Suspected Acute Coronary Syndrome Research Articles

The accuracy of The Emergency Severity Index Triage Score in Predicting Cardiac Events among Suspected Acute Coronary Syndrome Patients in The Emergency Department

The accuracy of The Emergency Severity Index Triage Score in Predicting Cardiac Events among Suspected Acute Coronary Syndrome Patients in The Emergency Department

Machine-Learning for Phenotyping and Prognostication of Myocardial Infarction and Injury in Suspected Acute Coronary Syndrome

BackgroundClinical work-up for suspected acute coronary syndrome (ACS) is resource intensive. ObjectivesThis study aimed to develop a machine learning model for digitally phenotyping myocardial injury and infarction and predict 30-day events in suspected ACS patients. MethodsTraining and testing data sets, predominantly derived from electronic health records, included suspected ACS patients presenting to 6 and 26 South Australian hospitals, respectively. All index presentations and 30-day death and myocardial infarction (MI) were adjudicated using the Fourth Universal Definition of MI. We developed 2 diagnostic prediction models which phenotype myocardial injury and infarction according to the Fourth UDMI (chronic myocardial injury vs acute myocardial injury patterns, the latter further differentiated into acute non-ischaemic myocardial injury, Types 1 and 2 MI) using eXtreme Gradient Boosting (XGB) and deep-learning (DL). We also developed an event prediction model for risk prediction of 30-day death or MI using XGB. Analyses were performed in Python 3.6. ResultsThe training and testing data sets had 6,722 and 8,869 participants, respectively. The diagnostic prediction XGB and deep learning models achieved an area under the curve of 99.2% ± 0.1% and 98.8% ± 0.2%, respectively, for differentiating an acute myocardial injury pattern from no injury or chronic myocardial injury pattern and achieved 95.5% ± 0.2% and 94.6% ± 0.9%, respectively, for differentiating type 1 MI from type 2 MI or acute nonischemic myocardial injury. The 30-day death/MI event prediction model achieved an area under the curve of 88.5% ± 0.5%. ConclusionsMachine learning models can digitally phenotype suspected ACS patients at index presentation and predict subsequent events within 30 days. These models require external validation in a randomized clinical trial to evaluate their impact in clinical practice.

Could Computed Tomography Coronary Angiography Replace Invasive Coronary Angiography as a First-Line Diagnostic Investigation in Suspected Acute Coronary Syndromes? A Decision-Analytic Model

The implementation of high-sensitivity cardiac troponin (hs-cTn) assays into clinical practice has resulted in the identification of a novel cohort of patients with modestly increased troponin concentrations. Subsequent increases in rates of coronary angiography have been observed, without significant increases in rates of coronary revascularisation. Computed tomography coronary angiography (CTCA) is a non-invasive investigation that offers the opportunity to decouple investigation from the impetus to revascularise, and may provide an alternative, more risk-appropriate initial investigative strategy for the cohort with low to moderate hs-cTn increases. This analysis seeks to define the threshold of pre-test probability of coronary revascularisation in patients with suspected acute coronary syndrome at which a strategy of initial CTCA is safe and a more cost-effective approach than standard invasive coronary angiography (ICA). A cost-benefit evaluation was conducted using a decision-analytic model. The primary outcome measure was the incremental cost-effectiveness ratio (ICER) of CTCA in comparison with ICA as an initial diagnostic investigation for patients with hs-cTnT levels between 5 and 100 ng/L. Secondary outcome measures of costs, patient outcomes, and quality-adjusted life years were analysed. Median base case ICER over 1,000 trials was $17,163 AUD but demonstrated large variability. Sensitivity analysis demonstrated that CTCA was cost-effective until the probability of requiring revascularisation was ∼60%, beyond which point CTCA was associated with higher costs and poorer outcomes than ICA. Computed tomography coronary angiography may be a cost-effective first-line investigation for patients with moderate hs-cTnT rises until/up to a 60% pre-test probability for receiving coronary revascularisation. To objectively assess the optimal circumstances of cost-effectiveness, prospective evaluation incorporating the estimated probability of revascularisation will be required.

Abstract 18473: Role of Linguistic Acculturation and Physical Activity With Risk of 1 Year Hospital Readmission After Suspected Acute Coronary Syndrome

Background: Disparities in acute coronary syndrome (ACS) outcomes after hospital care exist beyond racial and ethnic factors. In particular, low linguistic acculturation (LA) may impact care and lead to poorer prognosis. Few studies have examined LA’s impact on outcome disparities post-hospitalization and identified modifiable behaviors, such as physical activity (PA) engagement, that can mitigate risk. Aim: To evaluate the association of LA with 1-year hospital readmission risk among patients evaluated for ACS and examine PA as an effect modifier. Methods: Patients evaluated for ACS in the emergency unit (n=609, 47.8% female, 58.0% Hispanic, 63±12yrs) were studied. LA was classified into three levels (low, intermediate, high) based on patient’s self-reported native and preferred languages and English fluency. Continuous total PA was objectively assessed 30 days post-discharge via a GENEActiv accelerometer worn on the non-dominant wrist. One-year all-cause hospital readmissions were ascertained via hospital medical record searches. Cox regression models used high LA as referent group. Results: Over 1-year follow-up, 264 (44.0%) patients had a subsequent hospital admission. Low LA was associated with increased 1-year readmission risk after adjusting for demographic factors, comorbidities, disease severity, and PA indicators (intermediate HR=1.44; 95% CI: 0.91-2.28; low HR=1.63; 95% CI: 1.05-2.55; p-trend=0.035). PA moderated this association (p-interaction=0.003). Low LA was only associated with greater risk of 1-year readmission among those with low PA levels (below median of 158 min/day; HR=1.88; 95% CI: 1.00, 2.79). Among those with high PA, the association between low LA and risk of readmission was attenuated and not statistically significant (HR=1.46; 95% CI: 0.75, 2.83). Conclusion: Among a diverse cohort of patients with suspected ACS, LA was associated with reduced risk of 1-year hospital readmission. PA significantly moderated this relationship, with higher volumes of PA attenuating the positive association between low LA and increased risk of 1-year hospital readmission. These findings implicate low LA as a potential risk factor for readmission post-ACS and suggest increased engagement in PA can help mitigate this risk.

Changes in circulating ApoJ-Glyc levels in patients with suspected acute coronary syndrome: The EDICA trial

BackgroundMyocardial ischemia induces intracellular accumulation of non-glycosylated apolipoprotein J that results in a reduction of circulating glycosylated ApoJ (ApoJ-Glyc). The latter has been suggested to be a marker of transient myocardial ischemia. ObjectiveThis proof-of-concept clinical study aimed to assess whether changes in circulating ApoJ-Glyc could detect myocardial ischemia in patients attending the emergency department (ED) with chest pain suggestive of acute coronary syndrome (ACS). MethodsIn suspected ACS patients, EDICA (Early Detection of Myocardial Ischemia in Suspected Acute Coronary Syndromes by ApoJ-Glyc a Novel Pathologically based Ischemia Biomarker), a multicentre, international, cohort study assessed changes in 2 glycosylated variants of ApoJ-Glyc, (ApoJ-GlycA2 and ApoJ-GlycA6), in serum samples obtained at ED admission (0 h), and 1 h and 3 h thereafter, blinded to the clinical diagnosis (i.e. STEMI, NSTEMI, unstable angina, non-ischemic). Results404 patients were recruited; 291 were given a clinical diagnosis of “non-ischemic” chest pain and 113 were considered to have had an ischemic event. ApoJ-GlycA6 was lower on admission in ischemic compared with “non-ischemic” patients (66 [46–90] vs. 73 [56–95] μg/ml; P = 0.04). 74% of unstable angina patients (all with undetectable hs-Tn), had ischemic changes in ApoJ-Glyc at 0 h and 89% at 1 h. Initially low ApoJ-Glyc levels in 62 patients requiring coronary revascularization increased significantly after successful percutaneous intervention. ConclusionsCirculating ApoJ-Glyc concentrations decrease early in ED patients with myocardial ischemia compared with “non-ischemic” patients, even in the absence of troponin elevations. ApoJ-Glyc may be a useful marker of myocardial ischemia in the ED setting.

Abstract P327: Device-Measured Sedentary Behavior and Risk of 1-Year Hospital Readmission After Suspected Acute Coronary Syndrome

Background: Patients hospitalized with acute coronary syndrome (ACS) have an increased risk of a readmission during the first year after discharge; necessitating a need to identify modifiable therapeutic targets to improve outcomes. While moderate to vigorous physical activity (MVPA) has been a hallmark of secondary prevention efforts to prevent hospital readmission, sedentary behavior (SB) has emerged as a potentially unique and clinically important aspect of the physical activity profile. Yet, little is known regarding whether SB is associated with hospital readmission in ACS patients independent from or in addition to MVPA levels. Purpose: To examine the association between device-measured SB and risk of 1-year hospital readmission among patients evaluated for ACS, independent of MVPA. Methods: Patients (n=603, 47.8% female, 62.5±13.0 yrs) evaluated in the emergency department for ACS were fitted with a GENEActiv accelerometer in-hospital and were instructed to wear the device on their non-dominant wrist continuously in-hospital and for 30 days post-discharge. Hospital readmissions were ascertained by proactively searching medical records for any possible hospitalizations and by contacting participants or their closest contacts at 1- and 12-months follow-up; with supporting documentation secured from hospital medical records. Results: Over 1-year follow-up, 281 (46.6%) patients were readmitted. SB was associated with increased risk of 1-year hospital readmission after adjusting for socio-demographic factors, comorbidities, and disease severity indicators [HR per 1-hour per day increase in SB= 1.09, 95% CI: 1.01, 1.18]. The association remained significant after further adjusting for MVPA [HR per 1-hour per day increase in SB= 1.11, 95% CI: 1.02, 1.22]. In joint association analyses, high sedentary time in combination with low MVPA was associated with the greatest risk of 1-year hospital readmission in a fully adjusted model (HR: 2.18; 95%: CI: 1.44, 3.31) compared to the referent group (low SB/high MVPA). However, even among participants with higher levels of MVPA; high sedentary time was associated with a greater risk of 1-year re-hospitalization (HR: 1.54; 95% CI: 1.05, 2.27). For participants with low MVPA and low sedentary time, no significant association was observed (HR: 1.37; 95% CI: 0.84, 2.21). Conclusions: SB was associated with an increased risk of 1-year hospital readmission among patients evaluated for ACS. This increased risk was independent of MVPA and was not eliminated by high levels of MVPA. Implications of this study suggest that reducing SB should be considered as a modifiable therapeutic target in addition to MVPA to improve outcomes in ACS survivors.

Abstract 15858: Increased T Wave Amplitude in Lead Avr is a Strong Predictor of Reduced Left Ventricular Ejection Fraction in Suspected Acute Coronary Syndrome

Introduction: Non-invasive screening tools of cardiac function can play a significant role in the initial triage of patients with suspected acute coronary syndrome. Numerous ECG features have been previously linked with cardiac contractility in the general population. We sought to examine the prognostic value of positive T wave in lead aVR as a simple marker for real-time screening of reduced left ventricular ejection fraction (LVEF) in suspected acute coronary syndrome. Methods: We performed a secondary analysis of a prospective, observational cohort study of patients evaluated for suspected acute coronary syndrome. The parent study recruited consecutive patients evaluated at the emergency department of three UPMC-affiliated tertiary care hospitals. We included consecutive patients in whom an echocardiogram was performed during indexed encounter. LVEF were retrieved from the cardiologist-signed report. Baseline 12-lead ECGs were preprocessed using manufacturer specific algorithms. Amplitude of T wave in lead aVR were automatically measured at T peak in millivolts. Data analysis was performed using SPSS and alpha was set at 0.05 for two-sided hypothesis testing. Results: Our sample included 313 patients (aged 63 ± 15, 45% females, 35% Black). The mean LVEF was 57±13%. Most patients were in normal sinus rhythm (87%) or atrial fibrillation (13%). In Bivariate analysis, there was a significant and negative correlation between T wave amplitude in lead aVR and LVEF (Pearson r = -0.173, p = 0.002). T wave amplitude in lead aVR was significantly larger in patients with LVEF < 35% compared to their counterparts (-65±185 vs. -165±180, t(311) = -3.18, p = 0.002). Conclusions: Increasing T wave amplitude in lead aVR indicates lower LVEF in suspected acute coronary syndrome. This feature constitutes a simple visual marker to aid clinicians in identifying those with impaired cardiac function during emergency care.

Abstract 10852: Stable versus Dynamic Cardiac Symptom Characteristics Are Associated With Adverse Outcomes Among Individuals Transported by Ambulance for Suspected Acute Coronary Syndrome

Introduction: Acute coronary syndrome (ACS) is a potential life-threatening emergency; therefore, rapid diagnosis and life-saving reperfusion therapies are essential to prevent adverse outcomes. Patients with suspected ACS experience an array of symptoms, which cause patients to seek care (9-1-1 or self-transport) to the emergency department [ED]). Little is known, however, about the prognostic value of symptom characteristics experienced in the very early period of evolving ACS and its impact on adverse patient outcomes. The purpose of this study was to determine if early symptom changes reported in the prehospital period are associated with adverse outcomes. Methods Adults > 21 years of age with non-traumatic chest pain and/or anginal equivalent symptoms transported by ambulance were included. Cardiac symptoms were measured prospectively with the ACS Symptom Checklist, a validated 13-item tool that takes approximately one-minute to complete. Trained EMS personnel administered the ACS Symptom Checklist during ambulance transport (T1) and research specialists measured symptoms again in the ED (T2), after acute triage care was completed. Symptom changes were categorized as an increase, decrease, or both from T1 to T2. Changes in symptoms between T1 and T2 were defined as stable (0-3 symptoms) or dynamic ( > 4 symptoms). Adverse hospital outcomes included death, reinfarction, and/or new onset heart failure. Results To date, a total of 280 patients presenting to the ED by ambulance with suspected ACS have been enrolled (mean age 60.1 + 15.5 years; 51.2% female; 14.3% final diagnosis of ACS). Of 255(91.1%) patients with complete data, 143(51.1%) experienced stable symptoms and 112(40%) experienced dynamic symptoms. Patients with stable changes had significantly higher rates of adverse outcomes compared to patients with dynamic changes (11.9 versus 2.9%, p=0.007). Patients reporting shortness of breath at T1 or T2 were over 4 times likely to experience an adverse event (p=0.003, p=0007). Conclusions Patients with suspected ACS who have stable symptom changes were more likely to have an adverse hospital outcome. The underlying mechanism of plaque rupture in ACS may account for these differences in symptom characteristics but needs further study.

Snapshot of suspected acute coronary syndrome assessment processes in the emergency department: A national cross-sectional survey.

The Snapshot of Suspected ACS Assessment (SSAASY) study aims to describe the assessment processes for patients with suspected acute coronary syndrome (ACS) in Australian EDs, and to compare these processes with the National Heart Foundation of Australia and Cardiac Society of Australia and New Zealand (NHFA/CSANZ) guidelines. Between March and May 2021, a cross-sectional survey of Australian EDs was undertaken to investigate the assessment strategies used within the ED. All public and private hospitals identified as having dedicated EDs were invited to participate. Respondents provided data on hospital, ED and cardiac service characteristics. They also provided data on the risk stratification process recommended within their department (risk scores, troponin testing, objective testing for coronary artery disease). Awareness of the NHFA/CSANZ guidelines was assessed. Responses were received from 109/162 departments (67%). Most sites (n=100, 92%) reported using dedicated protocols developed by ED clinicians that included risk stratification scores. Highly sensitive troponin assays were used at 103 (94%) sites. Serial troponin testing was performed over 2h for low-risk patients in 53 (49%) sites and 2-3h for intermediate and high-risk patients in 74 (68%) sites. Further investigations included exercise stress tests (48%) and stress echocardiography (38%), with 45% of sites ordering outpatient investigations. The SSAASY study reported the strategies used to assess suspected ACS. In line with current NHFA/CSANZ guidelines, highly sensitive troponin assays are widely utilised. However, serial sampling intervals were longer than guideline recommendations, suggesting a translational gap between guidelines and clinical practice.

ApoJ-Glyc, an early marker of myocardial ischaemia, rapidly maps improved myocardial perfusion in STEMI patients undergoing successful primary PCI

Abstract Background Previous studies using experimental models and clinical retrospective samples have pointed to a potential role of glycosylated apolipoprotein J (ApoJ-Glyc) as a marker for the early detection of myocardial ischaemia. Ischaemia induces intracellular accumulation of non-glycosylated ApoJ that mirrors the reduction in ApoJ-Glyc serum levels in patients presenting with ST-segment elevation myocardial infarction (STEMI). Purpose The EDICA (Early Detection of Myocardial Ischaemia in Suspected Acute Coronary Syndromes by Apo J-Glyc as a Novel Pathologically based Ischaemia Biomarker) clinical trial assessed the performance of ApoJ-Glyc as a biomarker for the early detection of myocardial ischaemia in patients attending the A&E department with chest pain suggestive of acute coronary syndrome. Here, we report the observed changes in ApoJ-Glyc concentration in STEMI patients at baseline and after primary percutaneous coronary intervention (PPCI). Methods The EDICA trial, a multi-centre (10 sites), international, in vitro diagnostic study, assessed 404 patients attending the A&E department with suspected ACS. Of these, 291 patients had a final diagnosis of “non-ischaemic” event and 113 of “ischaemic” event. The main inclusion criterion was chest pain of suspected cardiac origin. Blood samples were obtained for the simultaneous assessment of high sensitivity-troponin and ApoJ-Glyc on admission (time 0) and at 1h and 3h thereafter. Two different glycosylated variants of ApoJ (ApoJ-GlycA2 and ApoJ-GlycA6) were analyzed with a novel ELISA in serum samples. Of the “ischaemic” patients, 33 had STEMI, of whom 85% underwent PPCI. Results As expected, in the presence of myocardial ischaemia, time 0 ApoJ-GlycA2 and ApoJ-GlycA6 serum levels decreased by 34% and 48%, respectively in STEMI patients, compared with non-ischaemic patients, i.e. ApoJ-GlycA2 in STEMI: 66 [52–95] μg/ml vs. non-ischaemic: 100 [72–131] μg/ml; P=0.0002; ApoJ-GlycA6 STEMI: 38 [34–67] vs. non-ischaemic: 73 [56–95] μg/ml; P<0.0001. ApoJ-GlycA6 showed a discriminating ability for the presence of STEMI with a 67% sensitivity and a 83% specificity (AUC=0.747, cut-off of 50μg/ml). In STEMI patients in whom PPCI successfully restored TIMI 3 flow, ApoJ-Glyc levels increased rapidly and significantly compared with time 0 levels (ApoJ-GlycA2: P=0.02 and P=0.003 for 1h and 3h; ApoJ-GlycA6: P=0.02 and P=0.002 for 1h and 3h) and compared to patients in whom PPCI was not performed (Table 1). Conclusions ApoJ-Glyc concentrations are reduced in STEMI patients on admission and increase rapidly after improved perfusion with PPCI, pointing to a potential role of this biomarker in the early detection of reversible ischaemia and the mapping of reversible changes. The mechanisms whereby ApoJ-Glyc levels rapidly and markedly increase after PPCI are speculative at present and deserve further investigation, together with the potential prognostic value of ApoJ-Glyc in this setting. Funding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Commission 2020-EIC-SMEInstrument Phase 2; Spanish Ministry of Science, Innovation and Universities

Peak Troponin and CMR to Guide Management in Suspected ACS and Nonobstructive Coronary Arteries

BackgroundPatients presenting with acute coronary syndrome (ACS) and nonobstructive coronary arteries are a diagnostic dilemma. Cardiac magnetic resonance (CMR) has an overall diagnostic yield of ∼75%; however, in ∼25% of patients, CMR does not identify any myocardial injury. Identifying the underlying diagnosis has important clinical implications for patients’ management and outcome. ObjectivesThe authors sought to assess whether the combination of CMR and peak troponin levels in patients with ACS and nonobstructive coronary arteries would lead to increased diagnostic yield. MethodsConsecutive patients with ACS and nonobstructive coronary arteries without an obvious cause underwent CMR. The primary endpoint of the study was the diagnostic yield of CMR. The Youden index was used to find the optimal diagnostic cut point for peak troponin T to combine with CMR to improve diagnostic yield. Logistic or Cox regression models were used to estimate predictors of a diagnosis by CMR. ResultsA total of 719 patients met the inclusion criteria. The peak troponin T threshold for optimal diagnostic sensitivity and specificity was 211 ng/L. Overall, CMR has a diagnostic yield of 74%. CMR performed <14 days from presentation and with a peak troponin of ≥211 ng/L (n = 198) leads to an improved diagnostic yield (94% vs 72%) compared with CMR performed ≥14 days (n = 245). When CMR was performed <14 days and with a peak troponin of <211 ng/L, the diagnostic yield was 76% (n = 86) compared with 53% (n = 190) when performed ≥14 days. An increase in 1 peak troponin decile increases the odds of the CMR identifying a diagnosis by 20% (OR: 1.20; P = 0.008, 95% CI: 1.05-1.36). ConclusionsThe combination of CMR performed <14 days from presentation and peak troponin T ≥211 ng/L leads to a very high diagnostic yield (94%) on CMR. The diagnostic yield remains high (72%) even when CMR is performed ≥14 days from presentation, but reduces to 53% when peak troponin T was <211 ng/L.

Characteristics and Outcomes of Aboriginal and Torres Strait Islander People Presenting to the Emergency Department With Suspected Acute Coronary Syndrome

Aboriginal and Torres Strait Islander people, who experience cardiac events at younger ages compared to non-Indigenous Australians, have been underrepresented in research examining risk stratification pathways for patients who present to and emergency department (ED) with suspected acute coronary syndrome (ACS).

Abstract 12636: ECG-Based Risk Stratification of Long-Term Mortality in Suspected Acute Coronary Syndrome

Introduction: Non-invasive risk stratification can play a significant role in the initial triage of patients with suspected acute coronary syndrome. Numerous ECG features have been previously linked with mortality in both the general and cardiac populations. We sought to build an ECG-based model that can predict time-to-death in high-risk chest pain patients transported by Emergency Medical Services. Methods: This was a prospective observational cohort study of patients evaluated for suspected acute coronary syndrome. The study recruited consecutive patients evaluated at the emergency department of three UPMC-affiliated tertiary care hospitals. We included consecutive patients in whom a prehospital echocardiogram was performed during indexed encounter. Baseline ECGs were preprocessed using manufacturer specific algorithms. We evaluated 554 temporal-spatial features of the 12-lead ECG in multivariate proportional hazards Cox regression model for predicting all-cause death during long term follow up. Death was ascertained using phenotyping UPMC electronic hospital records and through the CDC National Death Index database. Model fit was evaluated using C-statistic and AIC. We set alpha at 0.01 for two-tailed hypothesis testing. Results: Our sample included 2311 patients (aged 59 ± 16.6, 47% females, 41% Black). Over a median follow up period of 1868 days (IQR = 688; [Q1, Q3] = [1511, 2199]), there was 622 (26.9%) adjudicated deaths. During univariate analysis, 288 features were significantly associated with time-to-death. In the final multivariate model (c-statistic = 0.79, AIC = 9066.05), controlling for demographic and clinical data, 15 ECG features remained predictive of the study outcome, with Selvester score being the strongest predictor (Hazard Ratio = 1.09, 95% CI = 1.03 - 1.16). Other clinically important ECG features included horizontal-plane QRS axis, QRS-T angle, QTc interval, QTpeak, T peak-end, S wave morphology the inferior leads, QRS morphology in lead aVR, and T wave morphology in the anterior leads. Conclusions: The presenting 12-lead ECG can serve as a powerful risk stratification tool of long-term mortality in patients with chest pain. Selvester score can serve as a plausible and easy to use clinical decision tool.

Abstract 6984: Cost Effectiveness of a 1-Hour High-Sensitivity Troponin-t Protocol in Suspected Acute Coronary Syndrome: A Trial-Based Analysis of the Rapid-tnt Randomised Trial

Introduction: To better understand the economic impact of an accelerated 0/1-hour high-sensitivity troponin-T (hs-cTnT) protocol compared to conventional 0/3-hour protocol, we conducted a patient-level economic analysis of the RAPID-TnT randomised trial with a 12-month follow-up in patients presenting to emergency department (ED) with suspected acute coronary syndrome (ACS). Methods: An economic evaluation was conducted with 3265 patients randomised to either the 0/1-hour hs-cTnT protocol (n=1634) or the conventional 0/3-hour protocol (n=1631). The primary outcome measure was a composite of all-cause mortality and new/recurrent myocardial infarction (MI). Results: Mean per patients costs were numerically higher in the 0/1-hour arm compared to the conventional 0/3-hour arm (by $1830.56/patient, 95% confidence interval [95%CI]: $-1610.83 - 5271.96, P=0.30) with no statistically significant difference in primary outcome (0/1-hour: 62/1634 [3.8%], 0/3-hour: 82/1631 [5.0%], HR: 1.32 [95%CI: 095-1.83], P=0.1). The mean ED length of stay (LOS) was significantly lower in the 0/1-hour arm (by 0.63 hours/patient, 95%CI: 0.34-0.92, P&lt;0.001), but the cost saving was offset but the higher cumulative emergency-related inpatient costs (by $2247.31/patient, 95%CI: -656.55 - 5151.18, P=0.12). Restricting the analysis to patients with hs-cTnT≤29ng/L, the mean per patients cost remained numerically higher in the 0/1-hour arm (by $1480.24/patient, 95%CI:$-1097.62 - 2058.10, P=0.26), but the reduction in ED LOS was more pronounced (by 0.75 hours/patient, 95%CI: 0.46-1.05, P&lt;0.001). Conclusions: This economic evaluation suggest that there were no differences in costs and outcomes between the 0/1-hour hs-cTnT protocol and the conventional 0/3-hour protocol for the assessment of suspected ACS in ED after 1 year of follow-up from the Australian healthcare system perspective. Our observations suggest that the 0/1-hour hs-cTnT protocol improves initial ED efficiency with more rapid exclusion of ACS and discharge. However, the associated cost savings were offset by the subsequent emergency inpatient costs. Further refinements in cost-effective strategies to improve clinical outcomes whilst efficiently utilising healthcare resources is needed.

Abstract 10157: Incremental Medical Expenditure and Effectiveness of Early Non-invasive Cardiac Testing in Suspected Acute Coronary Syndrome

Introduction: The relationship between medical expenditure and long-term effectiveness of early (within 72 hours) non-invasive cardiac stress testing (NIT) in reducing future acute myocardial infraction (AMI) is not well understood. We estimated the value of early NIT after an emergency department (ED) evaluation for suspected acute coronary syndrome (ACS). Methods: This was a retrospective cohort study of adult (18+) patients with chest pain, presenting at EDs within the Kaiser Permanente Southern California health system from 10/2015-12/2018. We analyzed the direct medical expenditure associated with medical office visits, hospital facility and ED visits, pharmacy utilization, hospice stays, skilled nursing stays, home health, dialysis, laboratory and radiology utilization during the one year following the index chest pain ED visit. We also identified incidence of AMI during the 1-year follow-up. We used 2-stage residual inclusion instrumental variables (IV) techniques to evaluate the marginal effect of early NIT on total all cause expenditure as well as subgroups of utilization. We used control functions IV techniques to evaluate the marginal effect of NIT on AMI and calculated the number needed to treat (NNT) as the inverse of the absolute risk reduction. All models adjusted for socio-demographics, cardiovascular disease (CVD) history and treatment and non-CVD comorbidities. Results: The cohort included 91250 patients (mean age 58 years, female 58%) and 19% received early NIT. The marginal difference in total expenditure between the early NIT vs controls was $2,583 (95% CI $591 to $4,575) and was mainly related to the index ED visit (Table 1). Those who received early NIT had slightly lower risk of AMI during the 1-year follow-up (risk reduction 1.3% (-1.9% to -0.7%) resulting in NNT of 75. Conclusions: Early NIT offers minor risk reduction of AMI but with an increase of $2583 in expenditure. With a NNT of 75, the cost to avoid one AMI is estimated to be $193,725.

98 HEART, EDACS, and TIMI: Little Value After High-Sensitivity Troponin Testing

Emergency physicians are tasked with risk stratifying patients presenting with suspected acute coronary syndromes (SACS). In the era of contemporary troponin (Tn) assays, patients with a Tn above the upper reference level (URL; 99th percentile of a healthy population) were commonly admitted, with the remaining risk-stratified by the application of their published scoring systems (eg, TIMI, EDACS, HEART) into discharge or not (observe or admit) cohorts. With the availability of high-sensitivity Tn (hsTn), the contribution of scoring systems to the risk stratification of patients with low hsTn levels is uncertain.

Correction to: 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).

Correction to: 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).

Correlation between Percentage of Reticulated Platelets and Heart Score in Patients with Suspected Non-ST Elevation Acute Coronary Syndromes

Thrombus formation in non-ST Elevation Acute Coronary Syndrome (NSTE-ACS) causes increased plateletconsumption, leading to a 20-fold increase of Reticulated Platelets (RP) release. Reticulated platelets have more granulesand proteins that make them quickly forming thrombus than mature platelets, potent to form bigger thrombus, andincrease the risk of Major Adverse Cardiac Events (MACE). HEART score is a risk stratification for possible NSTE-ACS, whichcan predict MACE. The study aimed to analyze the correlation between the percentage of reticulated platelets and HEARTscore. This research was a correlation observational cross-sectional study performed in Dr. Hasan Sadikin Hospital,Bandung, from August 2018 to May 2019. The subjects were patients suspected with NSTE-ACS by clinicians in theEmergency Department of Dr. Hasan Sadikin Hospital. These subjects were assessed for the HEART score andRP percentage. This study involved 52 subjects consisting of a higher number of males (76.9%) aged 45-64 years old (69.2%).HEART score stratification in this study was mostly high risk (69.2%), but none was low risk. Mean of platelet count, absolute3 3 RP, and RP percentage were 271±73 x103/mm , 9.3±4.3 x 103/mm , and 3.6±1.7%, respectively. The correlation testbetween RP percentage and HEART score with a 95% confidence interval using Spearman's correlation test showed asignificant positive correlation with moderate strength (p &lt; 0.001 and r=0.475). The percentage of RP in this study was in thenormal range. However, there was a significant positive correlation with moderate strength between the percentage of RPand HEART scores in patients with suspected non-ST elevation acute coronary syndrome.

A031 Non-ACS Diagnosis in Suspected Acute Coronary Syndrome and Regional Variations - An ANZACS-QI Study

Rate of invasive coronary angiography (ICA) has risen over past two decades. Many non-coronary and non-cardiac conditions can mimic acute coronary syndrome (ACS), with less than 30% of chest pain presentations being ACS. There is a potential for inappropriate and unnecessary procedural risks. This study reviews New Zealand regional variation in non-ACS diagnosis in patients suspected of ACS. Consecutive patients ≥18y presenting with their first suspected ACS and underwent coronary angiography in 2015-2019 were identified from the ANZACS-QI registry. Two cohorts were compared: 1) suspected STEMI and 2) suspected NSTEACS. Patient demographics, investigations and discharge diagnosis were obtained from the registry. 30,317 patients were identified. 6059 (20%) suspected STEMI among which the rate of false-positive diagnosis across all district health boards (DHB) was <12% and appears independent of patient volume. In comparison, a wider variation exists for suspected NSTEACS, up to 27.3%, and demonstrates a general trend of higher non-ACS diagnosis in higher volume centres. The non-ACS condition most likely to raise suspicion for ACS on presentation and undergo ICA includes stress cardiomyopathy (11.9%), arrhythmia (10.4%), stable angina (9.3%) and myocarditis (7.9%). Low rates of false-positive diagnosis for patients presenting with suspected STEMI across the nation. Comparatively, non-ACS diagnoses rate is higher particularly in higher volume centres for suspected NSTEACS. However, ICA appears to be appropriately performed as diagnostic tools for common non-ACS conditions that can mimic potentially life-threatening ACS.

An Automated Fast Healthcare Interoperability Resources-Based 12-Lead Electrocardiogram Mobile Alert System for Suspected Acute Coronary Syndrome

PurposeFor patients with time-critical acute coronary syndrome, reporting electrocardiogram (ECG) findings is the most important component of the treatment process. We aimed to develop and validate an automated Fast Healthcare Interoperability Resources (FHIR)-based 12-lead ECG mobile alert system for use in an emergency department (ED).Materials and MethodsAn automated FHIR-based 12-lead ECG alert system was developed in the ED of an academic tertiary care hospital. The system was aimed at generating an alert for patients with suspected acute coronary syndrome based on interpretation by the legacy device. The alert is transmitted to physicians both via a mobile application and the patient's electronic medical record (EMR). The automated FHIR-based 12-lead ECG alert system processing interval was defined as the time from ED arrival and 12-lead ECG capture to the time when the FHIR-based notification was transmitted.ResultsDuring the study period, 3812 emergency visits and 1581 12-lead ECGs were recorded. The FHIR system generated 155 alerts for 116 patients. The alerted patients were significantly older [mean (standard deviation): 68.1 (12.4) years vs. 59.6 (16.8) years, p<0.001], and the cardiac-related symptom rate was higher (34.5% vs. 19%, p<0.001). Among the 155 alerts, 146 (94%) were transmitted successfully within 5 minutes. The median interval from 12-lead ECG capture to FHIR notification was 2.7 min [interquartile range (IQR) 2.2–3.1 min] for the group with cardiac-related symptoms and 3.0 min (IQR 2.5–3.4 min) for the group with non-cardiac-related symptoms.ConclusionAn automated FHIR-based 12-lead ECG mobile alert system was successfully implemented in an ED.