The Use of Very Low Concentrations of High-sensitivity Troponin T to Rule Out Acute Myocardial Infarction Using a Single Blood Test

Are medical history data fit for risk stratification of patients with chest pain in emergency care? Comparing data collected from patients using computerized history taking with data documented by physicians in the electronic health record in the CLEOS-CPDS prospective cohort study

OBJECTIVE

In acute chest pain management, risk stratification tools, including medical history, are recommended. We compared the fraction of patients with sufficient clinical data obtained using computerized history taking software (CHT) versus physician-acquired medical history to calculate established risk scores and assessed the patient-by-patient agreement between these 2 ways of obtaining medical history information.

MATERIALS AND METHODS

This was a prospective cohort study of clinically stable patients aged ≥ 18 years presenting to the emergency department (ED) at Danderyd University Hospital (Stockholm, Sweden) in 2017-2019 with acute chest pain and non-diagnostic ECG and serum markers. Medical histories were self-reported using CHT on a tablet. Observations on discrete variables in the risk scores were extracted from electronic health records (EHR) and the CHT database. The patient-by-patient agreement was described by Cohen's kappa statistics.

RESULTS

Of the total 1000 patients included (mean age 55.3 ± 17.4 years; 54% women), HEART score, EDACS, and T-MACS could be calculated in 75%, 74%, and 83% by CHT and in 31%, 7%, and 25% by EHR, respectively. The agreement between CHT and EHR was slight to moderate (kappa 0.19-0.70) for chest pain characteristics and moderate to almost perfect (kappa 0.55-0.91) for risk factors.

CONCLUSIONS

CHT can acquire and document data for chest pain risk stratification in most ED patients using established risk scores, achieving this goal for a substantially larger number of patients, as compared to EHR data. The agreement between CHT and physician-acquired history taking is high for traditional risk factors and lower for chest pain characteristics.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT03439449.

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.

Impact of a high sensitivity troponin accelerated diagnostic protocol on the safety and emergency department length of stay of chest pain in an academic tertiary hospital: a quality improvement study

PURPOSE

High-sensitivity troponin (hsTn) accelerated diagnostic protocols are highly recommended for evaluating acute coronary syndromes. Our goal was to improve care for chest pain patients through the safe adoption of an accelerated diagnostic protocol in our academic Emergency Department (ED) with an aim to reduce mean ED length of stay for chest pain patients by 1 h over 1.5 years. Pre-accelerated diagnostic protocol, our mean ED length of stay for chest pain patients was 9.0 h.

METHODS

Using the Model for Improvement, we implemented a two-hour accelerated diagnostic protocol and conducted two Plan-Do-Study-Act cycles and education efforts to improve accelerated diagnostic protocol compliance and decrease ED length of stay. Using control charts, we measured the mean monthly ED length of stay for chest pain patients to look for special cause evidence of improvement. Process measures measured compliance with the accelerated diagnostic protocol. Balancing measures included the ED length of stay for abdominal pain patients and the number of admissions and deaths at 7 days for chest pain patients.

RESULTS

Mean ED length of stay for chest pain patients decreased from 9.0 to 8.2 h post-accelerated diagnostic protocol. The mean time between troponins decreased from 3.9 to 3.0 h, and the percentage of second troponins repeated at < 2.75 h increased from 22.3% to 58.6%. For abdominal pain patients, ED length of stay decreased from 10.8 to 10.5 h. No chest pain patients died within 7 days pre- or post-accelerated diagnostic protocol. Pre-accelerated diagnostic protocol, 0.84% (41/4,905) were admitted within 7 days. Post-accelerated diagnostic protocol and accelerated diagnostic protocol compliant, 0.70% (13/1,844) were admitted. Post-accelerated diagnostic protocol and accelerated diagnostic protocol non-compliant, 1.1% (13/1,183) were admitted.

CONCLUSION

We safely introduced a hsTn accelerated diagnostic protocol in an academic ED. ED length of stay decreased for chest pain patients but did not meet our 1-h goal.

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.

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.

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.

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 Practice Guideline Used for Rule-Out of Myocardial Infarction at a Tertiary Cardiology Center

INTRODUCTION

With the current high burden on the healthcare system and limited resources, the efficient utilization of facilities is of utmost importance. We sought to present the practice guideline used at a high prevalence tertiary cardiology center and compare its safety and efficacy performance with the single high-sensitivity cardiac troponin T strategy, conventional and modified HEART score.

METHODS

In this prospective cohort study, consecutive patients presenting to the emergency department with chest pain or an angina equivalent were recruited. The primary endpoints consisted of major adverse cardiac events at index visits and 30-day follow-up. Patients were managed according to the practice guideline, and sensitivity and negative predictive values were compared.

RESULTS

Of the total 1548 patients, the mean age was 50.4 ± 15.7 years. Ninety-nine (10.9%) patients were admitted at the index visit, and 89 patients were consequently diagnosed with acute coronary symptoms. Six (0.007%) patients experienced major adverse cardiac events within the 30-day follow-up among discharged patients. Among 911 patients with at least 1 troponin, using single high-sensitivity cardiac troponin T, HEART score, and modified HEART score would have further admitted 805, 450, and 609 patients, respectively. The negative predictive value for all 4 algorithms did not significantly differ (99.2% vs. 100% vs. 99.3% vs. 99.6%, respectively).

CONCLUSIONS

The Tehran Herat Center protocol was a relatively safe protocol with high efficacy. Despite the high safety of the other diagnostic pathways, the high volume of patients needing additional evaluation could impose a high burden on the health care system.

Laboratory-related issues in the measurement of cardiac troponins with highly sensitive assays

A number of assay-related issues can affect the performance of cardiac troponin (cTn) measurement in everyday practice. In this respect, it is vital that all information on cTn assays is known and that the performance characteristics of assays are objectively assessed and adequately described. The advent of the latest generation of more sensitive cTn assays has heralded a new wave of information about low concentrations of cTn in blood. These recent generation assays have improved analytical sensitivity and corresponding performance at low cTn concentrations when compared to their predecessors, providing a convincing goal for laboratory medicine in helping clinicians in the diagnosis of acute myocardial infarction. Crucial to the clinical utility of highly sensitive cTn assays is the laboratorians' role in closely scrutinizing proposed assays and defining their value in relation to available evidence. Analytical, as well as pre-analytical and post-analytical, aspects must be documented. In this review, we describe what laboratory professionals should know about their cTn assay performance characteristics and the pre-analytical prerequisites for robustness to ensure optimal post-analytical reporting.

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.

High-sensitivity troponin assays for early rule-out of acute myocardial infarction in people with acute chest pain: a systematic review and economic evaluation

BACKGROUND

Early diagnosis of acute myocardial infarction is important, but only 20% of emergency admissions for chest pain will actually have an acute myocardial infarction. High-sensitivity cardiac troponin assays may allow rapid rule out of myocardial infarction and avoid unnecessary hospital admissions.

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of high-sensitivity cardiac troponin assays for the management of adults presenting with acute chest pain, in particular for the early rule-out of acute myocardial infarction.

METHODS

Sixteen databases were searched up to September 2019. Review methods followed published guidelines. Studies were assessed for quality using appropriate risk-of-bias tools. The bivariate model was used to estimate summary sensitivity and specificity for meta-analyses involving four or more studies; otherwise, random-effects logistic regression was used. The health economic analysis considered the long-term costs and quality-adjusted life-years associated with different troponin testing methods. The de novo model consisted of a decision tree and a state-transition cohort model. A lifetime time horizon (of 60 years) was used.

RESULTS

Thirty-seven studies (123 publications) were included in the review. The high-sensitivity cardiac troponin test strategies evaluated are defined by the combination of four factors (i.e. assay, number and timing of tests, and threshold concentration), resulting in a large number of possible combinations. Clinical opinion indicated a minimum clinically acceptable sensitivity of 97%. When considering single test strategies, only those using a threshold at or near to the limit of detection for the assay, in a sample taken at presentation, met the minimum clinically acceptable sensitivity criterion. The majority of the multiple test strategies that met this criterion comprised an initial rule-out step, based on high-sensitivity cardiac troponin levels in a sample taken on presentation and a minimum symptom duration, and a second stage for patients not meeting the initial rule-out criteria, based on presentation levels of high-sensitivity cardiac troponin and absolute change after 1, 2 or 3 hours. Two large cluster randomised controlled trials found that implementation of an early rule-out pathway for myocardial infarction reduced length of stay and rate of hospital admission without increasing cardiac events. In the base-case analysis, standard troponin testing was both the most effective and the most costly. Other testing strategies with a sensitivity of 100% (subject to uncertainty) were almost equally effective, resulting in the same life-year and quality-adjusted life-year gain at up to four decimal places. Comparisons based on the next best alternative showed that for willingness-to-pay values below £8455 per quality-adjusted life-year, the Access High Sensitivity Troponin I (Beckman Coulter, Brea, CA, USA) [(symptoms > 3 hours AND < 4 ng/l at 0 hours) OR (< 5 ng/l AND Δ < 5 ng/l at 0 to 2 hours)] would be cost-effective. For thresholds between £8455 and £20,190 per quality-adjusted life-year, the Elecsys® Troponin-T high sensitive (Roche, Basel, Switzerland) (< 12 ng/l at 0 hours AND Δ < 3 ng/l at 0 to 1 hours) would be cost-effective. For a threshold > £20,190 per quality-adjusted life-year, the Dimension Vista® High-Sensitivity Troponin I (Siemens Healthcare, Erlangen, Germany) (< 5 ng/l at 0 hours AND Δ < 2 ng/l at 0 to 1 hours) would be cost-effective.

CONCLUSIONS

High-sensitivity cardiac troponin testing may be cost-effective compared with standard troponin testing.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019154716.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Evidence Synthesis programme and will be published in full in Health Technology Assessment; Vol. 25, No. 33. See the NIHR Journals Library website for further project information.

Use of Self-Reported Computerized Medical History Taking for Acute Chest Pain in the Emergency Department - the Clinical Expert Operating System Chest Pain Danderyd Study (CLEOS-CPDS): Prospective Cohort Study

Background

Chest pain is one of the most common chief complaints in emergency departments (EDs). Collecting an adequate medical history is challenging but essential in order to use recommended risk scores such as the HEART score (based on history, electrocardiogram, age, risk factors, and troponin). Self-reported computerized history taking (CHT) is a novel method to collect structured medical history data directly from the patient through a digital device. CHT is rarely used in clinical practice, and there is a lack of evidence for utility in an acute setting.

Objective

This substudy of the Clinical Expert Operating System Chest Pain Danderyd Study (CLEOS-CPDS) aimed to evaluate whether patients with acute chest pain can interact effectively with CHT in the ED.

Methods

Prospective cohort study on self-reported medical histories collected from acute chest pain patients using a CHT program on a tablet. Clinically stable patients aged 18 years and older with a chief complaint of chest pain, fluency in Swedish, and a nondiagnostic electrocardiogram or serum markers for acute coronary syndrome were eligible for inclusion. Patients unable to carry out an interview with CHT (eg, inadequate eyesight, confusion or agitation) were excluded. Effectiveness was assessed as the proportion of patients completing the interview and the time required in order to collect a medical history sufficient for cardiovascular risk stratification according to HEART score.

Results

During 2017-2018, 500 participants were consecutively enrolled. The age and sex distribution (mean 54.3, SD 17.0 years; 213/500, 42.6% women) was similar to that of the general chest pain population (mean 57.5, SD 19.2 years; 49.6% women). Common reasons for noninclusion were language issues (182/1000, 18.2%), fatigue (158/1000, 15.8%), and inability to use a tablet (152/1000, 15.2%). Sufficient data to calculate HEART score were collected in 70.4% (352/500) of the patients. Key modules for chief complaint, cardiovascular history, and respiratory history were completed by 408 (81.6%), 339 (67.8%), and 291 (58.2%) of the 500 participants, respectively, while 148 (29.6%) completed the entire interview (in all 14 modules). Factors associated with completeness were age 18-69 years (all key modules: Ps<.001), male sex (cardiovascular: P=.04), active workers (all key modules: Ps<.005), not arriving by ambulance (chief complaint: P=.03; cardiovascular: P=.045), and ongoing chest pain (complete interview: P=.002). The median time to collect HEART score data was 23 (IQR 18-31) minutes and to complete an interview was 64 (IQR 53-77) minutes. The main reasons for discontinuing the interview prior to completion (n=352) were discharge from the ED (101, 28.7%) and tiredness (95, 27.0%).

Conclusions

A majority of patients with acute chest pain can interact effectively with CHT on a tablet in the ED to provide sufficient data for risk stratification with a well-established risk score. The utility was somewhat lower in patients 70 years and older, in patients arriving by ambulance, and in patients without ongoing chest pain. Further studies are warranted to assess whether CHT can contribute to improved management and prognosis in this large patient group.

Trial Registration

ClinicalTrials.gov NCT03439449; https://clinicaltrials.gov/ct2/show/NCT03439449

International Registered Report Identifier (IRRID)

RR2-10.1136/bmjopen-2019-031871

Diagnostic Performance of High-Sensitivity Cardiac Troponin T Strategies and Clinical Variables in a Multisite US Cohort

BACKGROUND

European data support the use of low high-sensitivity troponin (hs-cTn) measurements or a 0/1-hour (0/1-h) algorithm for myocardial infarction to exclude major adverse cardiac events (MACEs) among patients in the emergency department with possible acute coronary syndrome. However, modest US data exist to validate these strategies. This study evaluated the diagnostic performance of an initial hs-cTnT measure below the limit of quantification (LOQ: 6 ng/L), a 0/1-h algorithm, and their combination with history, ECG, age, risk factors, and initial troponin (HEART) scores for excluding MACE in a multisite US cohort.

METHODS

A prospective cohort study was conducted at 8 US sites, enrolling adult patients in the emergency department with symptoms suggestive of acute coronary syndrome and without ST-elevation on ECG. Baseline and 1-hour blood samples were collected, and hs-cTnT (Roche; Basel, Switzerland) was measured. Treating providers blinded to hs-cTnT results prospectively calculated HEART scores. MACE (cardiac death, myocardial infarction, and coronary revascularization) at 30 days was adjudicated. The proportion of patients with initial hs-cTnT measures below the LOQ and risk according to a 0/1-h algorithm was determined. The negative predictive value (NPV) was calculated for both strategies when used alone or with a HEART score.

RESULTS

Among 1462 participants with initial hs-cTnT measures, 46.4% (678 of 1462) were women and 37.1% (542 of 1462) were Black with an age of 57.6±12.9 (mean±SD) years. MACEs at 30 days occurred in 14.4% (210 of 1462) of participants. Initial hs-cTnT measures below the LOQ occurred in 32.8% (479 of 1462), yielding an NPV of 98.3% (95% CI, 96.7-99.3) for 30-day MACEs. A low-risk HEART score with an initial hs-cTnT below the LOQ occurred in 20.1% (294 of 1462), yielding an NPV of 99.0% (95% CI, 97.0-99.8) for 30-day MACEs. A 0/1-h algorithm was complete in 1430 patients, ruling out 57.8% (826 of 1430) with an NPV of 97.2% (95% CI, 95.9-98.2) for 30-day MACEs. Adding a low HEART score to the 0/1-h algorithm ruled out 30.8% (441 of 1430) with an NPV of 98.4% (95% CI, 96.8-99.4) for 30-day MACEs.

CONCLUSIONS

In a prospective multisite US cohort, an initial hs-cTnT below the LOQ combined with a low-risk HEART score has a 99% NPV for 30-day MACEs. The 0/1-h hs-cTnT algorithm did not achieve an NPV >99% for 30-day MACEs when used alone or with a HEART score. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02984436.

Emergency department routine data and the diagnosis of acute ischemic heart disease in patients with atypical chest pain

Background

Due to an aging population and the increasing proportion of patients with various comorbidities, the number of patients with acute ischemic heart disease (AIHD) who present to the emergency department (ED) with atypical chest pain is increasing. The aim of this study was to develop and validate a prediction model for AIHD in patients with atypical chest pain.

Methods and results

A chest pain workup registry, ED administrative database, and clinical data warehouse database were analyzed and integrated by using nonidentifiable key factors to create a comprehensive clinical dataset in a single academic ED from 2014 to 2018. Demographic findings, vital signs, and routine laboratory test results were assessed for their ability to predict AIHD. An extreme gradient boosting (XGB) model was developed and evaluated, and its performance was compared to that of a single-variable model and logistic regression model. The area under the receiver operating characteristic curve (AUROC) was calculated to assess discrimination. A calibration plot and partial dependence plots were also used in the analyses. Overall, 4,978 patients were analyzed. Of the 3,833 patients in the training cohort, 453 (11.8%) had AIHD; of the 1,145 patients in the validation cohort, 166 (14.5%) had AIHD. XGB, troponin (single-variable), and logistic regression models showed similar discrimination power (AUROC [95% confidence interval]: XGB model, 0.75 [0.71–0.79]; troponin model, 0.73 [0.69–0.77]; logistic regression model, 0.73 [0.70–0.79]). Most patients were classified as non-AIHD; calibration was good in patients with a low predicted probability of AIHD in all prediction models. Unlike in the logistic regression model, a nonlinear relationship-like threshold and U-shaped relationship between variables and the probability of AIHD were revealed in the XGB model.

Conclusion

We developed and validated an AIHD prediction model for patients with atypical chest pain by using an XGB model.

The internal quality control in the traceability era

To be accurate and equivalent, laboratory results should be traceable to higher-order references. Furthermore, their quality should fulfill acceptable measurement uncertainty (MU) as defined to fit the intended clinical use. With this aim, in vitro diagnostics (IVD) manufacturers should define a calibration hierarchy to assign traceable values to their system calibrators. Medical laboratories should know and verify how manufacturers have implemented the traceability of their calibrators and estimate the corresponding MU on clinical samples. Accordingly, the internal quality control (IQC) program should be redesigned to permit IVD traceability surveillance through the verification by medical laboratories that control materials, provided by the manufacturer as a part of measuring systems, are in the clinically suitable validation range (IQC component I). Separately, laboratories should also monitor the reliability of employed IVD measuring systems through the IQC component II, devoted to estimation of MU due to random effects and to obtaining MU of provided results, in order to apply prompt corrective actions if the performance is worsening when compared to appropriate analytical specifications, thus jeopardizing the clinical validity of test results.

Association of a Novel Protocol for Rapid Exclusion of Myocardial Infarction With Resource Use in a US Safety Net Hospital

IMPORTANCE

High-sensitivity cardiac troponin T (hs-cTnT) protocols for the evaluation of chest pain in the emergency department (ED) may reduce unnecessary resource use and overcrowding.

OBJECTIVE

To determine whether the implementation of a novel hs-cTnT protocol, which incorporated troponin values drawn at 0, 1, and 3 hours after ED presentation and the modified HEART score (history, electrocardiogram, age, risk factors), was associated with improvements in resource use while maintaining safety.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study from Parkland Health and Hospital System, a large safety net hospital in Dallas, Texas, included data on 31 543 unique ED encounters in which patients underwent electrocardiographic and troponin testing from January 1, 2017, to October 16, 2018. The hs-cTnT protocol was implemented in December 2017.

MAIN OUTCOMES AND MEASURES

Resource use outcomes included trends in ED dwell time, troponin to disposition decision time (the difference between the first troponin draw time and the time an order was placed for inpatient admission, admission to observation, or discharge), and final patient disposition. Safety outcomes included readmission for myocardial infarction and death.

RESULTS

In 31 543 encounters, mean (SD) patient age was 54 (14.4) years and 14 675 patients (48%) were female. Department dwell time decreased by a mean of -1.09 (95% CI, -2.81 to 0.64) minutes per month in the preintervention period. The decline was steeper after the intervention (-4.69 [95% CI, -9.05 to -0.33] minutes per month) (P for interaction = .007). The troponin to disposition time was increasing in the preintervention period by 1.72 (95% CI, 1.08 to 2.36) minutes per month; postintervention, the mean difference increased more slowly (0.37 [95% CI, -1.25 to 1.99 minutes per month; P value for interaction = .007]). The proportion of patients discharged from the ED increased after the intervention (48% vs 54%, P < .001). Thirty-day major adverse cardiac event rates were low and did not differ before and after the intervention.

CONCLUSIONS AND RELEVANCE

Implementation of a novel protocol incorporating serial hs-cTnT measurements over 3 hours with the Modified HEART Score was associated with reduction in ED dwell times and attenuation of temporal increases in time from troponin measurement to disposition. This or similar protocols to rule out myocardial infarction have the potential to reduce ED overcrowding and improve health care quality while maintaining safety.

Single test rule-out of acute myocardial infarction using the limit of detection of a new high-sensitivity troponin I assay

OBJECTIVES

To determine the diagnostic accuracy of a high-sensitivity cardiac troponin I (hs-cTnI) assay in patients presenting to the Emergency Department (ED) with suspected acute coronary syndromes. Specifically, we evaluated the use of a single blood test at the time of arrival in the ED, using low hs-cTnI cut-offs.

METHODS

In a prospective diagnostic test accuracy study at 14 centers, we included patients presenting to the ED with suspected ACS within 12 h of symptom onset. We drew blood for hs-cTnI (Siemens ADVIA Centaur, overall 99th percentile 47 ng/L, limit of quantification [LoQ] 2.50 ng/L) on arrival. Patients underwent serial cardiac troponin testing over 3-6 h. The primary outcome was an adjudicated diagnosis of acute myocardial infarction (AMI). We evaluated the incidence of major adverse cardiac events (MACE: death, AMI or revascularization) after 30 days. Test characteristics for hs-cTnI were calculated using previously reported cut-offs set at the LoQ and 5 ng/L.

RESULTS

We included 999 patients, including 131 (13.1%) with an adjudicated diagnosis of AMI. Compared to the LoQ (100.0% sensitivity [95% CI 95.9-100.0%]), 99.7% negative predictive value [NPV; 95% CI 97.6-100.0%]), a 5 ng/L cut-off had slightly lower sensitivity (99.2%; 95% CI 95.8-100.0%) and similar NPV (99.8%; 95% CI 98.6-100.0%) but would rule out more patients (28.6% at the LoQ vs 50.4% at 5 ng/L). MACE occurred in 2 (0.7%) patients with hs-cTnI below the LoQ and 7 (1.4%) patients with hs-cTnI < 5 ng/L. Accounting for time from symptom onset or ECG ischemia did not further improve sensitivity.

CONCLUSION

The Siemens ADVIA Centaur hs-cTnI assay has high sensitivity and NPV to rule out AMI with a single blood test in the ED. At the LoQ cut-off a sensitivity > 99% can be achieved. At a 5 ng/L cut-off it may be possible to rule out AMI for over 50% patients.

Diagnosis and risk stratification of chest pain patients in the emergency department: focus on acute coronary syndromes. A position paper of the Acute Cardiovascular Care Association

This paper provides an update on the European Society of Cardiology task force report on the management of chest pain. Its main purpose is to provide an update on the decision algorithms and diagnostic pathways to be used in the emergency department for the assessment and triage of patients with chest pain symptoms suggestive of acute coronary syndromes.

The Asia-Pacific Society of Cardiology (APSC) Expert Committee Consensus Recommendations for Assessment of Suspected Acute Coronary Syndrome Using High-Sensitivity Cardiac Troponin T in the Emergency Department

The Asia-Pacific Society of Cardiology (APSC) high-sensitivity troponin T (hs-TnT) consensus recommendations and rapid algorithm were developed to provide guidance for healthcare professionals in the Asia-Pacific region on assessing patients with suspected acute coronary syndrome (ACS) using a hs-TnT assay. Experts from Asia-Pacific convened in 2 meetings to develop evidence-based consensus recommendations and an algorithm for appropriate use of the hs-TnT assay. The Expert Committee defined a cardiac troponin assay as a high-sensitivity assay if the total imprecision is ≤10% at the 99th percentile of the upper reference limit and measurable concentrations below the 99th percentile are attainable with an assay at a concentration value above the assay's limit of detection for at least 50% of healthy individuals. Recommendations for single-measurement rule-out/rule-in cutoff values, as well as for serial measurements, were also developed. The Expert Committee also adopted similar hs-TnT cutoff values for men and women, recommended serial hs-TnT measurements for special populations, and provided guidance on the use of point-of-care troponin T devices in individuals suspected of ACS. These recommendations should be used in conjunction with all available clinical evidence when making the diagnosis of ACS.

Machine Learning to Predict the Likelihood of Acute Myocardial Infarction

BACKGROUND

Variations in cardiac troponin concentrations by age, sex, and time between samples in patients with suspected myocardial infarction are not currently accounted for in diagnostic approaches. We aimed to combine these variables through machine learning to improve the assessment of risk for individual patients.

METHODS

A machine learning algorithm (myocardial-ischemic-injury-index [MI3]) incorporating age, sex, and paired high-sensitivity cardiac troponin I concentrations, was trained on 3013 patients and tested on 7998 patients with suspected myocardial infarction. MI3 uses gradient boosting to compute a value (0-100) reflecting an individual's likelihood of a diagnosis of type 1 myocardial infarction and estimates the sensitivity, negative predictive value, specificity and positive predictive value for that individual. Assessment was by calibration and area under the receiver operating characteristic curve. Secondary analysis evaluated example MI3 thresholds from the training set that identified patients as low risk (99% sensitivity) and high risk (75% positive predictive value), and performance at these thresholds was compared in the test set to the 99th percentile and European Society of Cardiology rule-out pathways.

RESULTS

Myocardial infarction occurred in 404 (13.4%) patients in the training set and 849 (10.6%) patients in the test set. MI3 was well calibrated with a very high area under the receiver operating characteristic curve of 0.963 [0.956-0.971] in the test set and similar performance in early and late presenters. Example MI3 thresholds identifying low- and high-risk patients in the training set were 1.6 and 49.7, respectively. In the test set, MI3 values were <1.6 in 69.5% with a negative predictive value of 99.7% (99.5-99.8%) and sensitivity of 97.8% (96.7-98.7%), and were ≥49.7 in 10.6% with a positive predictive value of 71.8% (68.9-75.0%) and specificity of 96.7% (96.3-97.1%). Using these thresholds, MI3 performed better than the European Society of Cardiology 0/3-hour pathway (sensitivity, 82.5% [74.5-88.8%]; specificity, 92.2% [90.7-93.5%]) and the 99th percentile at any time point (sensitivity, 89.6% [87.4-91.6%]); specificity, 89.3% [88.6-90.0%]).

CONCLUSIONS

Using machine learning, MI3 provides an individualized and objective assessment of the likelihood of myocardial infarction, which can be used to identify low- and high-risk patients who may benefit from earlier clinical decisions.

CLINICAL TRIAL REGISTRATION

URL: https://www.anzctr.org.au. Unique identifier: ACTRN12616001441404.

High-Sensitivity Troponin and the Application of Risk Stratification Thresholds in Patients With Suspected Acute Coronary Syndrome

Supplemental Digital Content is available in the text.

Guidelines acknowledge the emerging role of high-sensitivity cardiac troponin (hs-cTnl) for risk stratification and the early rule-out of myocardial infarction, but multiple thresholds have been described. We evaluate the safety and effectiveness of risk stratification thresholds in patients with suspected acute coronary syndrome.

Chest pain in the ambulance; prevalence, causes and outcome - a retrospective cohort study

BACKGROUND

Chest pain is common in acute ambulance transports. This study aims to characterize and compare ambulance-transported chest pain patients to non-chest pain patients and evaluate if patient characteristics and accompanying symptoms accessible at the time of emergency call can predict cause and outcome in chest pain patients.

METHODS

Retrospective, observational population-based study, including acute ambulance transports. Patient characteristics and symptoms are included in a multivariable risk model to identify characteristics, associated with being discharged without an acute cardiac diagnosis and surviving 30 days after chest pain event.

RESULTS

In total, 10,033 of 61,088 (16.4%) acute ambulance transports were due to chest pain. In chest pain patients, 30-day mortality was 2.1% (95%CI 1.8-2.4) compared to 6.0% (95%CI 5.7-6.2) in non-chest pain patients. Of chest pain patients, 1054 (10.5%) were diagnosed with acute myocardial infarction, and 5068 (50.5%) were discharged without any diagnosis of disease. This no-diagnosis group had very low 30-day mortality, 0.4% (95%CI 0.2-0.9). Female gender, younger age, chronic pulmonary disease, absence of accompanying symptoms of dyspnoea, radiation, severe pain for > 5 min, clammy skin, uncomfortable, and nausea were associated with being discharged without an acute cardiac diagnosis and surviving 30 days after a chest pain event.

CONCLUSION

Chest pain is a common reason for ambulance transport, but the majority of patients are discharged without a diagnosis and with a high survival rate. Early risk prediction seems to hold a potential for resource downgrading and thus cost-saving in selected chest pain patients.

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.

Diagnostic Accuracy of a High-Sensitivity Cardiac Troponin Assay with a Single Serum Test in the Emergency Department

OBJECTIVES

We sought to evaluate diagnostic accuracy of a high-sensitivity cardiac troponin I (hs-cTnI) assay for acute coronary syndromes (ACS) in the emergency department (ED). The assay has high precision at low concentrations and can detect cTnI in 96.8% of healthy individuals.

METHODS

In successive prospective multicenter studies (“testing” and “validation”), we included ED patients with suspected ACS. We drew blood for hs-cTnI [Singulex Clarity® cTnI; 99th percentile, 8.67 ng/L; limit of detection (LoD), 0.08 ng/L] on arrival. Patients also underwent hs-cTnT (Roche Elecsys) testing over ≥3 h. The primary outcome was an adjudicated diagnosis of ACS, defined as acute myocardial infarction (AMI; prevalent or incident), death, or revascularization within 30 days.

RESULTS

The testing and validation studies included 665 and 2470 patients, respectively, of which 94 (14.1%) and 565 (22.9%) had ACS. At a 1.5-ng/L cutoff, hs-cTnI had good sensitivity for AMI in both studies (98.7% and 98.1%, respectively) and would have “ruled out” 40.1% and 48.9% patients. However, sensitivity was lower for ACS (95.7% and 90.6%, respectively). At a 0.8-ng/L cutoff, sensitivity for ACS was higher (97.5% and 97.9%, ruling out 28.6% patients in each cohort). The hs-cTnT assay had similar performance at the LoD (24.6% ruled out; 97.2% sensitivity for ACS).

CONCLUSIONS

The hs-cTnI assay could immediately rule out AMI in 40% of patients and ACS in &gt;25%, with similar accuracy to hs-cTnT at the LoD. Because of its high precision at low concentrations, this hs-cTnI assay has favorable characteristics for this clinical application.

Multicentre cross-sectional observational registry to monitor the safety of early discharge after rule-out of acute myocardial infarction by copeptin and troponin: the Pro-Core registry

OBJECTIVES

There is sparse information on the safety of early primary discharge from the emergency department (ED) after rule-out of myocardial infarction in suspected acute coronary syndrome (ACS). This prospective registry aimed to confirm randomised study results in patients at low-to-intermediate risk, with a broader spectrum of symptoms, across different institutional standards and with a range of local troponin assays including high-sensitivity cTn (hs-cTn), cardiac troponin (cTn) and point-of-care troponin (POC Tn).

DESIGN

Prospective, multicentre European registry.

SETTING

18 emergency departments in nine European countries (Germany, Austria, Switzerland, France, Spain, UK, Turkey, Lithuania and Hungary) PARTICIPANTS: The final study cohort consisted of 2294 patients (57.2% males, median age 57 years) with suspected ACS.

INTERVENTIONS

Using the new dual markers strategy, 1477 patients were eligible for direct discharge, which was realised in 974 (42.5%) of patients.

MAIN OUTCOME MEASURES

The primary endpoint was all-cause mortality at 30 days.

RESULTS

Compared with conventional workup after dual marker measurement, the median length of ED stay was 60 min shorter (228 min, 95% CI: 219 to 239 min vs 288 min, 95% CI: 279 to 300 min) in the primary dual marker strategy (DMS) discharge group. All-cause mortality was 0.1% (95% CI: 0% to 0.6%) in the primary DMS discharge group versus 1.1% (95% CI: 0.6% to 1.8%) in the conventional workup group after dual marker measurement. Conventional workup instead of discharge despite negative DMS biomarkers was observed in 503 patients (21.9%) and associated with higher prevalence of ACS (17.1% vs 0.9%, p<0.001), cardiac diagnoses (55.2% vs 23.5%, p<0.001) and risk factors (p<0.01), but with a similar all-cause mortality of 0.2% (95% CI: 0% to 1.1%) versus primary DMS discharge (p=0.64).

CONCLUSIONS

Copeptin on top of cardiac troponin supports safe discharge in patients with chest pain or other symptoms suggestive of ACS under routine conditions with the use of a broad spectrum of local standard POC, conventional and high-sensitivity troponin assays.

TRIAL REGISTRATION NUMBER

NCT02490969.

Experiences of a One-hour Algorithm in Chest Pain Patients With a Nonelevated Troponin T at Presentation

Supplemental Digital Content is available in the text.

Background:

We aimed to evaluate the use of a 1-hour measurement of high-sensitivity cardiac troponin T (hs-cTnT) in an emergency department (ED) population of chest pain patients with a nonelevated baseline hs-cTnT and to examine the prevalence of early dynamic changes in hs-cTnT and the association with admission rate, diagnosis, and outcome.

Methods:

All patients with a chief complaint of chest pain presenting to the ED of Karolinska University Hospital, Solna, Sweden, from December 2014 to September 2015 who had a baseline hs-cTnT of ≤14 ng/L and a second value obtained within >30 to ≤90 minutes were followed for 30 days regarding admission, readmission, myocardial infarction (MI), and death.

Results:

A total of 1091 patients were included. Dynamic 1-hour changes in hs-cTnT defined as an increase or decrease of ≥3 ng/L occurred in 23 patients (2.1%). Fifteen patients (65.2%) in the dynamic group were admitted, compared with 148 patients (13.9%) in the nondynamic group (P < 0.001). Four of the admitted patients (26.7%) in the dynamic and 1 (0.7%) in the nondynamic group were diagnosed with an MI (P < 0.001). No death or MI occurred within 30 days among those discharged from the ED.

Conclusions:

Dynamic 1-hour changes in hs-cTnT were uncommon but associated with a higher rate of admission and of MI in an unselected population of chest pain patients with a nonelevated hs-cTnT at presentation. Lack of dynamic changes makes MI highly unlikely, and a 1-hour measurement may facilitate an early rule out of MI but should be used together with clinical assessment.

Rapid rule-out of suspected acute coronary syndrome in the Emergency Department by high-sensitivity cardiac troponin T levels at presentation

The reliability of initial high-sensitivity cardiac troponin T (hs-cTnT) under limit-of-detection in ruling-out short- and long-term acute coronary events in subjects for suspected non-ST-segment elevation acute coronary syndrome (NSTE-ACS) is not definitely settled. In a retrospective chart review analysis, 1001 subjects with hs-cTnT ≤ 14 ng/L out of 4053 subjects with hs-cTnT measured at Emergency Department (ED) presentation were recruited. The main outcome measure is fatal or non-fatal myocardial infarction (MI) within 30 days; secondary outcomes are MI or major acute coronary events (MACE) as a combination of MI or re-hospitalization for unstable angina within 1 year. In subjects with hs-cTnT < 5 ng/L [32.6% of cases, mean age 63 years (interquartile range 23)], no cases (0%, NPV 100%) had MI within 30 days, 2 cases (0.6%, NPV 99.4%) MI at 1-year, and 11 cases (3.4%, NPV 96.6%) MACE at 1-year. Patients with hs-cTnT < 5 ng/L would have benefited from a shortened decision (9.30 h and 53% overnight ED stay saved). Hs-cTnT < 5 ng/L is confirmed as safe for patients and comfortable for physicians in ruling out MI or MACE both at short and long term, suggesting that a sizable number of patients can be rapidly discharged without unnecessary diagnostic tests and ED observation.

Combined testing of copeptin and high-sensitivity cardiac troponin T at presentation in comparison to other algorithms for rapid rule-out of acute myocardial infarction

BACKGROUND

We aimed to directly compare the diagnostic and prognostic performance of a dual maker strategy (DMS) with combined testing of copeptin and high-sensitivity (hs) cardiac troponin T (cTnT) at time of presentation with other algorithms for rapid rule-out of acute myocardial infarction (AMI).

METHODS

922 patients presenting to the emergency department with suspected AMI and available baseline copeptin measurements qualified for the present TRAPID-AMI substudy. Diagnostic measures using the DMS (copeptin <10, <14 or < 20 pmol/L and hs-cTnT≤14 ng/L), the 1 h-algorithm (hs-cTnT<12 ng/L and change <3 ng/L at 1 h), as well as the hs-cTnT limit-of-blank (LoB, <3 ng/L) and -detection (LoD, <5 ng/L) were compared. Outcomes were assessed as combined end-points of death and myocardial re-infarction.

RESULTS

True-negative rule-out using the DMS could be achieved in 50.9%-62.3% of all patients compared to 35.0%, 45.3% and 64.5% using LoB, LoD or the 1 h-algorithm, respectively. The DMS showed NPVs of 98.1%-98.3% compared to 99.2% for the 1 h-algorithm, 99.4% for the LoB and 99.3% for the LoD. Sensitivities were 93.5%-94.8%, as well as 96.8%, 98.7% and 98.1%, respectively. Addition of clinical low-risk criteria such as a HEART-score ≤ 3 to the DMS resulted in NPVs and sensitivities of 100% with a true-negative rule-out to 33.8%-41.6%. Rates of the combined end-point of death/MI within 30 days ranged between 0.2% and 0.3% for all fast-rule-out protocols.

CONCLUSION

Depending on the applied copeptin cut-off and addition of clinical low-risk criteria, the DMS might be an alternative to the hs-cTn-only-based algorithms for rapid AMI rule-out with comparable diagnostic measures and outcomes.

Cardiac Biomarkers in Emergency Care

This article critically reviews the latest evidence to guide the use of biomarkers for the diagnosis of acute coronary syndromes in practice. It shows how modern cardiac troponin assays can enable diagnoses to be ruled in or ruled out with a single blood test, with many more diagnoses confirmed or refuted in as little as 1 hour later. Finally, this article appraises the latest evidence for other cardiac biomarkers, such as heart-type fatty acid-binding protein and copeptin.

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.

High-Sensitivity Cardiac Troponin-Based Strategies for the Assessment of Chest Pain Patients-A Review of Validation and Clinical Implementation Studies

BACKGROUND

The introduction of high-sensitivity cardiac troponin (hs-cTn) assays has improved the early assessment of chest pain patients. A number of hs-cTn-based algorithms and accelerated diagnostic protocols (ADPs) have been developed and tested subsequently. In this review, we summarize the data on the performance and clinical utility of these strategies.

CONTENT

We reviewed studies investigating the diagnostic and prognostic performance of hs-cTn algorithms [level of detection (LoD) strategy, 0/1-h, 0/2-h, and 0/3-h algorithms) and of hs-cTn-based ADPs, together with the implications of these strategies when implemented as clinical routine. The LoD strategy, when combined with a nonischemic electrocardiogram, is best suited for safe rule-out of myocardial infarction and the identification of patients eligible for early discharge from the emergency department. The 0/1-h algorithms appear to identify most patients as being eligible for rule-out. The hs-cTn-based ADPs mainly focus on prognostic assessment, which is in contrast with the hs-cTn algorithms. They identify smaller proportions of rule-out patients, but there is increasing evidence from prospective studies on their successful clinical implementation. Such information is currently lacking for hs-cTn algorithms.

CONCLUSIONS

There is a trade-off between safety and efficacy for different hs-cTn-based strategies. This trade-off should be considered for the intended strategy, along with its user-friendliness and evidence from clinical implementation studies. However, several gaps in knowledge remain. At present, we suggest the use of an ADP in conjunction with serial hs-cTn results to optimize the early assessment of chest pain patients.

Detectable High-Sensitivity Cardiac Troponin within the Population Reference Interval Conveys High 5-Year Cardiovascular Risk: An Observational Study

BACKGROUND

Increased cardiac troponin I or T detected by high-sensitivity assays (hs-cTnI or hs-cTnT) confers an increased risk of adverse prognosis. We determined whether patients presenting with putatively normal, detectable cTn concentrations [> limit of detection and < upper reference limit (URL)] have increased risk of major adverse cardiovascular events (MACE) or all-cause mortality.

METHODS

A prospective 5-year follow-up of patients recruited in the emergency department with possible acute coronary syndrome (ACS) and cTn concentrations measured with hs-cTnI (Abbott) and hs-cTnT (Roche) assays. Cox regression models were generated with adjustment for covariates in those without MACE on presentation. Hazard ratios (HRs) for hs-cTn were calculated relative to the HRs at the median concentration.

RESULTS

Of 1113 patients, 836 were without presentation MACE. Of these, 138 incurred a MACE and 169 died during a median 5.8-year follow-up. HRs for MACE at the URLs were 2.3 (95% CI, 1.7-3.2) for hs-cTnI and 1.8 (95% CI, 1.3-2.4) for hs-cTnT. Corresponding HRs for mortality were 1.7 (95% CI, 1.2-2.2) for hs-cTnI and 2.3 (95 % CI, 1.7-3.1) for hs-cTnT. The HR for MACE increased with increasing hs-cTn concentration similarly for both assays, but the HR for mortality increased at approximately twice the rate for hs-cTnT than hs-cTnI. Patients with hs-cTnI ≥10 ng/L or hs-cTnT ≥16 ng/L had the same percentage of MACE at 5-year follow-up (33%) as patients with presentation MACE.

CONCLUSIONS

Many patients with ACS ruled out and putatively normal but detectable hs-cTnI concentrations are at similar long-term risk as those with MACE. hs-cTnT concentrations are more strongly associated with 5-year mortality than hs-cTnI.

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

BACKGROUND

Low concentrations of cardiac troponin (cTn) have been recommended for rapid rule-out of acute myocardial infarction (AMI). We examined the Beckman Coulter Access high-sensitivity cardiac troponin I (hs-cTnI) assay to identify a single test threshold that can safely rule out AMI.

METHODS

This analysis used stored samples collected in 2 prospective observational studies. In all, 1871 patients presenting to a tertiary emergency department with symptoms of acute coronary syndrome had blood taken for measurement of cTnI on presentation. The endpoint was type 1 myocardial infarction (T1MI). Sensitivity and negative predictive value (NPV) were calculated for hs-cTnI values below the 99th percentile.

RESULTS

Ninety-eight patients had T1MI (5.2%), and 638 (34.1%) patients had an hs-cTnI &lt;2 ng/L (limit of detection), with sensitivity of 99.0% (95% CI, 94.4%–100%) and NPV of 99.8% (95% CI, 99.1%–100%). No hs-cTnI value above a concentration of 2 ng/L achieved sensitivity of 99%. However, an NPV of 99.5% was achieved at values &lt;6 ng/L. A cutoff &lt;6 ng/L enabled 1475 (78.8%) patients to be ruled out on presentation with sensitivity of 93.9% (95% CI, 87.1%–97.7%).

CONCLUSIONS

A single baseline cTn &lt;2 ng/L measured with the Access hs-cTnI assay performed well for rule-out of AMI. This cutoff concentration identified 99% of patients with AMI and could reduce the number of patients requiring lengthy assessment. A cutoff of &lt;6 ng/L yielded a high NPV but missed more cases of AMI than would be acceptable to clinicians.

Understanding cardiac troponin part 2: early rule out of acute coronary syndrome

Chest pain of suspected cardiac origin is a very common emergency department presentation. Over the past decade, there has been an exponential growth in strategies that promote blood sampling at earlier and earlier time points after presentation to facilitate the rule out of acute coronary syndrome.In part 2 of this series, we examine key concepts from the recent literature with the aim of improving clinicians' understanding of the rule-out strategies available to them and provide a structured overview of strategies that facilitate discharge with blood testing over <3 hours.

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

This article synthesizes current best evidence for the evaluation of patients with suspected acute coronary syndrome (ACS) using high-sensitivity troponin assays, enabling physicians to effectively incorporate them into practice. Unlike conventional assays, high-sensitivity assays can precisely measure blood cardiac troponin concentrations in the vast majority of healthy individuals, facilitating the creation of rapid diagnostic algorithms. Very low troponin concentrations on presentation accurately rule out acute myocardial infarction (AMI) and enable the discharge of approximately 20% of patients after a single test, whereas an additional 30%-40% of patients can be safely discharged after short-interval serial sampling in as little as 1 or 2 hours. In contrast, highly abnormal troponin concentrations on presentation (more than 5 times the upper reference limit) or rapidly rising levels on serial testing can rapidly rule in AMI with high specificity. However, approximately one-third of patients remain in a biomarker-indeterminate "observation zone" even after serial sampling. These patients pose a disposition challenge to clinicians because although the differential diagnosis of elevated troponin concentrations is broad, these patients have an increased risk for short-term major adverse cardiac events. Use of repeated serial troponin sampling and structured clinical prediction tools may assist disposition for these patients, because no validated pathways currently exist to guide clinicians. Ongoing research to tailor diagnostic thresholds to individual patient characteristics may enable improved diagnostic accuracy and usher in a new era of personalized medicine in the evaluation of suspected ACS.

Age-sex distribution of patients with high-sensitivity troponin T levels below the 99th percentile

Background

Recently, very low concentrations of high-sensitivity cardiac troponin T (hs-cTnT), below the 99th percentile, have been used to immediately exclude acute myocardial infarction in certain patients without taking their age and sex into consideration.

Results

The hs-cTnT values below the 99th percentile (≤ 14 ng/L) were higher in men (p = 0.000) and significantly increased with age (p = 0.000) among both men and women. In addition, hs-cTnT was positively associated with age (r = 0.459, p = 0.000), myoglobin (r = 0.392, p = 0.000), and creatine kinase-MB (r = 0.133, p = 0.000). Moreover, males were younger (p = 0.001) and had higher myoglobin (p = 0.000) and creatine kinase-MB (p = 0.000) concentrations than females.

Materials and Methods

A total of 5585 consecutive subjects who presented with non-traumatic chest pain/discomfort to the inpatient, outpatient, or emergency department and who underwent high-sensitivity troponin T, myoglobin and creatine kinase-MB testing at presentation, with hs-cTnT below the 99thpercentile (≤ 14 ng/L), were eligible for enrollment.

Conclusions

We suggest that patients’ age, sex and levels of myocardial injury biomarkers should be taken into consideration when ruling out acute myocardial infarction and/or adverse prognostic implications in patients who have very low hs-cTnT concentrations.