Two-dimensional strain echocardiography differentiates cardiac amyloidosis from hypertrophic cardiomyopathy with preserved ejection fraction

Background: Ejection fraction is a poor parameter to assess left ventricular function in ventricular hypertrophy. It is highlyimportant to analyze aspects of ventricular mechanics that could differentiate cardiac amyloidosis from hypertrophic cardiomyopathy.Objective: The aim of this study was to compare longitudinal strain and other ventricular mechanical parameters betweenpatients with hypertrophic cardiomyopathy and cardiac amyloidosis, both with preserved ejection fraction.Methods: A comparative, prospective study was conducted in 15 patients with cardiac amyloidosis [Group (G) 1] and 15 patientswith hypertrophic cardiomyopathy (G2), both presenting preserved ejection fraction (>50%). Patients were analyzedwith speckle tracking echocardiography and strain and left ventricular (LV) rotational parameters. Longitudinal strain wasobtained from apical 4-, 3- and 2-chamber planes. Circumferential strain and ventricular rotation were obtained from LVtransverse planes. Twist: algebraic sum of apical and basal rotation (°), torsion [twist/LV base-apex distance (º/cm)] and thenew parameters: deformation product (global longitudinal strain × apical circumferential strain); deformation index: [twist/longitudinal strain (°/%)] and ejection fraction/global longitudinal strain ratio were calculated.Results: Patients with cardiac amyloidosis presented significantly lower ejection fraction (58.08%±6.16 vs. 67.15%±8.09;p=0.012) and global longitudinal strain values (–12.61%±4.32 vs. –17.15%±3.95; p=0.008) at the expense of basal segments.No significant differences were found for twist, torsion, and circumferential and radial strain. The product between longitudinalstrain and apical circumferential strain decreased, while the ejection fraction/global longitudinal strain ratio wassignificantly increased in patients with cardiac amyloidosis.Conclusions: The product of longitudinal strain × apical circumferential strain and the ejection fraction/global longitudinalstrain ratio are useful parameters that allow differentiating cardiac amyloidosis from hypertrophic cardiomyopathy patients.Introducción. La fracción de eyección (FEy) es un parámetro débil para evaluar la función ventricular en la hipertrofia ventricular. Es de fundamental importancia analizar aspectos de la mecánica ventricular que podrían diferenciarlas. Objetivo. Comparar el comportamiento del strain longitudinal y otros parámetros de la mecánica ventricular entre pacientes con miocardiopatía  hipertrófica (MCH) y Amilo dosis Cardíaca (AC)  ambos con FEY conservada. Metodología. Estudio comparativo, prospectivo realizado en 15 ptes con AC) (Grupo [G] 1) y 15 ptes con MCH [G] 2), ambos con FEy conservada (> 50%).Analizados con ecocardiografía speckle-tracking parámetros de strain y rotacionales del VI. El Strain Longitudinal (SL) se obtuvo a partir de planos apicales de 4, 3, y 2 cámaras. El Strain Circunferencial (SC) y la rotación ventricular a partir de planos transversales del VI. Se calculó el Giro: sumación de rotación apical y basal (º), Torsión (Giro /Distancia Base-Ápex del VI (°/cm))  y los nuevos parámetros: Producto de Deformación: (multiplicación entre el SLG y el SC apical); Índice de Deformación (°/%): (Giro/ SL), y (FEy/SL). Resultados. Los ptes con AC presentaron valores significativamente menores de FEy (58.08 % ± 6.16 vs 67.15 % ± 8.09; p=0.012) y de SL global (-12.61 % ± 4.32 vs -17.15 % ± 3.95; p=0.008) a expensas de los segmentos basales. Sin diferencias significativas con el Giro, la Torsión, el SC y el SR. El producto SL v SCa están disminuidos mientras que el cociente FEy/SLG se encuentra aumentado de manera significativa Conclusiones. El producto SL x SC apical y el cociente FEy/SLG son parámetros útiles que permiten diferenciar ptes con AC de ptes con  MCH

The Reservoir Function. Functional Evaluation of the Left Atrium by Two-dimensional Strain during Rest and Exercise Stress

Background: According to different guidelines, the echocardiographic evaluation of left atrial function based on dimensions, areas, volumes and diastolic function through pulsed-wave Doppler interrogation is fundamental, as left atrial dilatation has been shown to be a predictor of adverse cardiovascular events. The advent of new echocardiographic techniques has allowed the assessment of atrial deformation (strain) with curves that identify the reservoir, conduit and contractile function. However, there is still no consensus to define left atrial strain by speckle tracking in normal patients and its response with exercise. Objectives: The aim of this study was to establish the left atrial strain reference value at rest and during peak exercise stress echocardiography in healthy patients and to analyze the relationship between deformation and the E/e’ ratio to assess changes in atrial stiffness. Methods: This was a descriptive, prospective, observational study, including patients over 18 years of age, with no cardiovascular risk factors or previous history of comorbidities, who underwent an exercise stress echocardiography test between January and March 2017. A Vivid E 95 ultrasound system (GE Healthcare) was used, with 5MS MHz transducer and image acquisition frame rate between 60 and 70 frames per second at rest, and between 80 and 100 during exercise. Loops were obtained in 4-chamber and 2-chamber views, both at rest and at maximum exercise load, and were analyzed offline with EchoPac 201 software. Strain was measured tracing the borders of the left atrium at 1 mm from the mitral valve annulus, and manually adjusting the width of the region of interest to cover atrial wall thickness. The 6 segments were considered for each view and the average value of the curve corresponding to the reservoir was analyzed, as it was the most representative and reproducible. The average E/e’/left atrial strain × 100 ratio was used to calculate atrial stiffness. For the statistical analysis, categorical variables were expressed as percentages; quantitative variables were expressed as mean±SD and compared using paired t test. Significance was established for p <0.05. Results: Among the 34 patients meeting the inclusion criteria, 3 were excluded due to poor echocardiographic window at rest and 2 during exercise. Mean age of the remaining 29 patients (85% total feasibility) was 50±10.6 years and 16 were men. Intraobserver variability of reservoir calculated at rest and during exercise was 2.2±1.6% and 2.3±2.5%, respectively, and interobserver variability 6±7% and 4.6±4%. Conclusions:  In normal patients it was possible to assess left atrial reservoir function at rest and during maximum exercise stress with a significant increase of deformation and without changes in atrial stiffnessIntroducción: El estudio ecocardiográfico de la función global auricular izquierda, según guías, se basa en la medición de dimensiones, áreas, volúmenes y la función diastólica mediante la interrogación con Doppler pulsado. Su importancia es trascendental, ya que su dilatación ha demostrado ser un predictor de eventos cardiovasculares adversos. Con el advenimiento de las nuevas técnicas ecocardiográficas es posible evaluar la mecánica de la deformación de la pared auricular (strain) con curvas que identifican la función de reservorio, conducto y contracción. Sin embargo, aún no hay consenso para definir el valor de strain auricular izquierdo, determinado mediante speckle tracking, en pacientes normales y su respuesta con el ejercicio. Objetivos: Establecer el valor de referencia de strain auricular izquierdo en pacientes sanos en reposo y durante el pico de un ecoestrés de esfuerzo. Además, analizar la relación de la deformación con la E/e´ para determinar los cambios de rigidez auricular. Metodología: Estudio descriptivo, prospectivo, observacional. Se incluyeron los pacientes mayores de 18 años, sanos, sin factores de riesgo cardiovascular, ni antecedentes patológicos a los que se realizó un ecoestrés con ejercicio entre enero y marzo 2017. Se utilizó un Vivid E 95 (GE Healthcare), con transductor 5MS MHz, con adquisición de las imágenes con un frame rate entre 60-70 en reposo y entre 80-90 en el esfuerzo. Los loops se obtuvieron en las vistas de 4 cámaras y 2 cámaras, tanto en reposo como a la máxima carga de ejercicio y se analizaron offline (EchoPac Version 201). Para la medición de strain, se trazaron los bordes de la AI, a 1 mm de distancia del anillo de la válvula mitral, y se ajustó de manera manual el ancho de la zona de interés en relación con el espesor de la pared auricular. Se consideraron los 6 segmentos por cada vista y se analizó el valor promedio de la curva correspondiente al reservorio por ser la más representativa y reproducible. Para el valor de rigidez auricular se calculó el promedio E/e´/strain AI × 100. En el análisis estadístico, las variables categóricas se expresan como porcentaje y las cuantitativas como media ± DS y se comparan con la prueba de t para muestras pareadas. Se consideró significativa una p < 0,05. Resultados: De 34 pacientes con criterios de inclusión se excluyeron a 3 por mala ventana ecocardiográfica en reposo y 2 en el esfuerzo. De los 29 pacientes analizados (factibilidad total 85%), 16 fueron hombres con una media de edad de la población de 50 ± 10,6 años. La variabilidad intraobservador del cálculo del reservorio en reposo y esfuerzo fue del 2,2 % ± 1,6 y 2,3% ± 2,5 e interobservador de 6% ± 7 y 4,6% ± 4, respectivamente. Conclusiones: En una población normal resultó factible evaluar la función del reservorio de la aurícula izquierda en reposo y durante el esfuerzo máximo con un incremento significativo de la deformación, sin cambios de la rigidez auricular

Stress Echo 2030: the new ABCDE protocol defining the future of cardiac imaging

Functional testing with stress echocardiography is based on the detection of regional wall motion abnormality with two-dimensional echocardiography and is embedded in clinical guidelines. Yet, it under-uses the unique versatility of the technique, ideally suited to describe the different functional abnormalities underlying the same wall motion response during stress. Five parameters converge conceptually and methodologically in the state-of-the-art ABCDE protocol, assessing multiple vulnerabilities of the ischemic patient. The five steps of the ABCDE protocol are (1) step A: regional wall motion; (2) step B: B-lines by lung ultrasound assessing extravascular lung water; (3) step C: left ventricular contractile reserve by volumetric two-dimensional echocardiography; (4) step D: coronary flow velocity reserve in mid-distal left anterior descending coronary with pulsed-wave Doppler; and (5) step E: assessment of heart rate reserve with a one-lead electrocardiogram. ABCDE stress echo offers insight into five functional reserves: epicardial flow (A); diastolic (B), contractile (C), coronary microcirculatory (D), and chronotropic reserve (E). The new format is more comprehensive and allows better functional characterization, risk stratification, and personalized tailoring of therapy. ABCDE protocol is an 'ecumenic' and 'omnivorous' functional test, suitable for all stresses and all patients also beyond coronary artery disease. It fits the need for sustainability of the current era in healthcare, since it requires universally available technology, and is low-cost, radiation-free, and nearly carbon-neutral

Registro multicéntrico prospectivo de pacientes hospitalizados por síndrome coronario agudo sin elevación del segmento ST en centros de alta complejidad. Resultados intrahospitalarios y evolución a 6 meses (Buenos Aires I)

Background: Non-ST elevation acute coronary syndrome (NSTE-ACS) management has evolved over the past years, based on newpharmacological agents and progress in revascularization techniques. The aim of this study was to analyze the current managementof NSTE-ACS in high complexity centers of the city of Buenos Aires and the province of Buenos Aires.Methods: Patients hospitalized in 21 centers with coronary care unit, 24-hour catheterization lab availability and cardiovascularsurgery were prospectively enrolled in the study and followed up for 6 months after hospital discharge.Results: The registry included 1,100 consecutive patients: 61% corresponded to non-ST-segment elevation myocardial infarction and37.4% were unstable angina. Mean age was 65.4 ± 11.5 years and 77.2% were men; 27.6% had diabetes mellitus and 31.5% previousmyocardial infarction. An early invasive management was used in 86.7% of cases with a median time to coronary angiography of 18hours (IQR 7-27.7). During hospitalization, 5.2% of the patients presented reinfarction, 0.3% stroke and overall mortality was 2.7%.The rate of bleeding events ≥ BARC type 2 was 10.1%. At 6-month follow-up, the rates of reinfarction, ACS and overall mortalitywere 8.4%, 10.9% and 5.7%, respectively.Conclusions: The registry demonstrated a predominantly invasive therapeutic approach in patients with NSTE-ACS treated in highcomplexity centers with low rates of in-hospital complications and during follow-up.Introducción: El manejo de los síndromes coronarios agudos (SCA) sin elevación del segmento ST (SCASEST) ha sufrido cambios en los últimos años, basados en nuevos agentes farmacológicos y el avance de las técnicas de revascularización coronaria. El objetivo de este estudio fue determinar cómo es el manejo de los SCASEST en la actualidad en centros de alta complejidad de la ciudad y la provincia de Buenos Aires. Métodos: Se registraron en forma prospectiva pacientes hospitalizados en 21 centros con servicio de unidad coronaria, hemodinamia disponible las 24 horas y cirugía cardíaca. Se realizó seguimiento a 6 meses. Resultados: Se incluyeron 1100 pacientes consecutivos, un 62,6 % fue catalogado como infarto sin elevación del ST y 37,4 % como angina inestable. La edad media fue de 65,4 ± 11,5 años, con un 77,2 % de sexo masculino. Un 27,6 % presentaba diabetes mellitus y el 31,5 % infarto previo. El manejo inicial fue invasivo en el 86,7 %, con una mediana de tiempo a la cinecoronariografía de 18 horas (RIC 7-27,7). En la evolución intrahospitalaria, la incidencia de nuevo infarto fue del 5,2 %, el accidente cerebrovascular de 0,3 % y mortalidad total 2,7 %. La tasa de sangrado BARC ³ 2 fue del 10,1 %. En el seguimiento a 6 meses, la tasa de infarto fue de 8,4 %, SCA 10,9 % y la mortalidad total de 5,7 %. Conclusiones: El registro evidenció un abordaje terapéutico predominantemente invasivo de los pacientes con SCASEST en centros con alta complejidad, con baja prevalencia de complicaciones intrahospitalarias y en la evolució

Usefulness of the HEART Score with High-Sensitivity Troponin T for the Evaluation of Patients with Chest Pain

Background: The HEART score consists of a simple test designed to stratify patients who consult the emergency departmentfor chest pain, according to their risk of presenting an acute coronary syndrome in the short term. It was initially createdwith a fourth-generation troponin, but the advent of high-sensitivity cardiac troponin T required its incorporation into thescore and the re-evaluation of its behavior.Objectives: The aim of this study was to evaluate the behavior of the HEART score with high sensitivity cardiac troponin T.Methods: A prospective study was conducted including 1,464 patients who consulted at the emergency department due chestpain, with a non-ST-segment elevation electrocardiogram. The incidence of MACE (composite of acute myocardial infarction,death and revascularization) at 30 days was evaluated.Results: The index classified 739 patients (50.5%) as low risk, 515 (35.2%) as intermediate risk and 210 (14.3%) as high riskpatients. The composite of acute myocardial infarction, death and revascularization incidence was 1.35% in the first group,20%, in the second group and 71%, in the third group (log-rank test p<0.001). The area under the global curve for the compositeof acute myocardial infarction, death and revascularization was 0.91 (0.89-0.93).Conclusions: The HEART score using high-sensitivity cardiac troponin T has a great capacity to classify patients with chestpain according to their risk of presenting cardiovascular events in the short term.Introducción: El score HEART consiste en una prueba sencilla que fue diseñada para estratificar a los pacientes que consultanal servicio de emergencias por dolor torácico, según su riesgo de presentar un síndrome coronario agudo a corto plazo. Fuecreado inicialmente con troponina de cuarta generación, pero el advenimiento de la troponina de alta sensibilidad impuso suincorporación al score y la reevaluación de su comportamiento.Objetivo: Nos propusimos evaluar el comportamiento del score HEART con troponina de alta sensibilidad.Material y métodos: Se realizó un estudio prospectivo que incluyó 1464 pacientes (p) que consultaron al servicio de emergenciapor dolor torácico y que tenían electrocardiograma sin elevación del segmento ST. Se evaluó la incidencia de MACE (combinadode infarto agudo de miocardio, muerte y revascularización) a 30 días.Resultados: El índice clasificó 739 pacientes (50,5 %) como de bajo riesgo, 515 pacientes (35,2%) de riesgo intermedio y 210pacientes (14,3%) de alto riesgo. La incidencia de la combinación de infarto agudo de miocardio, muerte y revascularizaciónfue del 1,35% en el primer grupo; del 20%, en el segundo; y del 71%, en el tercero (long rank test p < 0,001). El área bajo lacurva global para la combinación de infarto agudo de miocardio, muerte y revascularización fue de 0,91 (0,89-0,93).Conclusiones: El score HEART que utiliza troponina de alta sensibilidad tiene una gran capacidad para clasificar pacientescon dolor torácico de acuerdo con su riesgo de presentar eventos cardiovasculares en el corto plazo

Results of the First Patients with Suspected Acute Coronary Syndrome Evaluated with the 1-hour Algorithm Proposed by the European Society of Cardiology

Background: The European Society of Cardiology (ESC) recommends an algorithm for the evaluation of chest pain with serialmeasurement of two high sensitivity troponins separated by one hour. However, the high efficacy and safety of the algorithmhas only been estimated according to assumptions based on theoretical models. We tested for the first time its performancein the real world by incorporating it into the daily routine of our center.Methods: This is a prospective, single center study using the ESC 0/1h algorithm with high sensitivity troponin T on unselectedpatients who presented at the emergency department with suspected non-ST-segment elevation acute myocardial infarction.Efficacy and safety were assessed in terms of the 30-day incidence of acute myocardial infarction, cardiovascular death andthe composite of acute myocardial infarction, death or coronary revascularization.Results: A total of 1,351 patients were included in the study. Mean age was 61±14 years, 12.4% were diabetics and 35.8% hadprevious history of coronary events. The rate of acute myocardial infarction was 11% and the rate of mortality 0.29%. Accordingto the application of the algorithm, 917 patients were catalogued as “rule out” (67%), 270 as “observe” (20%) and 164 as “rulein” (13%). The rate of acute myocardial infarction was 0.3% in “rule out”, 7% in “observe” and 77.4% in “rule in” (p <0.001).Moreover, death or coronary revascularization was 7.7% in “rule out”, 17.7% in “observe” and 80.4% in “rule in” (p <0.001).Conclusions: The 1-hour algorithm showed a good capacity to stratify patients presenting with suspicion of acute myocardialinfarction and a high negative predictive value to exclude infarction at 30 days, although this capacity decreases when theevent considered is the need for coronary revascularization.Introducción: La troponina de alta sensibilidad ha significado un aporte para el manejo de pacientes con dolor torácico. En los últimos años se han diseñado en Europa algoritmos rápidos con la medición seriada de 2 troponinas separadas por una hora. Nuestro objetivo fue validar prospectivamente dicho algoritmo con nuestros pacientes. Métodos: Evaluamos 1041 pacientes consecutivos que se presentaron con sospecha de infarto agudo de miocardio (IAM). El punto final primario fue el IAM a 30 días y el punto final secundario la tasa de revascularización coronaria a los 30 días. Resultados: La edad media de los pacientes fue de 61 ± 9 años, con un 67 % de hombres, 17,5 % de diabéticos y 35,9 % de evento coronario previo. La tasa de IAM fue del 10,3 % con una mortalidad del 0,19 %. De acuerdo a la aplicación del algoritmo  684 p fueron catalogados como “externar” (65,7%), 243 como “observar” (23,3 %) y 114 como “internar” (11%). La tasa del evento primario resultó de 0,3 % en “externar”, 6,6 % en “observar” y 78,9 % en “internar” (p<0,001). Por su lado la tasa del evento secundario resultó de 4,8 % en “externar”, 14,7 % en “observar” y 65,7 % en “internar” (p<0,001). Conclusión: El algoritmo de 1 hora presentó una buena capacidad para estratificar a las personas que consultan con sospecha de infarto agudo de miocardio con un gran valor predictivo negativo para excluir el evento de infarto a los 30 días, aunque dicha capacidad disminuye cuando el evento considerado es la necesidad de revascularización coronaria

Long Term Prognostic Value of Contractile Reserve Assessed by Global Longitudinal Strain in Patients with Asymptomatic Severe Aortic Stenosis

Background. Left ventricle (LV) global longitudinal strain (GLS) at rest has shown prognostic value in patients (pts) with severe aortic stenosis (SAS). Contractile reserve (CR) during exercise stress echo (ESE) estimated via GLS (CR-GLS) could better stratify the asymptomatic patients who could benefit from early intervention. Aims. To determine the long-term prognostic value of CR-GLS in patients with asymptomatic SAS with an ESE without inducible ischemia. Additionally, to compare the prognostic value of CR assessed via ejection fraction (CR-EF) and CR-GLS. Methods. In a prospective, single-center, observational study between 2013 and 2019, 101 pts with asymptomatic SAS and preserved left ventricular ejection fraction (LVEF) &gt; 55% were enrolled. CR was considered present with an exercise-rest increase in LVEF (Simpson&rsquo;s rule) &ge; 5 points and &gt; 2 absolute points in GLS. Patients were assigned to 2 groups (G): G1: 56 patients with CR-GLS present; and G2: 45 patients CR-GLS absent. All patients were followed up. Results. G2 Patients were older, with lower exercise capability, less aortic valve area (AVA), a higher peak aortic gradient, and less LVEF (71.5% &plusmn; 5.9 vs. 66.8% &plusmn; 7.9; p = 0.002) and GLS (%) at exercise (G1: &minus;22.2 &plusmn; 2.8 vs. G2: &minus;18.45 &plusmn; 2.4; p = 0.001). During mean follow-up of 46.6 &plusmn; 3.4 months, events occurred in 45 pts., with higher incidence in G2 (G2 = 57.8% vs. G1 = 42.2%, p &lt; 0.01). At Cox regression analysis, CR-GLS was an independent predictor of major cardiovascular events (HR: 1.98, 95% CI 1.09&ndash;3.58, p = 0.025). Event-free survival was lower for patients with CR-GLS absent (log rank test p = 0.022). CR-EF was not outcome predictive (log rank test p 0.095). Conclusions: In patients with asymptomatic SAS, the absence of CR-GLS during ESE is associated with worse prognosis. Additionally, CR-GLS was a better predictor of events than CR-EF

Vasodilator Strain Stress Echocardiography in Suspected Coronary Microvascular Angina

Background: In patients with Ischemia and non-obstructive coronary artery stenosis (INOCA) wall motion is rarely abnormal during stress echocardiography (SE). Our aim was to determine if patients with INOCA and reduced coronary flow velocity reserve (CVFR) have altered cardiac mechanics using two-dimensional speckle-tracking echocardiography (2DSTE) during SE. Methods: In a prospective, multicenter, international study, we recruited 135 patients with INOCA. Overall, we performed high dose (0.84 mg/kg) dipyridamole SE with combined assessment of CVFR and 2DSTE. The population was divided in patients with normal CVFR (>2, group 1, n = 95) and abnormal CVFR (≤2, group 2, n = 35). Clinical and 2DSTE parameters were compared between groups. Results: Feasibility was high for CFVR (98%) and 2DSTE (97%). A total of 130 patients (mean age 63 ± 12 years, 67 women) had complete flow and strain data. The two groups showed similar 2DSTE values at rest. At peak SE, Group 1 patients showed lower global longitudinal strain (p p p p Conclusions: In patients with INOCA, vasodilator SE with simultaneous assessment of CFVR and strain is highly feasible. Coronary microvascular dysfunction is accompanied by an impairment of global and layer-specific deformation indices during stress

Outcome of Applying the ESC 0/1-hour Algorithm in Patients With Suspected Myocardial Infarction.

BACKGROUND The European Society of Cardiology (ESC) recommends the 0/1-h algorithm for rapid triage of patients with suspected non-ST-segment elevation myocardial infarction (MI). However, its impact on patient management and safety when routinely applied is unknown. OBJECTIVES This study sought to determine these important real-world outcome data. METHODS In a prospective international study enrolling patients presenting with acute chest discomfort to the emergency department (ED), the authors assessed the real-world performance of the ESC 0/1-h algorithm using high-sensitivity cardiac troponin T embedded in routine clinical care and its associated 30-day rates of major adverse cardiac events (MACE) (the composite of cardiovascular death and MI). RESULTS Among 2,296 patients, non-ST-segment elevation MI prevalence was 9.8%. In median, 1-h blood samples were collected 65 min after the 0-h blood draw. Overall, 94% of patients were managed without protocol violations, and 98% of patients triaged toward rule-out did not require additional cardiac investigations including high-sensitivity cardiac troponin T measurements at later time points or coronary computed tomography angiography in the ED. Median ED stay was 2 h and 30 min. The ESC 0/1-h algorithm triaged 62% of patients toward rule-out, and 71% of all patients underwent outpatient management. Proportion of patients with 30-day MACE were 0.2% (95% confidence interval: 03% to 0.5%) in the rule-out group and 0.1% (95% confidence interval: 0% to 0.2%) in outpatients. Very low MACE rates were confirmed in multiple subgroups, including early presenters. CONCLUSIONS These real-world data document the excellent applicability, short time to ED discharge, and low rate of 30-day MACE associated with the routine clinical use of the ESC 0/1-h algorithm for the management of patients presenting with acute chest discomfort to the ED