Multicenter Evaluation of a 0-Hour/1-Hour Algorithm in the Diagnosis of Myocardial Infarction With High-Sensitivity Cardiac Troponin T

Implementing the European Society of Cardiology 0-h/1-h algorithm in patients presenting very early after chest pain

BACKGROUND

The European Society of Cardiology (ESC) recommends a 0-h/1-h (0/1-h) algorithm to classify patients with suspected non-ST-segment elevation myocardial infarction (NSTEMI). However, reliable evidence about patients who present early after the onset of symptoms is limited, likely because high-sensitivity cardiac troponin (hs-cTn) values cannot increase sufficiently within that time. This study aimed to evaluate the outcomes in real-world situations that utilized the 0/1-h algorithm.

METHODS

In a prospective, international, multicenter cohort study that enrolled 1638 patients presenting with acute chest pain to the emergency department, we assessed the performance of the 0/1-h algorithm using hs-cTnT and the associated 30-day rates of major adverse cardiac events: death and acute myocardial infarction (AMI).

RESULTS

Among 1074 patients, the prevalence of AMI was 16.0%. An approximately 60.1% (n = 645) of patients visited the hospital within 3 h after onset of chest pain (less than 1 h; 18.2% [n = 196], less than 2 h; 27.5% [n = 295], and less than 3 h; 14.3% [n = 154]). Moreover, the prevalence rates of AMI were similar at all times (1 h, 16.8%; 1-2 h, 20.7%; 2-3 h, 18.2%; p = .5). According to the ESC 0/1-h algorithm, the distribution patterns of rule-out, observe, and rule-in groups were similar; however, none of the patients was diagnosed with AMI or cardiac death in the rule-out group.

CONCLUSION

This study revealed the applicability of the 0/1-h algorithm for the management of early presenters.

Performance of the European Society of Cardiology 0/1-hour algorithm in the diagnosis of myocardial infarction with high-sensitivity cardiac troponin: Systematic review and meta-analysis

INTRODUCTION

A rapid rule-out or rule-in protocol based on the 0-hour/1-hour algorithm using high-sensitivity cardiac troponin (hs-cTn) is recommended by the European Society of Cardiology (ESC); recently multiple studies have validated it in their settings. We aimed to assess the diagnostic accuracy of the 2015 ESC guidelines for management of acute coronary syndrome in patients without ST-segment elevation 0-hour/1-hour algorithm using hs-cTn for the early rule-out and rule-in of acute myocardial infarction (AMI) on presentation.

METHODS

Systematic searches were conducted using PubMed, the Cochrane Library and the International Clinical Trials Registry Platform to identify prospective studies from 2015 to October 2019 involving adults presenting to the emergency department with possible acute coronary syndrome in which hs-cTn measurements were obtained according to the ESC algorithm and AMI outcomes were adjudicated during the initial hospitalization.

RESULTS

Eleven studies, involving 19,213 patients, were identified. Pooled prevalence of AMI during the index hospitalization was 11.3% (95% confidence interval (CI) 3.9-18.8%). Summary sensitivity and specificity in diagnosing AMI were 99% (95% CI 98-99%; I2 63%) and 91% (95% CI 91-92%; I2 96%) respectively. The summary positive likelihood ratio was 11.6 (95% CI 8.5-15.8; I2 97%) and the pooled likelihood ratio negative 0.02 (0.01-0.03; I2 52%). Cumulative all-cause mortality at 30 days in the rule-out group was 0.11%, and 2.8% in the rule-in group, and 30 days AMI in the rule-out group was 0.08%.

CONCLUSION

The ESC 0-hour/1-hour algorithm using high-sensitivity cardiac troponin has high diagnostic accuracy; it allows safe rule-out as well as accurate rule-in of AMI, with low cumulative 30-day mortality and AMI in patients assigned the rule-out zone.

Fifth generation troponin T assay is subject to antibody interference

BACKGROUND

The fifth generation (high-sensitivity) troponin T assay offers increased precision and analytical sensitivity to the predecessor method. The assay has proven utility in risk stratification and patient management. Upon clinical suspicion and discordant 4th generation troponin T and troponin I results, we investigated a sample for suspected interfering substances to the 5th generation troponin T assay.

METHODS

The analysis included a serial dilution, treatment with polyethylene glycol, commercial antibody blocking reagents, and size exclusion chromatography.

RESULTS

The sample diluted linearly (R² = 0.9957); however, experienced a dramatic reduction in concentration after both the polyethylene glycol and blocking agent treatment. Finally, size exclusion chromatography demonstrated assay reactivity around 970 kDa range.

CONCLUSIONS

These experiments elucidate a heterophilic antibody interference to the assay, and demonstrate potential measures to discern the interference.

Chest Pain Evaluation in the Emergency Department: Risk Scores and High-Sensitivity Cardiac Troponin

PURPOSE OF REVIEW

As many as 10 million patients present annually to the emergency department in the USA with symptoms concerning for acute myocardial infarction. The use of risk scores for patients with chest pain or equivalent without ST-segment elevation on the electrocardiogram. The adaptation in the USA of high sensitivity troponin assays requires rethinking of how to best optimize troponin testing within a risk score.

RECENT FINDINGS

Patients are risk stratified using a combination of validated risk scores, biomarkers, and both noninvasive and invasive testing. The advent of high-sensitivity troponins has served to augment existing risk scores in the identification of low-risk patients for early discharge, as well as led to the introduction of new rapid rule-out protocols by which acute myocardial infarction can be excluded by biomarker evaluation more quickly. The emergence of machine learning algorithms may further enhance provider's ability to quickly diagnose or exclude myocardial infarction in the emergency department. The addition of high sensitive troponin assays to established emergency department risk scores is providing new opportunities to improve the timeliness and accuracy of the evaluation of patients presenting with a possible myocardial infarction. Utilizing the time between troponin measures as a variable combined with clinical risk factors with new algorithms may further serve to improve diagnostic accuracy.

Early kinetics of cardiac troponin in suspected acute myocardial infarction

INTRODUCTION AND OBJECTIVES

Release kinetics of high-sensitivity cardiac troponin (hs-cTn) T and I in patients with acute myocardial infarction (AMI) are incompletely understood. We aimed to assess whether hs-cTnT/I release in early AMI is near linear.

METHODS

In a prospective diagnostic multicenter study the acute release of hs-cTnT and hs-cTnI within 1 and 2hours from presentation to the emergency department was quantified using 3 hs-cTnT/I assays in patients with suspected AMI. The primary endpoint was correlation between hs-cTn changes from presentation to 1 hour vs changes from presentation to 2hours, among all AMI patients and different prespecified subgroups. The final diagnosis was adjudicated by 2 independent cardiologists, based on serial hs-cTnT from the serial study blood samples and additional locally measured hs-cTn values.

RESULTS

Among 2437 patients with complete hs-cTnT data, AMI was the adjudicated diagnosis in 376 patients (15%). For hs-cTnT, the correlation coefficient between 0- to 1-hour change and 0- to 2 hour change was 0.931 (95%CI, 0.916-0.944), P <.001. Similar findings were obtained with hs-cTnI (Architect) with correlation coefficients between 0- to 1-hour change and 0- to 2 hour change of 0.969 and hs-cTnI (Centaur) of 0.934 (P <.001 for both). Findings were consistent among type 1 and type 2 AMI and in the subgroup of patients presenting very early after chest pain onset.

CONCLUSIONS

Patients presenting with early AMI showed a near linear release of hs-cTnT and hs-cTnI. This near linearity provides the pathophysiological basis for rapid diagnostic algorithms using 0- to 1-hour changes as surrogates for 0- to 2 hour or 0- to 3 hour changes. Registered at ClinicalTrials.gov (Identifier: NCT00470587).

Wahab MB, Zakaria MIB. A study on modified accelerated diagnostic protocol to safely discharge low-risk chest pain patients in emergency department

Background:

Evaluation of chest pain patients in emergency departments to distinguish between high-risk patients who require admission and low-risk patients who can be managed as outpatients is a challenging task.

Objective:

The aim of this study was to evaluate the efficacy of Observation Ward Short Stay Evaluation Service for Chest Pain Protocol to identify and safely discharge low-risk patients with low incidence of major adverse cardiac events within 30 days.

Methods:

This was a single center prospective observational study, conducted from 1 March 2016 to 31 August 2016 at the Emergency and Trauma Department, Hospital Kuala Lumpur, Kuala Lumpur. Observation Ward Short Stay Evaluation Service for Chest Pain Protocol was used to evaluate patients presented with chest pain or angina equivalents. The components involved Thrombolysis in Myocardial Infarction (TIMI) score, serial electrocardiograms, high-sensitivity cardiac troponin T, and exercise treadmill test. Low-risk patients were patients with TIMI < 2, normal serial electrocardiogram, high-sensitivity cardiac troponin T ≤ 14 ng/L, and negative exercise treadmill test. If anyone of the components was not fulfilled patients were considered as high risk, and they were either admitted or referred to clinic for further intervention. Low-risk patients were allowed for discharged. All patients were followed-up in 30 days for any incidence of major adverse cardiac events.

Results:

Totally, 174 patients were studied. Observation Ward Short Stay Evaluation Service for Chest Pain Protocol managed to discharge 102 (58.6%) patients, and 84 (82.4%) of them underwent exercise treadmill test. About 46 (54.8%) patients had negative exercise treadmill test, whereas 38 (45.2%) patients had either positive or inconclusive exercise treadmill test, and they were referred to physician clinic for further cardiac assessment. None of the patients with negative exercise treadmill test developed major adverse cardiac events in 30 days. The sensitivity and the negative predictive value (NPV) of Observation Ward Short Stay Evaluation Service for Chest Pain Protocol were both 100%.

Conclusion:

Observation Ward Short Stay Evaluation Service for Chest Pain Protocol can be applied in emergency departments to identify and safely discharge patients with low risk of major adverse cardiac events in 30 days.

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.

Is Duration of Symptoms Predictive of Acute Myocardial Infarction?

Patient interviews regarding the duration of symptoms are commonly conducted when evaluating a patient with possible acute myocardial infarction (AMI) and are believed to distinguish between AMI and non-AMI symptoms. In a single center, 569 patients evaluated in the emergency department (ED) for possible AMI from May 2013 to April 2015 were prospectively studied. Patients in the ED were asked by trained research personnel about the duration of their predominant symptom. The final diagnosis of AMI was determined by an independent cardiologist and emergency medicine physician in accordance with the third universal definition of AMI. Disagreements were settled by a third physician (cardiologist) who reviewed the case. There were 44 (8%) AMIs and 484 (85%) patients had chest pain as their predominant symptom. In the 26 type 1 AMIs, the median symptom duration was 3.3 hours, while in the 18 type 2 AMIs it was 1.3 hours. AMI was not present if symptom duration was under 20 minutes and was more likely during the 20-59 minute period. In conclusion, clinical symptoms still play a prominent role in the evaluation of a patient with possible AMI in the ED. Duration of symptoms was not very helpful in distinguishing between patients with AMI and those with non-AMI, except in the time interval of 20-59 minutes.

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.

Clinical outcomes for chest pain patients discharged home from emergency departments using high-sensitivity versus conventional cardiac troponin assays

BACKGROUND

High-sensitivity cardiac troponin (hs-cTn) assays enhance detection of lower circulating troponin concentrations, but the impact on outcomes in clinical practice is unclear. Our objective was to compare outcomes of chest pain patients discharged from emergency departments (EDs) using hs-cTn and conventional troponin (cTn) assays.

METHODS

We conducted an observational study of chest pain patients aged 40-105 years who presented to an ED from April 1, 2013, to March 31, 2017, and were discharged home. We compared 30-day and 1-year outcomes of EDs that used hs-cTn versus cTn assays. The primary outcome was a composite of all-cause death, myocardial infarction or unstable angina. Comparisons were conducted with (1) no adjustment; (2) adjustment for demographic, socioeconomic, and hospital characteristics; and (3) full clinical adjustment.

RESULTS

Among the 394,910 patients, 62,138 (15.7%) were evaluated at hs-cTn EDs and 332,772 (84.3%) were evaluated at cTn EDs. Patients discharged from hs-cTn EDs were less likely to have diabetes, hypertension, or prior heart disease. At 30 days, the unadjusted primary outcome rate was lower in hs-cTn EDs (0.9% vs 1.0%, P < .001). The 30-day hazard ratios for the primary outcome were 0.84 (95% CI 0.77-0.92) for no adjustment and 0.98 (95% CI 0.88-1.08) for full adjustment. Over 1 year, patients discharged from hs-cTn EDs had significantly fewer primary outcomes (3.7% vs 4.1%, P < .001) and lower hazard ratio (0.93; 95% CI 0.89-0.98) even after full adjustment.

CONCLUSIONS

Hs-cTn testing was associated with a significantly lower adjusted hazard of myocardial infarction, angina, and all-cause hospitalization at 1 year but not 30 days.

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.

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.

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 association of chest pain duration and other historical features with major adverse cardiac events

OBJECTIVE

We sought to determine if the duration of pain or other features of the history predict major adverse cardiac events (MACE) in patients with chest pain in the emergency department (ED).

METHODS

This was a prospective cohort study of patients presenting to a single ED with chest pain. Consenting patients filled out a survey about their symptoms. After 6 weeks, we assessed patients for MACE via chart review and direct contact. We used this data to calculate the likelihood ratios (LRs) of a number of historical features for acute myocardial infarction (MI) (primary endpoint) and MACE within 6 weeks (secondary endpoint). We planned a priori to analyze patients who reported chest pain for ≤1 min or continuously for ≥24 h.

RESULTS

We enrolled 1002 patients, and 83.6% had successful 6-week follow up. Regarding chest pain lasting for ≤1 min, the positive LR was 0.95 (95% CI 0.24 to 3.80) for acute MI and 0.67 (95% CI 0.17 to 2.72) for MACE within 6 weeks. The positive LRs of continuous pain lasting ≥24 h for acute MI and MACE within 6 weeks were 0.15 (95% CI 0.04 to 0.58) and 0.36 (95% CI 0.18 to 0.74), respectively. Amongst other historical features assessed, radiation to the right arm was the strongest positive predictor of acute MI.

CONCLUSION

Patients with continuous chest pain for ≥24 h are unlikely to have an acute MI. Chest pain lasting ≤1 min does not exclude acute MI.

MicroRNAs as Prognostic Markers in Acute Coronary Syndrome Patients-A Systematic Review

Background: The potential utility of microRNAs (miRNAs) in the diagnosis, prognosis, and treatment of multiple disease states has been an area of great interest since their discovery. In patients with cardiovascular disease, there is a large pool of literature amassed from the last decade assessing their diagnostic and prognostic potential. This systematic review sought to determine whether existing literature supports the use of miRNAs as prognostic markers after an Acute Coronary Syndrome (ACS) presentation. Methods: A systematic review of published articles from 2005–2019 using MEDLINE and EMBASE databases was undertaken independently by two reviewers. Studies addressing prognosis in an ACS population yielded 32 studies and 2 systematic reviews. Results/conclusion: 23 prospective studies reported significant differences in miRNA levels and 16 compared the predictive power of miRNAs. The most common miRNAs assessed included miR-133a, -208b, -21, -1, -34a, -150, and -423, shown to be involved in cell differentiation, apoptosis, and angiogenesis. Barriers to the use of miRNAs as prognostic markers include bias in miRNA selection, small sample size, variable normalization of data, and adjustment for confounders. Therefore, findings from this systematic review do not support the use of miRNAs for prognostication post-ACS beyond traditional cardiovascular risk factors, existing risk scores, and stratifications tools.

Comparison of four decision aids for the early diagnosis of acute coronary syndromes in the emergency department

Objectives

To directly compare the diagnostic accuracy of four decision aids (Troponin-only Manchester Acute Coronary Syndromes (T-MACS), History, ECG, Age, Risk factors and Troponin (HEART), Thrombolysis in Myocardial Infarction (TIMI) and Emergency Department Assessment of Chest Pain (EDACS)) used to expedite the early diagnosis of acute coronary syndromes (ACS) in the ED.

Methods

We prospectively included patients who presented to 14 EDs in England (February 2015 to June 2017) with suspected ACS within 12 hours of symptom onset. Data to enable evaluation of the T-MACS, HEART, TIMI and EDACS decision aids (without recalibration) were prospectively collected, blinded to patient outcome. We tested admission blood samples for high-sensitivity cardiac troponin I (hs-cTnI; Siemens ADVIA Centaur). Patients also underwent serial cardiac troponin testing over 3–12 hours. The target condition was an adjudicated diagnosis of acute myocardial infarction (AMI). We also evaluated the incidence of major adverse cardiac events (including death, AMI or coronary revascularisation) at 30 days. Diagnostic accuracy of each decision aid and hs-cTnI alone (using the limit of quantification cut-off, 3 ng/L) was evaluated by calculating sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

Results

Of 999 included patients, 132 (13.2%) had AMI. C-statistics were 0.96 for T-MACS, 0.78 for HEART and 0.69 for TIMI. The sensitivities of T-MACS, HEART, TIMI, EDACS and hs-cTnI <3 ng/L for AMI were 99.2% (95% CI 95.7% to 100.0%), 91.8% (85.0% to 96.2%), 97.5% (92.9% to 99.5%), 96.2% (92.2% to 99.4%) and 99.2% (95.9% to 100.0%), respectively. The respective strategies would have ruled out 46.5%, 34.9%, 19.4%, 48.3% and 28.8% patients. PPVs for the decision aids that identify ‘high-risk’ patients were 80.4% (T-MACS), 51.9% (TIMI) and 37.2% (HEART).

Conclusions

In this study, T-MACS could rule out AMI in 46.5% patients with 99.2% sensitivity. EDACS could rule out AMI in 48.3% patients with lower sensitivity, although the difference was not statistically significant. The HEART and TIMI scores had lower diagnostic accuracy.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

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

The HEART score in the era of the European Society of Cardiology 0/1-hour algorithm

Background:

The European Society of Cardiology’s 0/1-hour algorithm improves the early triage of patients towards “rule-out” or “rule-in” of non-ST-segment elevation myocardial infarction. The HEART score is a risk stratification tool for patients with undifferentiated chest pain. We sought to evaluate the performance of the European Society of Cardiology 0/1-hour algorithm and the HEART score to evaluate chest pain patients in the emergency department.

Methods:

In this prospective study, we applied the European Society of Cardiology 0/1-hour algorithm and the HEART score in 1355 consecutive patients who presented to the emergency department with symptoms suggestive of acute coronary syndrome without ST-segment elevation. Patients were followed for non-ST-segment elevation myocardial infarctions and major adverse cardiac events at 30 days: death, non-ST-segment elevation myocardial infarction, or unplanned coronary revascularization.

Results:

The European Society of Cardiology 0/1-hour algorithm classified 921 (68.0%) patients as “rule-out” and the HEART score classified 686 (50.6%) patients as “low-risk”. The 30-day incidence of non-ST-segment elevation myocardial infarctions was 0.32% in the European Society of Cardiology 0/1-hour algorithm “rule-out” patients versus 0.29% in the HEART score “low-risk” patients ( p=0.75). The rate of major adverse cardiac events was 7.7% in the European Society of Cardiology 0/1-hour algorithm “rule-out” patients versus 1.1% in the HEART score “low-risk” patients ( p<0.001).

Conclusion:

The European Society of Cardiology 0/1-hour algorithm identified more patients with low risk of non-ST-segment elevation myocardial infarctions at 30 days whereas for major adverse cardiac events, the HEART score had a greater capacity to detect low-risk patients.

Impact of statin use on high sensitive troponin T levels with moderate exercise

Background: High-sensitive cardiac troponin (hsTn) levels can be elevated due to non-pathological events such as strenuous exercise. However, the effect of statins on circulating hsTnT levels with moderate exercise is uncertain. Therefore, we evaluated the impact of statins on hsTnT level with moderate exercise. Methods: We enrolled a total of 56 patients: 26 statin users and 30 non-users. All patients were shown to have no coronary artery disease before participating in the study. Participants performed a fixed-protocol moderate level exercise. HsTnT levels were measured before and 4 h after the exercise. Participants were also grouped based on their hsTnT levels, as proposed in the recent European Society of Cardiology guideline (0-1 hour algorithm) for acute coronary syndromes without persistent ST-segment elevation. Results: Statin users showed a significant increase in serum hsTnT levels with moderate exercise (p = .004), whereas the control group showed a modest increase without statistical significance (p = .664). The percentage of patients whose hsTnT levels exceeded the rule-out limits for non-ST-segment myocardial infarction diagnosis (according to the 0-1 algorithm) after moderate exercise varied significantly between groups (p = .024). Conclusions: Statin therapy can cause a significant increase in hsTnT levels after moderate exercise. This increase can jeopardise the accuracy of clinical diagnoses based on the newly implemented algorithms. The awareness of these adverse effects of statins, mainly used by patients with high risk of coronary events, can prevent misdiagnosis or unnecessary hospitalisations.

A comparison of cardiac troponin T delta change methods and the importance of the clinical context in the assessment of acute coronary syndrome

Background

The management of patients presenting with symptoms suggestive of acute coronary syndrome is a significant challenge for clinicians. Guidelines for the diagnosis of acute myocardial infarction require a rise and/or fall of cardiac troponin, along with other criteria. Knowing what constitutes a significant delta change from baseline is still unclear and the literature is varied.

Methods

We compared three methods for determining cardiac troponin delta changes (relative, absolute and z-scores) for detecting acute myocardial infarction in 806 patients presenting to an emergency department with symptoms suggestive of acute coronary syndrome. Blood specimens were collected at admission and 2, 3, 4 and 6 h postadmission and tested on the Roche Elecsys high-sensitivity troponin T assay.

Results

A positive diagnosis for acute myocardial infarction was found in 39 (4.8%) patients. ROC AUC showed better performance for the absolute and z-score delta change (0.959–0.988 and 0.956–0.988, respectively) compared with relative delta change (0.921–0.960) at all time points in the diagnosis of acute myocardial infarction. Optimal timing for the second sample was at 4–6 h postadmission.

Conclusions

Although not statistically significant, the results show a trend of absolute and z-score delta change performing better than relative delta change for the diagnosis of acute myocardial infarction. The z-score approach allows for a single cut-off value across multiple high-sensitivity assays which could be useful in the clinical setting. Our study also highlighted the importance of interpreting cardiac troponin changes in the clinical context with a combination of the patient’s clinical history and electrocardiogram.

Clinical Use of a New High-Sensitivity Cardiac Troponin I Assay in Patients with Suspected Myocardial Infarction

BACKGROUND

We aimed to validate the clinical performance of the high-sensitivity cardiac troponin I [VITROS^® Immunodiagnostic Products hs Troponin I (hs-cTnI-VITROS)] assay.

METHODS

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

RESULTS

AMI was the adjudicated final diagnosis in 158 of 1231 (13%) patients. At presentation, the AUC for hs-cTnI-VITROS was 0.95 (95% CI, 0.93-0.96); for hs-cTnT-Elecsys, 0.94 (95% CI, 0.92-0.95); and for hs-cTnI-Architect, 0.92 (95% CI, 0.90-0.94). AUCs for hs-cTnI-Centaur and hs-cTnI-Access were 0.95 (95% CI, 0.94-0.97). Applying the derived hs-cTnI-VITROS-0/1-h algorithm (derivation cohort n = 519) to the validation cohort (n = 520), 53% of patients were ruled out [sensitivity, 100% (95% CI, 94.1-100)] and 14% of patients were ruled in [specificity, 95.6% (95% CI, 93.4-97.2)]. Patients ruled out by the 0/1-h algorithm had a survival rate of 99.8% at 30 days. Findings were confirmed in the secondary analyses using the adjudication including serial measurements of hs-cTnI-Architect.

CONCLUSIONS

The hs-cTnI-VITROS assay has at least comparable diagnostic accuracy with the currently best validated hs-cTnT and hs-cTnI assays.

CLINICALTRIALSGOV IDENTIFIER

NCT00470587.

Combining High-Sensitivity Cardiac Troponin I and Cardiac Troponin T in the Early Diagnosis of Acute Myocardial Infarction

BACKGROUND

Combining 2 signals of cardiomyocyte injury, cardiac troponin I (cTnI) and T (cTnT), might overcome some individual pathophysiological and analytical limitations and thereby increase diagnostic accuracy for acute myocardial infarction with a single blood draw. We aimed to evaluate the diagnostic performance of combinations of high-sensitivity (hs) cTnI and hs-cTnT for the early diagnosis of acute myocardial infarction.

METHODS

The diagnostic performance of combining hs-cTnI (Architect, Abbott) and hs-cTnT (Elecsys, Roche) concentrations (sum, product, ratio, and a combination algorithm) obtained at the time of presentation was evaluated in a large multicenter diagnostic study of patients with suspected acute myocardial infarction. The optimal rule-out and rule-in thresholds were externally validated in a second large multicenter diagnostic study. The proportion of patients eligible for early rule-out was compared with the European Society of Cardiology 0/1 and 0/3 hour algorithms.

RESULTS

Combining hs-cTnI and hs-cTnT concentrations did not consistently increase overall diagnostic accuracy as compared with the individual isoforms. However, the combination improved the proportion of patients meeting criteria for very early rule-out. With the European Society of Cardiology 2015 guideline recommended algorithms and cut-offs, the proportion meeting rule-out criteria after the baseline blood sampling was limited (6% to 24%) and assay dependent. Application of optimized cut-off values using the sum (9 ng/L) and product (18 ng²/L²) of hs-cTnI and hs-cTnT concentrations led to an increase in the proportion ruled-out after a single blood draw to 34% to 41% in the original (sum: negative predictive value [NPV] 100% [95% confidence interval (CI), 99.5% to 100%]; product: NPV 100% [95% CI, 99.5% to 100%]) and in the validation cohort (sum: NPV 99.6% [95% CI, 99.0-99.9%]; product: NPV 99.4% [95% CI, 98.8-99.8%]). The use of a combination algorithm (hs-cTnI <4 ng/L and hs-cTnT <9 ng/L) showed comparable results for rule-out (40% to 43% ruled out; NPV original cohort 99.9% [95% CI, 99.2-100%]; NPV validation cohort 99.5% [95% CI, 98.9-99.8%]) and rule-in (positive predictive value [PPV] original cohort 74.4% [95% Cl, 69.6-78.8%]; PPV validation cohort 84.0% [95% Cl, 79.7-87.6%]).

CONCLUSIONS

New strategies combining hs-cTnI and hs-cTnT concentrations may significantly increase the number of patients eligible for very early and safe rule-out, but do not seem helpful for the rule-in of acute myocardial infarction.

CLINICAL TRIAL REGISTRATION

URL (APACE): https://www.clinicaltrial.gov . Unique identifier: NCT00470587. URL (ADAPT): www.anzctr.org.au . Unique identifier: ACTRN12611001069943.

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.

A Randomized Trial of a 1-Hour Troponin T Protocol in Suspected Acute Coronary Syndromes: The Rapid Assessment of Possible Acute Coronary Syndrome in the Emergency Department With High-Sensitivity Troponin T Study (RAPID-TnT)

BACKGROUND

High-sensitivity troponin assays promise earlier discrimination of myocardial infarction. Yet, the benefits and harms of this improved discriminatory performance when incorporated within rapid testing protocols, with respect to subsequent testing and clinical events, has not been evaluated in an in-practice patient-level randomized study. This multicenter study evaluated the noninferiority of a 0/1-hour high-sensitivity cardiac troponin T (hs-cTnT) protocol in comparison with a 0/3-hour masked hs-cTnT protocol in patients with suspected acute coronary syndrome presenting to the emergency department (ED).

METHODS

Patients were randomly assigned to either a 0/1-hour hs-cTnT protocol (reported to the limit of detection [<5 ng/L]) or masked hs-cTnT reported to ≤29 ng/L evaluated at 0/3-hours (standard arm). The 30-day primary end point was all-cause death and myocardial infarction. Noninferiority was defined as an absolute margin of 0.5% determined by Poisson regression.

RESULTS

In total, 3378 participants with an emergency presentation were randomly assigned between August 2015 and April 2019. Ninety participants were deemed ineligible or withdrew consent. The remaining participants received care guided either by the 0/1-hour hs-cTnT protocol (n=1646) or the 0/3-hour standard masked hs-cTnT protocol (n=1642) and were followed for 30 days. Median age was 59 (49-70) years, and 47% were female. Participants in the 0/1-hour arm were more likely to be discharged from the ED (0/1-hour arm: 45.1% versus standard arm: 32.3%, P<0.001) and median ED length of stay was shorter (0/1-hour arm: 4.6 [interquartile range, 3.4-6.4] hours versus standard arm: 5.6 (interquartile range, 4.0-7.1) hours, P<0.001). Those randomly assigned to the 0/1-hour protocol were less likely to undergo functional cardiac testing (0/1-hour arm: 7.5% versus standard arm: 11.0%, P<0.001). The 0/1-hour hs-cTnT protocol was not inferior to standard care (0/1-hour arm: 17/1646 [1.0%] versus 16/1642 [1.0%]; incidence rate ratio, 1.06 [ 0.53-2.11], noninferiority P value=0.006, superiority P value=0.867), although an increase in myocardial injury was observed. Among patients discharged from ED, the 0/1-hour protocol had a negative predictive value of 99.6% (95% CI, 99.0-99.9%) for 30-day death or myocardial infarction.

CONCLUSIONS

This in-practice evaluation of a 0/1-hour hs-cTnT protocol embedded in ED care enabled more rapid discharge of patients with suspected acute coronary syndrome. Improving short-term outcomes among patients with newly recognized troponin T elevation will require an evolution in management strategies for these patients.

CLINICAL TRIAL REGISTRATION

URL: https://www.anzctr.org.au. Unique identifier: ACTRN12615001379505.

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.

Assessment and Treatment of Patients With Type 2 Myocardial Infarction and Acute Nonischemic Myocardial Injury

Although coronary thrombus overlying a disrupted atherosclerotic plaque has long been considered the hallmark and the primary therapeutic target for acute myocardial infarction (MI), multiple other mechanisms are now known to cause or contribute to MI. It is further recognized that an MI is just one of many types of acute myocardial injury. The Fourth Universal Definition of Myocardial Infarction provides a taxonomy for acute myocardial injury, including 5 subtypes of MI and nonischemic myocardial injury. The diagnosis of MI is reserved for patients with myocardial ischemia as the cause of myocardial injury, whether attributable to acute atherothrombosis (type 1 MI) or supply/demand mismatch without acute atherothrombosis (type 2 MI). Myocardial injury in the absence of ischemia is categorized as acute or chronic nonischemic myocardial injury. However, optimal evaluation and treatment strategies for these etiologically distinct diagnoses have yet to be defined. Herein, we review the epidemiology, risk factor associations, and diagnostic tools that may assist in differentiating between nonischemic myocardial injury, type 1 MI, and type 2 MI. We identify limitations, review new research, and propose a framework for the diagnostic and therapeutic approach for patients who have suspected MI or other causes of myocardial injury.

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-CPU: a prospective study on implementation of the ESC 0/1-hour algorithm and safety of discharge after rule-out of myocardial infarction

Background:

Although the value of fast diagnostic protocols in suspected acute coronary syndrome has been validated, there is insufficient real world evidence including patients with lower pre-test probability, atypical symptoms and confounding comorbidities. The feasibility, efficacy and safety of European Society of Cardiology (ESC) 0/1 and 0/3-hour algorithms using high-sensitivity troponin T were evaluated in a consecutive cohort with suspected acute coronary syndrome.

Methods:

During 12 months, 2525 eligible patients were enrolled. In a pre-implementation period of 6 months, the prevalence of protocols, disposition, lengths of emergency department stay and treatments were registered. Implementation of the 0/1-hour protocol was monitored for another 6 months. Primary endpoints comprised the change of diagnostic protocols and 30-day mortality after direct discharge from the emergency department.

Results:

Use of the ESC 0/1-hour algorithm increased by 270% at the cost of the standard 0/3-hour protocol. After rule-out (1588 patients), 1309 patients (76.1%) were discharged directly from the emergency department, with an all-cause mortality of 0.08% at 30 days (one death due to lung cancer). Median lengths of stay were 2.9 (1.9–3.8) and 3.2 (2.7–4.4) hours using a single high-sensitivity troponin T below the limit of detection (5 ng/L) at presentation and the ESC 0/1-hour algorithm, respectively, as compared to 5.3 (4.7–6.5) hours using the ESC 0/3-hour rule-out protocol (P<0.001). Discharge rates increased from 53.9% to 62.8% (P<0.001), without excessive use of diagnostic resources within 30 days.

Conclusion:

Implementation of the ESC 0/1-hour algorithm is feasible and safe, is associated with shorter emergency department stay than the ESC 0/3-hour protocol, and an increase in discharge rates.

Trial registration:

ClinicalTrials.gov, Unique identifier: NCT03111862.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Application of High-Sensitivity Troponin in Suspected Myocardial Infarction

BACKGROUND

Data regarding high-sensitivity troponin concentrations in patients presenting to the emergency department with symptoms suggestive of myocardial infarction may be useful in determining the probability of myocardial infarction and subsequent 30-day outcomes.

METHODS

In 15 international cohorts of patients presenting to the emergency department with symptoms suggestive of myocardial infarction, we determined the concentrations of high-sensitivity troponin I or high-sensitivity troponin T at presentation and after early or late serial sampling. The diagnostic and prognostic performance of multiple high-sensitivity troponin cutoff combinations was assessed with the use of a derivation-validation design. A risk-assessment tool that was based on these data was developed to estimate the risk of index myocardial infarction and of subsequent myocardial infarction or death at 30 days.

RESULTS

Among 22,651 patients (9604 in the derivation data set and 13,047 in the validation data set), the prevalence of myocardial infarction was 15.3%. Lower high-sensitivity troponin concentrations at presentation and smaller absolute changes during serial sampling were associated with a lower likelihood of myocardial infarction and a lower short-term risk of cardiovascular events. For example, high-sensitivity troponin I concentrations of less than 6 ng per liter and an absolute change of less than 4 ng per liter after 45 to 120 minutes (early serial sampling) resulted in a negative predictive value of 99.5% for myocardial infarction, with an associated 30-day risk of subsequent myocardial infarction or death of 0.2%; a total of 56.5% of the patients would be classified as being at low risk. These findings were confirmed in an external validation data set.

CONCLUSIONS

A risk-assessment tool, which we developed to integrate the high-sensitivity troponin I or troponin T concentration at emergency department presentation, its dynamic change during serial sampling, and the time between the obtaining of samples, was used to estimate the probability of myocardial infarction on emergency department presentation and 30-day outcomes. (Funded by the German Center for Cardiovascular Research [DZHK]; ClinicalTrials.gov numbers, NCT00470587, NCT02355457, NCT01852123, NCT01994577, and NCT03227159; and Australian New Zealand Clinical Trials Registry numbers, ACTRN12611001069943, ACTRN12610000766011, ACTRN12613000745741, and ACTRN12611000206921.).

[Troponin elevation-does every patient require coronary angiography?]

The determination of high-sensitivity troponin remains the gold standard in patients with acute chest pain and allows the early diagnosis and therapy of patients with acute myocardial infarction (AMI). Increased cardiac troponin levels are highly specific for myocardial damage. However, elevated troponin levels are not equivalent to AMI and therefore the clinical presentation and the electrocardiogram of each patient must be taken into account. Elevated troponin levels are found in numerous diseases but not every patient needs invasive coronary angiography.

Symptoms Predictive of Acute Myocardial Infarction in the Troponin Era: Analysis From the TRAPID-AMI Study

The TRAPID-AMI (High Sensitivity Cardiac Troponin T assay for rapid Rule-out of Acute Myocardial Infarction) study evaluated a rapid "rule-out" acute myocardial infarction (AMI). We evaluated what symptoms were associated with AMI as part of a substudy of TRAPID-AMI. There were 1282 patients evaluated from 12 centers in Europe, the United States of America, and Australia from 2011 to 2013. Multiple symptom variables were prospectively obtained and evaluated for association with the final diagnosis of AMI. Multivariate logistic regression analysis was done, and odds ratios (OR) were calculated. There were 213/1282 (17%) AMIs. Four independent predictors for the diagnosis of AMI were identified: radiation to right arm or shoulder [OR = 3.0; confidence interval (CI): 1.8-5.0], chest pressure (OR = 2.5; CI: 1.3-4.6), worsened by physical activity (OR = 1.7; CI: 1.2-2.5), and radiation to left arm or shoulder (OR = 1.7; CI: 1.1-2.4). In the entire group, 131 (10%) had radiation to right arm or shoulder, 897 (70%) had chest pressure, 385 (30%) worsened with physical activity, and 448 (35%) had radiation to left arm or shoulder. Duration of symptoms was not predictive of AMI. There were no symptoms predictive of non-AMI. Relationship between AMI size and symptoms was also studied. For 213 AMI patients, cardiac troponins I values were divided into 4 quartiles. Symptoms including pulling chest pain, supramammillary right location, and right arm/shoulder radiation were significantly more likely to occur in patients with larger AMIs. In a large multicenter trial, only 4 symptoms were associated with the diagnosis of AMI, and no symptoms that were associated with a non-AMI diagnosis.

Is high-sensitivity troponin, alone or in combination with copeptin, sensitive enough for ruling out NSTEMI in very early presenters at admission? A post hoc analysis performed in emergency departments

OBJECTIVES

Copeptin and high-sensitivity cardiac troponin (HS-cTn) assays improve the early detection of non-ST-segment elevation myocardial infarction (NSTEMI). Their sensitivities may, however, be reduced in very early presenters.

SETTING

We performed a post hoc analysis of three prospective studies that included patients who presented to the emergency department for chest pain onset (CPO) of less than 6 hours.

PARTICIPANTS

449 patients were included, in whom 12% had NSTEMI. CPO occurred <2 hours from ED presentation in 160, between 2 and 4 hours in 143 and >4 hours in 146 patients. The prevalence of NSTEMI was similar in all groups (9%, 13% and 12%, respectively, p=0.281).

MEASURES

Diagnostic performances of HS-cTn and copeptin at presentation were examined according to CPO. The discharge diagnosis was adjudicated by two experts, including cardiac troponin I (cTnI). HS-cTn and copeptin were blindly measured.

RESULTS

Diagnostic accuracies of cTnI, cTnI +copeptin and HS-cardiac troponin T (HS-cTnT) (but not HS-cTnT +copeptin) lower through CPO categories. For patients with CPO <2 hours, the choice of a threshold value of 14 ng/L for HS-cTnT resulted in three false negative (Sensitivity 80%(95% CI 51% to 95%); specificity 85% (95% CI 78% to 90%); 79% of correctly ruled out patients) and that of 5 ng/L in two false negative (sensitivity 87% (95% CI 59% to 98%); specificity 58% (95% CI 50% to 66%); 52% of correctly ruled out patients). The addition of copeptin to HS-cTnT induced a decrease of misclassified patients to 1 in patients with CPO <2 hours (sensitivity 93% (95% CI 66% to 100%); specificity 41% (95% CI 33% to 50%)).

CONCLUSION

A single measurement of HS-cTn, alone or in combination with copeptin at admission, seems not safe enough for ruling out NSTEMI in very early presenters (with CPO <2 hours).

TRIAL REGISTRATION NUMBER

DC-2009-1052.

Diagnosis of acute myocardial infarction in the presence of left bundle branch block

OBJECTIVE

Patients with suspected acute myocardial infarction (AMI) in the setting of left bundle branch block (LBBB) present an important diagnostic and therapeutic challenge to the clinician.

METHODS

We prospectively evaluated the incidence of AMI and diagnostic performance of specific ECG and high-sensitivity cardiac troponin (hs-cTn) criteria in patients presenting with chest discomfort to 26 emergency departments in three international, prospective, diagnostic studies. The final diagnosis of AMI was centrally adjudicated by two independent cardiologists according to the universal definition of myocardial infarction.

RESULTS

Among 8830 patients, LBBB was present in 247 (2.8%). AMI was the final diagnosis in 30% of patients with LBBB, with similar incidence in those with known LBBB versus those with presumably new LBBB (29% vs 35%, p=0.42). ECG criteria had low sensitivity (1%-12%) but high specificity (95%-100%) for AMI. The diagnostic accuracy as quantified by the receiver operating characteristics (ROC) curve of hs-cTnT and hs-cTnI concentrations at presentation (area under the ROC curve (AUC) 0.91, 95% CI 0.85 to 0.96 and AUC 0.89, 95% CI 0.83 to 0.95), as well as that of their 0/1-hour and 0/2-hour changes, was very high. A diagnostic algorithm combining ECG criteria with hs-cTnT/I concentrations and their absolute changes at 1 hour or 2 hours derived in cohort 1 (45 of 45(100%) patients with AMI correctly identified) showed high efficacy and accuracy when externally validated in cohorts 2 and 3 (28 of 29 patients, 97%).

CONCLUSION

Most patients presenting with suspected AMI and LBBB will be found to have diagnoses other than AMI. Combining ECG criteria with hs-cTnT/I testing at 0/1 hour or 0/2 hours allows early and accurate diagnosis of AMI in LBBB.

TRIAL REGISTRATION NUMBER

APACE: NCT00470587; ADAPT: ACTRN12611001069943; TRAPID-AMI: RD001107;Results.

An electrochemical troponin T aptasensor based on the use of a macroporous gold nanostructure

A specific troponin T (TnT) binding aptamer was identified and immobilized on an electrodeposited macroporous gold nanostructure using poly(ethylene glycol) 600, to fabricate a novel and ultrasensitive TnT aptasensor. The transducer surface on the gold disk electrode was characterized by field emission scanning electron microscopy, and immobilization of the aptamer was monitored by open circuit potential measurements. Binding of TnT by the aptamer was monitored by differential pulse voltammetry using ferro/ferricyanide as the redox probe. The aptamer has a high affinity and specificity, and the electrode is sensitive and selective. Best operated at a working potential of 0.23 V (vs. Ag/AgCl), the electrode can detected TnT in the 0.05 to 5.0 ng mL^-1 concentration range with a 23 pg mL^-1 detection limit. The method was applied to the determination of TnT in 99 spiked human serum samples, and the diagnostic sensitivity and specificity were 94 and 95%, respectively. Graphical abstract Schematic presentation of an electrochemical troponin T aptasensor. A macroporous gold nanostructure was electrodeposited followed by immobilization of a specific TnT aptamer. Binding of TnT by the aptamer was electrochemically monitored. MCH: mercaptohexanol; TnT: troponin T.

Clinical performance of a new point-of-care cardiac troponin I test

BACKGROUND

We evaluated the clinical performance of the Minicare cardiac troponin-I (cTnI), a new point-of-care (POC) cTnI test for the diagnosis of acute myocardial infarction (AMI) in a prospective, multicentre study (ISRCTN77371338).

METHODS

Of 474 patients (≥18 years) admitted to an emergency department (ED) or chest pain unit (CPU) with symptoms suggestive of acute coronary syndrome (ACS; ≤12 h from symptom onset), 465 were eligible. Minicare cTnI was tested immediately, 3 h and 6 h after presentation. AMI diagnoses were adjudicated independently based on current guidelines.

RESULTS

The diagnostic performance of the Minicare cTnI test at 3 h was similar for whole blood and in plasma: sensitivity 0.92 vs. 0.90; specificity 0.91 vs. 0.90; positive predictive value (PPV) 0.68 vs. 0.66; negative predictive value (NPV) 0.98 vs. 0.98; positive likelihood ratio (LR+) 10.18 vs. 9.41; negative likelihood ratio (LR-) 0.09 vs. 0.11. The optimal diagnostic performance was obtained at 3 h using cut-offs cTnI >43 ng/L plus cTnI change from admission ≥18.5 ng/L: sensitivity 0.90, specificity 0.96, PPV 0.81, NPV 0.98, and LR+ 21.54. The area under the receiver operating characteristics (ROC) curve for cTnI whole blood baseline value and absolute change after 3 h curve was 0.93.

CONCLUSIONS

These data support the clinical usefulness of Minicare cTnI within a 0 h/3 h-blood sampling protocol supported by current guidelines for the evaluation of suspected ACS.

[Biomarkers in the diagnosis of cardiovascular emergencies : Acute coronary syndrome and differential diagnoses]

In emergency situations, patients present with symptoms rather than diagnoses. Due to its high prevalence, the acute coronary syndrome (ACS) dominates acute diagnostics as a consequence of its chief complaint chest pain. The challenge for the attending physicians is that only a minor part of patients with chest pain are finally diagnosed with an acute myocardial infarction (AMI) and that other rare but dangerous differential diagnoses have to be kept in mind and-vice versa-severely ill patients with AMI may present with symptoms other than chest pain. Against this background, the initial evaluation of patients requires a process-orientated view beyond the key roles of clinical assessment and biomarkers. The use of cardiac troponin is mandatory for the diagnosis of ACS, but challenging in broader utilization due to the reduced clinical specificity. Further relevant biomarkers are copeptin in combination with cardiac troponin or natriuetic peptides, which help to diagnose relevant cardiac dysfunction in (acute) heart failure. In addition, patients who present with the symptom of a suspected cardiac syncope need the differential diagnosis of an underlying arrhythmia, which may be due to an ACS or reduced left ventricular (LV) function and other causes like pulmonary embolism or structural heart disease (e. g. aortic valve stenosis). This highlights that biomarker-based diagnostics are often crucial to decide after the initial clinical evaluation whether early imaging is needed or early discharge is possible.