Application of High-Sensitivity Troponin in Suspected Myocardial Infarction

Prognostic Value of Cardiovascular Biomarkers in the Population

Importance

Identification of individuals at high risk for atherosclerotic cardiovascular disease within the population is important to inform primary prevention strategies.

Objective

To evaluate the prognostic value of routinely available cardiovascular biomarkers when added to established risk factors.

Design, Setting, and Participants

Individual-level analysis including data on cardiovascular biomarkers from 28 general population-based cohorts from 12 countries and 4 continents with assessments by participant age. The median follow-up was 11.8 years.

Exposure

Measurement of high-sensitivity cardiac troponin I, high-sensitivity cardiac troponin T, N-terminal pro-B-type natriuretic peptide, B-type natriuretic peptide, or high-sensitivity C-reactive protein.

Main Outcomes and Measures

The primary outcome was incident atherosclerotic cardiovascular disease, which included all fatal and nonfatal events. The secondary outcomes were all-cause mortality, heart failure, ischemic stroke, and myocardial infarction. Subdistribution hazard ratios (HRs) for the association of biomarkers and outcomes were calculated after adjustment for established risk factors. The additional predictive value of the biomarkers was assessed using the C statistic and reclassification analyses.

Results

The analyses included 164 054 individuals (median age, 53.1 years [IQR, 42.7-62.9 years] and 52.4% were women). There were 17 211 incident atherosclerotic cardiovascular disease events. All biomarkers were significantly associated with incident atherosclerotic cardiovascular disease (subdistribution HR per 1-SD change, 1.13 [95% CI, 1.11-1.16] for high-sensitivity cardiac troponin I; 1.18 [95% CI, 1.12-1.23] for high-sensitivity cardiac troponin T; 1.21 [95% CI, 1.18-1.24] for N-terminal pro-B-type natriuretic peptide; 1.14 [95% CI, 1.08-1.22] for B-type natriuretic peptide; and 1.14 [95% CI, 1.12-1.16] for high-sensitivity C-reactive protein) and all secondary outcomes. The addition of each single biomarker to a model that included established risk factors improved the C statistic. For 10-year incident atherosclerotic cardiovascular disease in younger people (aged <65 years), the combination of high-sensitivity cardiac troponin I, N-terminal pro-B-type natriuretic peptide, and high-sensitivity C-reactive protein resulted in a C statistic improvement from 0.812 (95% CI, 0.8021-0.8208) to 0.8194 (95% CI, 0.8089-0.8277). The combination of these biomarkers also improved reclassification compared with the conventional model. Improvements in risk prediction were most pronounced for the secondary outcomes of heart failure and all-cause mortality. The incremental value of biomarkers was greater in people aged 65 years or older vs younger people.

Conclusions and Relevance

Cardiovascular biomarkers were strongly associated with fatal and nonfatal cardiovascular events and mortality. The addition of biomarkers to established risk factors led to only a small improvement in risk prediction metrics for atherosclerotic cardiovascular disease, but was more favorable for heart failure and mortality.

Advances in research on biomarkers associated with acute myocardial infarction: A review

Acute myocardial infarction (AMI), the most severe cardiovascular event in clinical settings, imposes a significant burden with its annual increase in morbidity and mortality rates. However, it is noteworthy that mortality due to AMI in developed countries has experienced a decline, largely attributable to the advancements in medical interventions such as percutaneous coronary intervention. This trend highlights the importance of accurate diagnosis and effective treatment to preserve the myocardium at risk and improve patient outcomes. Conventional biomarkers such as myoglobin, creatine kinase isoenzymes, and troponin have been instrumental in the diagnosis of AMI. However, recent years have witnessed the emergence of new biomarkers demonstrating the potential to further enhance the accuracy of AMI diagnosis. This literature review focuses on the recent advancements in biomarker research in the context of AMI diagnosis.

Comparison of the clinical chemistry score to other biomarker algorithms for rapid rule-out of acute myocardial infarction and risk stratification in patients with suspected acute coronary syndrome

BACKGROUND

The clinical chemistry score (CCS) comprising high-sensitivity cardiac troponins (hs-cTn), glucose and estimated glomerular filtration rate has been previously validated with superior accuracy for detection and risk stratification of acute myocardial infarction (AMI) compared to hs-cTn alone.

METHODS

The CCS was compared to other biomarker-based algorithms for rapid rule-out and prognostication of AMI including the hs-cTnT limit-of-blank (LOB, <3 ng/L) or limit-of-detection (LOD, <5 ng/L) and a dual marker strategy (DMS) (copeptin <10 pmol/L and hs-cTnT ≤14 ng/L) in 1506 emergency department (ED) patients with symptoms suggestive of acute coronary syndrome. Negative predictive values (NPV) and sensitivities for AMI rule-out, and 12-month combined endpoint rates encompassing mortality, myocardial re-infarction, as well as stroke were assessed.

RESULTS

NPVs of 100% (95% CI: 98.3-100%) were observed for CCS = 0, hs-cTnT LoB and hs-cTnT LoD with rule-out efficacies of 11.1%, 7.6% and 18.3% as well as specificities of 13.0% (95% CI: 9.9-16.6%), 8.8% (95% CI: 7.3-10.5%) and 21.4% (95% CI: 19.2-23.8%), respectively. A CCS ≤ 1 achieved a rule-out in 32.2% of all patients with a NPV of 99.6% (95% CI: 98.4-99.9%) and specificity of 37.4% (95% CI: 34.2-40.5%) compared to a rule-out efficacy of 51.2%, NPV of 99.0 (95% CI: 98.0-99.5) and specificity of 59.7% (95% CI: 57.0-62.4%) for the DMS. Rates of the combined end-point of death/AMI within 30 days ranged between 0.0% and 0.7% for all fast-rule-out protocols.

CONCLUSIONS

The CCS ensures reliable AMI rule-out with low short and long-term outcome rates for a specific ED patient subset. However, compared to a single or dual biomarker strategy, the CCS displays reduced efficacy and specificity, limiting its clinical utility.

Serial troponin-I and long-term outcomes in subjects with suspected acute coronary syndrome

AIMS

It is unclear how serial high-sensitivity troponin-I (hsTnI) concentrations affect long-term prognosis in individuals with suspected acute coronary syndrome (ACS).

METHODS AND RESULTS

Subjects who underwent two hsTnI measurements (Siemens TnI Flex® Reagent) separated by 1-7 h, during a first-time hospitalization for myocardial infarction, unstable angina, observation for suspected myocardial infarction, or chest pain from 2012 through 2019, were identified through Danish national registries. Individuals were stratified per their hsTnI concentration pattern (normal, rising, persistently elevated, or falling) and the magnitude of hsTnI concentration change (<20%, >20-50%, or >50% in either direction). We calculated absolute and relative mortality risks standardized to the distributions of risk factors for the entire study population. A total of 20 609 individuals were included of whom 2.3% had died at 30 days, and an additional 4.7% had died at 365 days. The standardized risk of death was highest among persons with a persistently elevated hsTnI concentration (0-30 days: 8.0%, 31-365 days: 11.1%) and lowest among those with two normal hsTnI concentrations (0-30 days: 0.5%, 31-365 days: 2.6%). In neither case did relative hsTnI concentration changes between measurements clearly affect mortality risk. Among persons with a rising hsTnI concentration pattern, 30-day mortality was higher in subjects with a >50% rise compared with those with a less pronounced rise (2.2% vs. <0.1%).

CONCLUSION

Among individuals with suspected ACS, those with a persistently elevated hsTnI concentration consistently had the highest risk of death. In subjects with two normal hsTnI concentrations, mortality was very low and not affected by the magnitude of change between measurements.

Diagnostic and prognostic value of cardiac troponins in emergency department patients presenting after a fall: A prospective, multicenter study

BACKGROUND

Emergency department (ED) presentations after a ground-level fall (GLF) are common. Falls were suggested to be another possible presenting feature of a myocardial infarction (MI), as unrecognized MIs are common in older adults. Elevated high-sensitivity cardiac troponin (hs-cTn) concentrations could help determine the etiology of a GLF in ED. We investigated the prevalence of both MI and elevated high-sensitivity cardiac troponin T (hs-cTnT) and I (hs-cTnI), as well as the diagnostic accuracy of hs-cTnT and hs-cTnI regarding MI, and their prognostic value in older ED patients presenting after a GLF.

METHODS

This was a prospective, international, multicenter, cohort study with a follow-up of up to 1 year. Patients aged 65 years or older presenting to the ED after a GLF were prospectively enrolled. Two outcome assessors independently reviewed all discharge records to ascertain final gold standard diagnoses. Hs-cTnT and hs-cTnI levels were determined from thawed samples for every patient.

RESULTS

In total, 558 patients were included. Median (IQR) age was 83 (77-89) years, and 67.7% were female. Elevated hs-cTnT levels were found in 384 (68.8%) patients, and elevated hs-cTnI levels in 86 (15.4%) patients. Three patients (0.5%) were ascertained the gold standard diagnosis MI. Within 30 days, 18 (3.2%) patients had died. Nonsurvivors had higher hs-cTnT and hs-cTnI levels compared with survivors (hs-cTnT 40 [23-85] ng/L in nonsurvivors and 20 [13-33] ng/L in survivors; hs-cTnI 25 [14-54] ng/L in nonsurvivors and 8 [4-16] ng/L in survivors; p < 0.001 for both).

CONCLUSIONS

A majority of patients (n = 364, 68.8%) presenting to the ED after a fall had elevated hs-cTnT levels and 86 (15.4%) elevated hs-cTnI levels. However, the incidence of MI in these patients was low (n = 3, 0.5%). Our data do not support the opinion that falls may be a common presenting feature of MI. We discourage routine troponin testing in this population. However, hs-cTnT and hs-cTnI were both found to have prognostic properties for mortality prediction up to 1 year.

A Single High-Sensitivity Cardiac Troponin T Strategy for Ruling Out Myocardial Infarction

Background

Ruling out acute myocardial infarction (AMI) in the emergency department (ED) is challenging. Studies have shown that a high-sensitivity cardiac troponin T (hs-cTnT) <5 ng/L or <6 ng/L at presentation (0 h) can be used to rule out AMI. The objective of this study was to identify whether an even higher hs-cTnT threshold can be used for a safe rule out of AMI in the ED.

Methods

The derivation cohort consisted of 24,973 ED patients with a primary complaint of chest pain. In this cohort, we identified the highest concentration of 0 h hs-cTnT that corresponded to a negative predictive value (NPV) of ≥99.5% for the primary endpoint of AMI/all-cause death within 30 days and the secondary endpoint of all-cause death within one year. The results were validated in two cohorts consisting of 132,021 and 1167 ED chest pain patients.

Results

The 0 h hs-cTnT threshold corresponding to a NPV of ≥99.5% for the primary endpoint was <9 ng/L (NPV: 99.6% and 95% CI: 99.5-99.7). This cutoff provided a sensitivity of 96.2% (95% CI: 95.2-97.1) and identified 59.7% of the patients as low risk compared to 35.8% and 43.9% with a 0 h hs-cTnT <5 ng/L and <6 ng/L, respectively. The results were similar in the validation cohorts and seemed to perform even better in patients where the 0 h hs-cTnT was measured >3 h after symptom onset and in those with a nonischemic ECG and nonhigh risk history.

Conclusions

A 0 h hs-cTnT cutoff of <9 ng/L safely rules out AMI/death within 30 days in a majority of chest pain patients and is a more effective strategy than the currently recommended <5 ng/L and <6 ng/L cutoffs. This trial is registered with NCT03421873.

Lower Limits for Reporting High-Sensitivity Cardiac Troponin Assays and Impact of Analytical Performance on Patient Misclassification

BACKGROUND

Cardiac troponin measurements are indispensable for the diagnosis of myocardial infarction and provide useful information for long-term risk prediction of cardiovascular disease. Accelerated diagnostic pathways prevent unnecessary hospital admission, but require reporting cardiac troponin concentrations at low concentrations that are sometimes below the limit of quantification. Whether analytical imprecision at these concentrations contributes to misclassification of patients is debated.

CONTENT

The International Federation of Clinical Chemistry Committee on Clinical Application of Cardiac Bio-Markers (IFCC C-CB) provides evidence-based educational statements on analytical and clinical aspects of cardiac biomarkers. This mini-review discusses how the reporting of low concentrations of cardiac troponins impacts on whether or not assays are classified as high-sensitivity and how analytical performance at low concentrations influences the utility of troponins in accelerated diagnostic pathways. Practical suggestions are made for laboratories regarding analytical quality assessment of cardiac troponin results at low cutoffs, with a particular focus on accelerated diagnostic pathways. The review also discusses how future use of cardiac troponins for long-term prediction or management of cardiovascular disease may require improvements in analytical quality.

SUMMARY

Clinical guidelines recommend using cardiac troponin concentrations as low as the limit of detection of the assay to guide patient care. Laboratories, manufacturers, researchers, and external quality assessment providers should extend analytical performance monitoring of cardiac troponin assays to include the concentration ranges applicable in these pathways.

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.

Direct Comparison of the European Society of Cardiology 0/1-Hour Vs. 0/2-Hour Algorithms in Patients with Acute Chest Pain

BACKGROUND

The recent guidelines from the European Society of Cardiology recommends using high-sensitivity cardiac troponin (hs-cTn) in either 0/1-h or 0/2-h algorithms to identify or rule out acute myocardial infarction (AMI). Several studies have reported good diagnostic accuracy with both algorithms, but few have compared the algorithms directly.

OBJECTIVE

We aimed to compare the diagnostic accuracy of the algorithms head-to-head, in the same patients.

METHODS

This was a secondary analysis of data from a prospective observational study; 1167 consecutive patients presenting with chest pain to the emergency department at Skåne University Hospital (Lund, Sweden) were enrolled. Only patients with a hs-cTnT sample at presentation AND after 1 AND 2 h were included in the analysis. We compared sensitivity, specificity, and negative (NPV) and positive predictive value (PPV). The primary outcome was index visit AMI.

RESULTS

A total of 710 patients were included, of whom 56 (7.9%) had AMI. Both algorithms had a sensitivity of 98.2% and an NPV of 99.8% for ruling out AMI, but the 0/2-h algorithm ruled out significantly more patients (69.3% vs. 66.2%, p < 0.001). For rule-in, the 0/2-h algorithm had higher PPV (73.4% vs. 65.2%) and slightly better specificity (97.4% vs. 96.3%, p = 0.016) than the 0/1-h algorithm.

CONCLUSION

Both algorithms had good diagnostic accuracy, with a slight advantage for the 0/2-h algorithm. Which algorithm to implement may thus depend on practical issues such as the ability to exploit the theoretical time saved with the 0/1-h algorithm. Further studies comparing the algorithms in combination with electrocardiography, history, or risk scores are needed.

Clinical Biochemistry of Serum Troponin

Accurate measurement and interpretation of serum levels of troponin (Tn) is a central part of the clinical workup of a patient presenting with chest pain suspicious for acute coronary syndrome (ACS). Knowledge of the molecular characteristics of the troponin complex and test characteristics of troponin measurement assays allows for a deeper understanding of causes of false positive and false negative test results in myocardial injury. In this review, we discuss the molecular structure and functions of the constituent proteins of the troponin complex (TnT, TnC, and TnI); review the different isoforms of Tn and where they are from; survey the evolution of clinical Tn assays, ranging from first-generation to high-sensitivity (hs); provide a primer on statistical interpretation of assay results based on different clinical settings; and discuss potential causes of false results. We also summarize the advances in technologies that may lead to the development of future Tn assays, including the development of point of care assays and wearable Tn sensors for real-time continuous measurement.

Multiple Cardiac Biomarkers to Improve Prediction of Cardiovascular Events: Findings from the Generation Scotland Scottish Family Health Study

BACKGROUND

Many studies have investigated whether single cardiac biomarkers improve cardiovascular risk prediction for primary prevention but whether a combined approach could further improve risk prediction is unclear. We aimed to test a sex-specific, combined cardiac biomarker approach for cardiovascular risk prediction.

METHODS

In the Generation Scotland Scottish Family Health Study, N-terminal pro-B-type natriuretic peptide (NT-proBNP), growth differentiation factor-15 (GDF-15), cardiac troponin I (cTnI), cardiac troponin T (cTnT), and C-reactive protein (CRP) were measured in stored serum using automated immunoassays. Sex-specific Cox models that included SCORE2 risk factors evaluated addition of single and combined biomarkers for prediction of major adverse cardiovascular events (MACE). Combined biomarker models were compared to a baseline model that included SCORE2 risk factors.

RESULTS

The study population comprised 18 383 individuals (58.9% women, median age of 48 years [25th-75th percentile, 35-58 years]). During the median follow up of 11.6 (25th-75th percentile, 10.8-13.0) years, MACE occurred in 942 (5.1%) individuals. The greatest increase in discrimination with addition of individual biomarkers to the base model was for women GDF-15 and for men NT-proBNP (change in c-index: + 0.010 for women and +0.005 for men). For women, combined biomarker models that included GDF-15 and NT-proBNP (+0.012) or GDF-15 and cTnI (+0.013), but not CRP or cTnT, further improved discrimination. For men, combined biomarker models that included NT-proBNP and GDF-15 (+0.007), NT-proBNP and cTnI (+0.006), or NT-proBNP and CRP (+0.008), but not cTnT, further improved discrimination.

CONCLUSIONS

A combined biomarker approach, particularly the use of GDF-15, NT-proBNP and cTnI, further refined cardiovascular risk estimates.

High-sensitivity cardiac troponin I for cardiovascular risk stratification in apparently healthy individuals

Troponin I and T as cardiac-specific biomarkers are highly useful tools not only in the diagnosis of acute coronary syndromes but also as independent predictors of several other clinical conditions. High-sensitivity cardiac troponin (hs-cTn) assays allow the detection of considerably low concentrations of cardiac troponin in apparently healthy and asymptomatic individuals, being a candidate tool for cardiovascular risk stratification in the general population. A group of Greek experts summarized the bulk of evidence regarding the use of hs-cTnI as a predictor of cardiovascular events and mortality in apparently healthy individuals and its additive value on top of existing risk stratification methods. This document could serve as a guide for the incorporation of hs-cTnI as an additional risk stratification tool in cardiovascular prevention strategies in apparently healthy individuals.

Troponin level at presentation as a prognostic factor among patients presenting with non-ST-segment elevation myocardial infarction

BACKGROUND

Timely reperfusion within 120 min is strongly recommended in patients presenting with non-ST-segment myocardial infarction (NSTEMI) with very high-risk features. Evidence regarding the use of high-sensitivity cardiac troponin (hs-cTn) concentration upon admission for the risk-stratification of patients presenting with NSTEMI to expedite percutaneous coronary intervention (PCI) and thus potentially improve outcomes is limited.

METHODS

All patients admitted to a tertiary care center ICCU between July 2019 and July 2022 were included. Hs-cTnI levels on presentaion were recorded, dividing patients into quartiles based on baseline hs-cTnI. Association between initial hs-cTnI and all-cause mortality during up to 3 years of follow-up was studied.

RESULTS

A total of 544 NSTEMI patients with a median age of 67 were included. Hs-cTnI levels in each quartile were: (a) ≤122, (b) 123-680, (c) 681-2877, and (d) ≥2878 ng/L. There was no difference between the initial hs-cTnI level groups regarding age and comorbidities. A higher mortality rate was observed in the highest hs-cTnI quartile as compared with the lowest hs-cTnI quartile (16.2% vs. 7.35%, p = .03) with hazard ratio (HR) for mortality of 2.6 (95% confidence interval [CI]: 1.23-5.4; p = .012) in the unadjusted model, and HR of 2.06 (95% CI: 1.01-4.79; p = .047) with adjustment for age, gender, serum creatinine, and significant comorbidities.

CONCLUSIONS

Patients with NSTEMI and higher hs-cTnI levels upon admission faced elevated mortality risk. This underscores the need for further prospective investigations into early reperfusion strategies' impact on NSTEMI patients' mortality, based on admission troponin elevation.

Establishing optimal cutoff values for high-sensitivity cardiac troponin algorithms in risk stratification of acute myocardial infarction

Acute myocardial infarction (AMI) is a leading cause of mortality globally, highlighting the need for timely and accurate diagnostic strategies. Cardiac troponin has been the biomarker of choice for detecting myocardial injury. A dynamic change in concentrations supports the diagnosis of AMI in the setting of evidence of acute myocardial ischemia. The new generation of high-sensitivity cardiac troponin (hs-cTn) assays has significantly improved analytical sensitivity but at the expense of decreased clinical specificity. As a result, sophisticated algorithms are required to differentiate AMI from non-AMI patients. Establishing optimal hs-cTn cutoffs for these algorithms to rule out and rule in AMI has been the subject of intensive investigations. These efforts have evolved from examining the utility of the hs-cTn 99th percentile upper reference limit, comparing the percentage versus absolute delta thresholds, and evaluating the performance of an early European Society of Cardiology-recommended 3 h algorithm, to the development of accelerated 1 h and 2 h algorithms that combine the admission hs-cTn concentrations and absolute delta cutoffs to rule out and rule in AMI. Specific cutoffs for individual confounding factors such as sex, age, and renal insufficiency have also been investigated. At the same time, concerns such as whether the small delta thresholds exceed the analytical and biological variations of hs-cTn assays and whether the algorithms developed in European study populations fit all other patient cohorts have been raised. In addition, the accelerated algorithms leave a substantial number of patients in a non-diagnostic observation zone. How to properly diagnose patients falling in this zone and those presenting with elevated baseline hs-cTn concentrations due to the presence of confounding factors or comorbidities remain open questions. Here we discuss the developments described above, focusing on criteria and underlying considerations for establishing optimal cutoffs. In-depth analyses are provided on the influence of biological variation, analytical imprecision, local AMI rate, and the timing of presentation on the performance metrics of the accelerated hs-cTn algorithms. Developing diagnostic strategies for patients who remain in the observation zone and those presenting with confounding factors are also reviewed.

Characterization of Myocardial Injury With High-Sensitivity Troponin

BACKGROUND

High-sensitivity troponin I, cardiac form (hs-cTnI) accelerates the assessment of acute coronary syndrome. Little has been documented about its performance, how it relates to different types of myocardial injury, and its impact on morbidity and mortality. This study sought to expand understanding of hs-cTnI by characterizing types of myocardial injury, the impact of comorbidities, and 30-day outcomes.

METHODS

The study retrospectively evaluated 1,975 patients with hs-cTnI levels obtained in the emergency department or inpatient setting from June to September 2020. Troponin was considered elevated if it was higher than the 99th percentile for either sex. Charts were reviewed to determine the presence of myocardial injury. Troponin elevation was adjusted for demographics, comorbidities, and kidney dysfunction. Thirty-day mortality and readmission rates were calculated.

RESULTS

Of 1,975 patients, 468 (24%) had elevated hs-cTnI, and 330 (17%) had at least 1 type of myocardial injury, type 2 myocardial infarction being the most frequent. Sensitivity and specificity using the 99th percentile as a cutoff were 99% and 92%, respectively. The average maximum hs-cTnI level was significantly higher for type 1 myocardial infarction (P < .001). Being male, Black, non-Hispanic, and a hospital inpatient were all associated with higher initial and peak hs-cTnI levels (P < .001). Elevated hs-cTnI level, age, heart disease, kidney dysfunction, and inpatient status were predictive of 30-day mortality on multivariate analysis.

CONCLUSION

Elevated hs-cTnI levels in emergency department and inpatient settings occurs most commonly because of type 2 myocardial infarction. Maximum hs-cTnI level is associated with the patient's particular type of myocardial injury, certain demographics, and cardiovascular comorbidities, and it may be a predictor of 30-day outcomes.

Emergency Department Cardiac Risk Stratification With High-Sensitivity vs Conventional Troponin HEART Pathway

Importance

Patients presenting to the emergency department with chest pain are routinely risk stratified for major adverse cardiac events using the HEART (History, Electrocardiogram, Age, Risk factors, and Troponin) score pathway, which incorporates clinical features, risk factors, electrocardiography findings, and initial serum troponin testing. A new HEART pathway incorporating high-sensitivity troponin level may improve risk stratification among patients with possible acute myocardial infarction (AMI).

Objective

To compare health outcomes and resource use among emergency department patients undergoing cardiac risk stratification with a HEART pathway using conventional vs high-sensitivity serum troponin.

Design, Setting, and Participants

This multicenter pre-post cohort study was conducted between January 1 and September 6, 2021, at 16 Kaiser Permanente Southern California hospitals during uptake of a high-sensitivity serum troponin assay and included 17 384 adult patients who presented to an emergency department with chest pain and were risk stratified with a HEART pathway based on conventional troponin or high-sensitivity troponin.

Exposures

A HEART pathway incorporating either conventional or high-sensitivity serum troponin was used to stratify study groups for risk of major adverse cardiac events within 30 days.

Main Outcomes and Measures

The primary outcome was detection of AMI in the emergency department and within 30 days.

Results

Of the 17 384 patients (median age, 58 years [IQR, 45-69 years]; 9767 women [56.2%]), 12 440 (71.6%) were risk stratified with a HEART pathway based on conventional troponin, and 4944 (28.4%) were risk stratified with a HEART pathway based on high-sensitivity troponin. Detection of AMI within 30 days was higher for the high-sensitivity troponin group than the conventional troponin group (288 [5.8%] vs 545 [4.4%]; P < .001), while the 30-day all-cause mortality rate was unchanged (16 [0.3%] vs 50 [0.4%]; P = .50). In the emergency department, 228 of 4944 patients (4.6%) in the high-sensitivity troponin group received a diagnosis of AMI compared with 251 of 12 440 patients (2.0%) in the conventional troponin group (P < .001). Among those who did not receive a diagnosis of AMI in the emergency department, an additional 60 patients (1.2%) in the high-sensitivity troponin group and 294 (2.4%) in the conventional troponin group (P < .001) received a diagnosis within 30 days. Patients in the high-sensitivity troponin group had lower rates of health care use compared with the conventional troponin group, including admission (605 [12.2%] vs 1862 [15.0%]; P < .001), stress testing within 7 days (506 [10.2%] vs 1591 [12.8%]; P < .001), and coronary revascularization within 30 days (51 [1.0%] vs 244 [2.0%]; P < .001).

Conclusions and Relevance

This multicenter pre-post cohort study suggests that a new HEART pathway incorporating high-sensitivity troponin may improve detection of AMI and decrease resource use among emergency department patients with chest pain.

Potential performance of a 0 h/1 h algorithm and a single cut-off measure of high-sensitivity troponin T in a diverse population: main results of the IN-HOPE study

AIMS

Chest pain is a major cause of medical evaluation at emergency department (ED) and demands observation to exclude the diagnosis of acute myocardial infarction (AMI). High-sensitivity cardiac troponin assays used as isolated measure and by 0- and 1-h algorithms are accepted as a rule-in/rule-out strategy, but there is a lack of validation in specific populations.

METHODS AND RESULTS

The IN-HOspital Program to systematizE Chest Pain Protocol (IN-HOPE study) is a multicentre study that prospectively included patients admitted to the ED due to suspected symptoms of AMI at 16 sites in Brazil. Medical decisions of all patients followed the standard approach of 0 h/3 h protocol, but, in addition, blood samples were also collected at 0 and 1 h and sent to a central laboratory (core lab) to measure high-sensitivity cardiac troponin T (hs-cTnT). To assess the theoretical performance of 0 h/1 h algorithm, troponin < 12 ng/L with a delta < 3 was considered rule-out while a value ≥ 52 or a delta ≥ 5 was considered a rule-in criterion (the remaining were considered as observation group). The main objective of the study was to assess, in a population managed by the 0 h/3 h protocol, the accuracy of 0 h/1 h algorithm overall and in groups with a higher probability of AMI. All patients were followed up for 30 days, and potential events were adjudicated. In addition to the prospective cohort, a retrospective analysis was performed assessing all patients with hs-cTnT measured during the year of 2021 but not included in the prospective cohort, regardless of the indication of the test. A total of 5.497 patients were included (583 in the prospective and 4.914 in the retrospective analysis). The prospective cohort had a mean age of 57.3 (± 14.8) and 45.6% of females with a mean HEART score of 4.0 ± 2.2. By the core lab analysis, 74.4% would be eligible for a rule-out approach (45.3% of them with a HEART score > 3) while 7.3% would fit the rule-in criteria. In this rule-out group, the negative predictive value for index AMI was 100% (99.1-100) overall and regardless of clinical scores. At 30 days, no death or AMI occurred in the rule-out group of both 0/1 and 0/3 h algorithms while 52.4% of the patients in the rule-in group (0 h/1 h) were considered as AMI by adjudication. In the observation group (grey zone) of 0 h/1 h algorithm, GRACE discriminated the risk of these patients better than HEART score. In the retrospective analysis, 1.091 patients had a troponin value of <5 ng/L and there were no cardiovascular deaths at 30 days in this group. Among all 4.914 patients, the 30-day risk of AMI or cardiovascular death increased according to the level of troponin: 0% in the group < 5 ng/L, 0.6% between 5 and 14 ng/L, 2.2% between 14 and 42 ng/L, 6.3% between 42 and 90 ng/L, and 7.7% in the level ≥ 90 ng/L.

CONCLUSION

In this large multicentre study, a 0 h/1 h algorithm had the potential to classify as rule-in or rule-out in almost 80% of the patients. The rule-out protocol had high negative predictive value regardless of clinical risk scores. Categories of levels of hs-cTn T also showed good accuracy in discriminating risk of the patients with a very favourable prognosis for cardiovascular death in the group with value < 5 ng/L.

CLINICALTRIALS.GOV

NCT04756362.

Global Effect of Modifiable Risk Factors on Cardiovascular Disease and Mortality

BACKGROUND

Five modifiable risk factors are associated with cardiovascular disease and death from any cause. Studies using individual-level data to evaluate the regional and sex-specific prevalence of the risk factors and their effect on these outcomes are lacking.

METHODS

We pooled and harmonized individual-level data from 112 cohort studies conducted in 34 countries and 8 geographic regions participating in the Global Cardiovascular Risk Consortium. We examined associations between the risk factors (body-mass index, systolic blood pressure, non-high-density lipoprotein cholesterol, current smoking, and diabetes) and incident cardiovascular disease and death from any cause using Cox regression analyses, stratified according to geographic region, age, and sex. Population-attributable fractions were estimated for the 10-year incidence of cardiovascular disease and 10-year all-cause mortality.

RESULTS

Among 1,518,028 participants (54.1% of whom were women) with a median age of 54.4 years, regional variations in the prevalence of the five modifiable risk factors were noted. Incident cardiovascular disease occurred in 80,596 participants during a median follow-up of 7.3 years (maximum, 47.3), and 177,369 participants died during a median follow-up of 8.7 years (maximum, 47.6). For all five risk factors combined, the aggregate global population-attributable fraction of the 10-year incidence of cardiovascular disease was 57.2% (95% confidence interval [CI], 52.4 to 62.1) among women and 52.6% (95% CI, 49.0 to 56.1) among men, and the corresponding values for 10-year all-cause mortality were 22.2% (95% CI, 16.8 to 27.5) and 19.1% (95% CI, 14.6 to 23.6).

CONCLUSIONS

Harmonized individual-level data from a global cohort showed that 57.2% and 52.6% of cases of incident cardiovascular disease among women and men, respectively, and 22.2% and 19.1% of deaths from any cause among women and men, respectively, may be attributable to five modifiable risk factors. (Funded by the German Center for Cardiovascular Research (DZHK); ClinicalTrials.gov number, NCT05466825.).

Flexible-Interval High-Sensitivity Troponin Velocity for the Detection of Acute Coronary Syndromes

Many algorithms for emergency department (ED) evaluation of acute coronary syndrome (ACS) using high-sensitivity troponin assays rely on the detection of a "delta," the difference in concentration over a predetermined interval, but collecting specimens at specific times can be difficult in the ED. We evaluate the use of troponin "velocity," the rate of change of troponin concentration over a flexible short interval for the prediction of major adverse cardiac events (MACEs) at 30 days. We conducted a prospective, observational study on a convenience sample of 821 patients who underwent ACS evaluation at a high-volume, urban ED. We determined the diagnostic performance of a novel velocity-based algorithm and compared the performance of 1- and 2-hour algorithms adapted from the European Society of Cardiology (ESC) using delta versus velocity. A total of 7 of 332 patients (2.1%) classified as low risk by the velocity-based algorithm experienced a MACE by 30 days compared with 35 of 221 (13.8%) of patients classified as greater than low risk, yielding a sensitivity of 83.3% (95% confidence interval [CI] 68.6% to 93.0%) and negative predictive value (NPV) of 97.9% (95% CI 95.9% to 98.9%). The ESC-derived algorithms using delta or velocity had NPVs ranging from 98.4% (95% CI 96.4% to 99.3%) to 99.6% (95% CI 97.0% to 99.9%) for 30-day MACEs. The NPV of the novel velocity-based algorithm for MACE at 30 days was borderline, but the substitution of troponin velocity for delta in the framework of the ESC algorithms performed well. In conclusion, specimen collection within strict time intervals may not be necessary for rapid evaluation of ACS with high-sensitivity troponin.

Predictive and prognostic value of different cardiac troponin assays: a nationwide register-based cohort study

AIMS

Guidelines do not differentiate between the available assays of cardiac troponin (cTn). We compared the prognostic and predictive ability of cTn assays.

METHODS AND RESULTS

This was a nationwide cohort study of patients with acute coronary syndrome (ACS) and ≥ 2 cTn measurements of one of four assays: Roche high-sensitivity cTnT (hs-cTnT), Abbott high sensitivity cTnI (hs-cTnI), Siemens Vista cTnI, and Siemens cTnI Ultra. Data were collected from Danish registries from 2009-18. Peak cTn concentration normalized to the 99th percentile was used. Outcomes were myocardial infarction (MI) during admission, one-year all-cause-, cardiovascular-, and non-cardiovascular mortality. Receiver operating characteristics and logistic regression calculating odds ratios (OR) were used. A total of 90 705 patients were included, of which 20 550 (23%) had MI. Siemens Vista cTnI was the strongest predictor of MI, Area under the curve (auc) 0.93 (95% CI 0.93-0.93). In 1 year 9012 (9.9%) of patients had died. An inverted U-shape relationship was observed between concentration of cTn and all-cause mortality. Hs-cTnT OR 21.3 (95% CI 18.4-24.8) at 2-5 times the 99th percentile and 12.1 (95% CI 10.3-14.1) for concentrations >100 times the 99th percentile. The inverted U-shape relationship was only present for non-cardiovascular mortality. The strongest predictor of cardiovascular mortality was hs-cTnT, OR 11.3 (95% CI 6.4-21.8) at 1-2 times the 99th percentile and 88.8 (95% CI 53.2-163.0) for concentrations >100 times the 99th percentile.

CONCLUSION

Siemens Vista cTnI was the strongest predictor of MI and hs-cTnT was the strongest predictor of mortality. An inverted U-shape relationship was observed between cTn concentration and non-cardiovascular mortality.

Biomarker-based prediction of fatal and non-fatal cardiovascular outcomes in individuals with diabetes mellitus

AIMS

The role of biomarkers in predicting cardiovascular outcomes in high-risk individuals is not well established. We aimed to investigate benefits of adding biomarkers to cardiovascular risk assessment in individuals with and without diabetes.

METHODS AND RESULTS

We used individual-level data of 95 292 individuals of the European population harmonized in the Biomarker for Cardiovascular Risk Assessment across Europe consortium and investigated the prognostic ability of high-sensitivity cardiac troponin I (hs-cTnI), N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and high-sensitivity C-reactive protein (hs-CRP). Cox-regression models were used to determine adjusted hazard ratios of diabetes and log-transformed biomarkers for fatal and non-fatal cardiovascular events. Models were compared using the likelihood ratio test. Stratification by specific biomarker cut-offs was performed for crude time-to-event analysis using Kaplan-Meier plots. Overall, 6090 (6.4%) individuals had diabetes at baseline, median follow-up was 9.9 years. Adjusting for classical risk factors and biomarkers, diabetes [HR 2.11 (95% CI 1.92, 2.32)], and all biomarkers (HR per interquartile range hs-cTnI 1.08 [95% CI 1.04, 1.12]; NT-proBNP 1.44 [95% CI 1.37, 1.53]; hs-CRP 1.27 [95% CI 1.21, 1.33]) were independently associated with cardiovascular events. Specific cut-offs for each biomarker identified a high-risk group of individuals with diabetes losing a median of 15.5 years of life compared to diabetics without elevated biomarkers. Addition of biomarkers to the Cox-model significantly improved the prediction of outcomes (likelihood ratio test for nested models P < 0.001), accompanied by an increase in the c-index (increase to 0.81).

CONCLUSION

Biomarkers improve cardiovascular risk prediction in individuals with and without diabetes and facilitate the identification of individuals with diabetes at highest risk for cardiovascular events.

Personalized diagnosis in suspected myocardial infarction

BACKGROUND

In suspected myocardial infarction (MI), guidelines recommend using high-sensitivity cardiac troponin (hs-cTn)-based approaches. These require fixed assay-specific thresholds and timepoints, without directly integrating clinical information. Using machine-learning techniques including hs-cTn and clinical routine variables, we aimed to build a digital tool to directly estimate the individual probability of MI, allowing for numerous hs-cTn assays.

METHODS

In 2,575 patients presenting to the emergency department with suspected MI, two ensembles of machine-learning models using single or serial concentrations of six different hs-cTn assays were derived to estimate the individual MI probability (ARTEMIS model). Discriminative performance of the models was assessed using area under the receiver operating characteristic curve (AUC) and logLoss. Model performance was validated in an external cohort with 1688 patients and tested for global generalizability in 13 international cohorts with 23,411 patients.

RESULTS

Eleven routinely available variables including age, sex, cardiovascular risk factors, electrocardiography, and hs-cTn were included in the ARTEMIS models. In the validation and generalization cohorts, excellent discriminative performance was confirmed, superior to hs-cTn only. For the serial hs-cTn measurement model, AUC ranged from 0.92 to 0.98. Good calibration was observed. Using a single hs-cTn measurement, the ARTEMIS model allowed direct rule-out of MI with very high and similar safety but up to tripled efficiency compared to the guideline-recommended strategy.

CONCLUSION

We developed and validated diagnostic models to accurately estimate the individual probability of MI, which allow for variable hs-cTn use and flexible timing of resampling. Their digital application may provide rapid, safe and efficient personalized patient care.

TRIAL REGISTRATION NUMBERS

Data of following cohorts were used for this project: BACC ( www.

CLINICALTRIALS

gov ; NCT02355457), stenoCardia ( www.

CLINICALTRIALS

gov ; NCT03227159), ADAPT-BSN ( www.australianclinicaltrials.gov.au ; ACTRN12611001069943), IMPACT ( www.australianclinicaltrials.gov.au , ACTRN12611000206921), ADAPT-RCT ( www.anzctr.org.au ; ANZCTR12610000766011), EDACS-RCT ( www.anzctr.org.au ; ANZCTR12613000745741); DROP-ACS ( https://www.umin.ac.jp , UMIN000030668); High-STEACS ( www.

CLINICALTRIALS

gov ; NCT01852123), LUND ( www.

CLINICALTRIALS

gov ; NCT05484544), RAPID-CPU ( www.

CLINICALTRIALS

gov ; NCT03111862), ROMI ( www.

CLINICALTRIALS

gov ; NCT01994577), SAMIE ( https://anzctr.org.au ; ACTRN12621000053820), SEIGE and SAFETY ( www.

CLINICALTRIALS

gov ; NCT04772157), STOP-CP ( www.

CLINICALTRIALS

gov ; NCT02984436), UTROPIA ( www.

CLINICALTRIALS

gov ; NCT02060760).

The Clinical Validation of a Common Analytical Change Criteria for Cardiac Troponin for Ruling in an Acute Cardiovascular Outcome in Patients Presenting with Ischemic Chest Pain Symptoms

Serial cardiac troponin (cTn) testing on patients with symptoms suggestive of acute coronary syndrome (ACS) is primarily to identify those patients with evolving myocardial injury. With the improved analytical performance of the high-sensitivity cTn (hs-cTn) assays, different change criteria have been proposed that are mostly assay dependent. Here, we developed and compared a new Common Change Criteria (3C for the combined criteria of >3 ng/L, >30%, or >15% based on the initial cTn concentration of <10 ng/L, 10 to 100 ng/L, or >100 ng/L, respectively) method, versus the 2 h assay-dependent absolute change criteria endorsed by the European Society of Cardiology (ESC), versus the common relative >20% change criterion. These different analytical change criteria were evaluated in 855 emergency department (ED) patients with symptoms of ACS and who had two samples collected 3 h apart. The cTn concentrations were measured with four different assays (Abbott hs-cTnI, Roche hs-cTnT, Ortho cTnI-ES, and Ortho hs-cTnI). The outcomes evaluated were myocardial infarction (MI) and a composite outcome (MI, unstable angina, ventricular arrhythmia, heart failure, or cardiovascular death) within 7 days of ED presentation. The combined change criteria (3C) method yielded higher specificities (range: 93.9 to 97.2%) as compared to the >20% criterion (range: 42.3 to 88.1%) for all four assays for MI. The 3C method only yielded a higher specificity estimate for MI for the cTnI-ES assay (95.9%) versus the absolute change criteria (71.7%). Similar estimates were obtained for the composite outcome. There was also substantial agreement between hs-cTnT and the different cTnI assays for MI with the 3C method, with the percent agreement being ≥95%. The Common Change Criteria (3C) method combining both absolute and different percent changes may be used with cTnI, hs-cTnT, and different hs-cTnI assays to yield similar high-specificity (rule-in) estimates for adverse cardiovascular events for patients presenting to the ED with ACS symptoms.

Use of high-sensitivity cardiac troponin in the emergency department: A policy resource and education paper (PREP) from the American College of Emergency Physicians

This Policy Resource and Education Paper (PREP) from the American College of Emergency Physicians (ACEP) discusses the use of high-sensitivity cardiac troponin (hs-cTn) in the emergency department setting. This brief review discusses types of hs-cTn assays as well as the interpretation of hs-cTn in the setting of various clinical factors such as renal dysfunction, sex, and the important distinction between myocardial injury versus myocardial infarction. In addition, the PREP provides one possible example of an algorithm for the use of a hs-cTn assay in patients in whom the treating clinician is concerned about potential acute coronary syndrome.

Development of saliva-based cardiac troponin I point-of-care test using alpha-amylase depletion: a feasibility study

INTRODUCTION

Cardiac troponin (cTn) is the biomarker of choice for detection of myocardial injury. There is a great need for simple point-of-care (POC) troponin testing among patients with chest pain, mainly in the prehospital setting. The purpose of this study was to evaluate the presence of cardiac troponin I (cTnI) in saliva of patients with myocardial injury using alpha-amylase depletion technique.

METHODS

Saliva samples were collected from 40 patients with myocardial injury who were tested positive for conventional high-sensitivity cardiac troponin T (cTnT) blood tests, and from 66 healthy volunteers. Saliva samples were treated for the removal of salivary alpha-amylase. Treated and untreated samples were tested with blood cTnI Rapid Diagnostic Test. Salivary cTnI levels were compared to blood cTnT levels.

RESULTS

Thirty-six of 40 patients with positive blood cTnT had positive salivary samples for cTnI following alpha-amylase depletion treatment (90.00% sensitivity). Moreover, three of the four negative saliva samples were obtained from patients with relatively low blood cTnT levels of 100 ng/L or less (96.88% sensitivity for 100 ng/L and above). The negative predictive value was 93.65% and rose up to 98.33% considering the 100 ng/L cutoff. Positive predictive values were 83.72% and 81.58%, respectively. Among 66 healthy volunteers and 7 samples yielded positive results (89.39% specificity).

CONCLUSION

In this preliminary work, the presence of cTnI in saliva was demonstrated for the first time to be feasibly identified by a POC oriented assay. The specific salivary alpha-amylase depletion technique was shown to be crucial for the suggested assay.

High sensitivity troponin-I threshold to predict perioperative myocardial infarction

BACKGROUND

High-sensitivity Troponin I (hs-cTnI) has largely replaced conventional troponin assays in an effort to improve detection of myocardial infarction. However, the mean displacement of hs-cTnI following coronary artery bypass graft (CABG) and the optimal threshold to detect perioperative myocardial infarction (MI) is unclear. Our objective is to describe mean hs-cTnI values at 6-12 h post-CABG and to determine the highest specificity while maintaining 100% sensitivity hs-cTnI cut-off values for diagnosis of perioperative or type-5 MI.

METHODS

Between 2016 and 2018, 374 patients underwent non-emergent, isolated CABG. Pre-operative and 6 h post-operative hs-cTnI values were recorded as well as ECG, echocardiographic and angiographic data.

RESULTS

Of 374 patients, 151 (40.3%) had normal and 224 (59.7%) had elevated preoperative hs-cTnI. Patients with normal preoperative hs-cTnI had a mean 6 h hs-cTnI of 9193 ng/l or 270X the upper normal value. Eleven patients (7.3%) presented with post-operative MI with a mean 6 h hs-cTnI of 50,218 ng/l or 1477X the upper normal value. Patients with elevated preoperative hs-cTnI had a mean 6 h hs-cTnI of 9449 ng/l or 292X the upper normal value. Eleven patients (4.9%) who presented with post-operative MI had a mean 6 h hs-cTnI of 26,823 ng/l or 789X the upper normal value.

CONCLUSIONS

We suggest hs-cTnI threshold of 80-fold in patients with normal pre-operative hs-cTnI and 2.7-fold in patients with elevated pre-operative hs-cTnI. These results have important implications for perioperative care and for surgical trial reporting.

Using logistic regression models to investigate the effects of high-sensitivity cardiac troponin T confounders on ruling in acute myocardial infarction

OBJECTIVES

Confounding factors, including sex, age, and renal dysfunction, affect high-sensitivity cardiac troponin T (hs-cTnT) concentrations and the acute myocardial infarction (AMI) diagnosis. This study assessed the effects of these confounders through logistic regression models and evaluated the diagnostic performance of an optimized, integrated prediction model.

METHODS

This retrospective study included a primary derivation cohort of 18,022 emergency department (ED) patients at a US medical center and a validation cohort of 890 ED patients at a Canadian medical center. Hs-cTnT was measured with 0/3 h sampling. The primary outcome was index AMI diagnosis. Logistic regression models were optimized to predict AMI using delta hs-cTnT and its confounders as covariates. The diagnostic performance of model cutoffs was compared to that of the hs-cTnT delta thresholds. Serial logistic regressions were carried out to evaluate the relationship between covariates.

RESULTS

The area under the curve of the best-fitted model was 0.95. The model achieved a 90.0% diagnostic accuracy in the validation cohort. The optimal model cutoff yielded comparable performance (90.5% accuracy) to the optimal sex-specific delta thresholds (90.3% accuracy), with 95.8% agreement between the two diagnostic methods. Serial logistic regressions revealed that delta hs-cTnT played a more predominant role in AMI prediction than its confounders, among which sex is more predictive of AMI (total effect coefficient 1.04) than age (total effect coefficient 0.05) and eGFR (total effect coefficient -0.008).

CONCLUSIONS

The integrated prediction model incorporating confounding factors does not outperform hs-cTnT delta thresholds. Sex-specific hs-cTnT delta thresholds remain to provide the highest diagnostic accuracy.

Trajectories of cardiac troponin in the decades before cardiovascular death: a longitudinal cohort study

BACKGROUND

High-sensitivity cardiac troponin testing is a promising tool for cardiovascular risk prediction, but whether serial testing can dynamically predict risk is uncertain. We evaluated the trajectory of cardiac troponin I in the years prior to a cardiovascular event in the general population, and determine whether serial measurements could track risk within individuals.

METHODS

In the Whitehall II cohort, high-sensitivity cardiac troponin I concentrations were measured on three occasions over a 15-year period. Time trajectories of troponin were constructed in those who died from cardiovascular disease compared to those who survived or died from other causes during follow up and these were externally validated in the HUNT Study. A joint model that adjusts for cardiovascular risk factors was used to estimate risk of cardiovascular death using serial troponin measurements.

RESULTS

In 7,293 individuals (mean 58 ± 7 years, 29.4% women) cardiovascular and non-cardiovascular death occurred in 281 (3.9%) and 914 (12.5%) individuals (median follow-up 21.4 years), respectively. Troponin concentrations increased in those dying from cardiovascular disease with a steeper trajectory compared to those surviving or dying from other causes in Whitehall and HUNT (Pinteraction < 0.05 for both). The joint model demonstrated an independent association between temporal evolution of troponin and risk of cardiovascular death (HR per doubling, 1.45, 95% CI,1.33-1.75).

CONCLUSIONS

Cardiac troponin I concentrations increased in those dying from cardiovascular disease compared to those surviving or dying from other causes over the preceding decades. Serial cardiac troponin testing in the general population has potential to track future cardiovascular risk.

Acute Coronary Syndrome: Disparities of Pathophysiology and Mortality with and without Peripheral Artery Disease

There are a number of devastating complications associated with peripheral artery disease, including limb amputations and acute limb ischemia. Despite the overlap, atherosclerotic diseases have distinct causes that need to be differentiated and managed appropriately. In coronary atherosclerosis, thrombosis is often precipitated by rupture or erosion of fibrous caps around atheromatous plaques, which leads to acute coronary syndrome. Regardless of the extent of atherosclerosis, peripheral artery disease manifests itself as thrombosis. Two-thirds of patients with acute limb ischemia have thrombi associated with insignificant atherosclerosis. A local thrombogenic or remotely embolic basis of critical limb ischemia may be explained by obliterative thrombi in peripheral arteries of patients without coronary artery-like lesions. Studies showed that thrombosis of the above-knee arteries was more commonly due to calcified nodules, which are the least common cause of luminal thrombosis associated with acute coronary events in patients with acute coronary syndrome. Cardiovascular mortality was higher in peripheral artery disease without myocardial infarction/stroke than in myocardial infarction/stroke without peripheral artery disease. The aim of this paper is to gather published data regarding the disparities of acute coronary syndrome with and without peripheral artery disease in terms of pathophysiology and mortality.

Rising and Falling High-Sensitivity Cardiac Troponin in Diagnostic Algorithms for Patients With Suspected Myocardial Infarction

Background High-sensitivity cardiac troponin (hs-cTn)-based diagnostic algorithms are recommended for the management of patients with suspected myocardial infarction (MI) without ST elevation. Although mirroring different phases of myocardial injury, falling and rising troponin patterns (FPs and RPs, respectively) are equally considered by most algorithms. We aimed to compare the performance of diagnostic protocols for RPs and FPs, separately. Methods and Results We pooled 2 prospective cohorts of patients with suspected MI and stratified patients to stable, FP, and RP during serial sampling separately for hs-cTnI and hs-cTnT and applied the European Society of Cardiology 0/1- and 0/3-hour algorithms comparing the positive predictive values to rule in MI. Overall, 3523 patients were included in the hs-cTnI study population. The positive predictive value for patients with an FP was significantly reduced compared with patients with an RP (0/1-hour: FP, 53.3% [95% CI, 45.0-61.4] versus RP, 76.9 [95% CI, 71.6-81.7]; 0/3-hour: FP, 56.9% [95% CI, 42.2-70.7] versus RP, 78.1% [95% CI, 74.0-81.8]). The proportion of patients in the observe zone was larger in the FP using 0/1-hour (31.3% versus 55.8%) and 0/3-hour (14.6% versus 38.6%) algorithms. Alternative cutoffs did not improve algorithm performances. Compared with stable hs-cTn, the risk for death or MI was highest in those with an FP (adjusted hazard ratio [HR], hs-cTnI 2.3 [95% CI, 1.7-3.2]; RP adjusted HR, hs-cTnI 1.8 [95% CI, 1.4-2.4]). Findings were similar for hs-cTnT tested in 3647 patients overall. Conclusions The positive predictive value to rule in MI by the European Society of Cardiology 0/1- and 0/3-hour algorithms is significantly lower in patients with FP than RP. These are at highest risk for incident death or MI. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifiers: NCT02355457, NCT03227159.

S-Scheme Porphyrin Covalent Organic Framework Heterojunction for Boosted Photoelectrochemical Immunoassays in Myocardial Infarction Diagnosis

Cardiac troponin I (cTnI) is an extremely sensitive biomarker for early indication of acute myocardial infarction (AMI). However, it still remains a tough challenge for many newly developed cTnI biosensors to achieve superior sensing performance including high sensitivity, rapid detection, and resistance to interference in clinical serum samples. Herein, a novel photocathodic immunosensor toward cTnI sensing has been successfully developed by designing a unique S-scheme heterojunction based on the porphyrin-based covalent organic frameworks (p-COFs) and p-type silicon nanowire arrays (p-SiNWs). In the novel heterojunction, the p-SiNWs are employed as the photocathode platform to acquire a strong photocurrent response. The in situ-grown p-COFs can accelerate the spatial migration rate of charge carriers by forming proper band alignment with the p-SiNWs. The crystalline π-conjugated network of p-COFs with abundant amino groups also promotes the electron transfer and anti-cTnI immobilizing process. The developed photocathodic immunosensor demonstrates a broad detection range of 5 pg/mL-10 ng/mL and a low limit of detection (LOD) of 1.36 pg/mL in clinical serum samples. Besides, the PEC sensor owns several advantages including good stability and superior anti-interference ability. By comparing our results with that of the commercial ELISA method, the relative deviations range from 0.06 to 0.18% (n = 3), and the recovery rates range from 95.4 to 109.5%. This work displays a novel strategy to design efficient and stable PEC sensing platforms for cTnI detection in real-life serums and provides guidance in future clinical diagnosis.

[Cardiac biomarkers and their clinical relevance]

Cardiac biomarkers are an integral, guideline-recommended part of the diagnosis and follow-up of heart diseases. High sensitivity tests for troponin I or T allow for the early diagnosis of myocardial infarction. Rule-in and rule-out algorithms based on the dynamic of plasma concentrations in the first hour after admission improve safe, evidence-based decision making for patients with acute chest pain. Low concentrations of brain natriuretic peptides (BNP or NT-proBNP) reliably exclude heart failure. Elevated BNP/NT-proBNP concentrations are part of the definition of all types of heart failure but require additional tests to diagnose heart failure. Chronic elevations of troponins and BNP/NT-proBNP identify subpopulations at increased risk of cardiovascular events even in the absence of manifest cardiac disease. Whether and how this risk can be reduced requires further evaluation. Several novel biomarkers were recently discovered and characterised. Their place in cardiovascular medicine has yet to be defined.

Machine learning for diagnosis of myocardial infarction using cardiac troponin concentrations

Although guidelines recommend fixed cardiac troponin thresholds for the diagnosis of myocardial infarction, troponin concentrations are influenced by age, sex, comorbidities and time from symptom onset. To improve diagnosis, we developed machine learning models that integrate cardiac troponin concentrations at presentation or on serial testing with clinical features and compute the Collaboration for the Diagnosis and Evaluation of Acute Coronary Syndrome (CoDE-ACS) score (0-100) that corresponds to an individual's probability of myocardial infarction. The models were trained on data from 10,038 patients (48% women), and their performance was externally validated using data from 10,286 patients (35% women) from seven cohorts. CoDE-ACS had excellent discrimination for myocardial infarction (area under curve, 0.953; 95% confidence interval, 0.947-0.958), performed well across subgroups and identified more patients at presentation as low probability of having myocardial infarction than fixed cardiac troponin thresholds (61 versus 27%) with a similar negative predictive value and fewer as high probability of having myocardial infarction (10 versus 16%) with a greater positive predictive value. Patients identified as having a low probability of myocardial infarction had a lower rate of cardiac death than those with intermediate or high probability 30 days (0.1 versus 0.5 and 1.8%) and 1 year (0.3 versus 2.8 and 4.2%; P < 0.001 for both) from patient presentation. CoDE-ACS used as a clinical decision support system has the potential to reduce hospital admissions and have major benefits for patients and health care providers.

The "cardiac neglect": a gentle reminder to radiologists interpreting contrast-enhanced abdominal MDCT

Myocardial infarction (MI) may be visible on contrast-enhanced multidetector computed tomography (MDCT) scans of the abdomen. In the previous literature, potentially missed MI in abdominal MDCTs was not perceived as an issue in radiology. This retrospective single-center study assessed the frequency of detectable myocardial hypoperfusion in contrast-enhanced abdominal MDCTs. We identified 107 patients between 2006 and 2022 who had abdominal MDCTs on the same day or the day before a catheter-proven or clinically evident diagnosis of MI. After reviewing the digital patient records and applying the exclusion criteria, we included 38 patients, with 19 showing areas of myocardial hypoperfusion. All MDCT studies were non ECG-gated. The delay between the MDCT examination and MI diagnosis was shorter in studies with myocardial hypoperfusion (7.4 ± 6.5 hours and 13.8 ± 12.5 hours) but not statistically significant p = 0.054 . Only 2 of 19 (11%) of these pathologies had been noted in the written radiology reports. The most common cardinal symptom was epigastric pain (50%), followed by polytrauma (21%). STEMI was significantly more common in cases of myocardial hypoperfusion p = 0.009 . Overall, 16 of 38 (42%) patients died because of acute MI. Based on extrapolations using local MDCT rates, we estimate several thousand radiologically missed MI cases worldwide per year.

Coronary low-attenuation plaque and high-sensitivity cardiac troponin

OBJECTIVE

In patients with acute chest pain who have had myocardial infarction excluded, plasma cardiac troponin I concentrations ≥5 ng/L are associated with risk of future adverse cardiovascular events. We aim to evaluate the association between cardiac troponin and coronary plaque composition in such patients.

METHODS

In a prespecified secondary analysis of a prospective cohort study, blinded quantitative plaque analysis was performed on 242 CT coronary angiograms of patients with acute chest pain in whom myocardial infarction was excluded. Patients were stratified by peak plasma cardiac troponin I concentration ≥5 ng/L or <5 ng/L. Associations were assessed using univariable and multivariable logistic regression analyses.

RESULTS

The cohort was predominantly middle-aged (62±12 years) men (69%). Patients with plasma cardiac troponin I concentration ≥5 ng/L (n=161) had a higher total (median 33% (IQR 0-47) vs 0% (IQR 0-33)), non-calcified (27% (IQR 0-37) vs 0% (IQR 0-28)), calcified (2% (IQR 0-8) vs 0% (IQR 0-3)) and low-attenuation (1% (IQR 0-3) vs 0% (IQR 0-1)) coronary plaque burden compared with those with concentrations <5 ng/L (n=81; p≤0.001 for all). Low-attenuation plaque burden was independently associated with plasma cardiac troponin I concentration ≥5 ng/L after adjustment for clinical characteristics (adjusted OR per doubling 1.62 (95% CI 1.17 to 2.32), p=0.005) or presence of any visible coronary artery disease (adjusted OR per doubling 1.57 (95% CI 1.07 to 2.37), p=0.026).

CONCLUSION

In patients with acute chest pain but without myocardial infarction, plasma cardiac troponin I concentrations ≥5 ng/L are associated with greater burden of low-attenuation coronary plaque.

Magnitude of troponin elevation in patients with biomarker evidence of myocardial injury: relative frequency and outcomes in a cohort study across a large healthcare system

BACKGROUND

Serum troponin levels correlate with the extent of myocyte necrosis in acute myocardial infarction (AMI) and predict adverse outcomes. However, thresholds of cardiac troponin elevation that could portend to poor outcomes have not been established.

METHODS

In this cohort study, we characterized all cardiac troponin elevations > 0.04 ng/mL (upper limit of normal [ULN]) from patients hospitalized with an ICD-9/10 diagnosis of AMI across our health system from 2012-2019. We grouped events into exponential categories of peak cardiac troponin and evaluated the association of these troponin categories with all-cause mortality, heart transplants, or durable left ventricular assist devices (LVAD). Patients with cardiac troponin > 10,000 × ULN were manually chart reviewed and described.

RESULTS

There were 18,194 AMI hospitalizations with elevated cardiac troponin. Peak troponin was 1-10 × ULN in 21.1%, 10-100 × ULN in 34.8%, 100-1,000 × ULN in 30.1%, 1,000-10,000 × ULN in 13.1%, and > 10,000 × ULN in 0.9% of patients. One-year mortality was 17-21% across groups, except in > 10,000 × ULN group where it was 33% (adjusted hazard ratio (99%CI) for > 10,000 × ULN group compared to all others: 1.86 (1.21, 2.86)). Hazards of one-year transplant and MCS were also significantly elevated in the > 10,000 × ULN group.

CONCLUSIONS

Elevation in cardiac troponin levels post AMI that are > 10,000 × ULN was rare but identified patients at particularly high risk of adverse events. These patients may benefit from clarification of goals of care and early referral for advanced heart failure therapies. These data have implications for conversion to newer high-sensitivity cardiac troponin assays whose maximum assay limit is often lower than traditional assays.

Healthcare cost burden of acute chest pain presentations

BACKGROUND

This study aimed to estimate the direct healthcare cost burden of acute chest pain attendances presenting to ambulance in Victoria, Australia, and to identify key cost drivers especially among low-risk patients.

METHODS

State-wide population-based cohort study of consecutive adult patients attended by ambulance for acute chest pain with individual linkage to emergency and hospital admission data in Victoria, Australia (1 January 2015-30 June 2019). Direct healthcare costs, adjusted for inflation to 2020-2021 ($A), were estimated for each component of care using a casemix funding method.

RESULTS

From 241 627 ambulance attendances for chest pain during the study period, mean chest pain episode cost was $6284, and total annual costs were estimated at $337.4 million ($68 per capita per annum). Total annual costs increased across the period ($310.5 million in 2015 vs $384.5 million in 2019), while mean episode costs remained stable. Cardiovascular conditions (25% of presentations) were the most expensive (mean $11 523, total annual $148.7 million), while a non-specific pain diagnosis (49% of presentations) was the least expensive (mean $3836, total annual $93.4 million). Patients classified as being at low risk of myocardial infarction, mortality or hospital admission (Early Chest pain Admission, Myocardial infarction, and Mortality (ECAMM) score) represented 31%-57% of the cohort, with total annual costs estimated at $60.6 million-$135.4 million, depending on the score cut-off used.

CONCLUSIONS

Total annual costs for acute chest pain presentations are increasing, and a significant proportion of the cost burden relates to low-risk patients and non-specific pain. These data highlight the need to improve the cost-efficiency of chest pain care pathways.

High-Sensitivity Cardiac Troponin Algorithms and the Value of Likelihood Ratios

High-sensitivity cardiac troponin (hs-cTn) is now the recommended biomarker for diagnosis of non-ST-elevation myocardial infarction, but proper interpretation varies based on the assay being used. Nearly uniformly, suggested interpretations of assay-specific hs-cTn results are based on predictive values, which are not applicable to most patients. Through application of a published hs-cTn algorithm to several patient scenarios, we will demonstrate that likelihood ratios are superior to predictive values for patient-centered test interpretation and decision-making. Furthermore, we will provide a blueprint for how to use existing published data presented with predictive values to calculate likelihood ratios. Changing the output of diagnostic accuracy studies and diagnostic algorithms from predictive values to likelihood ratios can improve patient care.

Review of current ECG consumer electronics (pros and cons)

BACKGROUND

Several wearable, medical-grade consumer ECG devices are now available and integrated into consumer electronics like multi sensor fitness watches and scales. Specific consumer ECGs can also come in the form of patches or thin sensor plates in credit card or other shapes. Watches with ECG capabilities are often multi vital sign sensor devices. The majority of these devices are usually connected to a mobile smartphone. However, there are pros and cons to their use.

METHODS

We review here an exemplary selection of modern consumer ECG devices based on device type, recording method and the number of standard ECG channels derived.

RESULTS

Single-channel consumer ECG devices such as Smart Watches can be useful for detecting and monitoring atrial fibrillation and flutter and other arrhythmias, as well as ectopic complexes. However, they are currently limited with respect to recording duration and information content (a single-channel or limb‑lead ECG having less diagnostic information than a 12‑lead ECG). While some non watch-based consumer ECG devices can now record all 6 limb leads to yield increased information, no consumer ECG devices can currently reliably detect ST-segment deviations, potentially indicating myocardial infarction or ischemic episodes. Moreover, barriers to use still exist for at-risk elderly people. Finally, there currently is no universal data exchange format.

CONCLUSION

Consumer ECG devices, whether in fitness or fashionable design, allow for reliable detection of atrial fibrillation. Timely detection of atrial fibrillation and subsequent treatment might protect against stroke, especially in high-risk groups, yet prospective evidence is still lacking. Six-channel consumer ECG and longer data collection capabilities extend potential functionality, including for the monitoring of ST-segments and QT intervals. However, no currently available devices are sufficiently suitable for the detection of myocardial infarction or ischemia, which is why portable 12-channel technologies are desirable. For the reliable detection of a myocardial infarction, the determination of specific myocardial infarction blood markers and evaluation of patient medical history still is indispensable in addition to the 12 lead ECG.

Outpatient Myocardial Perfusion Imaging Scan for a Low-Risk Chest Pain Cohort From the Emergency Department: A Retrospective Analysis

Chest pain accounts for a significant attendances at emergency departments (ED). We examined the utility of early stress myocardial perfusion imaging (SMPI) for stratification of low-risk patients post-ED discharge. A retrospective audit was conducted of patients with chest pain and normal troponin-T (<30Ng/L), who were discharged with outpatient SMPI (median = 3 days post-ED discharge) between January 2018 to January 2020. 880 patients were included and followed up for 12 months. Outcomes measured were: 1) Cardiac events (CE) within 1 year of visit or 2) Significant coronary artery disease (CAD) - coronary angiography demonstrating ≥70% stenosis of epicardial vessels or coronary revascularization procedures performed. In the SMPI negative group, 2 of 802 patients (0.25%) had significant CEs and 11 patients (1.37%) were diagnosed with significant CAD. Of the 78 SMPI positive patients, 1 (1.28%) had a significant CE, while 24 had significant CAD. SMPI had a sensitivity of 65.8%, specificity of 93.7%, positive predictive value of 32.1% and a negative predictive value of 98.4% for predicting adverse CE. Early SMPI post-ED discharge demonstrated high negative predictive value in predicting CEs or significant CAD diagnosis at up to 1 year, suggesting that low-risk patients discharge from ED with early outpatient SMPI is a safe management option.

Serial troponin-T and long-term outcomes in suspected acute coronary syndrome

BACKGROUND

Long-term prognostic implications of serial high-sensitivity troponin concentrations in subjects with suspected acute coronary syndrome are unknown.

METHODS AND RESULTS

Individuals with a first diagnosis of myocardial infarction, unstable angina, observation for suspected myocardial infarction, or chest pain from 2012 through 2019 who underwent two high-sensitivity troponin-T (hsTnT) measurements 1-7 h apart were identified through Danish national registries. Absolute and relative risks for death at days 0-30 and 31-365, stratified for whether subjects had normal or elevated hsTnT concentrations, and whether these concentrations changed by <20%, > 20 to 50%, or >50% in either direction from first to second measurement, were calculated through multivariable logistic regression with average treatment effect modeling. Of the 28 902 individuals included, 2.8% had died at 30 days, whereas 4.9% of those who had survived the first 30 days died between days 31-365. The standardized risk of death was highest among subjects with two elevated hsTnT concentrations (0-30 days: 4.3%, 31-365 days: 7.2%). In this group, mortality was significantly higher in those with a > 20 to 50% or >50% rise from first to second measurement, though only at 30 days. The risk of death was very low in subjects with two normal hsTnT concentrations (0-30 days: 0.1%, 31-365 days: 0.9%) and did not depend on relative or absolute changes between measurements.

CONCLUSIONS

Individuals with suspected acute coronary syndrome and two consecutively elevated hsTnT concentrations consistently had the highest risk of death. Mortality was very low in subjects with two normal hsTnT concentrations, irrespective of changes between measurements.

Circulating cardiac biomarkers, structural brain changes, and dementia: Emerging insights and perspectives

Diseases of the heart and brain are strongly linked to each other, and cardiac dysfunction is associated with cognitive decline and dementia. This link between cardiovascular disease and dementia offers opportunities for dementia prevention through prevention and treatment of cardiovascular risk factors and heart disease. Increasing evidence suggests the clinical utility of cardiac biomarkers as risk markers for structural brain changes and cognitive impairment. We propose the hypothesis that structural brain changes are the link between impaired cardiac function, as captured by blood-based cardiac biomarkers, and cognitive impairment. This review provides an overview of the literature and illustrates emerging insights into the association of markers of hemodynamic stress (natriuretic peptides) and markers of myocardial injury (cardiac troponins) with imaging findings of brain damage and cognitive impairment or dementia. Based on these findings, we discuss potential pathophysiological mechanisms underlying the association of cardiac biomarkers with structural brain changes and dementia. We suggest testable hypotheses and a research plan to close the gaps in understanding the mechanisms linking vascular damage and neurodegeneration, and to pave the way for targeted effective interventions for dementia prevention. From a clinical perspective, cardiac biomarkers open the window for early identification of patients at risk of dementia, who represent a target population for preventive interventions targeting modifiable cardiovascular risk factors to avert cognitive decline and dementia.

Machine learning for early prediction of acute myocardial infarction or death in acute chest pain patients using electrocardiogram and blood tests at presentation

AIMS

In the present study, we aimed to evaluate the performance of machine learning (ML) models for identification of acute myocardial infarction (AMI) or death within 30 days among emergency department (ED) chest pain patients.

METHODS AND RESULTS

Using data from 9519 consecutive ED chest pain patients, we created ML models based on logistic regression or artificial neural networks. Model inputs included sex, age, ECG and the first blood tests at patient presentation: High sensitivity TnT (hs-cTnT), glucose, creatinine, and hemoglobin. For a safe rule-out, the models were adapted to achieve a sensitivity > 99% and a negative predictive value (NPV) > 99.5% for 30-day AMI/death. For rule-in, we set the models to achieve a specificity > 90% and a positive predictive value (PPV) of > 70%. The models were also compared with the 0 h arm of the European Society of Cardiology algorithm (ESC 0 h); An initial hs-cTnT < 5 ng/L for rule-out and ≥ 52 ng/L for rule-in. A convolutional neural network was the best model and identified 55% of the patients for rule-out and 5.3% for rule-in, while maintaining the required sensitivity, specificity, NPV and PPV levels. ESC 0 h failed to reach these performance levels.

DISCUSSION

An ML model based on age, sex, ECG and blood tests at ED arrival can identify six out of ten chest pain patients for safe early rule-out or rule-in with no need for serial blood tests. Future studies should attempt to improve these ML models further, e.g. by including additional input data.

Computed tomography coronary angiography after excluding myocardial infarction: high-sensitivity troponin versus risk score-guided approach

BACKGROUND

Patients with suspected acute coronary syndrome (ACS) in whom myocardial infarction has been ruled out are still at risk of having obstructive coronary artery disease (CAD). This rate is higher among patients with intermediate high-sensitivity troponin I (hsTnI) concentrations (5 ng/L to 99th percentile) than low concentrations (<5 ng/L). Therefore, an intermediate concentration has been suggested as a candidate for downstream investigation with computed tomography coronary angiography (CTCA). We tried to compare the HEART score-guided vs. hsTnI-guided approach for identifying obstructive CAD.

METHODS

From a prospective cohort study of patients presenting to the emergency department with suspected ACS, 433 patients without elevated hsTnI who also underwent CTCA were selected and analyzed. The performances of hsTnI concentration and HEART score were compared using sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

RESULTS

Overall, 120 (27.7%) patients had obstructive CAD. Patients with intermediate hsTnI concentrations were more likely to have obstructive CAD than those with low hsTnI concentrations (40.0% vs. 18.1%); patients with non-low-risk HEART scores (≥4 points) were also more likely to have obstructive CAD than those with low-risk scores (0 to 3 points) (41.0% vs. 7.6%). The HEART score had higher sensitivity and NPV for detecting obstructive CAD in each classification than hsTnI concentration (sensitivity: 89.2% vs. 63.3% NPV: 92.4% vs. 81.9%, respectively).

CONCLUSION

After excluding myocardial infarction in patients with suspected ACS, adding the HEART score for selecting candidates for CTCA could improve patient risk stratification more accurately than relying on hsTnI concentration.

Single High-Sensitivity Point-of-Care Whole-Blood Cardiac Troponin I Measurement to Rule Out Acute Myocardial Infarction at Low Risk

BACKGROUND

High-sensitivity cardiac troponin (hs-cTn) laboratory assays are used to rule out myocardial infarction (MI) on presentation, but prolonged result turnaround times can delay patient management. Our primary aim was to identify patients at low risk of index MI using a rapid point-of-care (POC) whole-blood hs-cTnI assay at presentation with potential early patient discharge.

METHODS

Consecutive patients presenting to the emergency department from 2 prospective observational studies with suspected acute coronary syndrome were enrolled. A POC hs-cTnI assay (Atellica VTLi) threshold using whole blood at presentation, which resulted in a negative predictive value of ≥99.5% and sensitivity of >99% for index MI, was derived (SEIGE [Safe Emergency Department Discharge Rate]) and validated with plasma (SAMIE [Suspected Acute Myocardial Infarction in Emergency]). Event adjudications were established with hs-cTnI assay results from routine clinical care. The primary outcome was MI at 30 days.

RESULTS

A total of 1086 patients (8.1% with MI) were enrolled in a US derivation cohort (SEIGE) and 1486 (5.5% MI) in an Australian validation cohort (SAMIE). A derivation whole-blood POC hs-cTnI concentration of <4 ng/L provided a sensitivity of 98.9% (95% CI, 93.8%-100%) and negative predictive value of 99.5% (95% CI, 97.2%-100%) for ruling out MI. In the validation cohort, the sensitivity was 98.8% (95% CI, 93.3%-100%), and negative predictive value was 99.8% (95% CI, 99.1%-100%); 17.8% and 41.8%, respectively, were defined as low risk for discharge. The 30-day adverse cardiac events were 0.1% (n=1) for SEIGE and 0.8% (n=5) for SAMIE.

CONCLUSIONS

A POC whole-blood hs-cTnI assay permits accessible, rapid, and safe exclusion of MI and may expedite discharge from the emergency department.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04772157. URL: https://www.australianclinicaltrials.gov.au/anzctr_feed/form; Unique identifier: 12621000053820.

Association of Serial High-Sensitivity Cardiac Troponin T With Subsequent Cardiovascular Events in Patients Stabilized After Acute Coronary Syndrome: A Secondary Analysis From IMPROVE-IT

Importance

Studies have demonstrated an association between single measures of high-sensitivity troponin (hsTn) and future cardiovascular events in patients with chronic coronary syndromes. However, limited data exist regarding the association between changes in serial values of hsTn and subsequent cardiovascular events in this patient population.

Objective

To evaluate the association between changes in high-sensitivity troponin T (hsTnT) and subsequent cardiovascular events in patients stabilized after acute coronary syndrome (ACS).

Design, Setting, and Participants

This is a secondary analysis from the Improved Reduction of Outcomes: Vytorin Efficacy International Trial (IMPROVE-IT), a randomized clinical trial of ezetimibe vs placebo on a background of simvastatin in 18 144 patients hospitalized for an ACS across 1147 sites in 39 countries. The current biomarker substudy includes the 6035 participants consenting to the biomarker substudy with available hsTnT at months 1 and 4. Data were collected from October 26, 2005, through July 8, 2010, with the database locked October 21, 2014. Data were analyzed from February 28, 2021, through August 14, 2022.

Main Outcomes and Measures

The outcomes of interest were cardiovascular death, myocardial infarction (MI), stroke, or hospitalization for heart failure (HHF). Associations of absolute and relative changes in hsTnT between month 1 and month 4 as a function of the starting month 1 hsTnT and the composite outcome were examined using landmark analyses.

Results

Of 6035 patients in this analysis (median [IQR] age, 64 [57-71]), 1486 (24.6%) were female; 361 (6.0%) were Asian; 121 were (2.0%) Black; 252 (4.2%) were Spanish descent; 4959 were (82.2%) White; and 342 (5.7%) reported another race (consolidated owing to small numbers), declined to respond, or were not asked to report race owing to regulatory prohibitions. Most patients (4114 [68.2%]) had stable hsTnT values (change <3 ng/L), with 1158 (19.2%) and 763 (12.6%) having changes of 3 to less than 7 ng/L and 7 ng/L or more, respectively. After adjustment for clinical risk factors and stratification by the starting month 1 hsTnT level, an absolute increase in hsTnT of 7 ng/L or more was associated with a more than 3-fold greater risk of the composite outcome (adjusted hazard ratio [aHR], 3.33; 95% CI, 1.99-5.57; P < .001), whereas decreases of 7 ng/L or more were associated with similar to lower risk (aHR, 0.51; 95% CI, 0.26-1.03; P = .06) compared with stable values. There was a stepwise association moving from larger absolute decreases (aHR, 0.51; 95% CI, 0.26-1.03) to larger absolute increases (aHR, 3.33; 95% CI, 1.99-5.57) in hsTnT with future risk of the composite outcome (P trend <.001). A similar association was observed when analyzed on the basis of relative percent and continuous change.

Conclusions and Relevance

Among stable patients post-ACS, changes in hsTnT were associated with a gradient of risk of subsequent cardiovascular events across the range of starting hsTnT values. Serial assessment of hsTnT may refine risk stratification with the potential to guide therapy decisions in this patient population.

Trial Registration

ClinicalTrials.gov Identifier: NCT00202878.