Coronary Atherosclerotic Plaque Activity and Risk of Myocardial Infarction.

BACKGROUND: Total coronary atherosclerotic plaque activity across the entire coronary arterial tree is associated with patient-level clinical outcomes. OBJECTIVES: We aimed to investigate whether vessel-level coronary atherosclerotic plaque activity is associated with vessel-level myocardial infarction. METHODS: In this secondary analysis of an international multicenter study of patients with recent myocardial infarction and multivessel coronary artery disease, we assessed vessel-level coronary atherosclerotic plaque activity using coronary 18F-sodium fluoride positron emission tomography to identify vessel-level myocardial infarction. RESULTS: Increased 18F-sodium fluoride uptake was found in 679 of 2,094 coronary arteries and 414 of 691 patients. Myocardial infarction occurred in 24 (4%) vessels with increased coronary atherosclerotic plaque activity and in 25 (2%) vessels without increased coronary atherosclerotic plaque activity (HR: 2.08; 95% CI: 1.16-3.72; P = 0.013). This association was not demonstrable in those treated with coronary revascularization (HR: 1.02; 95% CI: 0.47-2.25) but was notable in untreated vessels (HR: 3.86; 95% CI: 1.63-9.10; Pinteraction = 0.024). Increased coronary atherosclerotic plaque activity in multiple coronary arteries was associated with heightened patient-level risk of cardiac death or myocardial infarction (HR: 2.43; 95% CI: 1.37-4.30; P = 0.002) as well as first (HR: 2.19; 95% CI: 1.18-4.06; P = 0.013) and total (HR: 2.50; 95% CI: 1.42-4.39; P = 0.002) myocardial infarctions. CONCLUSIONS: In patients with recent myocardial infarction and multivessel coronary artery disease, coronary atherosclerotic plaque activity prognosticates individual coronary arteries and patients at risk for myocardial infarction.

Long COVID and cardiovascular disease: a prospective cohort study.

BACKGROUND: Pre-existing cardiovascular disease (CVD) or cardiovascular risk factors have been associated with an increased risk of complications following hospitalisation with COVID-19, but their impact on the rate of recovery following discharge is not known. OBJECTIVES: To determine whether the rate of patient-perceived recovery following hospitalisation with COVID-19 was affected by the presence of CVD or cardiovascular risk factors. METHODS: In a multicentre prospective cohort study, patients were recruited following discharge from the hospital with COVID-19 undertaking two comprehensive assessments at 5 months and 12 months. Patients were stratified by the presence of either CVD or cardiovascular risk factors prior to hospitalisation with COVID-19 and compared with controls with neither. Full recovery was determined by the response to a patient-perceived evaluation of full recovery from COVID-19 in the context of physical, physiological and cognitive determinants of health. RESULTS: From a total population of 2545 patients (38.8% women), 472 (18.5%) and 1355 (53.2%) had CVD or cardiovascular risk factors, respectively. Compared with controls (n=718), patients with CVD and cardiovascular risk factors were older and more likely to have had severe COVID-19. Full recovery was significantly lower at 12 months in patients with CVD (adjusted OR (aOR) 0.62, 95% CI 0.43 to 0.89) and cardiovascular risk factors (aOR 0.66, 95% CI 0.50 to 0.86). CONCLUSION: Patients with CVD or cardiovascular risk factors had a delayed recovery at 12 months following hospitalisation with COVID-19. Targeted interventions to reduce the impact of COVID-19 in patients with cardiovascular disease remain an unmet need. TRAIL REGISTRATION NUMBER: ISRCTN10980107.

Cardiovascular and Noncardiovascular Prescribing and Mortality After Takotsubo Comparison With Myocardial Infarction and General Population.

Background: Takotsubo syndrome is an increasingly common cardiac emergency with no known evidence-based treatment. Objectives: The purpose of this study was to investigate cardiovascular mortality and medication use after takotsubo syndrome. Methods: In a case-control study, all patients with takotsubo syndrome in Scotland between 2010 and 2017 (n = 620) were age, sex, and geographically matched to individuals in the general population (1:4, n = 2,480) and contemporaneous patients with acute myocardial infarction (1:1, n = 620). Electronic health record data linkage of mortality outcomes and drug prescribing were analyzed using Cox proportional hazard regression models. Results: Of the 3,720 study participants (mean age, 66 years; 91% women), 153 (25%) patients with takotsubo syndrome died over the median of 5.5 years follow-up. This exceeded mortality rates in the general population (N = 374 [15%]; HR: 1.78 [95% CI: 1.48-2.15], P < 0.0001), especially for cardiovascular (HR: 2.47 [95% CI: 1.81-3.39], P < 0.001) but also noncardiovascular (HR: 1.48 [95% CI: 1.16-1.87], P = 0.002) deaths. Mortality rates were lower for patients with takotsubo syndrome than those with myocardial infarction (31%, 195/620; HR: 0.76 [95% CI: 0.62-0.94], P = 0.012), which was attributable to lower rates of cardiovascular (HR: 0.61 [95% CI: 0.44-0.84], P = 0.002) but not non-cardiovascular (HR: 0.92 [95% CI: 0.69-1.23], P = 0.59) deaths. Despite comparable medications use, cardiovascular therapies were consistently associated with better survival in patients with myocardial infarction but not in those with takotsubo syndrome. Diuretic (P = 0.01), anti-inflammatory (P = 0.002), and psychotropic (P < 0.001) therapies were all associated with worse outcomes in patients with takotsubo syndrome. Conclusions: In patients with takotsubo syndrome, cardiovascular mortality is the leading cause of death, and this is not associated with cardiovascular therapy use.

EPidemiology Of Cardiogenic sHock in Scotland (EPOCHS): A multicentre, prospective observational study of the prevalence, management and outcomes of cardiogenic shock in Scotland.

Background: Despite high rates of cardiovascular disease in Scotland, the prevalence and outcomes of patients with cardiogenic shock are unknown. Methods: We undertook a prospective observational cohort study of consecutive patients with cardiogenic shock admitted to the intensive care unit (ICU) or coronary care unit at 13 hospitals in Scotland for a 6-month period. Denominator data from the Scottish Intensive Care Society Audit Group were used to estimate ICU prevalence; data for coronary care units were unavailable. We undertook multivariable logistic regression to identify factors associated with in-hospital mortality. Results: In total, 247 patients with cardiogenic shock were included. After exclusion of coronary care unit admissions, this comprised 3.0% of all ICU admissions during the study period (95% confidence interval [CI] 2.6%-3.5%). Aetiology was acute myocardial infarction (AMI) in 48%. The commonest vasoactive treatment was noradrenaline (56%) followed by adrenaline (46%) and dobutamine (40%). Mechanical circulatory support was used in 30%. Overall in-hospital mortality was 55%. After multivariable logistic regression, age (odds ratio [OR] 1.04, 95% CI 1.02-1.06), admission lactate (OR 1.10, 95% CI 1.05-1.19), Society for Cardiovascular Angiographic Intervention stage D or E at presentation (OR 2.16, 95% CI 1.10-4.29) and use of adrenaline (OR 2.73, 95% CI 1.40-5.40) were associated with mortality. Conclusions: In Scotland the prevalence of cardiogenic shock was 3% of all ICU admissions; more than half died prior to discharge. There was significant variation in treatment approaches, particularly with respect to vasoactive support strategy.

Development of a long noncoding RNA-based machine learning model to predict COVID-19 in-hospital mortality.

Tools for predicting COVID-19 outcomes enable personalized healthcare, potentially easing the disease burden. This collaborative study by 15 institutions across Europe aimed to develop a machine learning model for predicting the risk of in-hospital mortality post-SARS-CoV-2 infection. Blood samples and clinical data from 1286 COVID-19 patients collected from 2020 to 2023 across four cohorts in Europe and Canada were analyzed, with 2906 long non-coding RNAs profiled using targeted sequencing. From a discovery cohort combining three European cohorts and 804 patients, age and the long non-coding RNA LEF1-AS1 were identified as predictive features, yielding an AUC of 0.83 (95% CI 0.82-0.84) and a balanced accuracy of 0.78 (95% CI 0.77-0.79) with a feedforward neural network classifier. Validation in an independent Canadian cohort of 482 patients showed consistent performance. Cox regression analysis indicated that higher levels of LEF1-AS1 correlated with reduced mortality risk (age-adjusted hazard ratio 0.54, 95% CI 0.40-0.74). Quantitative PCR validated LEF1-AS1's adaptability to be measured in hospital settings. Here, we demonstrate a promising predictive model for enhancing COVID-19 patient management.

Safety outcomes following COVID-19 vaccination and infection in 5.1 million children in England.

The risk-benefit profile of COVID-19 vaccination in children remains uncertain. A self-controlled case-series study was conducted using linked data of 5.1 million children in England to compare risks of hospitalisation from vaccine safety outcomes after COVID-19 vaccination and infection. In 5-11-year-olds, we found no increased risks of adverse events 1-42 days following vaccination with BNT162b2, mRNA-1273 or ChAdOX1. In 12-17-year-olds, we estimated 3 (95%CI 0-5) and 5 (95%CI 3-6) additional cases of myocarditis per million following a first and second dose with BNT162b2, respectively. An additional 12 (95%CI 0-23) hospitalisations with epilepsy and 4 (95%CI 0-6) with demyelinating disease (in females only, mainly optic neuritis) were estimated per million following a second dose with BNT162b2. SARS-CoV-2 infection was associated with increased risks of hospitalisation from seven outcomes including multisystem inflammatory syndrome and myocarditis, but these risks were largely absent in those vaccinated prior to infection. We report a favourable safety profile of COVID-19 vaccination in under-18s.

Is rapid acute coronary syndrome evaluation with high-sensitivity cardiac troponin less costly? An economic evaluation.

Objective: Protocols to evaluate for myocardial infarction (MI) using high-sensitivity cardiac troponin (hs-cTn) have the potential to drive costs upward due to the added sensitivity. We performed an economic evaluation of an accelerated protocol (AP) to evaluate for MI using hs-cTn to identify changes in costs of treatment and length of stay compared with conventional testing. Methods: We performed a planned secondary economic analysis of a large, cluster randomized trial across nine emergency departments (EDs) from July 2020 to April 2021. Patients were included if they were 18 years or older with clinical suspicion for MI. In the AP, patients could be discharged without further testing at 0 h if they had a hs-cTnI < 4 ng/L and at 1 h if the initial value were 4 ng/L and the 1-h value ≤7 ng/L. Patients in the standard of care (SC) protocol used conventional cTn testing at 0 and 3 h. The primary outcome was the total cost of treatment, and the secondary outcome was ED length of stay. Results: Among 32,450 included patients, an AP had no significant differences in cost (+$89, CI: -$714, $893 hospital cost, +$362, CI: -$414, $1138 health system cost) or ED length of stay (+46, CI: -28, 120 min) compared with the SC protocol. In lower acuity, free-standing EDs, patients under the AP experienced shorter length of stay (-37 min, CI: -62, 12 min) and reduced health system cost (-$112, CI: -$250, $25). Conclusion: Overall, the implementation of AP using hs-cTn does not result in higher costs.

Application of the Universal Definition of Myocardial Infarction in Clinical Practice in Scotland and Sweden.

Importance: Whether the diagnostic classifications proposed by the universal definition of myocardial infarction (MI) to identify type 1 MI due to atherothrombosis and type 2 MI due to myocardial oxygen supply-demand imbalance have been applied consistently in clinical practice is unknown. Objective: To evaluate the application of the universal definition of MI in consecutive patients with possible MI across 2 health care systems. Design, Setting, and Participants: This cohort study used data from 2 prospective cohorts enrolling consecutive patients with possible MI in Scotland (2013-2016) and Sweden (2011-2014) to assess accuracy of clinical diagnosis of MI recorded in hospital records for patients with an adjudicated diagnosis of type 1 or type 2 MI. Data were analyzed from August 2022 to February 2023. Main Outcomes and Measures: The main outcome was the proportion of patients with a clinical diagnosis of MI recorded in the hospital records who had type 1 or type 2 MI, adjudicated by an independent panel according to the universal definition. Characteristics and risk of subsequent MI or cardiovascular death at 1 year were compared. Results: A total of 50 356 patients were assessed. The cohort from Scotland included 28 783 (15 562 men [54%]; mean [SD] age, 60 [17] years), and the cohort from Sweden included 21 573 (11 110 men [51%]; mean [SD] age, 56 [17] years) patients. In Scotland, a clinical diagnosis of MI was recorded in 2506 of 3187 patients with an adjudicated diagnosis of type 1 MI (79%) and 122 of 716 patients with an adjudicated diagnosis of type 2 MI (17%). Similar findings were observed in Sweden, with 970 of 1111 patients with adjudicated diagnosis of type 1 MI (87%) and 57 of 251 patients with adjudicated diagnosis of type 2 MI (23%) receiving a clinical diagnosis of MI. Patients with an adjudicated diagnosis of type 1 MI without a clinical diagnosis were more likely to be women (eg, 336 women [49%] vs 909 women [36%] in Scotland; P < .001) and older (mean [SD] age, 71 [14] v 67 [14] years in Scotland, P < .001) and, when adjusting for competing risk from noncardiovascular death, were at similar or increased risk of subsequent MI or cardiovascular death compared with patients with a clinical diagnosis of MI (eg, 29% vs 18% in Scotland; P < .001). Conclusions and Relevance: In this cohort study, the universal definition of MI was not consistently applied in clinical practice, with a minority of patients with type 2 MI identified, and type 1 MI underrecognized in women and older persons, suggesting uncertainty remains regarding the diagnostic criteria or value of the classification.

Implementation of high sensitivity troponin into routine clinical practice - results of the extended CARdiac MArkers guideline uptake in Europe group (CARMAGUE) survey.

BACKGROUND: Measurement of cardiac troponin (cTn) by a high sensitivity method is now the recommended strategy for the detection of myocardial injury. An international survey was undertaken to assess how this has been implemented. METHODS: A questionnaire based around 14 domains on cardiac biomarkers was distributed electronically with the aid of professional societies accessed by a web link within the invitation. Results were returned electronically then extracted into a relational database for analysis. RESULTS: Responses were obtained from 663 laboratories across 76 countries ranging from 1 to 69 largest country. The majority of responses (79.6%) came from the European area. Responses were grouped into broad geographic areas for analysis. Most responses came from hospitals providing a local and regional service of which the majority provided angioplasty. cTn measurement was the dominant biomarker. The majority of laboratories include creatine kinase (CK) in their cardiac profile and approximately 50% also offer the MB isoenzyme of CK. The majority of laboratories (91.9%) measure cTn by a high sensitivity method. Sex specific reference ranges were typically implemented for cardiac troponin I but not for cardiac troponin T. The preferred unit of measurement was nanograms/L. A structured decision-making pathway utilising high sensitivity cTn measurement was used by 83.3% of laboratories who responded. Single sample rule out is common but the majority used serial sampling strategy based on measurement on admission and three hours. CONCLUSIONS: Measurement of cTn by a high sensitivity method is now well established internationally, the use of rapid diagnostic protocols lags behind.

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.

Kidney replacement therapy: trends in incidence, treatment, and outcomes of myocardial infarction and stroke in a nationwide Scottish study.

BACKGROUND AND AIMS: Patients with kidney failure have a higher risk of cardiovascular disease compared with the general population. Whilst temporal trends of myocardial infarction and stroke are declining in the general population, these have not been evaluated in patients with kidney failure. This study aimed to describe national trends in the incidence, treatment, and outcomes of myocardial infarction and stroke in patients with kidney failure (i.e. on dialysis or with a kidney transplant) over a 20-year period, stratified by age and sex. METHODS: In this retrospective national data linkage study, all patients with kidney failure in Scotland (UK) receiving kidney replacement therapy between January 1996 and December 2016 were linked to national hospitalization, prescribing, and death records. The primary outcomes were the incidence of myocardial infarction and stroke, and subsequent cardiovascular death. Generalized additive models were constructed to estimate age-standardized, sex-stratified incidence rates and trends in cardiovascular and all-cause death. RESULTS: Amongst 16 050 patients with kidney failure [52 (SD 15) years; 41.5% women], there were 1992 [66 (SD 12) years; 34.8% women] and 996 [65 (SD 13) years; 45.1% women] incident myocardial infarctions and strokes, respectively, between January 1996 and December 2016. During this period, the age-standardized incidence of myocardial infarction per 100 000 decreased in men {from 4376 [95% confidence interval (CI) 3998-4785] to 1835 (95% CI 1692-1988)} and women [from 3268 (95% CI 2982-3593) to 1369 (95% CI 1257-1491)]. Similarly, the age-standardized incidence of stroke per 100 000 also decreased in men [from 1978 (95% CI 1795-2175) to 799 (95% CI 729-875)] and women [from 2234 (95% CI 2031-2468) to 903 (95% CI 824-990)]. Compared with the general population, the incidence of myocardial infarction was four- to eight-fold higher in patients with kidney failure, whilst for stroke it was two- to four-fold higher. The use of evidence-based cardioprotective treatment increased over the study period, and the predicted probability of cardiovascular death within 1 year of myocardial infarction for a 66-year-old patient with kidney failure (mean age of the cohort) fell in men (76.6% to 38.6%) and women (76.8% to 38.8%), and also decreased in both sexes following stroke (men, from 63.5% to 41.4%; women, from 67.6% to 45.8%). CONCLUSIONS: The incidence of myocardial infarction and stroke has halved in patients with kidney failure over the past 20 years but remains significantly higher than in the general population. Despite improvements in treatment and outcomes, the prognosis of these patients following myocardial infarction and stroke remains poor.

Uniform or Sex-Specific Cardiac Troponin Thresholds to Rule Out Myocardial Infarction at Presentation.

BACKGROUND: Myocardial infarction can be ruled out in patients with a single cardiac troponin measurement. Whether use of a uniform rule-out threshold has resulted in sex differences in care remains unclear. OBJECTIVES: The purpose of this study was to evaluate implementation of a uniform rule-out threshold in females and males with possible myocardial infarction, and to derive and validate sex-specific thresholds. METHODS: The implementation of a uniform rule-out threshold (<5 ng/L) with a high-sensitivity cardiac troponin I assay was evaluated in consecutive patients presenting with possible myocardial infarction. The proportion of low-risk patients discharged from the emergency department and incidence of myocardial infarction or cardiac death at 30 days were determined. Sex-specific thresholds were derived and validated, and proportion of female and male patients were stratified as low-risk compared with uniform threshold. RESULTS: In 16,792 patients (age 58 ± 17 years; 46% female) care was guided using a uniform threshold. This identified more female than male patients as low risk (73% vs 62%), but a similar proportion of low-risk patients were discharged from the emergency department (81% for both) with fewer than 5 (<0.1%) patients having a subsequent myocardial infarction or cardiac death at 30 days. Compared with a uniform threshold of <5 ng/L, use of sex-specific thresholds would increase the proportion of female (61.8% vs 65.9%) and reduce the proportion of male (54.8% vs 47.8%) patients identified as low risk. CONCLUSIONS: Implementation of a uniform rule-out threshold for myocardial infarction was safe and effective in both sexes. Sex-specific rule-out thresholds should be considered, but their impact on effectiveness and safety may be limited.

Type 2 Myocardial Infarction-Poorly Understood, Underevaluated, and Too Often Ignored.

This Viewpoint discusses diagnosis of type 2 myocardial infarction.

PAR4 Antagonism in Patients With Coronary Artery Disease Receiving Antiplatelet Therapies.

BACKGROUND: BMS-986141 is a novel potent highly selective antagonist of PAR (protease-activated receptor) type 4. PAR4 antagonism has been demonstrated to reduce thrombus formation in isolation and in combination with factor Xa inhibition in high shear conditions in healthy people. We sought to determine whether PAR4 antagonism had additive antithrombotic effects in patients with coronary artery disease who were receiving antiplatelet therapy. METHODS: Forty-five patients with stable coronary heart disease and 10 healthy volunteers completed a phase 2a open-label 4-arm single-center study. Patients were allocated to 1 of 3 treatment arms for 7 days: (1) ticagrelor (90 mg BID), (2) aspirin (75 mg QD), or (3) the combination of ticagrelor and aspirin. Agonist-induced platelet aggregation, platelet activation, and ex vivo thrombus formation were measured before and 2 and 24 hours after a single oral 4-mg dose of BMS-986141 on the first study visit day in all participants. RESULTS: BMS-986141 demonstrated highly selective inhibition of PAR4-AP (agonist peptide)-induced platelet aggregation, P-selectin expression, and platelet-monocyte aggregate expression (P≤0.001 for all), which were unaffected by concomitant antiplatelet therapies. PAR4 antagonism reduced ex vivo thrombus area in high shear conditions in healthy volunteers (-21%; P=0.001) and in patients receiving ticagrelor alone (-28%; P=0.001), aspirin alone (-23%; P=0.018), or both in combination (-24%; P≤0.001). Plasma concentration of BMS-986141 correlated with PAR4-AP-induced platelet responses (P≤0.001 for all) and total thrombus area under high shear stress conditions (P≤0.01 for all). CONCLUSIONS: PAR4 antagonism has additive antithrombotic effects when used in addition to ticagrelor, aspirin, or their combination, in patients with stable coronary heart disease. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT05093790.

Imprecision of high-sensitivity cardiac troponin assays at the female 99th-percentile.

BACKGROUND: An analytical benchmark for high-sensitivity cardiac troponin (hs-cTn) assays is to achieve a coefficient of variation (CV) of ≤ 10.0 % at the 99th percentile upper reference limit (URL) used for the diagnosis of myocardial infarction. Few prospective multicenter studies have evaluated assay imprecision and none have determined precision at the female URL which is lower than the male URL for all cardiac troponin assays. METHODS: Human serum and plasma matrix samples were constructed to yield hs-cTn concentrations near the female URLs for the Abbott, Beckman, Roche, and Siemens hs-cTn assays. These materials were sent (on dry ice) to 35 Canadian hospital laboratories (n = 64 instruments evaluated) participating in a larger clinical trial, with instructions for storage, handling, and monthly testing over one year. The mean concentration, standard deviation, and CV for each instrument type and an overall pooled CV for each manufacturer were calculated. RESULTS: The CVs for all individual instruments and overall were ≤ 10.0 % for two manufacturers (Abbott CVpooled = 6.3 % and Beckman CVpooled = 7.0 %). One of four Siemens Atellica instruments yielded a CV > 10.0 % (CVpooled = 7.7 %), whereas 15 of 41 Roche instruments yielded CVs > 10.0 % at the female URL of 9 ng/L used worldwide (6 cobas e411, 1 cobas e601, 4 cobas e602, and 4 cobas e801) (CVpooled = 11.7 %). Four Roche instruments also yielded CVs > 10.0 % near the female URL of 14 ng/L used in the United States (CVpooled = 8.5 %). CONCLUSIONS: The number of instruments achieving a CV ≤ 10.0 % at the female 99th-percentile URL varies by manufacturer and by instrument. Monitoring assay precision at the female URL is necessary for some assays to ensure optimal use of this threshold in clinical practice.

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.