routinely collected administrative data. The trial is designed to detect a 20% relative risk difference in the primary outcome, or a 2.2% absolute difference, with 82% power. CONCLUSIONS: This pragmatic trial will assess whether adopting lower female hs-cTn thresholds leads to appropriate assessment of women with symptoms suggestive of myocardial infarction, thereby improving treatment and outcomes.

Identifying low-risk chest pain in the emergency department: Obstructive coronary artery disease and major adverse cardiac events

BACKGROUND

Accurate risk stratification for obstructive coronary artery disease (CAD) and major cardiac adverse events (MACE) is important in emergency departments. We compared six established chest pain risk scores (the HEART score, CAD basic model, CAD clinical model, TIMI, GRACE, uDF) for prediction of obstructive CAD and MACE.

METHODS

Patients who presented to the emergency department with chest pain or symptoms of suspected CAD and underwent coronary computed tomographic angiography were analyzed. The primary endpoint was adverse outcomes including the presence of obstructive CAD (≥50% stenosis) and the occurrence of MACE within 6 weeks. We compared the risk scores by the area under the receiver-operating characteristic curve (AUC) and calculated their respective net reclassification index (NRI).

RESULTS

Adverse outcomes occurred in 285 (28.4%) out of the 1002 patients included. For the prediction of adverse outcomes, the AUC of the HEART score (0.792) was superior to those of the CAD clinical model (0.760), CAD basic model (0.749), TIMI (0.749), uDF (0.703), and GRACE (0.653). In terms of the NRI, the HEART score significantly improved the reclassification abilities of the uDF (0.39), GRACE score (0.27), CAD basic model (0.11), TIMI (0.10), and CAD clinical model (0.08) (all P < 0.05). The HEART score also had the highest negative predictive value as well (0.893).

CONCLUSIONS

The HEART score was superior to other cardiac risk scores in predicting both obstructive CAD and MACE. However, due to the high false-negative rate (11%) of the HEART score, its use for identifying low-risk patients should be considered with caution.

Ideal high sensitivity troponin baseline cutoff for patients with renal dysfunction

OBJECTIVE

High-sensitivity cardiac troponin assays (hs-cTn) aid in diagnosis of myocardial infarction (MI). These assays have lower specificity for non-ST Elevation MI (NSTEMI) in patients with renal disease. Our objective was to determine an optimized cutoff for patients with renal disease.

METHODS

We conducted an a priori secondary analysis of a prospective FDA study in adults with suspected MI presenting to 29 academic urban EDs between 4/2015 and 4/2016. Blood was drawn 0, 1, 2-3, and 6-9 h after ED arrival. We recorded cTn and estimated glomerular filtrate rate (eGFR) by Chronic Kidney Disease Epidemiology Collaboration equation. The primary endpoint was NSTEMI (Third Universal Definition of MI), adjudicated by physicians blinded to hs-cTn results. We generated an adjusted hscTn rule-in cutoff to increase specificity.

RESULTS

2505 subjects were enrolled; 234 were excluded. Patients were mostly male (55.7%) and white (57.2%), median age was 56 years 472 patients [20.8%] had an eGFR <60 mL/min/1.73 m2. In patients with eGFR <15 mL/min/1.73 m2, a baseline rule-in cutoff of 120 ng/L led to a specificity of 85.0% and Positive Predictive Value (PPV) of 62.5% with 774 patients requiring further observation. Increasing the cutoff to 600 ng/L increased specificity and PPV overall and in every eGFR subgroup (specificity and PPV 93.3% and 78.9%, respectively for eGFR <15 mL/min/1.73m²), while increasing the number (79) of patients requiring observation.

CONCLUSIONS

An eGFR-adjusted baseline rule-in threshold for the Siemens Atellica hs-cTnI improves specificity with identical sensitivity. Further study in a prospective cohort with higher rates of renal disease is warranted.

Use of Troponin as a predictor for cardiovascular diseases in patients with type 2 Diabetes Mellitus

People with type 2 diabetes mellitus (T2DM) have two- to four-fold increased cardiovascular mortality in comparison to the general population. With the identification of new therapeutic targets and hypoglycemic drugs for T2DM, the need for a better stratification of CVD risk has emerged to select patients who may need intensive or specific treatment. At present, risk stratification is based on clinical, demographic, and biochemical factors. High sensitivity cardiac troponin (hs-cTn) increases after several ischemic and non-ischemic insults and it is considered a marker of myocardial injury. This review summarizes the main findings about hs-cTn utilization for risk stratification in people with T2DM and no clinical CVD. Several large observational studies have documented the association between hs-cTn and adverse cardiovascular outcomes in both the general population and in patients with T2DM. Lifestyle interventions, and particularly promotion of physical activity and adoption of healthy nutritional habits, have been associated to a significant benefit on hs-cTn release in the general population. Randomized controlled trials suggested that hypoglycemic, anti-hypertensive and lipid-lowering therapy may influence the degree of T2DM-induced cardiac injury. Besides these promising findings, the efficacy of an hs-cTn-based approach for CVD prevention in T2DM patients still requires more investigations.

Cardiac Myosin-Binding Protein C-From Bench to Improved Diagnosis of Acute Myocardial Infarction

Chest pain is responsible for 6-10% of all presentations to acute healthcare providers. Triage is inherently difficult and heavily reliant on the quantification of cardiac Troponin (cTn), as a minority of patients with an ultimate diagnosis of acute myocardial infarction (AMI) present with clear diagnostic features such as ST-elevation on the electrocardiogram. Owing to slow release and disappearance of cTn, many patients require repeat blood testing or present with stable but elevated concentrations of the best available biomarker and are thus caught at the interplay of sensitivity and specificity.We identified cardiac myosin-binding protein C (cMyC) in coronary venous effluent and developed a high-sensitivity assay by producing an array of monoclonal antibodies and choosing an ideal pair based on affinity and epitope maps. Compared to high-sensitivity cardiac Troponin (hs-cTn), we demonstrated that cMyC appears earlier and rises faster following myocardial necrosis. In this review, we discuss discovery and structure of cMyC, as well as the migration from a comparably insensitive to a high-sensitivity assay facilitating first clinical studies. This assay was subsequently used to describe relative abundance of the protein, compare sensitivity to two high-sensitivity cTn assays and test diagnostic performance in over 1900 patients presenting with chest pain and suspected AMI. A standout feature was cMyC's ability to more effectively triage patients. This distinction is likely related to the documented greater abundance and more rapid release profile, which could significantly improve the early triage of patients with suspected AMI.

Rapid rule out for suspected myocardial infarction: is the algorithm appropriate for all?

Aims

Patients presenting to the emergency department (ED) with cardiac chest pain and high-sensitive troponin I (HsTnI) less than 5 ng/L have very good prognosis and low risk for major adverse cardiovascular events. The 2015 European Society of Cardiology (ESC) guidelines for non-ST-elevation myocardial infarction (MI)/acute coronary syndrome (ACS) suggests that patients with normal high-sensitive troponin, which are free of chest pain and have a global registry of acute coronary events (GRACE) score less than 140 are eligible for discharge from the hospital for outpatient workup. Our hypothesis suggests that not all patients with GRACE score under 140 should be discharged for ambulatory tests even with undetectable HsTnI as recommended in the guidelines.

Methods and results

Population-based retrospective cohort study in a large tertiary care centre. The study population included all patients discharged from the hospital between 1 February 2016 and 28 February 2019 following rule out of MI. During the study period, a total of 13 800 patients were discharged from the hospital after rule out of MI. Among them, 9236 (67%) had HsTnI below 5 ng/L. A total of 7705 patients (83%) met the criteria for low (n = 7162) or moderate (n = 543) GRACE risk score. Moderate-risk patients had significantly more adverse events than low-risk patients (4.6% vs. 2.1%, P &lt; 0.001). They are in higher risk of death (0.5% vs. 0.1%, P = 0.042), revascularization (3.9% vs. 1.8%, P = 0.0047), and readmission due to ACS (1.1% vs. 0.4%, P = 0.031).

Conclusion

Patients presenting to the ED with chest pain and HsTnI less than 5 ng/L and GRACE score under 140 have 2–4% adverse event in 60 days. The differences between the groups suggest using rapid rule out algorithms for only low-risk patients with GRACE score under 73.

Artificial Intelligence for Diagnosis of Acute Coronary Syndromes: A Meta-analysis of Machine Learning Approaches

BACKGROUND

Machine learning (ML) encompasses a wide variety of methods by which artificial intelligence learns to perform tasks when exposed to data. Although detection of myocardial infarction has been facilitated with introduction of troponins, the diagnosis of acute coronary syndromes (ACS) without myocardial damage (without elevation of serum troponin) remains subjective, and its accuracy remains highly dependent on clinical skills of the health care professionals. Application of a ML algorithm may expedite management of ACS for either early discharge or early initiation of ACS management. We aim to summarize the published studies of ML for diagnosis of ACS.

METHODS

We searched electronic databases, including PubMed, Embase, and Web of Science from inception up to January 13, 2019, for studies that evaluated ML algorithms for the diagnosis of ACS in patients presenting with chest pain. We then used random-effects bivariate meta-analysis models to summarize the studies.

RESULTS

We retained 9 studies that evaluated ML in a total of 6292 patients. The prevalence of ACS in the evaluated cohorts ranged from relatively rare (7%) to common (57%). The pooled sensitivity and specificity were 0.95 and 0.90, respectively. The positive predictive values ranged from 0.64 to 1.0, and the negative predictive values ranged from 0.91 to 1.0. The positive and negative likelihood ratios ranged from 1.6 to 33.0 and 0.01 to 0.13, respectively.

CONCLUSIONS

The excellent sensitivity, negative likelihood ratio, and negative predictive values suggest that ML may be useful as an initial triage tool for ruling out ACS.

Clinical chemistry score versus high-sensitivity cardiac troponin I and T tests alone to identify patients at low or high risk for myocardial infarction or death at presentation to the emergency department

BACKGROUND

Testing for high-sensitivity cardiac troponin (hs-cTn) may assist triage and clinical decision-making in patients presenting to the emergency department with symptoms of acute coronary syndrome; however, this could result in the misclassification of risk because of analytical variation or laboratory error. We sought to evaluate a new laboratory-based risk-stratification tool that incorporates tests for hs-cTn, glucose level and estimated glomerular filtration rate to identify patients at risk of myocardial infarction or death when presenting to the emergency department.

METHODS

We constructed the clinical chemistry score (CCS) (range 0-5 points) and validated it as a predictor of 30-day myocardial infarction (MI) or death using data from 4 cohort studies involving patients who presented to the emergency department with symptoms suggestive of acute coronary syndrome. We calculated diagnostic parameters for the CCS score separately using high-sensitivity cardiac troponin I (hs-cTnI) and high-sensitivity cardiac troponin T (hs-cTnT).

RESULTS

For the combined cohorts (n = 4245), 17.1% of participants had an MI or died within 30 days. A CCS score of 0 points best identified low-risk participants: the hs-cTnI CCS had a sensitivity of 100% (95% confidence interval [CI] 99.5%-100%), with 8.9% (95% CI 8.1%-9.8%) of the population classified as being at low risk of MI or death within 30 days; the hs-cTnT CCS had a sensitivity of 99.9% (95% CI 99.2%-100%), with 10.5% (95% CI 9.6%-11.4%) of the population classified as being at low risk. The CCS had better sensitivity than hs-cTn alone (hs-cTnI < 5 ng/L: 96.6%, 95% CI 95.0%-97.8%; hs-cTnT < 6 ng/L: 98.2%, 95% CI 97.0%-99.0%). A CCS score of 5 points best identified patients at high risk (hs-cTnI CCS: specificity 96.6%, 95% CI 96.0%-97.2%; 11.2% [95% CI 10.3%-12.2%] of the population classified as being at high risk; hs-cTnT CCS: specificity 94.0%, 95% CI 93.1%-94.7%; 13.1% [95% CI 12.1%-14.1%] of the population classified as being at high risk) compared with using the overall 99th percentiles for the hs-cTn assays (specificity of hs-cTnI 93.2%, 95% CI 92.3-94.0; specificity of hs-cTnT 73.8%, 95% CI 72.3-75.2).

INTERPRETATION

The CCS score at the chosen cut-offs was more sensitive and specific than hs-cTn alone for risk stratification of patients presenting to the emergency department with suspected acute coronary syndrome. Study registration: ClinicalTrials.gov, nos. NCT01994577; NCT02355457.

Low High-Sensitivity Troponin Thresholds Identify Low-Risk Patients With Chest Pain Unlikely to Benefit From Further Risk Stratification

Background

Very low high-sensitivity cardiac troponin T (hs-cTnT) thresholds on presentation can rule out acute myocardial infarction (AMI), but the ability to identify patients at low risk of 30-day major adverse cardiac events (MACE) is less clear. This study examines the sensitivity of low concentrations of hs-cTnT on presentation to rule out 30-day MACE.

Methods

This prospective cohort study enrolled patients with chest pain presenting to the emergency department with nonischemic electrocardiograms who underwent AMI rule-out with an hs-cTnT assay. The primary outcome was 30-day MACE; secondary outcomes were individual MACE components. Because guidelines recommend using a single hs-cTnT strategy only for patients with more than 3 hours since symptom onset, a subgroup analysis was performed for this population. Outcomes were adjudicated on the basis of review of medical records and telephone follow-up.

Results

Of 1167 patients enrolled, 125 (10.7%) experienced 30-day MACE and 97 (8.3%) had AMI on the index visit. More than one-third of patients (35.6%) had presenting hs-cTnT concentrations below the limit of detection (5 ng/L), which was 94.4% (95% confidence interval [CI], 88.8-97.7) sensitive for 30-day MACE and 99.0% (95% CI, 94.5-100) sensitive for index AMI. Of 292 patients (25.0%) with hs-cTnT < 5 ng/L and at least 3 hours since symptom onset, only 3 experienced 30-day MACE (sensitivity 97.6%; 95% CI, 93.2-100) and none had AMI within 30 days (sensitivity 100%; 95% CI, 96.3-100).

Conclusions

Among patients with nonischemic electrocardiograms and > 3 hours since symptom onset, low hs-cTnT thresholds on presentation confer a very low risk of 30-day MACE. In the absence of a high-risk clinical presentation, further risk stratification is likely to be low yield.

The PROTROPIC feasibility study: prognostic value of elevated troponins in critical illness

PURPOSE

Elevated cardiac troponin concentrations in people with critical illness are associated with an increased risk of death. We aimed to assess the feasibility of a larger study to ascertain the utility of cardiac troponin as a prognostic tool for mortality in critically ill patients.

METHODS

Patients admitted to participating intensive care units during the one-month enrolment period were eligible. We excluded cardiac surgical patients and patients who were admitted and either died or were discharged within 12 hr. In enrolled patients, we measured high-sensitivity cardiac troponin I (hs-cTnI) and obtained electrocardiograms to ascertain the incidence of myocardial infarction (MI) and isolated troponin elevation. Our feasibility objectives were to measure recruitment rate, the proportion of patients who consented under a deferred consent model, and time required for data collection and study procedures.

RESULTS

Over a four-week enrolment period, 280 patients were enrolled using a deferred consent model. We obtained subsequent consent from 81% of patients. Study procedures and data collection required 1.7 hr per participant. Overall, 86 (38%) suffered a MI, 23 (10%) had an isolated hs-cTnI elevation, and 117 (52%) had no hs-cTnI elevation. The crude hospital mortality rate was 10% without an hs-cTnI elevation, 29% with an isolated hs-cTnl elevation (relative risk [RR]) 2.2; 95% confidence interval [CI], 1.0 to 6.0) and 29% with an MI (RR, 2.6; 95% CI, 1.4 to 5.1).

CONCLUSION

Myocardial injury with elevated hs-cTnI concentrations and MIs occur frequently during critical illness. This pilot study has established the feasibility of conducting a large-scale investigation addressing this issue.

Role of High-sensitivity Cardiac Troponin in Acute Coronary Syndrome

Chest pain is one of the most common reasons for an emergency room (ER) visit in the US, with almost 6 million ER visits annually. High-sensitivity cardiac troponin (hscTn) assays have the ability to rapidly rule in or rule out acute coronary syndrome with improved sensitivity, and they are increasingly being used. Though hscTn assays have been approved for use in European, Australian, and Canadian guidelines since 2010, the FDA only approved their use in 2017. There is no consensus on how to compare the results from various hscTn assays. A literature review was performed to analyze the advantages and limitations of using hscTn as a standard biomarker to evaluate patients with suspected ACS in the emergency setting.

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.

Cardiac Troponin - diagnostic problems and impact on cardiovascular disease

The definition of a high-sensitivity cardiac Troponin (cTn) assay describes the ability to quantify a cardiac biomarker level in at least 50% of healthy individuals. This advance in analytic sensitivity has come with a perceived loss of specificity in the most classic application - chest pain triage and the diagnosis of acute myocardial infarction (AMI). As cardiac Troponin can no longer be used as a dichotomous test, the medical field is increasingly moving towards a more granular interpretation. However, rapid rule-out/rule-in algorithms for AMI still rely on concrete thresholds for efficient triage, irrespective of the patient's comorbidities. Owing to a slightly elevated cTn value, evermore patients appear to fall into an indeterminate risk zone of diagnostic uncertainty. The reasons are manifold, spanning biological variation, analytical issues, increased plasma membrane permeability and the potential cytosolic release of cTn. This review provides a contemporary overview of the literature concerning the use of cardiac Troponin in chronic and acute cardiovascular care. Key messages High-sensitivity cardiac Troponin assays have transformed the assessment of cardiovascular disease. Rapid rule-out algorithms for chest pain triage have become increasingly complicated, but enable safe rule-out. Cardiac Troponin tracks mid- to long-term risk in patients with hyperlipidaemia, heart failure and renal dysfunction.

Evaluation of sex-specific cut-off values of high-sensitivity cardiac troponin I and T assays in an emergency department setting - Results from the Linz Troponin (LITROP) study

BACKGROUND

The aim of the present analysis was to evaluate sex-specific cut-off values of a high-sensitivity cardiac troponin T (hs-cTnT) assay and a high-sensitivity cardiac troponin I (hs-cTnI) assay in an emergency department setting.

METHODS

We retrospectively studied 1945 male and 1643 female emergency department patients in whom we had measured both Roche hs-cTnT and Abbott hs-cTnI routinely upon every troponin measurement request. We performed reclassification analyses of sex-specific thresholds versus sex-neutral thresholds of both assays. In addition, we performed sensitivity analyses to find those sex-specific cut-off values for the Roche hs-cTnT and the Abbott hs-cTnI assays with the lowest possible rate of discordant classifications by both assays.

RESULTS

Compared with the classification by the sex-neutral thresholds (i.e., 14 ng/L for hs-cTnT and 26 ng/L for hs-cTnI), using sex-specific thresholds (i.e., 16 ng/L in males and 9 ng/L in females for hs-cTnT; and in 34 ng/L males and 16 ng/L in females for hs-cTnI) resulted in a total reclassification rate of 4% for hs-cTnT and 3% for hs-cTnI in male individuals, and of 11% and 6%, respectively, in female individuals. In our cohort, the sex-specific hs-cTnT cut-off values currently in use (i.e., 16 ng/L in males and 9 ng/L in females) were best matched to a hs-cTnI cut-off value of 11 ng/L in male and 5 ng/L in female individuals. Conversely, the sex-specific hs-cTnI cut-off values currently in use (i.e., 34 ng/L in males and 16 ng/L in females) were best matched to a hs-cTnT cut-off value of 49 ng/L in male and 24 ng/L in female individuals. These "harmonised" cut-off values reduced discordant classifications between both assays by 43-68% compared to using cut-off values currently in use.

CONCLUSION

Especially in women, reclassification rates were high, when using sex specific versus sex-neutral thresholds. Best matching cut-off values for hs-cTnT and hs-cTnI were markedly different to those currently in use. These "harmonised" cut-off values minimised discordant classifications between both assays.