Rapid exclusion of acute myocardial infarction in patients with undetectable troponin using a high-sensitivity assay

Short-term prognosis of unstable angina in the era of high-sensitivity cardiac troponin: insights for early rule-out strategies

BACKGROUND

It is unclear if strategies to rule-out myocardial infarction (MI) based on a single high-sensitivity troponin T (hsTnT) measurement at the emergency department (ED) presentation may also exclude unstable angina.

METHODS

We measured hsTnT ex-post on the admission frozen blood sample of 644 subjects with Braunwald IIIB CK-MB-negative unstable angina. This analysis included the 240 patients with hsTnT value ≤99th percentile reference limit (UA). We evaluated the clinical outcome of UA patients and the applicability of two rule-out strategies based on the combination of a non-ischemic ECG with (1) a single hsTnT value below the Limit-of-Detection (LoD), (2) a TIMI risk score ≤1.

RESULTS

UA patients with hsTnT ≤99th percentile reference limit had a favorable 30-day outcome [0.8% MI, 0% cardiovascular death (CVD)], but the rate of CVD/MI at 180-day was 4.7%. Sensitivities for UA were 94.6% according to the 'TIMI ≤1-strategy' and 75.4% according to 'hsTnT-below-LoD-strategy', accounting for 5.4 and 24.6% missed diagnoses, respectively. A prognostic risk stratification to guide appropriate outpatient assessment in potential discharged unrecognized UA patients was developed: a risk score based on the combination of age >60 years and C-reactive protein >4.5 mg/L effectively stratified the 180-day CVD/MI occurrence: 0, 2.5 and 12.7% for score 0, 1 and 2 (log-rank = 0.001, C-statistic = 0.776).

CONCLUSION

Single measurement hsTnT strategies, successfully tested to rule-out MI, may allow safe ED discharge of patients with a suspected acute coronary syndrome: even if UA may not be excluded, its short-term prognosis is favorable. UA patients with a C-reactive protein >4.5 mg/L and older than 60 years have a substantial medium-term cardiovascular risk and may benefit from a timely outpatient diagnostic assessment.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Trial registration number

ISRCTN86184521.

Neutrophil to high-density lipoprotein ratio has a superior prognostic value in elderly patients with acute myocardial infarction: a comparison study

Background

The importance of the lipid-related biomarkers has been implicated in the pathological process and prognosis of acute myocardial infarction (AMI). Our work was conducted to discuss and compare the predictive ability of the neutrophil to high-density lipoprotein cholesterol (HDL-C) ratio (NHR) with other existing prognostic indices, for instance, the monocyte to HDL-C ratio (MHR) and the low-density lipoprotein cholesterol (LDL-C) to HDL-C ratio (LDL-C/HDL-C) in elderly patients with AMI.

Methods

Our population was 528 consecutive elderly AMI patients (65–85 years) who were enrolled from Tongji Hospital and grouped according to the cutoff points which were depicted by the receiver operating characteristic (ROC). The Kaplan-Meier curves were plotted with the survival data from the follow-up to investigate the difference between cutoff point-determined groups. Moreover, we assessed the impact of NHR, MHR, LDL-C/HDL-C on the long-term mortality and recurrent myocardial infarction (RMI) with Cox proportional hazard models.

Results

Mean duration of follow-up was 673.85 ± 14.32 days (median 679.50 days). According to ROC curve analysis, NHR ≥ 5.74, MHR ≥ 0.67, LDL-C/HDL-C ≥ 3.57 were regarded as high-risk groups. Kaplan-Meier analysis resulted that the high-NHR, high-MHR and high-LDL-C/HDL-C groups presented higher mortality and RMI rate than the corresponding low-risk groups in predicting the long-term clinical outcomes (log-rank test: all P < 0.050). In multivariate analysis, compared with MHR and LDL-C/HDL-C, only NHR was still recognized as a latent predictor for long-term mortality (harzard ratio [HR]: 1.96, 95% confidence interval [CI]: 1.02 to 3.75, P = 0.044) and long-term RMI (HR: 2.23, 95% CI: 1.04 to 4.79, P = 0.040). Furthermore, the positive correlation between NHR and Gensini score (r = 0.15, P < 0.001) indicated that NHR was relevant to the severity of coronary artery to some extent.

Conclusions

NHR, a novel laboratory marker, might be a predictor of the long-term clinical outcomes of elderly patients with AMI, which was superior to MHR and LDL-C/HDL-C.

Exploring Patient Experience of Chest Pain Before and After Implementation of an Early Rule-Out Pathway for Myocardial Infarction: A Qualitative Study

STUDY OBJECTIVE

High-sensitivity cardiac troponin assays enable myocardial infarction to be excluded in the emergency department (ED). As part of a prospective clinical trial, we explore how introducing an early rule-out pathway may affect patient experience of chest pain.

METHODS

In a qualitative study, participants presenting to the ED with suspected acute coronary syndrome, and for whom the diagnosis of myocardial infarction was excluded, were interviewed before (n=23) or after (n=26) implementation of an early rule-out pathway. Preimplementation, diagnosis of myocardial infarction was excluded on serial troponin testing requiring admission to the hospital. Postimplementation, diagnosis could be excluded in the ED, enabling direct patient discharge. Semistructured interviews exploring the patients' illness experience were conducted approximately 1 week postdischarge, transcribed verbatim, and analyzed thematically. Themes emerging pre- and postimplementation are described.

RESULTS

Common themes emerged across both pathways: participants commonly sought health care advice before presenting to the ED; a discordance may exist between the objective interpretation of troponin results by clinicians and the patients' experience of illness; and pretest information, trust in the clinician, and active listening may enhance reassurance gained from negative test results. Other themes related to the care pathway were that routine care procedures appeared to be a source of frustration for participants requiring hospital admission, and patients assessed with the early rule-out pathway appeared less likely to appraise their future health status.

CONCLUSION

The early rule-out of myocardial infarction may be enhanced by recognition of patient out-of-hospital experience and improved communication surrounding reassurance and future cardiovascular health goals.

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.

Enhanced triage for patients with suspected cardiac chest pain: the History and Electrocardiogram-only Manchester Acute Coronary Syndromes decision aid

Supplemental Digital Content is available in the text.

Several decision aids can ‘rule in’ and ‘rule out’ acute coronary syndromes (ACS) in the Emergency Department (ED) but all require measurement of blood biomarkers. A decision aid that does not require biomarker measurement could enhance risk stratification at triage and could be used in the prehospital environment. We aimed to derive and validate the History and ECG-only Manchester ACS (HE-MACS) decision aid using only the history, physical examination and ECG.

Diagnostic accuracy of the Troponin-only Manchester Acute Coronary Syndromes (T-MACS) decision aid with a point-of-care cardiac troponin assay

OBJECTIVE

Point-of-care (POC) cardiac troponin (cTn) assays have a rapid turnaround time but are generally less sensitive than laboratory-based assays. Previous research found that the Abbott i-Stat cardiac troponin I (cTnI) assay has good diagnostic accuracy when used with the Troponin-only Manchester Acute Coronary Syndromes (T-MACS) decision aid and serial sampling over 3 hours. Accuracy of other assays may differ. We therefore evaluated the diagnostic accuracy of a different POC cTnI assay with serial sampling over 3 hours, both with T-MACS and when used alone.

METHODS

In a prospective diagnostic accuracy study at eight EDs in England (July 2015-October 2017), we collected clinical data from consenting adults with suspected ACS at the time of assessment in the ED. Blood samples were drawn on arrival and 3 hours later for POC cTnI (Cardio 3 Triage, Alere). The target condition was an adjudicated diagnosis of acute myocardial infarction (AMI), based on reference standard serial laboratory-based cTn testing. We calculated test characteristics for POC cTnI using the limit of detection (LoD, 0.01 µg/L) and the T-MACS decision aid.

RESULTS

Of 347 participants, 59 (14.9%) had AMI. With serial POC cTnI testing over 3 hours, POC cTnI at the LoD cut-off ruled out AMI in 193 (55.6%) patients with 98.1% sensitivity (95% CI 89.9% to 100.0%) and 99.5% negative predictive value (NPV, 95% CI 96.5% to 99.9%). T-MACS ruled out AMI in 117 (33.7%) patients with 98.1% sensitivity (95% CI 89.9% to 100%) and 99.2% NPV (95% CI 94.3% to 99.9%). T-MACS ruled in AMI with 97.9% specificity (95% CI 95.8% to 99.5%) and 83.7% positive predictive value (95% CI 70.6% to 91.7%).

CONCLUSIONS

With serial sampling over 3 hours, the Alere Cardio 3 Triage cTnI assay has relatively high NPV for AMI using either the LoD cut-off alone or the T-MACS decision aid. However, wide CIs around the measures of diagnostic accuracy mean that further prospective testing of this strategy is required before clinical implementation.

TRIAL REGISTRATION NUMBER

UKCRN 18000.

Detecting unstable plaques in humans using cardiac CT: Can it guide treatments?

Advances in imaging technology have driven the rapid expansion in the use of CT in the assessment of coronary atherosclerotic plaque. Based on a rapidly growing evidence base, current guidelines recommend coronary CT angiography as the first-line diagnostic test for patients presenting with stable chest pain. There is a growing need to refine current methods for diagnosis and risk stratification to improve the individualisation of preventative therapies. Imaging assessments of high-risk plaque with CT can be used to differentiate stable from unstable patterns of coronary atherosclerosis and potentially to improve patient risk stratification. This review will focus on coronary imaging with CT with a specific focus on the detection of coronary atherosclerosis, high-risk plaque features, and the implications for patient management.

The impact of an acute chest pain pathway on the investigation and management of cardiac chest pain

Emergency department (ED) presentation with chest pain accounts for approximately 20% of acute hospital admissions, and delays in the investigation and management of these patients increase the pressure on emergency and medical departments. We implemented a pathway within our trust to improve the efficiency of acute chest pain management. This included the development of a chest pain management algorithm, a short-stay heart assessment centre and a policy to immediately transfer acute coronary syndrome patients to cardiology. The introduction of the chest pain pathway resulted in fewer admissions from the ED with chest pain (34.2% vs 19.0%; p<0.0001), a reduction in time from ED attendance to cardiology transfer (9.3 hours vs 5.7 hours; p<0.0001) and a reduction in time to angiography (62.5 hours vs 26.6 hours; p<0.0001). Length of stay was reduced for cardiology patients (4.7 days vs 2.4 days, p<0.001) and mean length of stay for all patients attending ED with chest pain was reduced by 8.3 hours (27.5 hours vs 19.1 hours; p<0.0001). The changes have significantly improved the management of acute chest pain within our trust and we would suggest that adoption of these changes in other trusts could significantly improve the quality of the care for these patients throughout the NHS.

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

BACKGROUND

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.

METHODS

Consecutive patients with suspected acute coronary syndrome (n=48 282) were enrolled in a multicenter trial across 10 hospitals in Scotland. In a prespecified secondary and observational analysis, we compared the performance of the limit of detection (<2 ng/L) and an optimized risk stratification threshold (<5 ng/L) using the Abbott high-sensitivity troponin I assay. Patients with myocardial injury at presentation, with ≤2 hours of symptoms or with ST-segment elevation myocardial infarction were excluded. The negative predictive value was determined in all patients and in subgroups for a primary outcome of myocardial infarction or cardiac death within 30 days. The secondary outcome was myocardial infarction or cardiac death at 12 months, with risk modeled using logistic regression adjusted for age and sex.

RESULTS

In total, 32 837 consecutive patients (61±17 years, 47% female) were included, of whom 23 260 (71%) and 12,716 (39%) had hs-cTnl concentrations of <5 ng/L and <2 ng/L at presentation. The negative predictive value for the primary outcome was 99.8% (95% CI, 99.7%-99.8%) and 99.9% (95% CI, 99.8%-99.9%) in those with hs-cTnl concentrations of <5 ng/L and <2 ng/L, respectively. At both thresholds, the negative predictive value was consistent in men and women and across all age groups, although the proportion of patients identified as low risk fell with increasing age. Compared with patients with hs-cTnl concentrations of ≥5 ng/L but <99th centile, the risk of myocardial infarction or cardiac death at 12 months was 77% lower in those <5 ng/L (5.3% vs 0.7%; adjusted odds ratio, 0.23 [95% CI, 0.19-0.28]) and 80% lower in those <2 ng/L (5.3% vs 0.3%; adjusted odds ratio, 0.20 [95% CI, 0.14-0.29]).

CONCLUSIONS

Use of risk stratification thresholds for hs-cTnl identify patients with suspected acute coronary syndrome and at least 2 hours of symptoms as low risk at presentation irrespective of age and sex.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT01852123.

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.

Efficacy of High-Sensitivity Troponin T in Identifying Very-Low-Risk Patients With Possible Acute Coronary Syndrome

Importance

Physicians need information on how to use the first available high-sensitivity troponin (hsTnT) assay in the United States to identify patients at very low risk for 30-day adverse cardiac events (ACE).

Objective

To determine whether a negative hsTnT assay at 0 and 3 hours following emergency department presentation could identify patients at less than 1% risk of a 30-day ACE.

Design, Setting, and Participants

A prospective, observational study at 15 emergency departments in the United States between 2011 and 2015 that included individuals 21 years and older, presenting to the emergency department with suspected acute coronary syndrome. Of 1690 eligible individuals, 15 (no cardiac troponin T measurement) and 320 (missing a 0-hour or 3-hour sample) were excluded from the analyses.

Exposures

Serial hsTnT measurements (fifth-generation Roche Elecsys hsTnT assay).

Main Outcomes and Measures

Serial blood samples from each patient were collected after emergency department presentation (once identified as a potential patient with acute coronary syndrome) and 3 hours, 6 to 9 hours, and 12 to 24 hours later. Adverse cardiac events were defined as myocardial infarction, urgent revascularization, or death. The upper reference level for the hsTnT assay, defined as the 99th percentile, was established as 19 ng/L in a separate healthy US cohort. Patients were considered ruled out for acute myocardial infarction if their hsTnT level at 0 hours and 3 hours was less than the upper reference level. Gold standard diagnoses were determined by a clinical end point committee. Evaluation of assay clinical performance for acute myocardial infarction rule-out was prespecified; the hypothesis regarding 30-day ACE was formulated after data collection.

Results

In 1301 healthy volunteers (50.4% women; median age, 48 years), the upper reference level was 19 ng/L. In 1600 patients with suspected acute coronary syndrome (48.4% women; median age, 55 years), a single hsTnTlevel less than 6 ng/L at baseline had a negative predictive value for AMI of 99.4%. In 974 patients (77.1%) with both 0-hour and 3-hour hsTnT levels of 19 ng/L or less, the negative predictive value for 30-day ACE was 99.3% (95% CI, 99.1-99.6). Using sex-specific cutpoints, C statistics for women (0.952) and men (0.962) were similar for acute myocardial infarction.

Conclusions and Relevance

A single hsTnT level less than 6 ng/L was associated with a markedly decreased risk of AMI, while serial levels at 19 ng/L or less identified patients at less than 1% risk of 30-day ACE.

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.

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.

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.

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.

One-Hour High Sensitivity Troponin Testing: A Safe and Effective Triage Tool for the Emergency Department

The latest European Society of Cardiology guideline on the management of acute coronary syndromes without persistent ST-elevation stipulates several acceptable pathways through which patients presenting with chest pain can be assessed for unstable coronary disease. This article reviews the data behind the "rule-in and rule-out algorithm," which can exclude acute myocardial infarction within 1 hour of presentation through the use of fifth generation high-sensitivity troponin assays.

Predictive value of global and territorial longitudinal strain imaging in detecting significant coronary artery disease in patients with myocardial infarction without persistent ST-segment elevation

INTRODUCTION

Two-dimensional (2D) speckle-tracking echocardiographic (STE) imaging is frequently performed in the assessment of cardiovascular diseases. We aim to investigate the role of the global and territorial longitudinal strain (GLS and TLS) values assessed via 2D STE imaging to detect significant coronary artery disease (CAD) in non-ST-segment elevation myocardial infarction (NSTEMI) patients without wall-motion abnormalities.

METHODS

This study enrolled 150 patients with the diagnosis of NSTEMI. Patients who had typical chest pain with unstable angina characteristics within the last 24 hours were 18-80 years of age and had a typical rise and/or fall of cardiac biomarkers were included. Myocardial functions were assessed via myocardial deformation analyses of 2D STE images.

RESULTS

The mean age of the CAD group was 52.91 ± 9.11, vs 50.31 ± 8.32 in the control group. In the CAD group, 56 patients were male (65%), whereas 21 were male (60%) in control group. GLS and TLS assessments demonstrated a statistically significant difference between CAD and control groups, with GLS values of -16.27 ± 1.91 and -18.74 ± 1.93 (P < 0.001), TLS-LAD values of -15.67 ± 1.83 and -18.54 ± 1.97 (P < 0.001), TLS-RCA values of -17.04 ± 1.81 and -19.20 ± 1.86 (P < 0.001), and TLS-Cx values of -17.40 ± 2.08 and -18.34 ± 2.18 (P = 0.028), respectively. Correlation analyses revealed that as high-sensitivity troponin (hsTnT) values increased, GLS decreased significantly, and further, an increase in severity of CAD resulted in decreased TLS-LAD, -CX and -RCA (TLS-LAD: P < 0.001, r = -0.743; TLS-CX: P < 0.001, r = -0.449; TLS-RCA: P < 0.001, r = -0.737). Multivariate analyses indicated that GLS and GRACE ACS risk scores are independent predictors of CAD in patients with NSTEMI (GLS: OR = 0.514, P < 0.001; GRACE score: OR = 0.938, P = 0.007).

CONCLUSIONS

Global longitudinal strain (GLS) assessed with 2D STE is a promising, easy to perform and quick imaging method to predict CAD in patients with NSTEMI.

Oral Chaperone Therapy Migalastat for Treating Fabry Disease: Enzymatic Response and Serum Biomarker Changes After 1 Year

Long‐term effects of migalastat therapy in clinical practice are currently unknown. We evaluated migalastat efficacy and biomarker changes in a prospective, single‐center study on 14 patients with Fabry disease (55 ± 14 years; 11 men). After 1 year of open‐label migalastat therapy, patients showed significant changes in alpha‐galactosidase‐A activity (0.06–0.2 nmol/minute/mg protein; P = 0.001), left ventricular myocardial mass index (137–130 g/m²; P = 0.037), and serum creatinine (0.94–1.0 mg/dL; P = 0.021), accounting for deterioration in estimated glomerular filtration rate (87–78 mL/minute/1.73 m²; P = 0.012). The enzymatic increase correlated with myocardial mass reduction (r = −0.546; P = 0.044) but not with renal function (r = −0.086; P = 0.770). Plasma globotriaosylsphingosine was reduced in therapy‐naive patients (10.9–6.0 ng/mL; P = 0.021) and stable (9.6–12.1 ng/mL; P = 0.607) in patients switched from prior enzyme‐replacement therapy. These first real‐world data show that migalastat substantially increases alpha‐galactosidase‐A activity, stabilizes related serum biomarkers, and improves cardiac integrity in male and female patients with amenable Fabry disease mutations.

Optimising antiplatelet utilisation in the acute care setting: a novel threshold for medical intervention in suspected acute coronary syndromes

OBJECTIVES

To construct a model to optimise and personalise recommendations for antiplatelet prescription for patients with suspected acute coronary syndrome (ACS). Acknowledging that emergency physicians work with diagnostic uncertainty, we sought to identify the point at which the probability of ACS is sufficiently high that the benefits of antiplatelet treatment outweigh the risks. Second, we evaluated the projected clinical impact of this approach by using a clinical prediction model (Troponin-only Manchester Acute Coronary Syndromes (T-MACS)) to calculate the probability of ACS.

METHODS

We conducted three systematic reviews, quantifying the effects of ticagrelor, clopidogrel or aspirin-alone treatment strategies for ACS (November 2017). We extracted data for (a) clinical outcomes and (b) weighted patient preferences (utilities) for each outcome. We then constructed utilitarian models, simulating the probability of clinical outcomes with different treatment strategies. This identified the threshold probability of ACS at which each treatment strategy became superior.We validated this approach in a prospective diagnostic study including patients with suspected ACS that was conducted at two large UK teaching hospitals (St George's Hospital London recruited October 2015 to June 2017 and Manchester Royal Infirmary: February 2015 to August 2017). We calculated the probability of ACS using T-MACS. The diagnosis of ACS was adjudicated based on serial high-sensitivity troponin testing and 30-day follow-up.

RESULTS

We constructed three models using data from six studies. Prescribing ticagrelor had greatest overall benefit when the probability of ACS exceeded 8.0%. Below that threshold, aspirin alone yielded greater benefit. The validation study included 660 patients, of which 87 (13.2%) had ACS. Prescription of combined antiplatelet strategy to patients with >8% probability of ACS had greater utility than aspirin alone.

CONCLUSION

Treatment with ticagrelor appears to yield greater net benefit for patients when the probability of ACS >8%. The clinical and cost-effectiveness of this 'precision medicine' approach warrants further study.

Comparison of fourteen rule-out strategies for acute myocardial infarction

BACKGROUND

The clinical availability of high-sensitivity cardiac troponin (hs-cTn) has enabled the development of several innovative strategies for the rapid rule-out of acute myocardial infarction (AMI). Due to the lack of direct comparisons, selection of the best strategy for clinical practice is challenging.

METHODS

In a prospective international multicenter diagnostic study enrolling 3696 patients presenting with suspected AMI to the emergency department, we compared the safety and efficacy of 14 different hs-cTn-based strategies: hs-cTn concentrations below the limit of detection (LoD), dual-marker combining hs-cTn with copeptin, ESC 0 h/1 h-algorithm, 0 h/2 h-algorithm, 2 h-ADP-algorithm, NICE-algorithm, and ESC 0 h/3 h-algorithm, each using either hs-cTnT or hs-cTnI. The final diagnosis of AMI was adjudicated by two independent cardiologists using all available clinical information including cardiac imaging and serial hs-cTn concentrations.

RESULTS

AMI was the final diagnosis in 16% of patients. Using hs-cTnT, safety quantified by the negative predictive value (NPV) and sensitivity was very high (99.8-100% and 99.5-100%) and comparable for all strategies, except the dual-marker approach (NPV 98.7%, sensitivity 96.7%). Similarly, using hs-cTnI, safety quantified by the NPV and sensitivity was very high (99.7-100% and 98.9-100%) and comparable for all strategies, except the dual-marker approach (NPV 96.9%, sensitivity 90.4%) and the NICE-algorithm (NPV 99.1%, sensitivity 94.7%). Efficacy, quantified by the percentage of patients eligible for rule-out, differed markedly, and was lowest for LoD-algorithm (15.7-26.8%).

CONCLUSION

All rapid rule-out algorithms, except the dual-marker strategy and the NICE-algorithm using hs-cTnI, favorably combine safety and efficacy, and can be considered for routine clinical practice.

CLINICAL TRIAL REGISTRATION

NCT00470587, http://clinicaltrials.gov/show/NCT00470587.

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.

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

INTRODUCTION

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

METHODS AND ANALYSIS

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

ETHICS AND DISSEMINATION

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

TRIAL REGISTRATION NUMBER

ISRCTN86184521; Pre-results.

Reliability of the CARE rule and the HEART score to rule out an acute coronary syndrome in non-traumatic chest pain patients

In patients consulting in the Emergency Department for chest pain, a HEART score ≤ 3 has been shown to rule out an acute coronary syndrome (ACS) with a low risk of major adverse cardiac event (MACE) occurrence. A negative CARE rule (≤ 1) that stands for the first four elements of the HEART score may have similar rule-out reliability without troponin assay requirement. We aim to prospectively assess the performance of the CARE rule and of the HEART score to predict MACE in a chest pain population. Prospective two-center non-interventional study. Patients admitted to the ED for non-traumatic chest pain were included, and followed-up at 6 weeks. The main study endpoint was the 6-week rate of MACE (myocardial infarction, coronary angioplasty, coronary bypass, and sudden unexplained death). 641 patients were included, of whom 9.5% presented a MACE at 6 weeks. The CARE rule was negative for 31.2% of patients, and none presented a MACE during follow-up [0, 95% confidence interval: (0.0-1.9)]. The HEART score was ≤ 3 for 63.0% of patients, and none presented a MACE during follow-up [0% (0.0-0.9)]. With an incidence below 2% in the negative group, the CARE rule seemed able to safely rule out a MACE without any biological test for one-third of patients with chest pain and the HEART score for another third with a single troponin assay.

Prognostic significance and dynamic change of plasma macrophage migration inhibitory factor in patients with acute ST-elevation myocardial infarction

Macrophage migration inhibitory factor (MIF) has been reported as an inflammatory cytokine in many inflammatory diseases, including rheumatoid arthritis and ischemic diseases. However, dynamic changes of MIF within the first 24 hours on admission and potential prognostic significance following ST-elevation myocardial infarction (STEMI) have been little known. In this study, we examined the dynamic change of MIF level and its potential diagnostic and prognostic value after the onset of STEMI. Plasma MIF levels were evaluated in symptomatic subjects who received coronary angiogram with a median 27 months follow-up for the development of major adverse cardiovascular events (MACEs).Of all 993 subjects, patients with STEMI showed a significantly higher MIF levels than in patients with non-ST elevation acute coronary syndrome, stable angina, and normal coronary artery, respectively (P < .01). Plasma MIF levels elevated as early as 12 hours post-onset of STEMI and peaked rapidly within 24 hours, and remained elevated from about day 5 till day 9 during hospitalization. In multivariate analysis, MIF was associated with a decreased risk of MACEs occurrence in STEMI patients after adjustment for traditional cardiovascular risk factors [hazard ratio 0.81, (0.72-0.90), P < .001]. The ROC curve for MACEs was 0.72 (95% CI 0.62-0.80, P < .001) and 0.85 (95% CI 0.80-0.90, P < .001) using Framingham risk factors only and combined with MIF, individually.Measurement of MIF adds potential information for the early diagnosis of acute STEMI and significantly improves risk prediction of MACEs when added to a prognostic model with traditional Framingham risk factors.

High-sensitivity troponin in the evaluation of patients with suspected acute coronary syndrome: a stepped-wedge, cluster-randomised controlled trial

BACKGROUND

High-sensitivity cardiac troponin assays permit use of lower thresholds for the diagnosis of myocardial infarction, but whether this improves clinical outcomes is unknown. We aimed to determine whether the introduction of a high-sensitivity cardiac troponin I (hs-cTnI) assay with a sex-specific 99th centile diagnostic threshold would reduce subsequent myocardial infarction or cardiovascular death in patients with suspected acute coronary syndrome.

METHODS

In this stepped-wedge, cluster-randomised controlled trial across ten secondary or tertiary care hospitals in Scotland, we evaluated the implementation of an hs-cTnI assay in consecutive patients who had been admitted to the hospitals' emergency departments with suspected acute coronary syndrome. Patients were eligible for inclusion if they presented with suspected acute coronary syndrome and had paired cardiac troponin measurements from the standard care and trial assays. During a validation phase of 6-12 months, results from the hs-cTnI assay were concealed from the attending clinician, and a contemporary cardiac troponin I (cTnI) assay was used to guide care. Hospitals were randomly allocated to early (n=5 hospitals) or late (n=5 hospitals) implementation, in which the high-sensitivity assay and sex-specific 99th centile diagnostic threshold was introduced immediately after the 6-month validation phase or was deferred for a further 6 months. Patients reclassified by the high-sensitivity assay were defined as those with an increased hs-cTnI concentration in whom cTnI concentrations were below the diagnostic threshold on the contemporary assay. The primary outcome was subsequent myocardial infarction or death from cardiovascular causes at 1 year after initial presentation. Outcomes were compared in patients reclassified by the high-sensitivity assay before and after its implementation by use of an adjusted generalised linear mixed model. This trial is registered with ClinicalTrials.gov, number NCT01852123.

FINDINGS

Between June 10, 2013, and March 3, 2016, we enrolled 48 282 consecutive patients (61 [SD 17] years, 47% women) of whom 10 360 (21%) patients had cTnI concentrations greater than those of the 99th centile of the normal range of values, who were identified by the contemporary assay or the high-sensitivity assay. The high-sensitivity assay reclassified 1771 (17%) of 10 360 patients with myocardial injury or infarction who were not identified by the contemporary assay. In those reclassified, subsequent myocardial infarction or cardiovascular death within 1 year occurred in 105 (15%) of 720 patients in the validation phase and 131 (12%) of 1051 patients in the implementation phase (adjusted odds ratio for implementation vs validation phase 1·10, 95% CI 0·75 to 1·61; p=0·620).

INTERPRETATION

Use of a high-sensitivity assay prompted reclassification of 1771 (17%) of 10 360 patients with myocardial injury or infarction, but was not associated with a lower subsequent incidence of myocardial infarction or cardiovascular death at 1 year. Our findings question whether the diagnostic threshold for myocardial infarction should be based on the 99th centile derived from a normal reference population.

FUNDING

The British Heart Foundation.

Risk stratification and role for additional diagnostic testing in patients with acute chest pain and normal high-sensitivity cardiac troponin levels

Background

Normal high sensitivity cardiac troponin (hs-cTn) assays rule out acute myocardial infarction (AMI) with great accuracy, but additional non-invasive testing is frequently ordered. This observational study evaluates whether clinical characteristics can contribute to risk stratification and could guide referral for additional testing.

Methods

918 serial patients with acute chest pain and normal hs-cTnT levels were prospectively included. Major adverse cardiac events (MACE) and non-invasive test results were assessed during one-year follow-up. Patients were classified as low and high risk based on clinical characteristics.

Results

MACE occurred in 6.1% of patients and mainly comprised revascularizations (86%). A recent abnormal stress test, suspicious history, a positive family history and higher baseline hs-cTnT levels were independent predictors of MACE with odds ratios of 16.00 (95%CI:6.25–40.96), 16.43 (6.36–42.45), 2.33 (1.22–4.42) and 1.10 (1.01–1.21), respectively. Absence of both recent abnormal stress test and suspicious history identified 86% of patients. These patients were at very low risk for MACE (0.4% in 30-days and 2.3% in one-year). Despite this, the majority (287/345 = 83%) of additional tests were performed in low risk patients, with <10% abnormal test findings. The diagnostic yield was significantly higher in the remaining higher risk patients, 40% abnormal test findings and a positive predictive value of 70% for MACE. Similar results were observed in patients without known coronary artery disease.

Conclusions

Clinical characteristics can be used to identify low risk patients with acute chest pain and normal hs-cTnT levels. Current strategies in the emergency department result in numerous additional tests, which are mostly ordered in patients at very low risk and have a low diagnostic yield.

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.

Clinical implications of high-sensitivity cardiac troponins

Cardiac troponin assays have become more sensitive over the years leading to the clinical introduction of high-sensitivity cardiac troponin assays in 2010. Their use has revolutionized the assessment of patients with chest pain in the emergency department by allowing earlier rule-in and rule-out of myocardial infarction leading to shorter stays in the emergency department and reduced admissions for chest pain. The incidence of myocardial infarction has increased slightly, and patients with myocardial infarction diagnosed with high-sensitivity cardiac troponins have been found to have a reduced risk of reinfarction, though without an impact on survival. High-sensitivity cardiac troponins are powerful predictors of long-term mortality and cardiovascular disease in the general population as well as in patients with chest pain with or without cardiovascular disease. The increase in risk for death and cardiovascular disease associated with high-sensitivity cardiac troponins is graded and starts already at detectable levels, well below the upper normal level. The aim of this review was to describe the clinical use and consequences of the introduction of high-sensitivity cardiac troponins. In addition, the importance of persistently elevated troponin levels for prognosis and what investigations may be appropriate to perform in patients with stable troponin elevations are discussed.

Prognostic implications of high-sensitivity cardiac troponin T assay in a real-world population with non-ST-elevation acute coronary syndrome

Background

High-sensitivity cardiac troponin T (hsTnT) was recently approved for clinical use by the Food and Drug Administration. The transition from contemporary to hsTnT assays requires a thorough understanding of the clinical differences between these assays.

Hypothesis

HsTnT may provide a more accurate prognostic stratification than contemporary cardiac troponin I (cTnI) in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS).

Methods

HsTnT and cTnI were measured in 644 patients with CK-MB negative NSTE-ACS who were enrolled in the prospective multicenter SPAI (Stratificazione Prognostica dell'Angina Instabile) study. Patients were stratified at the 99th percentile reference limit for each assay. The primary endpoint was cardiovascular death (CVD) or non-fatal myocardial infarction (MI); the secondary endpoint was the occurrence of unstable angina (UA). Follow-up lasted 180 days.

Results

Patients with hsTnT ≥99th percentile were at higher risk of CVD/MI (30-day: 5.9% vs 0.8%, p = 0.001; 180-day: 11.1% vs 4.7%, p = 0.004), also after adjusting for TIMI Risk Score. No significant difference in CVD/MI at 180-day was found between hsTnT-positive/cTnI-negative and hsTnT-negative/cTnI-negative patients (adjHR 1.61, 95% CI 0.74-3.49, p = 0.232). Occurrence of UA was not differently distributed between hsTnT groups dichotomized at the 99th percentile (12.4% vs 12.5% p = 0.54).

Conclusions

Our investigation on a real-world NSTE-ACS population showed good prognostic performance of hsTnT in the risk stratification of the hard endpoint, but did not demonstrate the improved prognostic ability of hsTnT over contemporary cTn. Neither troponin assay predicted the recurrence of UA, suggesting the acute rise of cardiac troponin as a marker of severity, but not the occurrence of future coronary instability.

Validation of high-sensitivity performance for a United States Food and Drug Administration cleared cardiac troponin I assay

BACKGROUND

High-Sensitivity (hs) cardiac troponin (cTn) assays are categorized by two criteria: (i) cTn values above the limit of detection (LoD) for >50% of male and female healthy cohorts of ≥300 individuals; (ii) imprecision ≤10% total %CV for sex-specific 99th-percentile clinical decision values (CDVs). No documented hs-Tn assay has yet been FDA-cleared.

METHODS

The PATHFAST cTnI-II assay's LoD was 2.3 ng/L using CLSI EP-17. The AACC Universal Sample Bank of 847 healthy men (50.6%) and women (49.4%) was used to determine 99th-percentile CDVs with Nonparametric, Harrell-Davis and Robust modeling. Health/Medication questionnaires and Amino-terminal proBNP, Hemoglobin A_1c and estimated Glomerular Filtration Rate surrogates excluded underlying health conditions.

RESULTS

The cTnI-II test's total CV was 6.1% at 29 ng/L and 7.1% at 22 ng/L; the LoD was 2.3 ng/L. Of the full 847-member healthy cohort, 113 (13.3%) were excluded by abnormal surrogate biomarkers. The final 734-member healthy population had the following (% > LoD): overall, 487 (66.3%); women, 186 (52.8%); and men, 301 (78.8%). 99th-percentile CDVs by Nonparametric modeling were: 28 ng/L (90% CI: 20-30), overall final 732-member healthy population; 20 ng/L (90% CI: 13-30), 352 women; and 30 ng/L (90% CI: 21-37), 382 men. Differences between sex-specific CDVs were not significantly different (p > .05) with Nonparametric or Harrell-Davis modeling; however, Robust Modeling did show significance (<0.05), with lower CDVs at 11 ng/L (90% CI: 9-12) and 16 ng/L (90% CI: 15-18) for the female and male cohorts, respectively.

CONCLUSIONS

cTnI-II is the only FDA-cleared assay that has demonstrated high-sensitivity cTn assay. Use of recommended modeling in >300 healthy subjects for determining sex-specific 99th-percentile CDVs did not show statistically significant differences except with the Robust modeling.

Sensitive Troponin I and Stress Testing in the Emergency Department for the Early Management of Chest Pain Using 2-Hour Protocol

BACKGROUND

Despite improvements in identifying high-risk patients with non-ST segment ACS (acute coronary syndrome), low risk patients presenting with atypical chest pain and non-diagnostic Electrocardiogram (ECG) continued to undergo unnecessary admissions and testing. Since 1992, our chest pain protocol included using 4-hour serial biomarkers from ED admission in combination with stress testing to evaluate these patients. Our study aimed at determining whether a new accelerated diagnostic protocol using sensitive cardiac troponin I (cTnI) 2 hours after admission to the ED followed by stress testing is safe and effective in emergency settings, allowing for appropriate triage, earlier discharge and reducing costs.

METHODS

We conducted a single center randomized trial at Presence St. Francis Hospital Chest pain center in Evanston, Illinois enrolling sixty-four consecutive patients with atypical chest pain and non-diagnostic ECG, participants were randomized to accelerated 2 hrs protocol or our pre-existing 4-hrs protocol. Sixty patients completed the protocol and were randomized to either a 2-hour (29 patients) or 4-hour protocol using both I-STAT and PATHFAST cTnI (31 Patients). Troponin I was evaluated at 0 and at 2 hours from ED presentation with and additional draw for patients in the 4-hour rule out-group. Patients with normal serial biomarkers were then evaluated with stress testing and qualified for earlier discharge if the stress test was negative, while those with a positive biomarker at any time were admitted. Thirty-six patients had exercise treadmill stress test and 24 patients had either nuclear or Echo stress test.

RESULTS

Fifty-three patients had a normal stress test and were discharged home. One patient in the 4-hour group with normal serial troponins developed ventricular tachycardia/fibrillation during the recovery period of a regular stress test. Six patients had a positive PATHFAST cTnI and a normal I-STAT cTnI at 2-hours. Two out of these six patients evaluated by coronary angiography. One patient had severe tortuous coronaries but no significant obstructive lesion and one had a severe CAD who needed Coronary artery bypass grafting (CABG). Three of the six patients had a normal stress test and one patient decided to leave without further testing. None of the patients with a normal stress test had a major cardiac event or adverse cardiac outcome at six-month follow up.

CONCLUSION

This study demonstrates that the 2 hours accelerated protocol using high sensitivity Troponin assay at 0 and 2 hours with comprehensive clinical evaluation and ECG followed by stress testing might be successful in identifying low-risk patient population who may benefit from early discharge from ED reducing associated costs and length of stay.

The (Dis) Utility of a Change in Troponin I for Diagnosis of Non-ST-Segment Elevation Myocardial Infarction in an Observation Unit

BACKGROUND

Observation units (OUs) may be an efficient and effective setting to diagnose and risk stratify patients with coronary ischemia and myocardial infarction (MI). Given improved cardiac troponin I (cTnI) assays and expanded utilization of OUs, it is not uncommon for patients with mildly elevated cTnI to be evaluated in OUs. We investigated the serial cTnI results in OU patients to determine whether absolute or relative cTnI changes were useful for the diagnosis of MI.

METHODS

This was a retrospective study of 260 patients placed in the OU from a single center in 2007, with an initial cTnI in the indeterminate range of 0.04-0.2 ng/ml (Siemens ultrasensitive), and a second cTnI was drawn at 6 hours. The diagnosis of MI was determined based on the third universal definition of MI by consensus review of 2 cardiologists, with adjudication by a third cardiologist in case of disagreement.

RESULTS

Of the 260 patients, 25 (9.6%) were determined to have MI at OU presentation. The optimal absolute and relative change in cTnI for MI diagnosis by receiver operating characteristic curve analysis were 0.02 ng/ml and 40%, respectively. There was initial cardiologist disagreement in 60% (15/25) of MI cases despite full review of serial cTnI and cardiac testing results. At 30 days, there were 3 adverse events: 2 deaths and 1 MI.

CONCLUSIONS

The diagnosis of MI in OU with low-level cTnI elevation is problematic. Furthermore, there is only marginal diagnostic utility of serial changes in cTnI in this patient population.

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.

Clinical Significance of Elevated High-sensitivity Troponin T in Low Likelihood Acute Coronary Syndrome Patients

High-sensitivity cardiac troponin T (hs-cTnT) is widely used in Oman and other Gulf countries. The availability of newer generation hs-cTnT has increased the sensitivity of diagnosing non-ST-elevation acute coronary syndrome (ACS). They utilize same antibodies as fourth-generation assay but can measure 10-fold lower levels of cTnT. Any detectable level above the 99^th percentile of population suggests myocardial damage. However, the cause could be non-ACS. Therefore, the increase in sensitivity of hs-cTnT assays for ACS comes at the cost of a reduced ACS specificity because more patients with other causes of myocardial injury are detected than with previous cTnT assays. Hence, there is large confusion among emergency physicians regarding optimal cutoff values to definitely confirm non-ST-elevation ACS, especially in patients with low likelihood of ACS. This review summarizes the available clinical and biochemical data to make recommendations about hs-cTnT cutoff values which will guide physicians to take decision in patients presenting with low likelihood ACS.

A Risk Assessment Score and Initial High-sensitivity Troponin Combine to Identify Low Risk of Acute Myocardial Infarction in the Emergency Department

OBJECTIVES

Early discharge of patients with presentations triggering assessment for possible acute coronary syndrome (ACS) is safe when clinical assessment indicates low risk, biomarkers are negative, and electrocardiograms (ECGs) are nonischemic. We hypothesized that the Emergency Department Assessment of Chest Pain Score (EDACS) combined with a single measurement of high-sensitivity cardiac troponin (hs-cTn) could allow early discharge of a clinically meaningful proportion of patients.

METHODS

We pooled data from four patient cohorts from New Zealand and Australia presenting to an emergency department with symptoms suggestive of ACS. The primary outcome was major adverse cardiac events (MACE) within 30 days of presentation. In patients with a nonischemic ECG we evaluated the sensitivity for MACE and percentage low risk of every combination of high-sensitivity cardiac troponin T (hs-cTnT) concentration and high-sensitivity cardiac troponin I (hs-cTnI) concentration with EDACS. We used a standard smoothing technique on the probability density function for hs-cTn and EDACS and applied bootstrapping to determine the optimal threshold combinations, namely, the combination that maximized the percentage low risk with ≥98.5% sensitivity for MACE.

RESULTS

From 2,536 patients, 2,258 presented without an ischemic ECG of whom 272 (12.1%) had a MACE within 30 days. The optimal threshold for hs-cTnI was 7 ng/L combined with an EDACS threshold of 16 (36.8% patients low risk). The optimal thresholds for hs-cTnT were 8 ng/L combined with an EDACS threshold of 15 (30.2% patients low risk).

CONCLUSION

Single measurements of both hs-cTnI and hs-cTnT at presentation combined with EDACS to identify over 30% of patients as low risk and therefore eligible for safe early discharge after only one blood draw.

Unstable angina in the era of high-sensitivity troponin testing: a genuine entity and a cautionary tale

High-sensitivity cardiac troponin assays have emerged as a powerful tool in the management of patients presenting acutely to hospital with suspected cardiac chest pain. Recent guidelines emphasize the reassurance offered by low troponin concentrations early after admission. We describe a patient with known coronary artery disease, who presented with a classical history of recurrent myocardial ischaemia. High-sensitivity cardiac Troponin-I concentrations remained in the low-normal sex-specific reference range, despite serial testing on the day of admission, and despite recurrent pain with dynamic ECG changes. Urgent coronary angiography confirmed severe multi-vessel disease. He required an intra-aortic balloon pump within 24 h due to clinical instability, and had urgent coronary artery bypass surgery a few days later. This case confirms that "unstable angina" remains a genuine entity. It highlights the hazards of over-reliance on any single test and serves as a reminder of the importance of integrating tests with clinical assessment.