External validation of a rapid algorithm using high-sensitivity troponin assay results for evaluating patients with suspected acute myocardial infarction

OBJECTIVE

We sought to validate the clinical performance of a rapid assessment pathway incorporating the Siemens Atellica IM high sensitivity cardiac troponin I (hs-cTnI) assay in patients presenting to the emergency department (ED) with suspected acute myocardial infarction (AMI).

METHODS

This was a multicentre prospective observational study of adult ED patients presenting to five Australian hospitals between November 2020 and September 2021. Participants included those with symptoms of suspected AMI (without ST-segment elevation MI on presentation ECG). The Siemen's Atellica IM hs-cTnI laboratory-based assay was used to measure troponin concentrations at admission and after 2-3 hours and cardiologists adjudicated final diagnoses. The HighSTEACS diagnostic algorithm was evaluated, incorporating hs-cTnI concentrations at presentation and absolute changes within the first 2 to 3 hours. The primary outcome was index AMI, including type 1 or 2 non-ST segment elevation MI (NSTEMI) or ST-elevation MI (STEMI) following presentation. 30-day major adverse cardiac outcomes (including AMI, urgent revascularisation or cardiac death) were also reported. The trial was registered with the Australian and New Zealand Clinical Trials Registry.

RESULTS

1994 patients were included. The average age was 56.2 years (SD=15.6), and 44.9% were women. 118 (5.9%) patients had confirmed index AMI. The 2-hour algorithm defined 61.3% of patients as low risk. Sensitivity was 99.1% (94.0%-99.9%) and negative predictive value was 99.9% (99.3%-100%). 24.4% of patients were deemed intermediate risk. When applying the parameters for high risk, 252 (14.3%) were identified, with a specificity of 91.5% (88.7%-93.6%) and a PPV of 42.0% (35.6-48.7%).

CONCLUSIONS

A 2-hour algorithm based on the HighSTEACS strategy using the Siemens Atellica IM hs-cTnI laboratory-based assay enables safe and efficient risk assessment of emergency patients with suspected AMI.

TRIAL REGISTRATION NUMBER

ACTRN12621000053820.

Attitudes towards artificial intelligence in emergency medicine

OBJECTIVE

To assess Australian and New Zealand emergency clinicians' attitudes towards the use of artificial intelligence (AI) in emergency medicine.

METHODS

We undertook a qualitative interview-based study based on grounded theory. Participants were recruited through ED internal mailing lists, the Australasian College for Emergency Medicine Bulletin, and the research teams' personal networks. Interviews were transcribed, coded and themes presented.

RESULTS

Twenty-five interviews were conducted between July 2021 and May 2022. Thematic saturation was achieved after 22 interviews. Most participants were from either Western Australia (52%) or Victoria (16%) and were consultants (96%). More participants reported feeling optimistic (10/25) than neutral (6/25), pessimistic (2/25) or mixed (7/25) towards the use of AI in the ED. A minority expressed scepticism regarding the feasibility or value of implementing AI into the ED. Multiple potential risks and ethical issues were discussed by participants including skill loss from overreliance on AI, algorithmic bias, patient privacy and concerns over liability. Participants also discussed perceived inadequacies in existing information technology systems. Participants felt that AI technologies would be used as decision support tools and not replace the roles of emergency clinicians. Participants were not concerned about the impact of AI on their job security. Most (17/25) participants thought that AI would impact emergency medicine within the next 10 years.

CONCLUSIONS

Emergency clinicians interviewed were generally optimistic about the use of AI in emergency medicine, so long as it is used as a decision support tool and they maintain the ability to override its recommendations.

Implementation of an integrated emergency department acute atrial fibrillation pathway safely reduces cardioversions and hospitalisations: A comparative pre-post study

OBJECTIVE

Atrial fibrillation/flutter (AF/AFL) accounts for high rates of ED presentations and hospital admissions. There is increasing evidence to suggest that delaying cardioversion for acute uncomplicated AF is safe, and that many patients will spontaneously revert to sinus rhythm (SR). We conducted a before-and-after evaluation of AF/AFL management after a change in ED pathway using a conservative 'rate-and-wait' approach, incorporating next working day outpatient clinic follow-up and delayed cardioversion if required.

METHODS

We performed a before-and-after retrospective cohort study examining outcomes for patients who presented to the ED in Christchurch, New Zealand, with acute uncomplicated AF/AFL in the 1-year period before and after the implementation of a new conservative management pathway.

RESULTS

A total of 360 patients were included in the study (182 'Pre-pathway' vs 178 'Post-Pathway'). Compared to the pre-pathway cohort, those managed under the new pathway had an 81.2% reduction in ED cardioversions (n = 32 vs n = 6), and 50.7% reduction in all cardioversions (n = 65 vs n = 32). There was a 31.6% reduction in admissions from ED (n = 54 vs n = 79). ED length of stay (3.9 h vs 3.8 h, net difference -0.1 h, 95% confidence interval [CI] -0.6 to 0.3), 1-year ED AF representation (32.4% vs 26.4%, net difference -6.0% [95% CI -16.0% to 3.9%]), 1-year ED ischaemic stroke presentation (2.2% in both groups) and 7-day all-cause mortality rates (hazard ratio 1.05 [95% CI 0.6 to 1.9]) were all similar.

CONCLUSIONS

Using a conservative 'rate-and-wait' strategy with early follow-up for patients presenting to ED with AF/AFL can safely reduce unnecessary cardioversions and avoidable hospitalisations.

The cost savings of the rural accelerated chest pain pathway for low-risk chest pain in rural general practice: a cost minimisation analysis

Introduction The rural accelerated chest pain pathway (RACPP) has been shown to safely reduce the number of transfers to hospital for patients who present with chest pain to rural general practice. Aim This study aimed to estimate the costs associated with assessing patients with low-risk chest pain using the RACPP in rural general practice compared with transporting such patients to a distant emergency department (ED). Methods This was a retrospective cost minimisation analysis. All patients with low-risk chest pain that were assessed in New Zealand (NZ) rural general practice using the RACPP between 1 June 2018 and 31 December 2019 were asked to participate. The costs incurred by patients were determined by an online survey. Patients were also asked to estimate the costs if they would have been transferred to ED. System costs were obtained from the relevant healthcare organisations. The main outcome measure was the total cost for patients who present with low-risk chest pain. Results In total, 15 patients (22.7% response rate) responded to the survey. Using the RACPP in general practice resulted in a median cost saving of NZ$1184 (95% CI: $1111 to $1468) compared with transferring the same patient to ED. Discussion Although limited by low enrolment, this study suggests that there are significant savings if the RACPP is used to assess patients with low-risk chest pain in rural NZ general practice.

Corrigendum to: The cost savings of the rural accelerated chest pain pathway for low-risk chest pain in rural general practice: a cost minimisation analysis

Introduction The rural accelerated chest pain pathway (RACPP) has been shown to safely reduce the number of transfers to hospital for patients who present with chest pain to rural general practice. Aim This study aimed to estimate the costs associated with assessing patients with low-risk chest pain using the RACPP in rural general practice compared with transporting such patients to a distant emergency department (ED). Methods This was a retrospective cost minimisation analysis. All patients with low-risk chest pain that were assessed in New Zealand (NZ) rural general practice using the RACPP between 1 June 2018 and 31 December 2019 were asked to participate. The costs incurred by patients were determined by an online survey. Patients were also asked to estimate the costs if they would have been transferred to ED. System costs were obtained from the relevant healthcare organisations. The main outcome measure was the total cost for patients who present with low-risk chest pain. Results In total, 15 patients (22.7% response rate) responded to the survey. Using the RACPP in general practice resulted in a median cost saving of NZ$1184 (95% CI: $1111 to $1468) compared with transferring the same patient to ED. Discussion Although limited by low enrolment, this study suggests that there are significant savings if the RACPP is used to assess patients with low-risk chest pain in rural NZ general practice.

Paediatric fever management practices and antipyretic use among doctors and nurses in New Zealand emergency departments

OBJECTIVES

To assess (i) paediatric fever management practices among New Zealand ED doctors and nurses, including adherence to best practice guidelines; and (ii) the acceptability of a randomised controlled trial (RCT) of antipyretics for relief of discomfort in young children.

METHODS

A cross-sectional survey of doctors and nurses across 11 New Zealand EDs. The primary outcome of adherence to paediatric fever management best practice guidelines was assessed with clinical vignettes and defined as single antipyretic use for the relief of fever-related discomfort.

RESULTS

Out of 602 participants (243 doctors, 353 nurses and six unknown; response rate 47.5%), only 64 (10.6%, 95% confidence interval [CI] 8.3-13.4%) demonstrated adherence to best practice guidelines. In a febrile settled child with normal fluid intake, the percentage of participants that would use antipyretics doubled with abnormal vital signs (33.7% vs 72.9%, difference -39.2%, 95% CI -44.4% to -34.0%). Most participants would use antipyretics for reduced fluid intake (n = 494, 82.1%, 95% CI 78.8-85.0%) in a febrile settled child. Over half (n = 339, 57.1%, 95% CI 53.0-61.1%) would advise giving antipyretics to prevent febrile convulsions. Most (n = 467, 80.0%, 95% CI 76.5-83.1%) participants agreed that a RCT of antipyretics in febrile children <2 years of age with relief of discomfort as a primary outcome is needed.

CONCLUSIONS

Just over 10% of New Zealand ED doctors and nurses demonstrated adherence to paediatric fever management best practice guidelines. A RCT of antipyretics in febrile children <2 years of age specifically addressing relief of discomfort as a primary outcome is strongly supported.

Chest pain workup in the presence of atrial fibrillation: impacts on troponin testing, myocardial infarction diagnoses, and long-term prognosis

AIMS

Patients presenting to the emergency department (ED) with chest pain require evaluation for acute coronary syndrome (ACS). Atrial fibrillation (AF) can lead to troponin (cTn) elevation in the absence of ACS. There is limited evidence informing the impact of AF on the diagnostic performance of cTn testing for the diagnosis of Type 1 myocardial infarction (T1MI), or the association between AF and long-term outcomes in this context.

METHODS AND RESULTS

This study used the IMPACT and ADAPT study databases to compile a combined cohort of 3496 adults presenting to ED with chest pain between 2007 and 2014, with early cTn testing during ED workup. The mean age was 56.6 years, and 40.2% were female. Outcomes included adjudicated diagnoses for the index admission and mortality to 1-year after presentation. The specificity of initial cTn testing for T1MI diagnosis was lower for patients in AF compared with those not in AF (79.2% vs. 95.4%, P < 0.001), largely due to a relative increase in Type 2 myocardial infarction diagnoses. Sensitivity for T1MI did not differ between patients with or without AF (88.5% vs. 91.5%, P = 0.485). AF was associated with increased 1-year mortality (10.4% vs. 2.3%, P < 0.001), although this was not significant on multivariable analysis.

CONCLUSION

The specificity of serial cTn testing for the diagnosis of T1MI in patients presenting to ED with chest pain is reduced in the presence of AF. Further studies are needed to establish whether optimised cTn thresholds for patients with AF can improve workup and outcomes.

Use of the Theoretical Domains Framework to explore factors influencing paediatric fever management practices and antipyretic use in New Zealand emergency departments

AIM

To explore factors influencing fever management practices and antipyretic use among New Zealand Emergency Department (ED) doctors and nurses using the Theoretical Domains Framework (TDF).

METHODS

Cross-sectional survey of doctors and nurses across 11 New Zealand EDs. The questionnaire examined eight of 12 TDF domains, based on a generic questionnaire validated to assess TDF-based determinants of health-care professional behaviour. Relevant domains were identified by the frequency of beliefs; the presence of conflicting beliefs within a domain; and the likely strength of impact of a belief on paediatric fever management in the ED.

RESULTS

About 602 participants (243 doctors, 353 nurses and 6 unknown) completed the survey (response rate 47.5%). Over half (351/591, 59.6%, 95% confidence interval (CI) 55.5-63.5%) knew the content of clinical practice guidelines regarding antipyretic use in febrile children (TDF Domain Knowledge), or had been trained to ensure antipyretics are given to febrile children only if they appear distressed (347/592, 58.6%, 95% CI 54.5-62.6%) (Skills). Over 40% (246/590, 95% CI 37.7-45.8%) aim to reduce the fever before discharge (Goals). Most (444/591, 75.1%, 95% CI 71.4-78.6%) participants felt capable of explaining appropriate antipyretic use to parents/care givers (Beliefs about Capabilities). Only a minority (155/584, 26.5%, 95% CI 23.0-30.3%) thought that they can ensure antipyretics are given to febrile children only if they appear distressed when the ED is busy (Environmental Context and Resources).

CONCLUSIONS

Using the TDF, we identified factors influencing fever management practices and antipyretic use in the ED. These factors can guide the design of targeted, theory-informed knowledge translation strategies.

Finding acute coronary syndrome with serial troponin testing for rapid assessment of cardiac ischemic symptoms (FAST-TRAC): a study protocol

Objective

To determine the utility of a highly sensitive troponin assay when utilized in the emergency department.

Methods

The FAST-TRAC study prospectively enrolled >1,500 emergency department patients with suspected acute coronary syndrome within 6 hours of symptom onset and 2 hours of emergency department presentation. It has several unique features that are not found in the majority of studies evaluating troponin. These include a very early presenting population in whom prospective data collection of risk score parameters and the physician’s clinical impression of the probability of acute coronary syndrome before any troponin data were available. Furthermore, two gold standard diagnostic definitions were determined by a pair of cardiologists reviewing two separate data sets; one that included all local troponin testing results and a second that excluded troponin testing so that diagnosis was based solely on clinical grounds. By this method, a statistically valid head-to-head comparison of contemporary and high sensitivity troponin testing is obtainable. Finally, because of a significant delay in sample processing, a unique ability to define the molecular stability of various troponin assays is possible.

Trial registration

ClinicalTrials.gov Identifier NCT00880802

A prospective multi-centre study assessing the safety and effectiveness following the implementation of an accelerated chest pain pathway using point-of-care troponin for use in New Zealand rural hospital and primary care settings

Aims

Most rural hospitals and general practices in New Zealand (NZ) are reliant on point-of-care troponin. A rural accelerated chest pain pathway (RACPP), combining an electrocardiogram (ECG), a structured risk score (Emergency Department Assessment of Chest Pain Score), and serial point-of-care troponin, was designed for use in rural hospital and primary care settings across NZ. The aim of this study was to evaluate the safety and effectiveness of the RACPP.

Methods and results

A prospective multi-centre evaluation following implementation of the RACPP was undertaken from 1 July 2018 to 31 December 2020 in rural hospitals, rural and urban general practices, and urgent care clinics. The primary outcome measure was the presence of 30-day major adverse cardiac events (MACEs) in low-risk patients. The secondary outcome was the percentage of patients classified as low-risk that avoided transfer or were eligible for early discharge. There were 1205 patients enrolled in the study. 132 patients were excluded. Of the 1073 patients included in the primary analysis, 474 (44.0%) patients were identified as low-risk. There were no [95% confidence interval (CI): 0–0.3%] MACE within 30 days of the presentation among low-risk patients. Most of these patients (91.8%) were discharged without admission to hospital. Almost all patients who presented to general practice (99%) and urgent care clinics (97.6%) were discharged to home directly.

Conclusion

The RACPP is safe and effective at excluding MACEs in NZ rural hospital and primary care settings, where it can identify a group of low-risk patients who can be safely discharged home without transfer to hospital.

International Validation of the Canadian Syncope Risk Score : A Cohort Study

BACKGROUND

The Canadian Syncope Risk Score (CSRS) was developed to predict 30-day serious outcomes not evident during emergency department (ED) evaluation.

OBJECTIVE

To externally validate the CSRS and compare it with another validated score, the Osservatorio Epidemiologico della Sincope nel Lazio (OESIL) score.

DESIGN

Prospective cohort study.

SETTING

Large, international, multicenter study recruiting patients in EDs in 8 countries on 3 continents.

PARTICIPANTS

Patients with syncope aged 40 years or older presenting to the ED within 12 hours of syncope.

MEASUREMENTS

Composite outcome of serious clinical plus procedural events (primary outcome) and the primary composite outcome excluding procedural interventions (secondary outcome).

RESULTS

Among 2283 patients with a mean age of 68 years, the primary composite outcome occurred in 7.2%, and the composite outcome excluding procedural interventions occurred in 3.1% at 30 days. Prognostic performance of the CSRS was good for both 30-day composite outcomes and better compared with the OESIL score (area under the receiver-operating characteristic curve [AUC], 0.85 [95% CI, 0.83 to 0.88] vs. 0.74 [CI, 0.71 to 0.78] and 0.80 [CI, 0.75 to 0.84] vs. 0.69 [CI, 0.64 to 0.75], respectively). Safety of triage, as measured by the frequency of the primary composite outcome in the low-risk group, was higher using the CSRS (19 of 1388 [0.6%]) versus the OESIL score (17 of 1104 [1.5%]). A simplified model including only the clinician classification of syncope (cardiac syncope, vasovagal syncope, or other) variable at ED discharge-a component of the CSRS-achieved similar discrimination as the CSRS (AUC, 0.83 [CI, 0.80 to 0.87] for the primary composite outcome).

LIMITATION

Unable to disentangle the influence of other CSRS components on clinician classification of syncope at ED discharge.

CONCLUSION

This international external validation of the CSRS showed good performance in identifying patients at low risk for serious outcomes outside of Canada and superior performance compared with the OESIL score. However, clinician classification of syncope at ED discharge seems to explain much of the performance of the CSRS in this study. The clinical utility of the CSRS remains uncertain.

PRIMARY FUNDING SOURCE

Swiss National Science Foundation & Swiss Heart Foundation.

Performance of the American Heart Association/American College of Cardiology/Heart Rhythm Society versus European Society of Cardiology guideline criteria for hospital admission of patients with syncope

BACKGROUND

Current American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) and European Society of Cardiology (ESC) guidelines recommend different strategies to avoid low-yield admissions in patients with syncope.

OBJECTIVE

The purpose of this study was to directly compare the safety and efficacy of applying admission criteria of both guidelines to patients presenting with syncope to the emergency department in 2 multicenter studies.

METHODS

The international BASEL IX (BAsel Syncope EvaLuation) study (median age 71 years) and the U.S. SRS (Improving Syncope Risk Stratification in Older Adults) study (median age 72 years) were investigated. Primary endpoints were sensitivity/specificity for the adjudicated diagnosis of cardiac syncope (BASEL IX only) and 30-day major adverse cardiovascular events (30d-MACE).

RESULTS

Among 2560 patients in the BASEL IX and 2085 in SRS studies, ACC/AHA/HRS and ESC criteria recommended admission for a comparable number of patients in BASEL IX (27% vs 28%), but ACC/AHA/HRS criteria less often in SRS (19% vs 32%; P <.01). Recommendations were discordant in ∼25% of patients. In BASEL IX, sensitivity for cardiac syncope and 30d-MACE among patients without admission criteria was comparable for ACC/AHA/HRS and ESC criteria (64% vs 65%, P = .86; and 67% vs 71%, P = .15, respectively). In SRS, sensitivity for 30d-MACE was lower with ACC/AHA/HRS (54%) vs ESC criteria (88%; P <.001). Similarly, specificity for cardiac syncope and 30d-MACE in BASEL IX was comparable for both guidelines, but in SRS the ACC/AHA/HRS guidelines showed a higher specificity for 30d-MACE than the ESC guidelines.

CONCLUSION

ACC/AHA/HRS and ESC guidelines showed disagreement regarding admission for 1 in 4 patients and had only modest sensitivity, all indicating possible opportunities for improvements.

Implementation and evaluation of a rural general practice assessment pathway for possible cardiac chest pain using point-of-care troponin testing: a pilot study

OBJECTIVES

To assess the feasibility and acceptability, and additionally to preliminarily evaluate, the effectiveness and safety of an accelerated diagnostic chest pain pathway in rural general practice using point-of-care troponin to identify patients at low risk of acute myocardial infarction, avoiding unnecessary patient transfer to hospital and enabling early discharge home.

DESIGN

A prospective observational pilot evaluation.

SETTING

Twelve rural general (family) practices in the Midlands region of New Zealand.

PARTICIPANTS

Patients aged ≥18 years who presented acutely to rural general practice with suspected ischaemic chest pain for whom the doctor intended transfer to hospital for serial troponin measurement.

OUTCOME MEASURES

The proportion of patients managed using the low-risk pathway without transfer to hospital and without 30-day major adverse cardiac event (MACE); pathway adherence; rate of 30-day MACE; patient satisfaction with care; and agreement between point-of-care and laboratory measured troponin concentrations.

RESULTS

A total of 180 patients were assessed by the pathway. The pathway classified 111 patients (61.7%) as low-risk and all were managed in rural general practice with no 30-day MACE (0%, 95% CI 0.0% to 3.3%). Adherence to the low-risk pathway was 95.5% (106 out of 111). Of the 56 patients classified as non-low-risk and referred to hospital, 9 (16.1%) had a 30-day MACE. A further 13 non-low-risk patients were not transferred to hospital, with no events. The sensitivity of the pathway for 30-day MACE was 100.0% (95% CI 70.1% to 100%). Of low-risk patients, 94% reported good to excellent satisfaction with care. Good concordance was observed between point-of-care and duplicate laboratory measured troponin concentrations.

CONCLUSIONS

The use of an accelerated diagnostic chest pain pathway incorporating point-of-care troponin in a rural general practice setting was feasible and acceptable, with preliminary results suggesting that it may safely and effectively reduce the urgent transfer of low-risk patients to hospital.

745 Thunderclap headache syndrome presenting to the emergency department: an international multicentre observational cohort study

Background

Acute headache is a common reason for presentation to emergency departments. Some have significant structural pathology requiring further intervention. Emergency clinicians often rely on presenting headache features (such as thunderclap onset) to guide the need for neuroimaging and further investigation. It is unclear whether these features discriminate accurately or how the investigations of patients presenting with thunderclap headache differs internationally.

Objectives

To determine the proportion of patients presenting with thunderclap onset of headache from a general headache cohort and compare demographics, investigation strategy and final diagnosis, across an international sample of patients.

Methods

An international, multicentre, observational prospective cohort study. This planned sub-study focussed on patients presenting with thunderclap onset headache, with characteristics compared to the general headache cohort. The prospective observational design was chosen to capture real-world data on current international practice.

Results

The study recruited 4536 patients across 67 hospitals and 10 countries during 2019. Of this, 644 patients presented with thunderclap headache onset (14.2%). Median age was 44. The majority of patients self-referred to hospital. CT brain imaging was performed in 62.7% cases and lumbar puncture in 10.6%, with wide international variation. New Zealand reported the highest rate of neuroimaging, 78.4% of patients presenting with thunderclap headache, compared to 25.0% in Romania. All cases of subarachnoid haemorrhage (SAH) were diagnosed on CT imaging results.

When compared with the parent cohort of all headache patients presenting to the ED, those with thunderclap headache had a significantly higher rate of serious cranial pathology (13.7% vs 8.5%, p<0.001) and final diagnosis of SAH (3.6% vs 0.8% p<0.001).

Conclusions

Thunderclap headache presenting to the ED appears to correlate with a higher risk for serious intracranial pathology and/or SAH. Investigation strategies varied within this international cohort. Neuroimaging rates did not align with international guidelines, suggesting potential for further work on standardisation.

Thunderclap headache syndrome presenting to the emergency department: an international multicentre observational cohort study

BACKGROUND

Most headache presentations to emergency departments (ED) have benign causes; however, approximately 10% will have serious pathology. International guidelines recommend that patients describing the onset of headache as 'thunderclap' undergo neuroimaging and further investigation. The association of this feature with serious headache cause is unclear. The objective of this study was to determine if patients presenting with thunderclap headache are significantly more likely to have serious underlying pathology than patients with more gradual onset and to determine compliance with guidelines for investigation.

METHODS

This was a planned secondary analysis of an international, multicentre, observational study of adult ED patients presenting with a main complaint of headache. Data regarding demographics, investigation strategies and final ED diagnoses were collected. Thunderclap headache was defined as severe headache of immediate or almost immediate onset and peak intensity. Proportion of patients with serious pathology in thunderclap and non-thunderclap groups were compared by χ² test.

RESULTS

644 of 4536 patients presented with thunderclap headache (14.2%). CT brain imaging and lumbar puncture were performed in 62.7% and 10.6% of cases, respectively. Among patients with thunderclap headache, serious pathology was identified in 10.9% (95%CI 8.7% to 13.5%) of cases-significantly higher than the proportion found in patients with a different headache onset (6.6% (95% CI 5.9% to 7.4%), p<0.001.). The incidence of subarachnoid haemorrhage (SAH) was 3.6% (95% CI 2.4% to 5.3%) in those with thunderclap headache vs 0.3% (95% CI 0.2% to 0.5%) in those without (p<0.001). All cases of SAH were diagnosed on CT imaging. Non-serious intracranial pathology was diagnosed in 87.7% of patients with thunderclap headache.

CONCLUSIONS

Thunderclap headache presenting to the ED appears be associated with higher risk for serious intracranial pathology, including SAH, although most patients with this type of headache had a benign cause. Neuroimaging rates did not align with international guidelines, suggesting potential need for further work on standardisation.

Sensitivity of modern multislice CT for subarachnoid haemorrhage at incremental timepoints after headache onset: a 10-year analysis

BACKGROUND

CT performed within 6 hours of headache onset is highly sensitive for the detection of subarachnoid haemorrhage (SAH). Beyond this time frame, if the CT is negative for blood, a lumbar puncture is often performed. Technology improvements in image noise reduction, resolution and motion artefact have enhanced the performance of multislice CT (MSCT) and may have further improved sensitivity. We aimed to describe how the sensitivity to SAH of modern MSCT changes with time from headache onset.

METHODS

This was a retrospective analysis of electronic data collected as part of routine care among all patients presenting to Christchurch Hospital diagnosed with a SAH between 1 January 2008 and 31 December 2017. Patients were imaged with MSCT. The primary outcome was the proportion of patients with spontaneous aneurysmal SAH (identified via coding and confirmed by clinical and radiological records) that had a positive MSCT. The secondary outcome was the proportion of patients with any type of spontaneous SAH that had a positive MSCT.

RESULTS

There were 347 patients with an SAH of whom 260 were aneurysmal SAH. MSCT identified 253 (97.3%) of all aneurysmal SAH and 332 (95.7%) of all SAH. The sensitivity of MSCT was 99.6% (95% CI 97.6 to 100) for aneurysmal SAH and 99.0% (95% CI 97.1 to 99.8) for all SAH at 48 hours after headache onset. At 24 hours after headache onset, the sensitivity for aneurysmal SAH was 100% (95% CI 98.3 to 100).

CONCLUSION

These data suggest that it may be possible to extend the timeframe from headache onset within which modern MSCT can be used to rule out aneurysmal SAH.

Concussive Symptoms Following Pediatric Mild Traumatic Brain Injury

OBJECTIVES

To determine the proportion of children with postconcussive symptoms (PCSs) and to explore the influence of noninjury and injury factors on parents' PCS report at 3 months postinjury.

DESIGN

A cross-sectional analysis of the 3-month postinjury data from a larger, prospective, longitudinal study.

METHODS

Parents and their child aged 2 to 12 years who presented at the emergency department with either a mild traumatic brain injury (mTBI) or a superficial injury to the head (SIH) were recruited. Parents reported their child's symptoms at the time of injury and at 3 months postinjury. Child, family/parent, and injury characteristics were considered as potential predictors. Logistic regression was conducted to determine which factors increase the likelihood of parents' PCS report.

RESULTS

At 3 months postinjury, 30% and 13% of children in the mTBI and SIH groups exhibited 1 or more symptoms, respectively. On the other hand, 18% (mTBI) and 8% (SIH) continued to have ongoing problems when 2 or more symptoms were considered at follow-up. The final model, which included child's sex, injury group, number of symptoms at the time of injury, and parental stress, had a significant predictive utility in determining parents' report of 1 or more symptoms at follow-up. Only parental stress continued to be a significant predictor when considering 2 or more symptoms at 3 months postinjury.

CONCLUSIONS

Children with mTBI have worse outcomes than children with SIH at follow-up, with parents more likely to report 1 or more ongoing symptoms if their children had an mTBI. Postinjury assessment of parental stress and ongoing symptom monitoring in young children with mTBI will allow for timely provision of support for the family.

Early standardized clinical judgement for syncope diagnosis in the emergency department

BACKGROUND

The diagnosis of cardiac syncope remains a challenge in the emergency department (ED).

OBJECTIVE

Assessing the diagnostic accuracy of the early standardized clinical judgement (ESCJ) including a standardized syncope-specific case report form (CRF) in comparison with a recommended multivariable diagnostic score.

METHODS

In a prospective international observational multicentre study, diagnostic accuracy for cardiac syncope of ESCJ by the ED physician amongst patients ≥ 40 years presenting with syncope to the ED was directly compared with that of the Evaluation of Guidelines in Syncope Study (EGSYS) diagnostic score. Cardiac syncope was centrally adjudicated independently of the ESCJ or conducted workup by two ED specialists based on all information available up to 1-year follow-up. Secondary aims included direct comparison with high-sensitivity cardiac troponin I (hs-cTnI) and B-type natriuretic peptide (BNP) concentrations and a Lasso regression to identify variables contributing most to ESCJ.

RESULTS

Cardiac syncope was adjudicated in 252/1494 patients (15.2%). The diagnostic accuracy of ESCJ for cardiac syncope as quantified by the area under the curve (AUC) was 0.87 (95% CI: 0.84-0.89), and higher compared with the EGSYS diagnostic score (0.73 (95% CI: 0.70-0.76)), hs-cTnI (0.77 (95% CI: 0.73-0.80)) and BNP (0.77 (95% CI: 0.74-0.80)), all P < 0.001. Both biomarkers (alone or in combination) on top of the ESCJ significantly improved diagnostic accuracy.

CONCLUSION

ESCJ including a standardized syncope-specific CRF has very high diagnostic accuracy and outperforms the EGSYS score, hs-cTnI and BNP.

Artificial intelligence MacHIne learning for the detection and treatment of atrial fibrillation guidelines in the emergency department setting (AIM HIGHER): Assessing a machine learning clinical decision support tool to detect and treat non-valvular atrial fibrillation in the emergency department

OBJECTIVE

Advanced machine learning technology provides an opportunity to improve clinical electrocardiogram (ECG) interpretation, allowing non-cardiology clinicians to initiate care for atrial fibrillation (AF). The Lucia Atrial Fibrillation Application (Lucia App) photographs the ECG to determine rhythm detection, calculates CHA2DS2-VASc and HAS-BLED scores, and then provides guideline-recommended anticoagulation. Our purpose was to determine the rate of accurate AF identification and appropriate anticoagulation recommendations in emergency department (ED) patients ultimately diagnosed with AF.

METHODS

We performed a single-center, observational retrospective chart review in an urban California ED, with an annual census of 70,000 patients. A convenience sample of hospitalized patients with AF as a primary or secondary discharge diagnosis were evaluated for accurate ED AF diagnosis and ED anticoagulation rates. This was done by comparing the Lucia App against a gold standard board-certified cardiologist diagnosis and using the American College of Emergency Physicians AF anticoagulation guidelines.

RESULTS

Two hundred and ninety seven patients were enrolled from January 2016 until December 2019. The median age was 79 years and 44.1% were female. Compared to the gold standard diagnosis, the Lucia App detected AF in 98.3% of the cases. Physicians recommended guideline-consistent anticoagulation therapy in 78.5% versus 98.3% for the Lucia App. Of the patients with indications for anticoagulation and discharged from the ED, only 25.0% were started at discharge.

CONCLUSION

Use of a cloud-based ECG identification tool can allow non-cardiologists to achieve similar rates of AF identification as board-certified cardiologists and achieve higher rates of guideline-recommended anticoagulation therapy in the ED.

Presentation, Treatment and Long-Term Outcomes of a Multidisciplinary Acute Atrial Fibrillation Pathway: A 12-Month Follow-Up Study

AIM

Atrial fibrillation/flutter (AF/AFL) is associated with high rates of emergency department (ED) visits and acute hospitalisation. A recently established multidisciplinary acute AF treatment pathway seeks to avoid hospital admissions by early discharge of haemodynamically stable, low risk patients from the ED with next-working-day return to a ward-based AF clinic for further assessment. We conducted a preliminary analysis of the clinical outcomes of this pathway.

METHODS

We retrospectively reviewed clinical records of all patients assessed at the AF clinic at Christchurch Hospital over a 12-month period. Data related to presentation, patient characteristics, treatment, and 12-month outcomes were analysed.

RESULTS

A total of 143 patients (median age 65, interquartile range: 57-74 years, 59% male, 87% European) were assessed. Of these, 87 (60.8%) presented with their first episode of AF/AFL. Spontaneous cardioversion occurred in 41% at ED discharge, and this increased to 73% at AF clinic review. Electrical cardioversion was subsequently performed in 16 patients (11.2%), and 16 (11.2%) ultimately required hospital admission (eight to facilitate electrical cardioversion). At a median of 1 day, 83.9% were discharged from the AF clinic in sinus rhythm. During 12-month follow-up, there were 25 AF-related hospitalisations (20 patients, 14%) and one patient underwent electrical cardioversion; additionally, one patient had had a stroke and eight had bleeding complications giving a combined outcome rate of 6.3%.

CONCLUSION

Utilising a rate-control strategy with ED discharge and early return to a dedicated AF clinic can safely prevent the majority of hospitalisations, avert unnecessary procedures, and facilitate longitudinal care.

Study protocol for an observational study to evaluate an accelerated chest pain pathway using point-of-care troponin in New Zealand rural and primary care populations

INTRODUCTION Accelerated diagnostic chest pain pathways are used widely in urban New Zealand hospitals. These pathways use laboratory-based troponin assays with good analytical precision. Widespread implementation has not occurred in many of New Zealand's rural hospitals and general practices as they are reliant on point-of-care troponin assays, which are less sensitive and precise. An accelerated chest pain pathway using point-of-care troponin has been adapted for use in rural settings. A pilot study in a low-risk rural population showed no major adverse cardiac events at 30 days. A larger study is required to be confident that the pathway is safe. AIMS To assess the safety and effectiveness of an accelerated chest pain pathway adapted for rural settings and general practice using point-of-care troponin to identify low-risk patients and allow early discharge. METHODS This is a prospective observational study of an accelerated chest pain pathway using point-of-care troponin in rural hospitals and general practices in New Zealand. A total of 1000 patients, of whom we estimate 400 will be low risk, will be enrolled in the study. OUTCOME MEASURES The primary outcome is the proportion of patients identified by the pathway as low risk for a 30-day major adverse cardiac event. Secondary outcomes include the proportion of low-risk patients who were discharged directly from general practice or rural hospitals, the proportion of patients reclassified as having acute myocardial infarction by the pathway and the proportion of patients with low and intermediate risk safely managed in the rural hospital.

Troponin elevation pattern and subsequent cardiac and non-cardiac outcomes: Implementing the Fourth Universal Definition of Myocardial Infarction and high-sensitivity troponin at a population level

Background

The Fourth Universal Definition of Myocardial Infarction (MI) differentiates MI from myocardial injury. We characterised the temporal course of cardiac and non-cardiac outcomes associated with MI, acute and chronic myocardial injury.

Methods

We included all patients presenting to public emergency departments in South Australia between June 2011–Sept 2019. Episodes of care (EOCs) were classified into 5 groups based on high-sensitivity troponin-T (hs-cTnT) and diagnostic codes: 1) Acute MI [rise/fall in hs-cTnT and primary diagnosis of acute coronary syndrome], 2) Acute myocardial injury with coronary artery disease (CAD) [rise/fall in hs-cTnT and diagnosis of CAD], 3) Acute myocardial injury without CAD [rise/fall in hs-cTnT without diagnosis of CAD], 4) Chronic myocardial injury [elevated hs-cTnT without rise/fall], and 5) No myocardial injury. Multivariable flexible parametric models were used to characterize the temporal hazard of death, MI, heart failure (HF), and ventricular arrhythmia.

Results

372,310 EOCs (218,878 individuals) were included: acute MI (19,052 [5.12%]), acute myocardial injury with CAD (6,928 [1.86%]), acute myocardial injury without CAD (32,231 [8.66%]), chronic myocardial injury (55,056 [14.79%]), and no myocardial injury (259,043 [69.58%]). We observed an early hazard of MI and HF after acute MI and acute myocardial injury with CAD. In contrast, subsequent MI risk was lower and more constant in patients with acute injury without CAD or chronic injury. All patterns of myocardial injury were associated with significantly higher risk of all-cause mortality and ventricular arrhythmia.

Conclusions

Different patterns of myocardial injury were associated with divergent profiles of subsequent cardiac and non-cardiac risk. The therapeutic approach and modifiability of such excess risks require further research.

High flow oxygen and risk of mortality in patients with a suspected acute coronary syndrome: pragmatic, cluster randomised, crossover trial

OBJECTIVE

To determine the association between high flow supplementary oxygen and 30 day mortality in patients presenting with a suspected acute coronary syndrome (ACS).

DESIGN

Pragmatic, cluster randomised, crossover trial.

SETTING

Four geographical regions in New Zealand.

PARTICIPANTS

40 872 patients with suspected or confirmed ACS included in the All New Zealand Acute Coronary Syndrome Quality Improvement registry or ambulance ACS pathway during the study periods. 20 304 patients were managed using the high oxygen protocol and 20 568 were managed using the low oxygen protocol. Final diagnosis of ST elevation myocardial infarction (STEMI) and non-STEMI were determined from the registry and ICD-10 discharge codes.

INTERVENTIONS

The four geographical regions were randomly allocated to each of two oxygen protocols in six month blocks over two years. The high oxygen protocol recommended oxygen at 6-8 L/min by face mask for ischaemic symptoms or electrocardiographic changes, irrespective of the transcapillary oxygen saturation (SpO₂). The low oxygen protocol recommended oxygen only if SpO₂ was less than 90%, with a target SpO₂ of less than 95%.

MAIN OUTCOME MEASURE

30 day all cause mortality determined from linkage to administrative data.

RESULTS

Personal and clinical characteristics of patients managed under both oxygen protocols were well matched. For patients with suspected ACS, 30 day mortality for the high and low oxygen groups was 613 (3.0%) and 642 (3.1%), respectively (odds ratio 0.97, 95% confidence interval 0.86 to 1.08). For 4159 (10%) patients with STEMI, 30 day mortality for the high and low oxygen groups was 8.8% (n=178) and 10.6% (n=225), respectively (0.81, 0.66 to 1.00) and for 10 218 (25%) patients with non-STEMI was 3.6% (n=187) and 3.5% (n=176), respectively (1.05, 0.85 to 1.29).

CONCLUSION

In a large patient cohort presenting with suspected ACS, high flow oxygen was not associated with an increase or decrease in 30 day mortality.

TRIAL REGISTRATION

ANZ Clinical Trials ACTRN12616000461493.

Development of an electrocardiogram-based risk calculator for a cardiac cause of syncope

OBJECTIVE

To develop an ECG-based tool for rapid risk assessment of a cardiac cause of syncope in patients ≥40 years.

METHODS

In a prospective international multicentre study, 2007 patients ≥40 years presenting with syncope were recruited in the emergency department (ED) of participating centres ranging from large university hospitals to smaller rural hospitals in eight countries from May 2010 to July 2017. 12-Lead ECG recordings were obtained at ED presentation following the syncopal event. The primary diagnostic outcome, a cardiac cause of syncope, was centrally adjudicated by two independent cardiologists using all available clinical information including 12-month follow-up. ECG predictors for a cardiac cause of syncope were identified using penalised backward selection and a continuous-scale likelihood was calculated based on regression analysis coefficients. Findings were validated in an independent US multicentre cohort including 2269 patients.

RESULTS

In the derivation cohort, a cardiac cause of syncope was adjudicated in 267 patients (16%). Seven ECG criteria were identified as predictors for this outcome: heart rate and QTc-interval (continuous predictors), rhythm, atrioventricular block, ST-segment depression, bundle branch block and ventricular extrasystole/non-sustained ventricular tachycardia (categorical predictors). Diagnostic accuracy of these combined predictors for a cardiac cause of syncope was high (area under the curve 0.80, 95% CI 0.77 to 0.83). Overall, 138 patients (8%) were rapidly triaged towards rule-out and 181 patients (11%) towards rule-in of a cardiac cause of syncope. External validation showed similar performance.

CONCLUSION

In patients ≥40 years with a syncopal event, a combination of seven ECG criteria enabled rapid assessment of the likelihood that syncope was due to a cardiac cause.

TRIAL REGISTRATION NUMBER

NCT01548352 (BASEL IX), NCT01802398 (SRS study).

Where are children seen in Australian emergency departments? Implications for research efforts

OBJECTIVE

With most paediatric emergency research in Australia conducted at tertiary EDs, it is important to understand how presentations differ between those at tertiary paediatric EDs and all other EDs.

METHODS

Retrospective epidemiological study assessing paediatric case-mix and time-based performance metrics (aged 0-14 years) obtained from a national health service minimum dataset for the 2017-2018 financial year, comparing tertiary paediatric EDs and all other EDs. We defined a 'major tertiary paediatric hospital' as one which was accredited for training in both paediatric emergency medicine and paediatric intensive care.

RESULTS

Of the 1 695 854 paediatric ED presentations, 23.8% were seen in nine major metropolitan tertiary paediatric hospitals. Reasons for presentations were more distinctive between cohorts among children aged 10-14 years, where psychiatric illness (5.2% vs 2.5%) and neurological illness (4.5% vs 2.5%) were more commonly seen in major tertiary paediatric EDs. Australian Indigenous children were significantly less likely to present to tertiary paediatric EDs (3.0%), compared with other EDs (9.7%) (odds ratio 0.27, 95% confidence interval 0.26-0.27). While median waiting times were longer in major tertiary paediatric EDs (28 min [interquartile range 11-65]) than in other EDs (20 min [interquartile range 8-48], P < 0.001), patients were also less likely to leave without being seen (5.5% in tertiary paediatric EDs vs 6.9% in other EDs; odds ratio 0.80, 95% confidence interval 0.78-0.81).

CONCLUSIONS

The present study identified key areas of difference in paediatric presentations between tertiary paediatric EDs and other EDs. It is vital to broaden paediatric ED research beyond tertiary paediatric centres, to ensure relevance and generalisability.

Incidence, characteristics, determinants, and prognostic impact of recurrent syncope

AIMS

The aim of this study is to characterize recurrent syncope, including sex-specific aspects, and its impact on death and major adverse cardiovascular events (MACE).

METHODS AND RESULTS

We characterized recurrent syncope in a large international multicentre study, enrolling patients ≥40 years presenting to the emergency department (ED) with a syncopal event within the last 12 h. Syncope aetiology was centrally adjudicated by two independent cardiologists using all information becoming available during syncope work-up and long-term follow-up. Overall, 1790 patients were eligible for this analysis. Incidence of recurrent syncope was 20% [95% confidence interval (CI) 18-22%] within the first 24 months. Patients with an adjudicated final diagnosis of cardiac syncope (hazard ratio (HR) 1.50, 95% CI 1.11-2.01) or syncope with an unknown aetiology even after central adjudication (HR 2.11, 95% CI 1.54-2.89) had an increased risk for syncope recurrence. Least Absolute Shrinkage and Selection Operator regression fit on all patient information available early in the ED identified >3 previous episodes of syncope as the only independent predictor for recurrent syncope (HR 2.13, 95% CI 1.64-2.75). Recurrent syncope carried an increased risk for death (HR 1.87, 95% CI 1.26-2.77) and MACE (HR 2.69, 95% CI 2.02-3.59) over 24 months of follow-up, however, with a time-dependent effect. These findings were confirmed in a sensitivity analysis excluding patients with syncope recurrence or MACE before or during ED evaluation.

CONCLUSION

Recurrence rates of syncope are substantial and vary depending on syncope aetiology. Importantly, recurrent syncope carries a time-dependent increased risk for death and MACE.

TRIAL REGISTRATION

BAsel Syncope EvaLuation (BASEL IX, ClinicalTrials.gov registry number NCT01548352).

Incidence, characteristics and prognosis of different cardiac etiologies underlying cardiac syncope

Background

Cardiac syncope has been shown to carry the highest hazard for all-cause death compared to other causes of syncope including vasovagal and orthostatic syncope. However, little is known about the incidence, characteristics and prognosis of different cardiac etiologies underlying cardiac syncope.

Purpose

To evaluate the incidence, characteristics and prognosis of different cardiac etiologies underlying cardiac syncope.

Methods

We enrolled patients presenting to the emergency department (ED) with syncope in a large prospective international multicentre study. The cause of syncope (cardiac vs non-cardiac) including the detailed cardiac aetiology (if cardiac) was centrally adjudicated by two independent cardiologists based on detailed in-hospital as well as outpatient cardiac work-up during 360 days following presentation. Cardiac syncope was classified into four groups: bradyarrhythmia, tachyarrhythmia, structural disease and other (cardiopulmonary and great vessels), as recommended in the ESC Syncope Guidelines. All-cause death during 2-years follow-up was the primary outcome.

Results

Among 2025 patients presenting with syncope to the ED, cardiac syncope was the final adjudicated diagnoses in 318 (15.7%) patients. The incidence rate of all-cause death among cardiac syncope patients was 103 cases per 1000 person-years. Bradyarrhythmia was the most frequent primary cause of cardiac syncope (n=146, 45.9%) followed by tachyarrhythmia (n=75, 23.6%), structural disease (n=64, 20.1%) and other cardiac (n=26, 8.2%). Patients were 37% female with a median age of 77 years (IQR 67–83) showing no statistically significant difference between subgroups. Clinical characteristics differed significantly among the four subgroups. E.g. syncope occurred during exercise in 12 patients (8.2%) with bradyarrhythmia, 10 patients (13.3%) with tachyarrhythmia, 16 patients (25%) with structural disease, and 5 patients (19%) with other cardiac (p&lt;0.01). Likely of most importance, long-term mortality differed significantly among the four different cardiac subgroups. The multivariable-adjusted hazard ratios (HR) among patients with bradyarrhythmia, tachyarrhythmia, structural disease and other cardiac as compared to patients with vasovagal syncope, the HR were 1.3 (95% CI 0.7–2.5), 4.6 (95% CI 2.3–9.1), 3.1 (95% CI 1.5–6.4) and 5.9 (95% CI 2.3–15.2), respectively (Figure 1).

Conclusions

Bradyarrhythmia, tachyarrhythmia, and structural cardiac disease are the dominant causes of cardiac syncope. Interestingly, with the appropriate therapy initiated long-term mortality of bradyarrhythmia is comparable to that of vasovagal syncope, while long-term mortality of tachyarrhythmia and structural cardiac disease were substantially increased 3 to 5 fold.

Figure 1. Kaplan-Meier curve

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): The Swiss National Science Foundation, the Swiss Heart Foundation, the Stiftung für kardiovaskuläre Forschung Basel, the University of Basel and the University Hospital Basel.

Validation of a machine learned model to predict the diagnosis of myocardial infarction

Introduction

The myocardial-ischemic-injury-index (MI3) is a promising machine learned algorithm that predicts the likelihood of myocardial infarction in patients with suspected acute coronary syndrome. Whether this algorithm performs well in unselected patients or predicts recurrent events is unknown.

Methods

In an observational analysis from a multi-centre randomised trial, we included all patients with suspected acute coronary syndrome and serial high-sensitivity cardiac troponin I measurements without ST-segment elevation myocardial infarction. Using gradient boosting, MI3 incorporates age, sex, and two troponin measurements to compute a value (0–100) reflecting an individual's likelihood of myocardial infarction, and estimates the negative predictive value (NPV) and positive predictive value (PPV). Model performance for an index diagnosis of myocardial infarction, and for subsequent myocardial infarction or cardiovascular death at one year was determined using previously defined low- and high-probability thresholds (1.6 and 49.7, respectively).

Results

In total 20,761 of 48,282 (43%) patients (64±16 years, 46% women) were eligible of whom 3,278 (15.8%) had myocardial infarction. MI3 was well discriminated with an area under the receiver-operating-characteristic curve of 0.949 (95% confidence interval 0.946–0.952) identifying 12,983 (62.5%) patients as low-probability (sensitivity 99.3% [99.0–99.6%], NPV 99.8% [99.8–99.9%]), and 2,961 (14.3%) as high-probability (specificity 95.0% [94.7–95.3%], PPV 70.4% [69–71.9%]). At one year, subsequent myocardial infarction or cardiovascular death occurred more often in high-probability compared to low-probability patients (17.6% [520/2,961] versus 1.5% [197/12,983], P&lt;0.001).

Conclusions

In unselected consecutive patients with suspected acute coronary syndrome, the MI3 algorithm accurately estimates the likelihood of myocardial infarction and predicts probability of subsequent adverse cardiovascular events.

Performance of MI3 at example thresholds

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Medical Research Council

Utility of echocardiography in patients with suspected acute myocardial infarction in the presence of left bundle-branch block

Background

Rapid identification of acute myocardial infarction (AMI) as life-threatening disorder by clinical assessment, cardiac troponin and the electrocardiogram (ECG) is important for the early initiation of highly effective, evidence-based therapy. Patients presenting with suspected AMI and left bundle branch block (LBBB) to the emergency department (ED) represent a unique diagnostic and therapeutic challenge, as altered ventricular depolarization masks changes in ventricular repolarization associated with myocardial ischemia. Current guidelines suggest, based on expert opinion, early echocardiography as a helpful tool in patients with suspected AMI and LBBB to identify new wall motion abnormalities, which guides further diagnostics strategies in these patients.

Purpose

To evaluate the diagnostic accuracy of echocardiography among patients with suspected AMI and LBBB in the recorded ECG at ED presentation.

Methods

We prospectively evaluated the diagnostic accuracy of echocardiography in patients with LBBB presenting with chest discomfort to 26 ED's in three international, prospective, diagnostic studies. Two independent cardiologists centrally adjudicated the final diagnosis in each study according to the universal definition of myocardial infarction. All patients underwent a clinical assessment that included standardized and detailed medical history including assessment of chest pain characteristics, vital signs, physical examination, 12-lead ECG, continuous ECG rhythm monitoring, pulse oximetry, standard blood test, and chest radiography and echocardiography if indicated. We compared echocardiographic findings in patients with LBBB who were diagnosed with an AMI to those without an AMI.

Results

Among 283 patients presenting with chest pain and LBBB to the ED, AMI was the final diagnosis in 36% (102 of 283 patients) of patients. An echocardiography had been performed in 100/283 patients (35%) in the emergency department. AMI was the final diagnosis in 41/100 (41%) of patients. A wall motion abnormality in any region was seen in 77 (77%) of patients with no difference between patients diagnosed with AMI (33 patients, 81%) versus without AMI (44 patients, 75%, p=0.49). Additionally, we found no differences for each wall region (Table 1). Most patients with LBBB had moderately reduced left ventricular ejection fraction (LVEF, median 40%), a dilated left atrium (67%) or left ventricular hypertrophy (55%) without any differences between the two groups (Table 1).

Conclusions

Early echocardiography in patients with suspected AMI and LBBB provided only limited utility to identify patients, which may benefit from immediate coronary angiography. Our findings scrutinize current guidelines and downgrades the utility of echocardiography in this setting.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): Swiss National Science Foundation, the Swiss Heart Foundation, the European Union, the Cardiovascular Research Foundation Basel, the University Hospital Basel, Queensland Emergency Medicine Research Foundation, Christchurch Heart Institute and Health Research Council and Heart Foundation of New Zealand, Christchurch Emergency Care Foundation

CSANZ Position Statement on the Evaluation of Patients Presenting With Suspected Acute Coronary Syndromes During the COVID-19 Pandemic

A pandemic of Coronavirus-19 disease was declared by the World Health Organization on March 11, 2020. The pandemic is expected to place unprecedented demand on health service delivery. This position statement has been developed by the Cardiac Society of Australia and New Zealand to assist clinicians to continue to deliver rapid and safe evaluation of patients presenting with suspected acute cardiac syndrome at this time. The position statement complements, and should be read in conjunction with, the National Heart Foundation of Australia & Cardiac Society of Australia and New Zealand: Australian Clinical Guidelines for the Management of Acute Coronary Syndromes 2016: Section 2 'Assessment of Possible Cardiac Chest Pain'.

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

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

Factors influencing physician risk estimates for acute cardiac events in emergency patients with suspected acute coronary syndrome

BACKGROUND

Emergency physicians frequently assess risk of acute cardiac events (ACEs) in patients with undifferentiated chest pain. Such estimates have been shown to have moderate to high sensitivity for ACE but are conservative. Little is known about the factors implicitly used by physicians to determine the pretest probability of risk. This study sought to identify the accuracy of physician risk estimates for ACE in patients presenting to the ED with chest pain and to identify the demographic and clinical information emergency physicians use in their determination of patient risk.

METHODS

This study used data from two prospective studies of consenting adult patients presenting to the ED with symptoms of possible acute coronary syndrome. ED physicians estimated the pretest probability of ACE. Multiple linear regression analysis was used to identify predictors of physician risk estimates. Logistic regression was used to determine whether there was a correlation between physicians' estimated risk and ACE.

RESULTS

Increasing age, male sex, abnormal ECG features, heavy/crushing chest pain and risk factors were correlated with physician risk estimates. Physician risk estimates were consistently found to be higher than the expected proportion of ACE from the sampled population.

CONCLUSION

Physicians systematically overestimate ACE risk. A range of factors are associated with physician risk estimates. These include factors strongly predictive of ACE, such as age and ECG characteristics. They also include other factors that have been shown to be unreliable predictors of ACE in an ED setting, such as typicality of pain and risk factors.

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.

P2723Diagnosis 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 incidence of AMI, and diagnostic performance of specific electrocardiographic (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. Presence of LBBB, ECG criteria, and final diagnoses were centrally adjudicated by two independent cardiologists using the fourth universal definition of myocardial infarction.

Results

Among 8830 patients, LBBB was present in 247 patients (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%). The diagnostic accuracy as quantified by the receiver-operating-characteristics curve of hs-cTnT and hs-cTnI concentrations at presentation (AUC 0.91; 95% CI 0.85–0.96 and 0.89; 95% CI 0.83–0.95) as well as that of their 0/1h and 0/2h changes was very high. A diagnostic algorithm (Figure 1) combining ECG criteria with hs-cTnT/I concentrations and their absolute changes at 1h or 2h derived in cohort 1 (45 of 45 (100%) of patients with AMI correctly identified), showed high efficacy and accuracy when externally validated in cohort 2 & 3 (28 of 29 patients, 97%).

Figure 1

Conclusion

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

Acknowledgement/Funding

European Union, Swiss National Foundation, University Hospital Basel, University Basel

P1756The protein APRIL predicts adverse outcomes in DAPT patients better than NT-proBNP and troponin

Aim

Dual antiplatelet therapy (DAPT) is a mainstay of post-ACS treatment. However, prediction of adverse events in these patients needs improving. We show here that the TNFα-related protein APRIL (which is produced in platelets and atherosclerotic plaque) is a superior predictor of MACE and new MI in DAPT recipients post-ACS.

Methods

We prospectively recruited 518 patients presenting with the primary complaint of acute chest pain to our hospital ED. Patients were adjudicated to have ACS by 2 independent cardiologists in accordance with ESC guidelines with hsTnI as biomarker. Plasma EDTA samples taken at presentation and 2 hours after were interrogated for APRIL measurements using a two site ELISA. Clinical data/variables, standard biochemistry analytes, hsTnT and NT-proBNP were also measured. Statistical assessments were made using SPSS v23 (IBM). Data for all biomarkers were treated as continuous variables and are presented as median (interquartile range, (IQR)). Statistical assessment of the comparative diagnostic abilities of APRIL, hsTnT, NT-proBNP and hsTnI were assessed using receiver operator curve (ROC) area under the curve (AUC) analysis. The comparative power of each biomarker (log values) to predict new MACE, MI, bleeding and mortality in 1) the whole group and in 2) DAPT recipients alone, within 2 yrs of index presentation was undertaken using a logistic regression base model (95% CI) that included all clinical variables and hsTnI and hsTnT, with APRIL and NT-proBNP each included in additional multivariate analyses.

Results

Of the 518 recruited patients (median age 63 (IQR: 54–73, 35% female), 152 were adjudicated to have ACS (29%, 115 MI, 37 UAP). Presentation APRIL levels were higher in those with a cardiac versus non-cardiac cause for presentation (3.0, (2.0–4.7) vs. 2.4, (1.6–3.8) ng/mL, P=0.001) and positively correlated with hsTnT and NT-proBNP (all P<0.001), but it did not add to the hsTnI (ROC = 0.96) or hsTnT (ROC =0.92) assisted diagnosis of ACS. In all 518 patients, in the multivariate regression model, APRIL was a significant independent predictor of mortality (n=54, P=0.032), new MI (n=43, P=0.006), new ADHF (n=24, P=0.016) and MACE (n=71, P=0.005) that was additive to NT-proBNP and troponin. In DAPT recipients alone (n=156), APRIL was the only biomarker to independently predict new MI (n=27, 95% CI: 1.125–3.982, P=0.020) and MACE (n=37, 95% CI: 1.058–3.389, P=0.031). None of the markers, only age, predicted bleeding episodes.

Conclusion

APRIL is an platelet/plaque derived marker that provides independent risk assessment in ACS patients. In DAPT recipients, the ability of APRIL to predict new MI and MACE is superior to that of cardiac troponins and NT-proBNP and could be used to identify high risk individuals.

Acknowledgement/Funding

Health Research Council of New Zealand; Heart Foundation of New Zealand

P2674Rapid rule-out of myocardial infarction with a novel high precision point-of-care troponin assay appears safe and effective

Background

High sensitivity troponin assays were developed to improve analytical sensitivity and precision at the decision cut-points for the diagnosis and rule out of acute myocardial infarction (AMI). Central laboratory assays have achieved this but point of care assays, which have the ability to accelerate decision making due to much shorter turnaround times, have remained lacking.

Purpose

To ascertain the threshold for decision making and subsequent clinical utility for ruling out AMI on presentation in patients attending the emergency department acutely with chest pain, using a high precision point of care troponin assay (TnI Nx), (i-STAT, Abbott).

Methods

We measured arrival TnI-Nx concentrations in stored plasma samples in adults presenting acutely to the emergency department with chest pain. The primary outcome was an AMI or cardiac death on index admission or within 30 days. We used 2000 bootstrapped data sets to derive and validate a suitable threshold for TnI-Nx before calculating diagnostic test performance. We pre-specified this threshold must have a <1% false negative rate for the primary outcome. We compared this with a core laboratory high sensitivity troponin I (hs-TnI) (Abbott Architect) using the early rule-out cut-point (European Society of Cardiology) at the limit of detection (2 ng/L).

Results

We recruited 1320 patients of whom 192 (14.1%) had the primary outcome. The TnI-Nx threshold was determined to be 8 ng/L with subsequent sensitivity of 99.0% (95% confidence interval: 97.3% to 100%), negative predictive value of 99.7% (99.2% to 100%) and specificity of 59.0% (56.0% to 62.0%). The hs-TnI had a sensitivity of 99.5% (98.2% to 100%), negative predictive value of 99.7% (99.0% to 100%), and specificity of 28.4% (25.8% to 31.2%) at 2ng/L.

Conclusion

A high precision point of care assay, TnI-Nx, with a decision threshold of 8ng/L, has comparable rule out performance compared with a core laboratory high sensitivity assay and therefore could potentially be used for early decision making in the assessment of acute chest pain.

Acknowledgement/Funding

Research grant from Abbott Point of Care. Senior Research Fellowship from ECF, CMRF and CDHB. Clinical Research Fellowship from NZ HRC

P3408The signal peptide of CNP is a novel predictor of MI, MACE and bleeding risk in chest pain patients

Aim

CNP is an important vascular and cardiac derived member of the natriuretic peptide family. We have previously provided the first reports that the signal peptide of CNP (CNPsp) is present in the human circulation and is elevated in those with chest pain suspicious of ACS. Here, show that CNPsp levels are highly predictive of new MI, MACE and post-index bleeding in patients presenting with potential ACS.

Methods

We prospectively recruited 493 patients presenting with the primary complaint of acute chest pain to our hospital ED. Patients were adjudicated as ACS by 2 independent cardiologists in accordance with ESC guidelines with hsTnI as biomarker. Plasma EDTA samples taken at presentation and 2 hours after were interrogated for CNPsp measurements using our validated, specific assay. Clinical data/variables, standard biochemistry analytes, hsTnT and NT-proBNP (both Roche Cobas e411) were also measured. Statistical assessments were made using SPSS v23. Data for all biomarkers were treated as continuous variables and are presented as median (interquartile range, (IQR)). Statistical assessment of the comparative abilities of CNPsp, hsTnT, NT-proBNP and hsTnI (log values) to predict new MACE, MI, bleeding and mortality within 2 yrs of index presentation was undertaken using a logistic regression base model (95% CI) that included all clinical variables and hsTnI and hsTnT and NT-proBNP, with CNPsp added to into the multivariate analyses.

Results

Of the 493 recruited patients (median age 63 (IQR: 54–73, 35% female), 148 were adjudicated to have ACS (30%, 109 MI, 39 UAP). Presentation CNPsp levels were not higher in those with adjudicated ACS versus non-ACS (51, (45–65) vs. 50, (42–63) pmol/L, P=0.412), did not correlate with hsTnI, hsTnT or NT-proBNP, but were significantly lower in those with a history of MI (49, (42–59) vs. 51, (43–64) pmol/L, P=0.044). In contrast, they were significantly higher in those with ECG ST-depression (56, (47–85) vs. 50 (42–62) pmol/L, P=0.038). In the multivariate regression model of all 493 patients, lower values of CNPsp were a significant multivariate predictor of new MI (n=37, 95% CI: 0.06–0.89, P=0.038), MACE (n=64, 95% CI: 0.08–0.81, P=0.020) and new bleeding (n=40, 95% CI: 0.05–0.63, P=0.005) within 2 years of presentation. This predictive ability was additive and independent from NT-proBNP and troponin.

Conclusion

This is the first report that CNPsp measurement provides meaningful and independent risk assessment of important outcomes in ACS patients. In particular, the fact that lower levels of CNPsp are predictive of negative MI, MACE and bleeding outcomes suggests that CNPsp may have an unappreciated protective role in the cardiovascular system.

Acknowledgement/Funding

Health Research Council of New Zealand; Heart Foundation of New Zealand

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

BACKGROUND

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

METHODS

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

RESULTS

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

INTERPRETATION

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

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.