High-sensitivity cardiac troponin I at presentation in patients with suspected acute coronary syndrome: a cohort study

Safety and feasibility of triage and rapid discharge of patients with chest pain from emergency room: a pragmatic, randomised non-inferiority control trial of the European Society of Cardiology (ESC) 0-1 hour pathway vs. conventional 0-3 hour accelerated diagnostic protocol

Patients presenting with chest pain represent a significant proportion of Emergency Department (ED) attendances but only a minority, typically 10%, have a final diagnosis of myocardial infarction (MI). Prompt discharge of patients without MI will alleviate ED overcrowding as well as improve patient satisfaction and reduce exposure to risk of hospital acquired infections such as Covid 19. The measurement of cardiac troponin (cTn) by a high sensitivity method is recommended by the National Institute for health and Care Excellence (NICE) for rapid categorisation of patients presenting with chest pain. Strategies proposed include measurement on admission and one hour from admission (ESC 0-1-hour pathway, the recent guideline approved pathway which has not been implemented widely), and measurement on admission and three hours from admission (0-3-hour pathway, which is conventional and widely adopted). The primary objective of this study is twofold: firstly, to assess the safety, feasibility, and impact of implementing the ESC (European Society of Cardiology) 0-1-hour pathway in clinical practice by reference to the more established ESC 0-3-hour protocol. The principal outcome measure will be the safety of the ESC 0-1-hour protocol. However, there are concerns that the time from sample draw to result availability (typically around 60 minutes) will impact on the feasibility of the ESC 0-1-hour pathway. Secondly, therefore, our goal is to evaluate whether measurement of high sensitivity troponin by a bedside analyser (point of care testing, POCT), which will produce results in 15 minutes is a feasible alternative to laboratory testing. We will compare the results produced by POCT with the laboratory results in the context of the ESC 0-1 hour and 0-3-hour pathway, as a nested controlled study in the context of a randomised controlled trial. (clinicaltrials.gov: NCT05322395).

Risk scores and coronary artery disease in patients with suspected acute coronary syndrome and intermediate cardiac troponin concentrations

BACKGROUND

Guidelines recommend the use of risk scores to select patients for further investigation after myocardial infarction has been ruled out but their utility to identify those with coronary artery disease is uncertain.

METHODS

In a prospective cohort study, patients with intermediate high-sensitivity cardiac troponin I concentrations (5 ng/L to sex-specific 99th percentile) in whom myocardial infarction was ruled out were enrolled and underwent coronary CT angiography (CCTA) after hospital discharge. History, ECG, Age, Risk factors, Troponin (HEART), Emergency Department Assessment of Chest Pain Score (EDACS), Global Registry of Acute Coronary Event (GRACE), Thrombolysis In Myocardial Infarction (TIMI), Systematic COronary Risk Evaluation 2 and Pooled Cohort Equation risk scores were calculated and the odds ratio (OR) and diagnostic performance for obstructive coronary artery disease were determined using established thresholds.

RESULTS

Of 167 patients enrolled (64±12 years, 28% female), 29.9% (50/167) had obstructive coronary artery disease. The odds of having obstructive disease were increased for all scores with the lowest and highest increase observed for an EDACS score ≥16 (OR 2.2 (1.1-4.6)) and a TIMI risk score ≥1 (OR 12.9 (3.0-56.0)), respectively. The positive predictive value (PPV) was low for all scores but was highest for a GRACE score >88 identifying 39% as high risk with a PPV of 41.9% (30.4-54.2%). The negative predictive value (NPV) varied from 77.3% to 95.2% but was highest for a TIMI score of 0 identifying 26% as low risk with an NPV of 95.2% (87.2-100%).

CONCLUSIONS

In patients with intermediate cardiac troponin concentrations in whom myocardial infarction has been excluded, clinical risk scores can help identify patients with and without coronary artery disease, although the performance of established risk thresholds is suboptimal for utilisation in clinical practice.

TRIAL REGISTRATION NUMBER

NCT04549805.

Adoption of high-sensitivity cardiac troponin for risk stratification of patients with suspected myocardial infarction: a multicentre cohort study

Background

Guidelines recommend high-sensitivity cardiac troponin to risk stratify patients with possible myocardial infarction and identify those eligible for discharge. Our aim was to evaluate adoption of this approach in practice and to determine whether effectiveness and safety varies by age, sex, ethnicity, or socioeconomic deprivation status.

Methods

A multi-centre cohort study was conducted in 13 hospitals across the United Kingdom from November 1st, 2021, to October 31st, 2022. Routinely collected data including high-sensitivity cardiac troponin I or T measurements were linked to outcomes. The primary effectiveness and safety outcomes were the proportion discharged from the Emergency Department, and the proportion dead or with a subsequent myocardial infarction at 30 days, respectively. Patients were stratified using peak troponin concentration as low (<5 ng/L), intermediate (5 ng/L to sex-specific 99th percentile), or high-risk (>sex-specific 99th percentile).

Findings

In total 137,881 patients (49% [67,709/137,881] female) were included of whom 60,707 (44%), 42,727 (31%), and 34,447 (25%) were stratified as low-, intermediate- and high-risk, respectively. Overall, 65.8% (39,918/60,707) of low-risk patients were discharged from the Emergency Department, but this varied from 26.8% [2200/8216] to 93.5% [918/982] by site. The safety outcome occurred in 0.5% (277/60,707) and 11.4% (3917/34,447) of patients classified as low- or high-risk, of whom 0.03% (18/60,707) and 1% (304/34,447) had a subsequent myocardial infarction at 30 days, respectively. A similar proportion of male and female patients were discharged (52% [36,838/70,759] versus 54% [36,113/67,109]), but discharge was more likely if patients were <70 years old (61% [58,533/95,227] versus 34% [14,428/42,654]), from areas of low socioeconomic deprivation (48% [6697/14,087] versus 43% [12,090/28,116]) or were black or asian compared to caucasian (62% [5458/8877] and 55% [10,026/18,231] versus 46% [35,138/75,820]).

Interpretation

Despite high-sensitivity cardiac troponin correctly identifying half of all patients with possible myocardial infarction as being at low risk, only two-thirds of these patients were discharged. Substantial variation in the discharge of patients by age, ethnicity, socioeconomic deprivation, and site was observed identifying important opportunities to improve care.

Funding

UK Research and Innovation.

Prognostic significance of troponin in patients with malignancy (NIHR Health Informatics Collaborative TROP-MALIGNANCY study)

BACKGROUND

Cardiac troponin is commonly raised in patients presenting with malignancy. The prognostic significance of raised troponin in these patients is unclear.

OBJECTIVES

We sought to investigate the relation between troponin and mortality in a large, well characterised cohort of patients with a routinely measured troponin and a primary diagnosis of malignancy.

METHODS

We used the National Institute for Health Research (NIHR) Health Informatics Collaborative data of 5571 patients, who had troponin levels measured at 5 UK cardiac centres between 2010 and 2017 and had a primary diagnosis of malignancy. Patients were classified into solid tumour or haematological malignancy subgroups. Peak troponin levels were standardised as a multiple of each laboratory's 99th -percentile upper limit of normal (xULN).

RESULTS

4649 patients were diagnosed with solid tumours and 922 patients with haematological malignancies. Raised troponin was an independent predictor of mortality in all patients (Troponin > 10 vs. <1 adjusted HR 2.01, 95% CI 1.73 to 2.34), in solid tumours (HR 1.84, 95% CI 1.55 to 2.19), and in haematological malignancy (HR 2.72, 95% CI 1.99 to 3.72). There was a significant trend in increasing mortality risk across troponin categories in all three subgroups (p < 0.001).

CONCLUSION

Raised troponin level is associated with increased mortality in patients with a primary diagnosis of malignancy regardless of cancer subtype. Mortality risk is stable for patients with a troponin level below the ULN but increases as troponin level increases above the ULN in the absence of acute coronary syndrome.

Trends in cardiovascular disease incidence among 22 million people in the UK over 20 years: population based study

OBJECTIVE

To investigate the incidence of cardiovascular disease (CVD) overall and by age, sex, and socioeconomic status, and its variation over time, in the UK during 2000-19.

DESIGN

Population based study.

SETTING

UK.

PARTICIPANTS

1 650 052 individuals registered with a general practice contributing to Clinical Practice Research Datalink and newly diagnosed with at least one CVD from 1 January 2000 to 30 June 2019.

MAIN OUTCOME MEASURES

The primary outcome was incident diagnosis of CVD, comprising acute coronary syndrome, aortic aneurysm, aortic stenosis, atrial fibrillation or flutter, chronic ischaemic heart disease, heart failure, peripheral artery disease, second or third degree heart block, stroke (ischaemic, haemorrhagic, and unspecified), and venous thromboembolism (deep vein thrombosis or pulmonary embolism). Disease incidence rates were calculated individually and as a composite outcome of all 10 CVDs combined and were standardised for age and sex using the 2013 European standard population. Negative binomial regression models investigated temporal trends and variation by age, sex, and socioeconomic status.

RESULTS

The mean age of the population was 70.5 years and 47.6% (n=784 904) were women. The age and sex standardised incidence of all 10 prespecified CVDs declined by 19% during 2000-19 (incidence rate ratio 2017-19 v 2000-02: 0.80, 95% confidence interval 0.73 to 0.88). The incidence of coronary heart disease and stroke decreased by about 30% (incidence rate ratios for acute coronary syndrome, chronic ischaemic heart disease, and stroke were 0.70 (0.69 to 0.70), 0.67 (0.66 to 0.67), and 0.75 (0.67 to 0.83), respectively). In parallel, an increasing number of diagnoses of cardiac arrhythmias, valve disease, and thromboembolic diseases were observed. As a result, the overall incidence of CVDs across the 10 conditions remained relatively stable from the mid-2000s. Age stratified analyses further showed that the observed decline in coronary heart disease incidence was largely restricted to age groups older than 60 years, with little or no improvement in younger age groups. Trends were generally similar between men and women. A socioeconomic gradient was observed for almost every CVD investigated. The gradient did not decrease over time and was most noticeable for peripheral artery disease (incidence rate ratio most deprived v least deprived: 1.98 (1.87 to 2.09)), acute coronary syndrome (1.55 (1.54 to 1.57)), and heart failure (1.50 (1.41 to 1.59)).

CONCLUSIONS

Despite substantial improvements in the prevention of atherosclerotic diseases in the UK, the overall burden of CVDs remained high during 2000-19. For CVDs to decrease further, future prevention strategies might need to consider a broader spectrum of conditions, including arrhythmias, valve diseases, and thromboembolism, and examine the specific needs of younger age groups and socioeconomically deprived populations.

Unstable Angina Risk Stratification Using High-Sensitivity Cardiac Troponin and Coronary Angiography

Patients formerly diagnosed with unstable angina (UA) are being reclassified as non-ST-elevation myocardial infarction with the widespread adoption of high-sensitivity troponin (hsTn) assays, leading to significant changes in the incidence and prognosis of UA. This study aimed to evaluate the value of hsTn and the presence of significant obstructive coronary artery disease (CAD) in the risk stratification of patients with UA. We conducted a retrospective, single-center study of 742 patients hospitalized for UA between 2016 and 2021. The primary end point of this study was all-cause mortality. The secondary outcome (major adverse cardiac events [MACEs]) was defined as a composite of nonfatal myocardial infarction (MI), hospitalization for heart failure (hHF), and repeated coronary angiography because of recurring UA (rUA) after the index event. The outcomes were assessed within 1 month, 1 year, and up to 5 years of follow-up. The average follow-up duration was 45 ± 24 months, and 37.2% (n = 276) of patients completed a 5-year follow-up. No in-hospital death was observed, and 6.9% of patients died during follow-up, which was more commonly a late event (>12 months). The composite secondary end point (MI+hHF+rUA) was observed in 16.7% of the patients. There were 3.2% nonfatal MI, 2.3% hHF, and 11.6% rUA during follow-up. We developed a risk model (UA mortality risk) using variables with the highest discriminatory power: age, hsTn, and ST-segment deviation. Our model performed well against the Global Registry of Acute Coronary Events and Thrombolysis in Myocardial Infarction risk scores in predicting death during follow-up. Obstructive CAD on coronary angiography was the only independent predictor of MACEs during follow-up. In conclusion, a contemporary cohort of patients with UA presented with favorable prognosis, particularly, within the first year after the index event. Nonsignificant increases in hsTn levels add to the risk stratification of patients with UA, and the presence of obstructive CAD was the only independent predictor of MACEs, highlighting the potential importance of assessing coronary anatomy.

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.

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.

Performance evaluation of a novel high-sensitivity cardiac troponin T assay: analytical and clinical perspectives

OBJECTIVES

To evaluate the analytical characteristics of a novel high-sensitivity cardiac troponin T (hs-cTnT) test on the automatic light-initiated chemiluminescent assay (LiCA®) system, and validated its diagnostic performance for non-ST-segment elevation myocardial infarction (NSTEMI).

METHODS

Studies included an extensive analytical evaluation and established the 99th percentile upper reference limit (URL) from apparently healthy individuals, followed by a diagnostic performance validation for NSTEMI.

RESULTS

Sex-specific 99th percentile URLs were 16.0 ng/L (1.7 % CV: coefficient of variation) for men (21-92 years) and 13.4 ng/L (2.0 % CV) for women (23-87 years) in serum, and 30.6 ng/L (0.9 % CV) for men (18-87 years) and 20.2 ng/L (1.4 % CV) for women (18-88 years) in heparin plasma. Detection rates in healthy individuals ranged from 98.9 to 100 %. An excellent agreement was identified between LiCA® and Elecsys® assays with a correlation coefficient of 0.993 and mean bias of -0.7 % (-1.8-0.4 %) across the full measuring range, while the correlation coefficient and overall bias were 0.967 and -1.1 % (-2.5-0.3 %) for the lower levels of cTnT (10-100 ng/L), respectively. At the specific medical decision levels (14.0 and 52.0 ng/L), assay difference was estimated to be <5.0 %. No significant difference was found between these two assays in terms of area under curve (AUC), sensitivity and specificity, negative predictive value (NPV) and positive predictive value (PPV) for the diagnosis of NSTEMI.

CONCLUSIONS

LiCA® hs-cTnT is a reliable 3rd-generation (level 4) high-sensitivity assay for detecting cardiac troponin T. The assay is acceptable for practical use in the diagnosis of NSTEMI.

External validation of a rapid algorithm using high-sensitivity troponin assay results for evaluating patients with suspected acute myocardial infarction

OBJECTIVE

We sought to validate the clinical performance of a rapid assessment pathway incorporating the Siemens Atellica IM high sensitivity cardiac troponin I (hs-cTnI) assay in patients presenting to the emergency department (ED) with suspected acute myocardial infarction (AMI).

METHODS

This was a multicentre prospective observational study of adult ED patients presenting to five Australian hospitals between November 2020 and September 2021. Participants included those with symptoms of suspected AMI (without ST-segment elevation MI on presentation ECG). The Siemen's Atellica IM hs-cTnI laboratory-based assay was used to measure troponin concentrations at admission and after 2-3 hours and cardiologists adjudicated final diagnoses. The HighSTEACS diagnostic algorithm was evaluated, incorporating hs-cTnI concentrations at presentation and absolute changes within the first 2 to 3 hours. The primary outcome was index AMI, including type 1 or 2 non-ST segment elevation MI (NSTEMI) or ST-elevation MI (STEMI) following presentation. 30-day major adverse cardiac outcomes (including AMI, urgent revascularisation or cardiac death) were also reported. The trial was registered with the Australian and New Zealand Clinical Trials Registry.

RESULTS

1994 patients were included. The average age was 56.2 years (SD=15.6), and 44.9% were women. 118 (5.9%) patients had confirmed index AMI. The 2-hour algorithm defined 61.3% of patients as low risk. Sensitivity was 99.1% (94.0%-99.9%) and negative predictive value was 99.9% (99.3%-100%). 24.4% of patients were deemed intermediate risk. When applying the parameters for high risk, 252 (14.3%) were identified, with a specificity of 91.5% (88.7%-93.6%) and a PPV of 42.0% (35.6-48.7%).

CONCLUSIONS

A 2-hour algorithm based on the HighSTEACS strategy using the Siemens Atellica IM hs-cTnI laboratory-based assay enables safe and efficient risk assessment of emergency patients with suspected AMI.

TRIAL REGISTRATION NUMBER

ACTRN12621000053820.

Cardiovascular risk of veterans' football: An observational cohort study with follow-up

BACKGROUND

The cardiac stress for veteran football players during match is considerable. In this specific elderly population, the kinetics of exercise-induced cardiac troponin I (cTnI) and B-Type natriuretic peptide (BNP) could potentially be related to cardiovascular risk factors (CVRF) and cardiovascular disease and are therefore be investigated for their usefulness as an complement to established screening measures.

METHODS

cTnI and BNP was measured in 112 veteran football players (age: 51 ± 10 years) within 30 minutes pre- and post-match. Players with elevated cTnI (cTnI-positive) and a control group (out of the 112 veteran players) with normal cTnI (cTnI-negative) underwent cardiac follow-up 4.2 ± 3.5 months post-match, comprising history, resting and stress ECG (including 30 minutes pre- and post cTnI and BNP), and echocardiography.

RESULTS

In 33 players (29%) cTnI and in 6 players BNP (5%) exceeded the upper range limit for increased risk of myocardial damage (cTnI ≥ 5 ng/l) and myocardial wall stress (BNP ≥ 100 pg/ml) post-match, respectively. No correlation was observed between Δ cTnI (pre- vs. post-match) and the number of CVRF (r = -0.06, p = 0.50). Follow-up was conducted in 62 players (31 cTnI-positive and 31 cTnI-negative players) of which 6 (10%, 3 cTnI positive and 3 cTnI negative players) had cardiac abnormalities (hypertrophic cardiomyopathy n = 2, coronary artery disease n = 2, coronary artery anomaly n = 1, hypertensive heart disease n = 1).

CONCLUSION

Veterans' football matches elicit increases in BNP and particularly cTnI in a considerable number of players. However, these biochemical alterations do not indicate acute cardiac damage as evidenced by follow-up. Routine determination of cardiac biomarkers is unlikely to improve cardiovascular screening in veteran football players.

Auxiliary roles of nardilysin in the early diagnosis of acute coronary syndrome: a prospective cohort study, the Nardi-ACS study

Acute coronary syndrome (ACS) includes myocardial infarction (MI) and unstable angina (UA). MI is defined by elevated necrosis markers, preferably high-sensitivity cardiac troponins (hs-cTn). However, it takes hours for cTn to become elevated after coronary occlusion; therefore, difficulties are associated with diagnosing early post-onset MI or UA. The aim of this prospective cohort study was to examine the diagnostic ability of serum nardilysin (NRDC) for the early detection of ACS. This study consisted of two sequential cohorts, the Phase I cohort, 435 patients presenting to the emergency room (ER) with chest pain, and the Phase II cohort, 486 patients with chest pain who underwent coronary angiography. The final diagnosis was ACS in 155 out of 435 patients (35.6%) in the phase I and 418 out of 486 (86.0%) in the phase II cohort. Among 680 patients who presented within 24 h of onset, 466 patients (68.5%) were diagnosed with ACS. Serum NRDC levels were significantly higher in patients with ACS than in those without ACS. The sensitivity of NRDC in patients who presented within 6 h after the onset was higher than that of hsTnI, and the AUC of NRDC within 1 h of the onset was higher than that of hsTnI (0.718 versus 0.633). Among hsTnI-negative patients (300 of 680 patients: 44.1%), 136 of whom (45.3%) were diagnosed with ACS, the sensitivity and the NPV of NRDC were 73.5 and 65.7%, respectively. When measured in combination with hsTnI, NRDC plays auxiliary roles in the early diagnosis of ACS.

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.

Cardiac troponin I as predictor for cardiac and other mortality in the German randomized lung cancer screening trial (LUSI)

Cardiac Troponin I (cTnI) could be used to identify individuals at elevated risk of cardiac death in lung cancer (LC) screening settings. In a population-based, randomized LC screening trial in Germany ("LUSI" study) serum cTnI was measured by high-sensitivity assay in blood samples collected at baseline, and categorized into unquantifiable/low (< 6 ng/L), intermediate (≥ 6-15 ng/L), and elevated (≥ 16 ng/L). Cox proportional-hazard models were used to estimate risk of all-cause and cardiac mortality with cTnI levels. After exclusion criteria, 3653 participants were included for our analyses, of which 82.4% had low, 12.8% intermediate and 4.8% elevated cTnI, respectively. Over a median follow up of 11.87 years a total of 439 deaths occurred, including 67 caused by cardiac events. Within the first 5 years after cTnI measurement, intermediate or elevated cTnI levels showed approximately 1.7 (HR = 1.69 [95% CI 0.57-5.02) and 4.7-fold (HR = 4.66 [1.73-12.50]) increases in risk of cardiac death relative to individuals with unquantifiable/low cTnI, independently of age, sex, smoking and other risk factors. Within this time interval, a risk model based on age, sex, BMI, smoking history and cTnI showed a combined area under the ROC curve (AUC) of 73.6 (58.1-87.3), as compared to 70.4 (53.3-83.5) for a model without cTnI. Over the time interval of > 5-10 years after blood donation, the relative risk associations with cTnI and were weaker. cTnI showed no association with mortality from any other (non-cardiac) cause. Our findings show that cTnI may be of use for identifying individuals at elevated risk specifically of short-term cardiac mortality in the context of LC screening.

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.

Troponin T is elevated in a relevant proportion of patients with 5q-associated spinal muscular atrophy

Troponin T concentration (TNT) is commonly considered a marker of myocardial damage. However, elevated concentrations have been demonstrated in numerous neuromuscular disorders, pointing to the skeletal muscle as a possible extracardiac origin. The aim of this study was to determine disease-related changes of TNT in 5q-associated spinal muscular atrophy (SMA) and to screen for its biomarker potential in SMA. We therefore included 48 pediatric and 45 adult SMA patients in this retrospective cross-sequential observational study. Fluid muscle integrity and cardiac markers were analyzed in the serum of treatment-naïve patients and subsequently under disease-modifying therapies. We found a TNT elevation in 61% of SMA patients but no elevation of the cardiospecific isoform Troponin I (TNI). TNT elevation was more pronounced in children and particularly infants with aggressive phenotypes. In adults, TNT correlated to muscle destruction and decreased under therapy only in the subgroup with elevated TNT at baseline. In conclusion, TNT was elevated in a relevant proportion of patients with SMA with emphasis in infants and more aggressive phenotypes. Normal TNI levels support a likely extracardiac origin. Although its stand-alone biomarker potential seems to be limited, exploring TNT in SMA underlines the investigation of skeletal muscle integrity markers.

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.

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.

Serial high sensitivity troponin sampling in patients with SARS-CoV-2 infection

INTRODUCTION

Multiple studies have investigated the role of cardiac troponin (cTn) in the risk stratification of patients with COVID-19. Most of these investigations are based on cTn values at presentation and do not consider the prognostic significance of cTn changes over time. This study aimed to investigate the prognostic role of serial cTn measurements in patients hospitalized with COVID-19 with samples that were not obtained for clinical indications.

METHODS

Patients hospitalized between April 2020 and March 2021 with PCR-confirmed SARS-CoV-2 infection were evaluated. Blood samples collected for any reason were stored for subsequent analysis. If clinical high sensitivity hs-cTnT (Roche) was not measured, samples were tested separately in batches. Hs-cTnI (Abbott) was also evaluated.

RESULTS

There were 228 unique patients. There were 21 (9.2 %) deaths. No patient with a low hs-cTnT (<6 ng/L) died and 1 patient with low hs-cTnI (<5 ng/L) died. Myocardial injury was associated with higher odds of death, when defined by hs-cTnT (OR: 7.88, 95 % CI: 2.04-30.40, p = 0.003) or hs-cTnI (OR: 7.46, 95 % CI: 2.68-20.77, p < 0.001). This association remained after propensity weighting. An increasing pattern was associated with higher odds of death compared to a stable pattern for hs-cTnT (OR: 5.45, 95 % CI: 1.81-16.40, p = 0.003) and hs-cTnI (OR: 4.49, 95 % CI: 1.02-19.81, p = 0.048). Among patients with myocardial injury defined by hs-cTnT, an increasing pattern was associated with higher odds of death compared to a decreasing pattern (OR: 4.80, 95 % CI: 1.16-19.97, p = 0.031).

CONCLUSIONS

Patients hospitalized with COVID-19 with myocardial injury have higher odds of death. Serial hs-cTn testing provides additional risk stratification in these patients.

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.

Predictors of Revascularization in Patients with Unstable Angina

BACKGROUND

The factors that determine the necessity of coronary artery revascularization in patients with unstable angina (UA) have been supported by limited data. Therefore, this study aimed to identify the predictors of revascularization in patients with UA.

METHODS

The study included the recorded data of 3668 patients with UA who underwent cardiac catheterization (age 66 ± 9.2, men 70%); 2615 of them (71%) underwent revascularization (percutaneous transluminal coronary angioplasty (PTCA), coronary artery bypass graft (CABG), or hybrid revascularization. The remaining 1053 patients (29%) had no significant coronary stenosis and were regarded as controls. Multivariable logistic regression analysis was performed to separate the predictors of revascularization.

RESULTS

It was found that severe angina (OR 2.7, 95%CI 1.9-3.7), male gender (OR 1.4, 95%CI 1.1-1.7), and hyperlipidemia were the predictors of revascularization. It was also noted that intraventricular conduction disorders including left and right bundle branch blocks and a history of previous revascularization and myocardial infarction were associated with lower odds of revascularization.

CONCLUSION

Overall, however, the predictive value of the studied factors proved to be poor and may still point to the multifactorial nature of significant coronary artery stenosis and the need for revascularization in patients with UA.

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.

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.

Chronic Kidney Disease Associated with Ischemic Heart Disease: To What Extent Do Biomarkers Help?

Chronic kidney disease represents a complex and multifaceted pathology characterized by the presence of structural or functional renal anomalies associated with a persistent reduction in renal function. As the disease progresses, complications arise due to the chronic inflammatory syndrome, hydro-electrolytic disorders, and toxicity secondary to the uremic environment. Cardiovascular complications are the leading cause of death for these patients. Ischemic cardiac pathology can be both a consequence and complication of chronic kidney disease, highlighting the need to identify specific cardiorenal dysfunction biomarkers targeting pathophysiological mechanisms common to both conditions. This identification is crucial for establishing accurate diagnoses, prognoses, and risk stratifications for patients. This work is intended to elucidate the intricate relationship between chronic kidney disease and ischemic heart disease and to investigate the roles of cardiorenal biomarkers, including cardiac troponin, natriuretic peptides, galectin-3, copeptin, fibroblast growth factor 23 and its co-receptor Klotho, soluble suppression of tumorigenicity 2, and plasma growth differentiation factor 15.

Multicenter, Prospective, Randomized Controlled Trial of High-Sensitivity Cardiac Troponin I-Guided Combination Angiotensin Receptor Blockade and Beta-Blocker Therapy to Prevent Anthracycline Cardiotoxicity: The Cardiac CARE Trial

BACKGROUND

Anthracycline-induced cardiotoxicity has a variable incidence, and the development of left ventricular dysfunction is preceded by elevations in cardiac troponin concentrations. Beta-adrenergic receptor blocker and renin-angiotensin system inhibitor therapies have been associated with modest cardioprotective effects in unselected patients receiving anthracycline chemotherapy.

METHODS

In a multicenter, prospective, randomized, open-label, blinded end-point trial, patients with breast cancer and non-Hodgkin lymphoma receiving anthracycline chemotherapy underwent serial high-sensitivity cardiac troponin testing and cardiac magnetic resonance imaging before and 6 months after anthracycline treatment. Patients at high risk of cardiotoxicity (cardiac troponin I concentrations in the upper tertile during chemotherapy) were randomized to standard care plus cardioprotection (combination carvedilol and candesartan therapy) or standard care alone. The primary outcome was adjusted change in left ventricular ejection fraction at 6 months. In low-risk nonrandomized patients with cardiac troponin I concentrations in the lower 2 tertiles, we hypothesized the absence of a 6-month change in left ventricular ejection fraction and tested for equivalence of ±2%.

RESULTS

Between October 2017 and June 2021, 175 patients (mean age, 53 years; 87% female; 71% with breast cancer) were recruited. Patients randomized to cardioprotection (n=29) or standard care (n=28) had left ventricular ejection fractions of 69.4±7.4% and 69.1±6.1% at baseline and 65.7±6.6% and 64.9±5.9% 6 months after completion of chemotherapy, respectively. After adjustment for age, pretreatment left ventricular ejection fraction, and planned anthracycline dose, the estimated mean difference in 6-month left ventricular ejection fraction between the cardioprotection and standard care groups was -0.37% (95% CI, -3.59% to 2.85%; P=0.82). In low-risk nonrandomized patients, baseline and 6-month left ventricular ejection fractions were 69.3±5.7% and 66.4±6.3%, respectively: estimated mean difference, 2.87% (95% CI, 1.63%-4.10%; P=0.92, not equivalent).

CONCLUSIONS

Combination candesartan and carvedilol therapy had no demonstrable cardioprotective effect in patients receiving anthracycline-based chemotherapy with high-risk on-treatment cardiac troponin I concentrations. Low-risk nonrandomized patients had similar declines in left ventricular ejection fraction, bringing into question the utility of routine cardiac troponin monitoring. Furthermore, the modest declines in left ventricular ejection fraction suggest that the value and clinical impact of early cardioprotection therapy need to be better defined in patients receiving high-dose anthracycline.

REGISTRATION

URL: https://doi.org; Unique identifier: 10.1186/ISRCTN24439460. URL: https://www.clinicaltrialsregister.eu/ctr-search/search; Unique identifier: 2017-000896-99.

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.

HEART Score Recalibration Using Higher Sensitivity Troponin T

STUDY OBJECTIVE

We examined the diagnostic performance of a recalibrated History, Electrocardiogram, Age, Risk factors, Troponin (HEART), and Thrombolysis in Myocardial Infarction (TIMI) score in patients with suspected acute cardiac syndrome (ACS). Recalibration of troponin thresholds was performed, including shifting from the 99th percentile to the limit of detection (LOD) or to the limit of quantification (LOQ) We compared the discharge potential and safety of the recalibrated composite scores using a single presentation high-sensitivity cardiac troponin (hs-cTn) T to the conventional scores and with a LOD/LOQ troponin strategy alone.

METHODS

We undertook a 2-center prospective cohort study in the United Kingdom (UK) (2018) (Clinicaltrials.gov NCT03619733) to specifically assess recalibrated risk scores (shifting the troponin subset scoring from 99th percentile to LOD [UK]) and combined the results of this with secondary analyses of 2 prospective cohort studies in the UK (2011) and the United States (2018, using LOQ rather than LOD). The primary outcome was major adverse cardiovascular events (MACE), defined as adjudicated type 1 myocardial infarction (MI), urgent coronary revascularization, and all-cause death, at 30 days. We evaluated the original scores using hs-cTn below the 99th percentile and recalibrated scores using hs-cTn

RESULTS

We studied 3,752 patients (3,003 in the UK and 749 in the United States). Median age was 58 years, and 48% were female. At 30 days, 330/3,752 (8.8%) experienced MACE. The sensitivities of the original HEART less or equal to 3 and recalibrated HEART less or equal to 3 scores for rule-out were 96.1% (95% confidence interval [CI], 93.4 to 97.9) and 98.6% (95% CI, 96.5 to 99.5) respectively; the original TIMI less or equal to 1 and recalibrated TIMI less or equal to 1 scores' sensitivities were 79.7% (95% CI, 74.9 to 83.9) and 96.1% (95% CI, 93.4 to 97.9) respectively; and nonischemic ECG with hs-cTn T below the 99th percentile and hs-cTn T less than LOD/LOQ was 79.7% (95%CI, 0.749 to 0.839) and 99.1% (95% CI, 0.974 to 0.998), respectively. Recalibrated HEART less or equal to 3 was projected to discharge 14% more patients than hs-cTn T less than LOD/LOQ. The improved sensitivity of rule-out for recalibrated HEART less than or equal to 3 came at the cost of reduced specificity (50.8% versus 53.8% for recalibrated HEART and conventional HEART respectively).

CONCLUSION

This study indicates that recalibrated HEART score of less or equal to 3 is a feasible and safe early discharge strategy using a single presentation hs-cTnT. This finding should be further tested using competitor hs-cTn assays in independent prospective cohorts before implementation.

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Key Words Collapse

MESH Headings

• Humans
• Female
• Middle Aged
• Male
• Troponin T
• Prospective Studies
• Troponin
• Myocardial Infarction/diagnosis
• Myocardial Infarction/complications
• Acute Coronary Syndrome/diagnosis
• Biomarkers
• Emergency Service, Hospital

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Grants

• K08 HL130546 NHLBI NIH HHS

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Affiliation(s)

Aleem U Khand Liverpool University Hospital, Liverpool, UK; Liverpool Heart and Chest Hospital, Liverpool, UK; Liverpool Centre for Cardiovascular Diseases, University of Liverpool, Liverpool, UK.
Barbra Backus Erasmus Medical Center, Rotterdam, Netherlands
Michael Campbell Liverpool University Hospital, Liverpool, UK
Freddy Frost Liverpool Centre for Cardiovascular Diseases, University of Liverpool, Liverpool, UK
Liam Mullen Liverpool Heart and Chest Hospital, Liverpool, UK
Michael Fisher Liverpool University Hospital, Liverpool, UK; Liverpool Heart and Chest Hospital, Liverpool, UK
Konstantinos C Theodoropoulos Liverpool Heart and Chest Hospital, Liverpool, UK
Mohammed Obeidat Liverpool University Hospital, Liverpool, UK
Kate Batouskaya Liverpool University Hospital, Liverpool, UK
Edward W Carlton North Bristol NHS Trust, Bristol, UK
Kirsten Van Meerten Albert Schweitzer Hospital, Dordrecht, The Netherlands
Kai Neoh Liverpool University Hospital, Liverpool, UK
Ahmed Dakshi Liverpool University Hospital, Liverpool, UK
Bryn E Mumma Department of Emergency Medicine, University of California, Davis School of Medicine, Sacramento, CA

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A new clinical classification of acute myocardial infarction

The existence of a universal definition of myocardial infarction-which involves classification into multiple subtypes-has promoted the use of standard diagnostic criteria across the world. However, this classification has not been applied consistently in practice and is perceived by some as too complicated. Where there is diagnostic uncertainty, patients have worse outcomes. This uncertainty has also impacted on the validity of the diagnosis of myocardial infarction in clinical trials. To address these issues and to encourage clinicians to recognize that different mechanisms of myocardial infarction have differing treatment implications, we propose an alternative clinical classification for consideration; one that recognizes that myocardial infarction can arise spontaneously, secondary to another condition, or as a complication of a cardiac procedure. This classification is aligned with clinical practice and proposes more objective and specific diagnostic criteria that, if agreed by international consensus, could reduce diagnostic uncertainty in practice and research.

Reactogenicity, immunogenicity and breakthrough infections following heterologous or fractional second dose COVID-19 vaccination in adolescents (Com-COV3): A randomised controlled trial

BACKGROUND

This was the first study to investigate the reactogenicity and immunogenicity of heterologous or fractional second dose COVID-19 vaccine regimens in adolescents.

METHODS

A phase II, single-blind, multi-centre, randomised-controlled trial recruited across seven UK sites from September to November 2021, with follow-up visits to August 2022. Healthy 12-to-16 years olds were randomised (1:1:1) to either 30 µg BNT162b2 (BNT-30), 10 µg BNT162b2 (BNT-10), or NVX-CoV2373 (NVX), 8 weeks after a first 30 µg dose of BNT162b2. The primary outcome was solicited systemic reactions in the week following vaccination. Secondary outcomes included immunogenicity and safety. 'Breakthrough infection' analyses were exploratory.

FINDINGS

148 participants were recruited (median age 14 years old, 62% female, 26% anti-nucleocapsid IgG seropositive pre-second dose); 132 participants received a second dose. Reactions were mostly mild-to-moderate, with lower rates in BNT-10 recipients. No vaccine-related serious adverse events occurred. Compared to BNT-30, at 28 days post-second dose anti-spike antibody responses were similar for NVX (adjusted geometric mean ratio [aGMR]) 1.09 95% confidence interval (CI): 0.84, 1.42] and lower for BNT-10 (aGMR 0.78 [95% CI: 0.61, 0.99]). For Omicron BA.1 and BA.2, the neutralising antibody titres for BNT-30 at day 28 were similar for BNT-10 (aGMR 1.0 [95% CI: 0.65, 1.54] and 1.02 [95% CI: 0.71, 1.48], respectively), but higher for NVX (aGMR 1.7 [95% CI: 1.07, 2.69] and 1.43 [95% CI: 0.96, 2.12], respectively). Compared to BNT-30, cellular immune responses were greatest for NVX (aGMR 1.73 [95% CI: 0.94, 3.18]), and lowest for BNT-10 (aGMR 0.65 [95% CI: 0.37, 1.15]) at 14 days post-second dose. Cellular responses were similar across the study arms by day 236 post-second dose. Amongst SARS-CoV-2 infection naïve participants, NVX participants had an 89% reduction in risk of self-reported 'breakthrough infection' compared to BNT-30 (adjusted hazard ratio [aHR] 0.11 [95% CI: 0.01, 0.86]) up until day 132 after second dose. BNT-10 recipients were more likely to have a 'breakthrough infection' compared to BNT-30 (aHR 2.14 [95% CI: 1.02, 4.51]) up to day 132 and day 236 post-second dose. Antibody responses at 132 and 236 days after second dose were similar for all vaccine schedules.

INTERPRETATION

Heterologous and fractional dose COVID-19 vaccine schedules in adolescents are safe, well-tolerated and immunogenic. The enhanced performance of the heterologous schedule using NVX-CoV2373 against the Omicron SARS-CoV-2 variant suggests this mRNA prime and protein-subunit boost schedule may provide a greater breadth of protection than the licensed homologous schedule.

FUNDING

National Institute for Health Research and Vaccine Task Force.

TRIAL REGISTRATION

International Standard Randomised Controlled Trial Number registry: 12348322.

High-Sensitivity Cardiac Troponin for Risk Assessment in Patients With Chronic Coronary Artery Disease

BACKGROUND

Cardiac troponin is used for risk stratification of patients with acute coronary syndromes; however, the role of testing in other settings remains unclear.

OBJECTIVES

The aim of this study was to evaluate whether cardiac troponin testing could enhance risk stratification in patients with chronic coronary artery disease independent of disease severity and conventional risk measures.

METHODS

In a prospective cohort of consecutive patients with symptoms suggestive of stable angina attending for outpatient coronary angiography, high-sensitivity cardiac troponin I was measured before angiography, and clinicians were blinded to the results. The primary outcome was myocardial infarction or cardiovascular death during follow-up.

RESULTS

In 4,240 patients (age 66 years [IQR: 59-73 years], 33% female), coronary artery disease was identified in 3,888 (92%) who had 255 (6%) primary outcome events during a median follow-up of 2.4 years (IQR: 1.3-3.6 years). In patients with coronary artery disease, troponin concentrations were 2-fold higher in those with an event compared with those without (6.7 ng/L [IQR: 3.2-14.2 ng/L] vs 3.3 ng/L [IQR: 1.7-6.6 ng/L]; P < 0.001). Troponin concentrations were associated with the primary outcome after adjusting for cardiovascular risk factors and coronary artery disease severity (adjusted HR: 2.3; 95% CI: 1.7-3.0, log10 troponin; P < 0.001). A troponin concentration >10 ng/L identified patients with a 50% increase in the risk of myocardial infarction or cardiovascular death.

CONCLUSIONS

In patients with chronic coronary artery disease, cardiac troponin predicts risk of myocardial infarction or cardiovascular death independent of cardiovascular risk factors and disease severity. Further studies are required to evaluate whether routine testing could inform the selection of high-risk patients for treatment intensification. (Myocardial Injury in Patients Referred for Coronary Angiography [MICA]; ISRCTN15620297).

Troponin in early presenters to rule out myocardial infarction

AIMS

Whether a single cardiac troponin measurement can safely rule out myocardial infarction in patients presenting within a few hours of symptom onset is uncertain. The study aim was to assess the performance of troponin in early presenters.

METHODS AND RESULTS

In patients with possible myocardial infarction, the diagnostic performance of a single measurement of high-sensitivity cardiac troponin I at presentation was evaluated and externally validated in those tested ≤3, 4-12, and >12 h from symptom onset. The limit-of-detection (2 ng/L), rule-out (5 ng/L), and sex-specific 99th centile (16 ng/L in women; 34 ng/L in men) thresholds were compared. In 41 103 consecutive patients [60 (17) years, 46% women], 12 595 (31%) presented within 3 h, and 3728 (9%) had myocardial infarction. In those presenting ≤3 h, a threshold of 2 ng/L had greater sensitivity and negative predictive value [99.4% (95% confidence interval 99.2%-99.5%) and 99.7% (99.6%-99.8%)] compared with 5 ng/L [96.5% (96.2%-96.8%) and 99.3% (99.1%-99.4%)]. In those presenting ≥3 h, the sensitivity and negative predictive value were similar for both thresholds. The sensitivity of the 99th centile was low in early and late presenters at 71.4% (70.6%-72.2%) and 92.5% (92.0%-93.0%), respectively. Findings were consistent in an external validation cohort of 7088 patients.

CONCLUSION

In early presenters, a single measurement of high-sensitivity cardiac troponin I below the limit of detection may facilitate the safe rule out of myocardial infarction. The 99th centile should not be used to rule out myocardial infarction at presentation even in those presenting later following symptom onset.

Single Troponin Measurement to Rule Out Myocardial Infarction: JACC Review Topic of the Week

The term "single-sample rule-out" refers to the ability of very low concentrations of high-sensitivity cardiac troponin (hs-cTn) on presentation to exclude acute myocardial infarction with high clinical sensitivity and negative predictive value. Observational and randomized studies have confirmed this ability. Some guidelines endorse use of a concentration of hs-cTn at the assay's limit of detection, while other studies have validated the use of higher concentrations, allowing this approach to identify a greater proportion of patients at low risk. In most studies, at least 30% of patients can be triaged with this approach. The concentration of hs-cTn varies according to the assay used and sometimes how regulations permit reporting. It is clear that patients need to be at least 2 hours from the onset of symptoms being evaluated. Caution is warranted, particularly with older patients, women, and patients with underlying cardiac comorbidities.

Performance of a prehospital HEART score in patients with possible myocardial infarction: a prospective evaluation

INTRODUCTION

The History, Electrocardiogram (ECG), Age, Risk Factors and Troponin (HEART) score is commonly used to risk stratify patients with possible myocardial infarction as low risk or high risk in the Emergency Department (ED). Whether the HEART score can be used by paramedics to guide care were high-sensitivity cardiac troponin testing available in a prehospital setting is uncertain.

METHODS

In a prespecified secondary analysis of a prospective cohort study where paramedics enrolled patients with suspected myocardial infarction, a paramedic Heart, ECG, Age, Risk Factors (HEAR) score was recorded contemporaneously, and a prehospital blood sample was obtained for subsequent cardiac troponin testing. HEART and modified HEART scores were derived using laboratory contemporary and high-sensitivity cardiac troponin I assays. HEART and modified HEART scores of ≤3 and ≥7 were applied to define low-risk and high-risk patients, and performance was evaluated for an outcome of major adverse cardiac events (MACEs) at 30 days.

RESULTS

Between November 2014 and April 2018, 1054 patients were recruited, of whom 960 (mean 64 (SD 15) years, 42% women) were eligible for analysis and 255 (26%) experienced a MACE at 30 days. A HEART score of ≤3 identified 279 (29%) as low risk with a negative predictive value of 93.5% (95% CI 90.0% to 95.9%) for the contemporary assay and 91.4% (95% CI 87.5% to 94.2%) for the high-sensitivity assay. A modified HEART score of ≤3 using the limit of detection of the high-sensitivity assay identified 194 (20%) patients as low risk with a negative predictive value of 95.9% (95% CI 92.1% to 97.9%). A HEART score of ≥7 using either assay gave a lower positive predictive value than using the upper reference limit of either cardiac troponin assay alone.

CONCLUSIONS

A HEART score derived by paramedics in the prehospital setting, even when modified to harness the precision of a high-sensitivity assay, does not allow safe rule-out of myocardial infarction or enhanced rule-in compared with cardiac troponin testing alone.

Troponin in acute chest pain to risk stratify and guide effective use of computed tomography coronary angiography (TARGET-CTCA): a randomised controlled trial

BACKGROUND

The majority of patients with suspected acute coronary syndrome presenting to the emergency department will be discharged once myocardial infarction has been ruled out, although a proportion will have unrecognised coronary artery disease. In this setting, high-sensitivity cardiac troponin identifies those at increased risk of future cardiac events. In patients with intermediate cardiac troponin concentrations in whom myocardial infarction has been ruled out, this trial aims to investigate whether outpatient computed tomography coronary angiography (CTCA) reduces subsequent myocardial infarction or cardiac death.

METHODS

TARGET-CTCA is a multicentre prospective randomised open label with blinded endpoint parallel group event driven trial. After myocardial infarction and clear alternative diagnoses have been ruled out, participants with intermediate cardiac troponin concentrations (5 ng/L to 99th centile upper reference limit) will be randomised 1:1 to outpatient CTCA plus standard of care or standard of care alone. The primary endpoint is myocardial infarction or cardiac death. Secondary endpoints include clinical, patient-centred, process and cost-effectiveness. Recruitment of 2270 patients will give 90% power with a two-sided P value of 0.05 to detect a 40% relative risk reduction in the primary endpoint. Follow-up will continue until 97 primary outcome events have been accrued in the standard care arm with an estimated median follow-up of 36 months.

DISCUSSION

This randomised controlled trial will determine whether high-sensitivity cardiac troponin-guided CTCA can improve outcomes and reduce subsequent major adverse cardiac events in patients presenting to the emergency department who do not have myocardial infarction.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03952351. Registered on May 16, 2019.

A novel breakthrough in wrist-worn transdermal troponin-I-sensor assessment for acute myocardial infarction

Aims

Clinical differentiation of acute myocardial infarction (MI) from unstable angina and other presentations mimicking acute coronary syndromes (ACS) is critical for implementing time-sensitive interventions and optimizing outcomes. However, the diagnostic steps are dependent on blood draws and laboratory turnaround times. We tested the clinical feasibility of a wrist-worn transdermal infrared spectrophotometric sensor (transdermal-ISS) in clinical practice and assessed the performance of a machine learning algorithm for identifying elevated high-sensitivity cardiac troponin-I (hs-cTnI) levels in patients hospitalized with ACS.

Methods and results

We enrolled 238 patients hospitalized with ACS at five sites. The final diagnosis of MI (with or without ST elevation) and unstable angina was adjudicated using electrocardiography (ECG), cardiac troponin (cTn) test, echocardiography (regional wall motion abnormality), or coronary angiography. A transdermal-ISS-derived deep learning model was trained (three sites) and externally validated with hs-cTnI (one site) and echocardiography and angiography (two sites), respectively. The transdermal-ISS model predicted elevated hs-cTnI levels with areas under the receiver operator characteristics of 0.90 [95% confidence interval (CI), 0.84-0.94; sensitivity, 0.86; and specificity, 0.82] and 0.92 (95% CI, 0.80-0.98; sensitivity, 0.94; and specificity, 0.64), for internal and external validation cohorts, respectively. In addition, the model predictions were associated with regional wall motion abnormalities [odds ratio (OR), 3.37; CI, 1.02-11.15; P = 0.046] and significant coronary stenosis (OR, 4.69; CI, 1.27-17.26; P = 0.019).

Conclusion

A wrist-worn transdermal-ISS is clinically feasible for rapid, bloodless prediction of elevated hs-cTnI levels in real-world settings. It may have a role in establishing a point-of-care biomarker diagnosis of MI and impact triaging patients with suspected ACS.

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.

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.

Conformational switching of aptamer biointerfacing graphene-gold nanohybrid for ultrasensitive label-free sensing of cardiac Troponin I

The development of hybrid biofunctionalized nanomaterials has emerged as an attractive substitute for development of advanced biosensing platforms with superior synergistic properties. Herein, we report a label-free ultrasensitive electrochemical aptasensor comprising nanohybrid of graphene oxide (GO) and aptamer conjugated gold nanoparticles (GNP-A) for detection of cardiac biomarker Troponin I (TnI). The GNP-A are homogenously arranged by self-assembly on GO sheet to construct nanohybrid (GO@GNP-A) onto which the biomarker protein is analysed. TnI interactions at the aptamer biointerfaced nanohybrid surface causes electrochemical signal enhancement probed by using a redox active molecule. The consecutive increase in current signal is strongly attributed to conformational switching of aptamer and charge neutralization at the interface induced by TnI binding. The sensitivity of the nanohybrid aptasensor platform was found to be 0.001 pg/mL. The study has been further substantiated in Acute Myocardial Infarction (AMI) clinical samples for usage towards early, sensitive and efficient point-of-care detection of TnI.

Analytical performance comparing siemens whole blood point of care Atellica VTLi to the central laboratory plasma Atellica IM high-sensitivity cardiac troponin I assays

INTRODUCTION

This study examined the analytical performance of a whole blood (WB) point of care (POC) hs-cTnI assay compared to a plasma central laboratory hs-cTnI assay in patients presenting with ischemic symptoms to a US emergency department.

METHODS

Fresh WB specimens collected at 0 and 2 h from 1089 consecutive patients (2152 total from 1076 matched specimens) were analyzed for hs-cTnI using WB on POC Siemens Atellica VTLi assay and plasma on central laboratory Siemens Atellica IM assay. Concordances were determined based on concentrations ranging from < limit of detection (LoD), LoD to overall and sex specific 99th percentiles from both the IFCC manufacturer package inserts and Universal Sample Bank (USB) data, and > 99th percentiles. Method comparisons were calculated using Passing Bablok regression and Bland Altmann plots, and linear regression determined by Pearson correlation coefficient.

RESULTS

Baseline concentration comparisons showed: POC VTLi < LoD 4-5 %, ≥ LoD 95 %; Atellica IM < LoD 5-7 %, and ≥ LoD 94-95 %. From the 2152 paired 0 and 2-hour samples, based on 99th percentiles, overall concordance was 91-92 % (kappa 0.72-0.77) and discordance 8 %. Passing Bablok regression analysis using 1924 specimens between LoD to 500 ng/L showed: slopes 0.469-0.490; y-intercepts 1.753-2.028; r values 0.631-0.817. Pearson correlation coefficient showed moderate to strong correlation strength, even with up to 53 % cTnI concentrations variance (Passing Bablok slopes) vs 27.0-40.1 % (Bland-Altmann plots).

CONCLUSIONS

Up to 95 % of measured samples were > LoD for both the POC (Atellica VTLi) and central laboratory (Atellica IM) hs-cTnI assays. Moderate to strong concordance and correlation were observed between assays, despite up to 53 % variances in cTnI concentration.

Morphological and Functional Remodeling of the Ischemic Heart Correlates with Homocysteine Levels

Background: Homocysteine (Hcy) is involved in various methylation processes, and its plasma level is increased in cardiac ischemia. Thus, we hypothesized that levels of homocysteine correlate with the morphological and functional remodeling of ischemic hearts. Thus, we aimed to measure the Hcy levels in the plasma and pericardial fluid (PF) and correlate them with morphological and functional changes in the ischemic hearts of humans. Methods: Concentration of total homocysteine (tHcy) and cardiac troponin-I (cTn-I) of plasma and PF were measured in patients undergoing coronary artery bypass graft (CABG) surgery (n = 14). Left-ventricular (LV) end-diastolic diameter (LVED), LV end-systolic diameter (LVES), right atrial, left atrial (LA) area, thickness of interventricular septum (IVS) and posterior wall, LV ejection fraction (LVEF), and right ventricular outflow tract end-diastolic area (RVOT EDA) of CABG and non-cardiac patients (NCP; n = 10) were determined by echocardiography, and LV mass was calculated (cLVM). Results: Positive correlations were found between Hcy levels of plasma and PF, tHcy levels and LVED, LVES and LA, and an inverse correlation was found between tHcy levels and LVEF. cLVM, IVS, and RVOT EDA were higher in CABG with elevated tHcy (>12 µM/L) compared to NCP. In addition, we found a higher cTn-I level in the PF compared to the plasma of CABG patients (0.08 ± 0.02 vs. 0.01 ± 0.003 ng/mL, p < 0.001), which was ~10 fold higher than the normal level. Conclusions: We propose that homocysteine is an important cardiac biomarker and may have an important role in the development of cardiac remodeling and dysfunction in chronic myocardial ischemia in humans.

Coronary computed tomography angiography in the evaluation of acute chest pain in patients with elevated high sensitive cardiac troponin I (hs-cTn) level

Aims CCTA is a well-established and safe imaging modality for the diagnosis of CAD and is gate keeping for invasive coronary angiography (ICA). We aimed to examine CCTA performance in patients presenting with ACP and dynamic hs-cTn elevation compatible with MI but not exceeding 7 folds of the URL. We also examined the performance of GRACE and PTP consortium scores in this population of patients.

Derivation and validation of a high sensitivity troponin-T HEART pathway

BACKGROUND

The HEART Pathway is widely used for chest pain risk stratification but has yet to be optimized for high sensitivity troponin T (hs-cTnT) assays.

METHODS

We conducted a secondary analysis of STOP-CP, a prospective cohort study enrolling adult ED patients with symptoms suggestive of acute coronary syndrome at 8 sites in the United States (US). Patients had a 0- and 1-hour hs-cTnT measured and a HEAR score completed. A derivation set consisting of 729 randomly selected participants was used to derive a hs-cTnT HEART Pathway with rule-out, observation, and rule-in groups for 30-day cardiac death or myocardial infarction (MI). Optimal baseline and 1-hour troponin cutoffs were selected using generalized cross validation to achieve a negative predictive value (NPV) >99% for rule out and positive predictive value (PPV) >60% or maximum Youden index for rule-in. Optimal 0-1-hour delta values were derived using generalized cross validation to maximize the NPV for the rule-out group and PPV for the rule-in group. The hs-cTnT HEART Pathway performance was validated in the remaining cohort (n = 723).

RESULTS

Among the 1452 patients, 30-day cardiac death or MI occurred in 12.7% (184/1452). Within the derivation cohort the optimal hs-cTnT HEART Pathway classified 36.5% (266/729) into the rule-out group, yielding a NPV of 99.2% (95% CI: 98.2-100) for 30-day cardiac death or MI. The rule-in group included 15.4% (112/729) with a PPV of 55.4% (95% CI: 46.2-64.6). In the validation cohort, the hs-cTnT HEART Pathway ruled-out 37.6% (272/723), of which 2 had 30-day cardiac death or MI, yielding a NPV of 99.3% (95% CI: 98.3-100). The rule-in group included 14.5% (105/723), yielding a PPV of 57.1% (95% CI: 47.7-66.6).

CONCLUSIONS

A novel hs-cTnT HEART Pathway with serial 0- and 1-hour hs-cTnT measures has high NPV and moderate PPV for 30-day cardiac death or MI.