Characteristics of Patients With Acute Coronary Syndrome and Normal Electrocardiogram.

Background: Patients with acute coronary syndrome (ACS) and normal electrocardiogram (ECG) may have an increased risk of late diagnosis and complications of the disease. Objective: To study the demographic, angiographic and echocardiographic characteristics of patients hospitalized for ACS in whom the ECG was normal on admission to the hospital. Methods: This retrospective study included patients who were hospitalized for ACS without ST-elevation between 2015 and 2023 and who had coronary artery disease (CAD) confirmed by coronary angiography. By further inspection of the electronic databases, patients with ACS who had a normal ECG on admission were filtered out and analyzed separately. Results: Of the total 3137 patients with suspected ACS without ST-elevation, 129 patients (4.1%) were diagnosed as having ACS with a normal ECG. In three patients a non-atherosclerotic cause for the ACS was found. A significantly higher proportion of patients had single-vessel (54.3%) compared to two-vessel (29.5%) and three-vessel (14%) CAD. In addition to a normal ECG, 5.7% of patients with single-vessel CAD and 3.5% of patients with multi-vessel CAD had normal troponin levels and normal regional LV systolic function on echocardiography. Conclusion: Less than 5% of hospitalized patients with ACS without ST-elevation had a normal ECG on admission. The majority of these patients have single-vessel CAD. In about 5% of patients with single-vessel CAD, neither elevated troponin levels nor LV asynergy are detected.

Myosin's powerstroke transitions define atomic scale movement of cardiac thin filament tropomyosin.

Dynamic interactions between the myosin motor head on thick filaments and the actin molecular track on thin filaments drive the myosin-crossbridge cycle that powers muscle contraction. The process is initiated by Ca2+ and the opening of troponin-tropomyosin-blocked myosin-binding sites on actin. The ensuing recruitment of myosin heads and their transformation from pre-powerstroke to post-powerstroke conformation on actin produce the force required for contraction. Cryo-EM-based atomic models confirm that during this process, tropomyosin occupies three different average positions on actin. Tropomyosin pivoting on actin away from a TnI-imposed myosin-blocking position accounts for part of the Ca2+ activation observed. However, the structure of tropomyosin on thin filaments that follows pre-powerstroke myosin binding and its translocation during myosin's pre-powerstroke to post-powerstroke transition remains unresolved. Here, we approach this transition computationally in silico. We used the myosin helix-loop-helix motif as an anchor to dock models of pre-powerstroke cardiac myosin to the cleft between neighboring actin subunits along cardiac thin filaments. We then performed targeted molecular dynamics simulations of the transition between pre- and post-powerstroke conformations on actin in the presence of cardiac troponin-tropomyosin. These simulations show Arg 369 and Glu 370 on the tip of myosin Loop-4 encountering identically charged residues on tropomyosin. The charge repulsion between residues causes tropomyosin translocation across actin, thus accounting for the final regulatory step in the activation of the thin filament, and, in turn, facilitating myosin movement along the filament. We suggest that during muscle activity, myosin-induced tropomyosin movement is likely to result in unencumbered myosin head interactions on actin at low-energy cost.

Comparison of Del Nido (a different application) and crystalloid blood cardioplegia on arrhythmia and early results.

BACKGROUND: The results of the use of del-Nido(DN) solution using a different method or crystalloid blood cardioplegia in coronary bypass patients were compared. We aimed to investigate the effects on intraoperative and postoperative arrhythmias, arrhythmia durations and early results. METHODS: The study included 175 patients using crystalloid blood cardioplegia (Group 1) and 150 patients using DN solution(Group 2). In the DN group, 75% of the calculated plegia dose was given first. the remaining part was applied by giving from grafts. Intraoperative/postoperative data were compared. RESULTS: There was no significant difference between the groups in terms of demographic characteristics. Preop troponin level was similar.(p = 0.190) However, there was a statistical difference between the postoperative 6th hour.(p = 0.001) There was no difference in troponin values at the postoperative 24th hour. (p = 0.631) Spontaneous rhythm occurred at the cardiopulmonary by pass (CPB) weaning stage in most of the patients in Group 2 (95.3%). Although the need for temporary pacing was less in Group 2, it was not significant.(p = 0.282) No patient required permanent pacing. CPB duration, cross clamp times and intraoperative glucose levels, intensive care follow-up times and hospitalization times were found to be shorter in Group 2. Although the postoperative atrial fibrillation frequency was similar (p = 0.261), the time to return to sinus was lower in Group 2.(p = 0.001). CONCLUSION: The use of DN cardioplegia solution provides significant positive contributions to avoid arrhythmias compared to crystalloid blood cardioplegia. DN solution applied with this method may contribute to reducing the anxieties associated with its use in isolated coronary artery bypass surgery.

Ablação septal por radiofrequência na cardiomiopatia hipertrófica obstrutiva: a troponina é bom marcador de sucesso terapêutico? / Radiofrequency septal ablation in obstructive hypertrophic cardiomyopathy: is troponin a good marker of therapeutic success?

INTRODUÇÃO: A terapia de redução septal na Cardiomiopatia Hipertrófica Obstrutiva (CMHO) é indicada quando há sintomas refratários à terapêutica otimizada. Dentre estas terapias, recentemente foi proposta a ablação septal por radiofrequência (RF) com cateteres utilizados na eletrofisiologia para ablação de arritmias atriais e ventriculares. A ablação por RF é realizada com auxílio de ecocardiograma transesofágico com melhor controle da área abordada e redução do risco de lesões ao sistema de condução. Este trabalho tem como intuito apresentar uma série de casos de pacientes com CMHO que foram abordados por meio de ablação septal por RF, avaliando-se se a elevação dos níveis séricos de troponina, se correlacionam com a redução do gradiente intraoperatório e sucesso terapêutico. MÉTODOS: Estudo observacional, do tipo coorte histórica por análise de prontuário. As variáveis foram descritas por estatísticas de posição e escala para variáveis contínuas e frequências absolutas e relativas para variáveis categóricas (ou categorizadas). As análises foram realizadas com auxílio do software R (R Core Team, 2022). E os testes de hipótese utilizarão nível de significância de 5%. RESULTADOS: Analisaram-se 36 pacientes, sendo 18 (50%) do sexo masculinos. A troponina foi dosada no pré-operatório e no pós-operatório imediato, porém foi realizada usando tipos diferentes entre os pacientes, seguindo descrita como número de vezes acima do valor de referência. Observou-se uma elevação acima dos valores de referência em 83,3% dos pacientes analisados, e antes do procedimento, dois pacientes já apresentavam troponina acima do valor de referência, e se mantiveram acima após. Também se observou uma redução do GVSVE no intraoperatório de 38.3mmHg [30.7 a 45.8] com p<0,01. O gráfico 1 apresenta a relação do logaritmo do número de vezes da troponina acima do valor de referência contra o gradiente máximo pós-procedimento e das respectivas diferenças em relação ao valor de base (pré-procedimento). A correlação de Spearman foi respectivamente 0,47 (p = 0,065), não evidenciando uma correlação entre os achados. Gráfico 1. Dispersão do logaritmo diferença do número de vezes da troponina acima do valor de referência contra a redução gradiente máximo pós-procedimento. CONCLUSÃO: Apesar dos valores de troponina estarem maiores pós procedimento, concluímos que a troponina não deve ser usada como marcador de sucesso terapêutico.

Biochemical and Hematological Profile of Covid-19 Patients on Mechanical Ventilation.

Beakground: The prevalence of cardiovascular diseases in COVID-19 patients, such as hypertension, diabetes mellitus, and chronic obstructive pulmonary disease, which are the most common comorbid conditions in COVID-19 patients, is considered a risk factor for premature mortality in the population. The aim of the study is to compare the standard biochemical and hematological markers of COVID-19 patients on mechanical ventilation and those who have recovered, and to identify differences by gender and comorbidities, as well as the dominant marker in comorbidities that frequently shows statistical significance, in order to investigate its prognostic value in further research. METHODS: The study is a retrospective study of patients with RT-PCR confirmed presence of the Sars-CoV-2 virus who were hospitalized at the Zenica Cantonal Hospital. The study lasted from February to April 2021. RESULTS: The results of the study, which included a sample of 302 participants, indicate that men were more represented in both the mechanical ventilation group and the recovered group, with 59.6% compared to women with 40.4%. Among the investigated biochemical and hematological parameters, there was a significantly higher number of leukocytes, urea, creatinine, LDH, and troponin in patients on mechanical ventilation, while the number of platelets was significantly higher in recovered patients. The most common comorbidity was hypertension in both groups of patients, with 24.5%. In patients on mechanical ventilation with cardiovascular disease, there was a significantly higher number of leukocytes, urea, creatinine, LDH, and troponin. In the same patients with three comorbidities, there was a significantly higher number of leukocytes, troponin, and LDH, while recovered patients without comorbidities had a significantly higher number of platelets. CONCLUSIONS: The male gender and comorbidities remain a vicious circle in COVID-19 infection, while biochemical and hematological markers can help in forecasting and improve the clinical treatment of these high-risk patients.

Could paramedics use the HEART Pathway to identify patients at low-risk of myocardial infarction in the prehospital setting?

In the Emergency Department, patients with suspected myocardial infarction can be risk stratified using the HEART pathway, which has recently been amended for prehospital use and modified for the incorporation of a high-sensitivity cardiac troponin test. In a prospective analysis, the performance of both HEART pathways in the prehospital setting, with a high-sensitivity cardiac troponin test using 3 different thresholds, was evaluated for major adverse cardiac events at 30 days. We found that both low-risk HEART pathways, when using the most conservative cardiac troponin thresholds, approached but did not reach accepted rule-out performance in the Emergency Department.

Comparison of troponin and natriuretic peptides in Takotsubo syndrome and acute coronary syndrome: a meta-analysis.

OBJECTIVE: Takotsubo syndrome (TTS) is an acute heart failure syndrome which resembles acute coronary syndrome (ACS) at presentation. Differentiation requires coronary angiography, but where this does not occur immediately, cardiac biomarkers may provide additional utility. We performed a meta-analysis to compare troponin and natriuretic peptides (NPs) in TTS and ACS to determine if differences in biomarker profile can aid diagnosis. METHODS: We searched five literature databases for studies reporting NPs (Brain NP (BNP)/NT-pro-BNP) or troponin I/T in TTS and ACS, identifying 28 studies for troponin/NPs (5618 and 1145 patients, respectively). RESULTS: Troponin was significantly lower in TTS than ACS (standardised mean difference (SMD) -0.86; 95% CI, -1.08 to -0.64; p<0.00001), with an absolute difference of 75 times the upper limit of normal (×ULN) higher in ACS than TTS. Conversely, NPs were significantly higher in TTS (SMD 0.62; 95% CI, 0.44 to 0.80; p<0.00001) and 5.8×ULN greater absolutely. Area under the curve (AUC) for troponin in ACS versus TTS was 0.82 (95% CI, 0.70 to 0.93), and 0.92 (95% CI, 0.80 to 1.00) for ST-segment elevation myocardial infarction versus TTS. For NPs, AUC was 0.69 (95% CI, 0.48 to 0.89). Combination of troponin and NPs with logistic regression did not improve AUC. Recursive Partitioning and Regression Tree analysis calculated a troponin threshold ≥26×ULN that identified 95% cases as ACS where and specificity for ACS were 85.71% and 53.57%, respectively, with 94.32% positive predictive value and 29.40% negative predictive value. CONCLUSIONS: Troponin is lower and NPs higher in TTS versus ACS. Troponin had greater power than NPs at discriminating TTS and ACS, and with troponin ≥26×ULN patients are far more likely to have ACS.

The CRP troponin test (CTT) stratifies mortality risk in patients with non-ST elevation myocardial infarction (NSTEMI).

INTRODUCTION: The C-reactive protein (CRP)-troponin-test (CTT) comprises simultaneous serial measurements of CRP and cardiac troponin and might reflect the systemic inflammatory response in patients with acute coronary syndrome. We sought to test its ability to stratify the short- and long-term mortality risk in patients with non-ST elevation myocardial infarction (NSTEMI). METHODS: We examined 1,675 patients diagnosed with NSTEMI on discharge who had at least two successive measurements of combined CRP and cardiac troponin within 48 h of admission. A tree classifier model determined which measurements and cutoffs could be used to best predict mortality during a median follow-up of 3 years [IQR 1.8-4.3]. RESULTS: Patients with high CRP levels ( > 90th percentile, >54 mg/L) had a higher 30-day mortality rate regardless of their troponin test findings (16.7% vs. 2.9%, p < 0.01). However, among patients with "normal" CRP levels ( < 54 mg/L), those who had high troponin levels ( > 80th percentile, 4,918 ng/L) had a higher 30-day mortality rate than patients with normal CRP and troponin concentrations (7% vs. 2%, p < 0.01). The CTT test result was an independent predictor for overall mortality even after adjusting for age, sex, and comorbidities (HR = 2.28 [95% CI 1.56-3.37], p < 0.01 for patients with high troponin and high CRP levels). CONCLUSIONS: Early serial CTT results may stratify mortality risk in patients with NSTEMI, especially those with "normal" CRP levels. The CTT could potentially assess the impact of inflammation during myocardial necrosis on the outcomes of patients with NSTEMI and identify patients who could benefit from novel anti-inflammatory therapies.

Prognostic value of perioperative high sensitivity troponin in patients undergoing hip and knee arthroplasty.

The authors conducted a prospective observational study to investigate the prognostic value of high-sensitivity Troponin I (hs-TnI) in the short- and long-term periods after orthopedic surgery, including Total Hip and Knee Arthroplasty (THA and TKA, respectively), in a tertiary orthopedic center in Brazil. Perioperative Myocardial Injury (PMI) was defined as an absolute increase in hs-TnI of ≥ 26 ng/L above preoperative values. The primary endpoint was all-cause mortality assessed at 30 days and 18 months after surgery. The secondary endpoint consisted of a composite outcome: cardiovascular death, acute myocardial infarction, angina requiring revascularization, and/or stroke. The authors compared Relative Risks (RR) of all-cause mortality and composite outcomes in patients with or without PMI at 30 days and 18 months. A Cox proportional hazards model for long-term outcomes was calculated and adjusted for age > 70 years, gender, and Revised Cardiac Risk Index (RCRI) class ≥ 2. PMI occurred in 3.4 % of all surgeries. At 30-days, 6.6 % of patients with PMI had died versus none without PMI. At 18 months, 20.0 % of PMI versus 4.7 % without PMI had died (RR = 5.0; 95 % Confidence Interval [95 % CI 1.3-19.3]). Based on composite outcomes in short and long-term periods, the RRs were 16.2 (95 % CI 2.7-96.5) and 7.7 (95 % CI 2.2-26.6), respectively. PMI was associated with all-cause mortality after 18 months and increased risk for a composite outcome (Hazard Ratio [HR = 3.97], 95 % CI 1.13-13.89 and HR = 5.80, 95 % CI 1.93-17.45, respectively). Patients with PMI who underwent THA or TKA presented worse short- and long-term prognoses compared to those without PMI.

Intensive Blood Pressure Lowering in Individuals With Low Diastolic Blood Pressure and Elevated Troponin Levels in SPRINT.

BACKGROUND: Among individuals with hypertension and low diastolic blood pressure (DBP), the optimal BP target remains controversial due to concerns that BP lowering may reduce coronary perfusion. We determined the impact of intensive BP control among individuals with elevated systolic BP who have low DBP and elevated hs-cTnT (high-sensitivity cardiac troponin T) levels. METHODS AND RESULTS: A total of 8828 participants in SPRINT (Systolic Blood Pressure Intervention Trial) were stratified by baseline DBP. Those with low DBP (<70 mm Hg) were further stratified by elevated hs-cTnT (≥14 ng/L) at baseline. The effects of intensive versus standard BP lowering on a cardiovascular disease composite end point, all-cause death, and 1-year change in hs-cTnT were determined. The combination of low DBP/high hs-cTnT was independently associated with a higher risk for cardiovascular disease and all-cause death, as well as greater 1-year increases in hs-cTnT, compared with DBP ≥70 mm Hg. However, randomization to intensive versus standard BP lowering led to similar reductions in cardiovascular disease risk among individuals with low DBP/high hs-cTnT (hazard ratio [HR], 0.82 [95% CI, 0.57-1.19]), low DBP/low hs-cTnT (HR, 0.48 [95% CI, 0.29-0.79]), and DBP ≥70 mm Hg (HR, 0.73 [95% CI, 0.60-0.89]; P for interaction=0.20). Intensive BP lowering also led to a reduction in all-cause death that was similar across groups (P for interaction=0.57). CONCLUSIONS: In this nonprespecified subgroup analysis of SPRINT, individuals with low DBP and elevated hs-cTnT, low DBP and nonelevated hs-cTnT, and DBP ≥70 mm Hg derived similar cardiovascular disease and mortality benefits from intensive BP lowering. These findings warrant confirmation in other studies.

Clinical Value of Troponin Levels to Cardiac Function and Prognosis in Patients with Fulminant Myocarditis.

Troponin (Tn) is a biomarker related to myocardial necrosis and is elevated in patients with myocarditis. This study aimed to investigate the association between cardiac Tn levels and the course of cardiac function, and prognosis in patients with fulminant myocarditis (FM) receiving percutaneous mechanical circulatory support (MCS).We used data from a multicenter retrospective registry, CHANGE PUMP 2, which included 216 patients with FM who required MCS. Among them, 141 patients whose Tn levels were available were analyzed. The patients were divided into low and high Tn groups according to the median values of TnT and TnI.The median age was 54 years, and 59.6% were male. The TnT and TnI on day 1 (at MCS initiation) were 3.8 (1.4-10.0) and 21.4 (8.4-68.8) ng/mL. While the left ventricular ejection fraction (LVEF) was similar on day 1 (25.0% versus 24.5%), the low Tn group showed better LVEF improvement on day 7 than the high Tn group (45.0% versus 25.3%, P < 0.001). LVEF at 1 year after admission was higher in the low Tn group (65.0% versus 59.7%, P = 0.039). The low Tn group had a better 90-day composite endpoint in death, durable left ventricular assist device implantation, and heart transplantation compared to the high Tn group (hazard ratio 0.47, 95% CI 0.23-0.95).Tn levels were associated with short- and long-term cardiac recovery and adverse outcomes in patients with FM receiving MCS due to cardiogenic shock.

Differentiating electrocardiographic indications of massive and submassive pulmonary embolism: A cross-sectional study in Southern Iran from 2015 to 2020.

BACKGROUND: Although using electrocardiogram (ECG) for pulmonary embolism (PE) risk stratification has shown mixed results, it is currently used as supplementary evidence in risk stratification. This cross-sectional study aimed to assess and compare ECG findings of massive and submassive PE versus segmental PE. METHODS: This cross-sectional study included 250 hospitalized patients with a confirmed diagnosis of acute PE from 2015 to 2020 in Southern Iran. Demographic variables, clinical data, troponin levels, on-admission ECG findings, echocardiography findings, and ECG findings 24 h after receiving anticoagulants or thrombolytics were extracted. RESULTS: Patients diagnosed with submassive or massive PE exhibited significantly higher rates of right axis deviation (p = .010), abnormal ST segment (p < .0001), S1Q3T3 pattern (p < .0001), inverted T wave in leads V1-V3 (p < .0001), inverted T wave in leads V4-V6 (p < .0001), and inverted T wave in leads V1-V6 (p < .0001). In a multivariable model, inverted T wave in leads V1-V3, inverted T wave in leads V4-V6, pulse rate, and positive troponin test were the statistically independent variables for predicting submassive or massive PE. Furthermore, inverted T wave in leads V1-V3 (sensitivity: 85%, specificity: 95%, accuracy: 93%, AUC: 0.902) and troponin levels (sensitivity: 72%, specificity: 86%, accuracy: 83%, AUC: 0.792) demonstrated the best diagnostic test performance for discriminating submassive or massive PE from segmental PE. CONCLUSION: In addition to clinical rules, ECG can serve as an ancillary tool for assessing more invasive testing and earlier aggressive treatments among patients with PE, as it can provide valuable information for the diagnosis and risk stratification of submassive or massive PE.

The significance of B-type natriuretic peptide in predicting early mortality among pulmonary embolism patients, alongside troponin: insights from a multicentric registry.

BACKGROUND: Early mortality assessment in acute pulmonary embolism (PE) is crucial for treatment decisions. The role of natriuretic peptides in this context is debated. This study explores elevated B-type natriuretic peptide (BNP) levels, relative to the upper normal limit (UNL), predicting mortality in PE, comparing with troponin (Tn). METHODOLOGY: A multicenter PE registry analyzed predictive values for early mortality risk using BNP and Tn, based on proportional elevation to the UNL. Patients followed current PE guidelines. RESULTS: Among 1677 PE patients, BNP's AUC exceeded Tn for all-cause (0.727 vs. 0.614) and PE-related mortality (0.785 vs. 0.644), though nonsignificant. BNP's cutoff was 3.5 times UNL for both all-cause and PE-related mortalities; Tn cutoffs were 1.38 and 1.23 times UNL, respectively. CONCLUSION: Elevated BNP relative to UNL significantly predicts all-cause and PE-related mortality. While akin to Tn, BNP merits consideration in assessing acute PE risk, especially in intermediate-high-risk cases.

Levels of Circulating Ketone Bodies in Patients Undergoing Cardiac Surgery on Cardiopulmonary Bypass.

Ketone bodies (KBs) are energy-efficient substrates utilized by the heart depending on its metabolic demand and substrate availability. Levels of circulating KBs have been shown to be elevated in acute and chronic cardiovascular disease and are associated with severity of disease in patients with heart failure and functional outcome after myocardial infarction. To investigate whether this pattern similarly applies to patients undergoing cardiac surgery involving cardiopulmonary bypass (CPB), we analysed prospectively collected pre- and postoperative blood samples from 192 cardiac surgery patients and compared levels and perioperative changes in total KBs with Troponin T as a marker of myocardial cell injury. We explored the association of patient characteristics and comorbidities for each of the two biomarkers separately and comparatively. Median levels of KBs decreased significantly over the perioperative period and inversely correlated with changes observed for Troponin T. Associations of patient characteristics with ketone body perioperative course showed notable differences compared to Troponin T, possibly highlighting factors acting as a "driver" for the change in the respective biomarker. We found an inverse correlation between perioperative change in ketone body levels and changes in troponin, indicating a marked decrease in ketone body concentrations in patients exhibiting greater myocardial cell injury. Further investigations aimed at better understanding the role of KBs on perioperative changes are warranted.

Discrimination of the acute pulmonary embolism subtypes based on the novel MAPH score.

Acute pulmonary embolism (APE) is a thromboembolism situation that can be central or peripheral. APE risk analysis and classification are essential for therapy planning. Our aim is to determine the novel MAPH score (including age, mean platelet volume (MPV), total protein, and hematocrit parameters) that can distinguish APE subtypes. Our retrospective cohort analysis includes 97 APE patients referred to the emergency medicine department who underwent pulmonary computed tomography angiography (CTA) in 24 h from 2020 to 2022. The hospital information system provided demographic, clinical, laboratory, and pulmonary CTA data. APE was classified into central (46 patients) and peripheral (51 patients) depending on the area of vascular involvement. The central APE group had higher hypertension (HT) (67.4%) and atrial fibrillation (AF) (39.1%) incidence than the peripheral APE group (all p values > 0.05). The central APE had higher total protein and platelet counts (p = 0.003 and p = 0.036), but peripheral APE had higher troponin values (p = 0.029). Central APE had 2.17 ± 0.85 MAPH and peripheral APE 1.76 ± 0.95 (p = 0.029). HT, AF, platelet count, and MAPH score differed significantly in univariate logistic regression (all p values < 0.05). However, only platelet count varied in multivariate logistic regression (p = 0.042). ROC curve analysis revealed that the MAPH score predicts central APE with 83% sensitivity and 45% specificity at a cut-off level of 1.5. The new MAPH score as an indicator of blood viscosity may distinguish between central and peripheral APE. Our result is significant, especially for centers with limited examinations, as it may accelerate the diagnosis and treatment processes. We think that our results might guide future investigations.

Safety and Effectiveness of the High-Sensitivity Cardiac Troponin HEART Pathway in Patients With Possible Acute Coronary Syndrome.

BACKGROUND: The HEART Pathway (History, Electrocardiogram, Age, Risk factors, Troponin) can be used with high-sensitivity cardiac troponin to risk stratify emergency department patients with possible acute coronary syndrome. However, data on whether a high-sensitivity HEART Pathway (hs-HP) are safe and effective is lacking. METHODS: An interrupted time series study was conducted at 5 North Carolina sites in 26 126 adult emergency department patients being investigated for possible acute coronary syndrome and without ST-segment-elevation myocardial infarction. Patients were accrued into 16-month preimplementation and postimplementation cohorts with a 6-month wash-in phase. Preimplementation (January 2019 to April 2020), the traditional HEART Pathway was used with 0- and 3-hour contemporary troponin measures (Siemens). In the postimplementation period (November 2020 to February 2022), a modified hs-HP was used with 0- and 2-hour high-sensitivity cardiac troponin (Beckman Coulter) measures. The primary safety and effectiveness outcomes were 30-day all-cause death or myocardial infarction and 30-day hospitalizations. These outcomes and early discharge rate (emergency department discharge without stress testing or coronary angiography) were determined from health records and death index data. Outcomes were compared preimplementation versus postimplementation using χ2 tests and multivariable logistic regression to adjust for potential confounders. RESULTS: Preimplementation and postimplementation cohorts included 12 317 and 13 809 patients, respectively, of them 52.7% (13 767/26 126) were female with a median age of 54 years (interquartile range, 42-66). Rates of 30-day death or MI were 6.8% (945/13 809) postimplementation and 7.7% (948/12 317) preimplementation (adjusted odds ratio, 1.00 [95% CI, 0.90-1.11]). hs-HP implementation was associated with 19.9% (95% CI, 18.7%-21.1%) higher early discharges (post versus pre: 63.6% versus 43.7%; adjusted odds ratio, 2.22 [95% CI, 2.10-2.35]). The hs-HP was also associated with 16.1% (95% CI, 14.9%-17.3%) lower 30-day hospitalizations (postimplementation versus preimplementation, 31.4% versus 47.5%; adjusted odds ratio, 0.51 [95% CI, 0.48-0.54]). Among early discharge patients, death or myocardial infarction occurred in 0.5% (41/8780) postimplementation versus 0.4% (22/5383) preimplementation (P=0.61). CONCLUSIONS: hs-HP implementation is associated with increased early discharges without increasing adverse events. These findings support the use of a modified hs-HP to improve chest pain care.

Machine Learning for Myocardial Infarction Compared With Guideline-Recommended Diagnostic Pathways.

BACKGROUND: Collaboration for the Diagnosis and Evaluation of Acute Coronary Syndrome (CoDE-ACS) is a validated clinical decision support tool that uses machine learning with or without serial cardiac troponin measurements at a flexible time point to calculate the probability of myocardial infarction (MI). How CoDE-ACS performs at different time points for serial measurement and compares with guideline-recommended diagnostic pathways that rely on fixed thresholds and time points is uncertain. METHODS: Patients with possible MI without ST-segment-elevation were enrolled at 12 sites in 5 countries and underwent serial high-sensitivity cardiac troponin I concentration measurement at 0, 1, and 2 hours. Diagnostic performance of the CoDE-ACS model at each time point was determined for index type 1 MI and the effectiveness of previously validated low- and high-probability scores compared with guideline-recommended European Society of Cardiology (ESC) 0/1-hour, ESC 0/2-hour, and High-STEACS (High-Sensitivity Troponin in the Evaluation of Patients With Suspected Acute Coronary Syndrome) pathways. RESULTS: In total, 4105 patients (mean age, 61 years [interquartile range, 50-74]; 32% women) were included, among whom 575 (14%) had type 1 MI. At presentation, CoDE-ACS identified 56% of patients as low probability, with a negative predictive value and sensitivity of 99.7% (95% CI, 99.5%-99.9%) and 99.0% (98.6%-99.2%), ruling out more patients than the ESC 0-hour and High-STEACS (25% and 35%) pathways. Incorporating a second cardiac troponin measurement, CoDE-ACS identified 65% or 68% of patients as low probability at 1 or 2 hours, for an identical negative predictive value of 99.7% (99.5%-99.9%); 19% or 18% as high probability, with a positive predictive value of 64.9% (63.5%-66.4%) and 68.8% (67.3%-70.1%); and 16% or 14% as intermediate probability. In comparison, after serial measurements, the ESC 0/1-hour, ESC 0/2-hour, and High-STEACS pathways identified 49%, 53%, and 71% of patients as low risk, with a negative predictive value of 100% (99.9%-100%), 100% (99.9%-100%), and 99.7% (99.5%-99.8%); and 20%, 19%, or 29% as high risk, with a positive predictive value of 61.5% (60.0%-63.0%), 65.8% (64.3%-67.2%), and 48.3% (46.8%-49.8%), resulting in 31%, 28%, or 0%, who require further observation in the emergency department, respectively. CONCLUSIONS: CoDE-ACS performs consistently irrespective of the timing of serial cardiac troponin measurement, identifying more patients as low probability with comparable performance to guideline-recommended pathways for MI. Whether care guided by probabilities can improve the early diagnosis of MI requires prospective evaluation. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00470587.