High-Sensitivity Cardiac Troponin I and the Diagnosis of Coronary Artery Disease in Patients With Suspected Angina Pectoris

Cardiac biomarkers and CT coronary angiography for the assessment of coronary heart disease

Over the last 30 years, the widespread use of cardiac biomarkers has transformed the diagnostic evaluation of patients with coronary heart disease. Cardiac troponin is integral to the definition of acute myocardial infarction. High-sensitivity cardiac troponin (hs-cTn) assays can improve risk stratification to facilitate both the rapid rule out of myocardial infarction and prediction of future cardiovascular events. Numerous circulating biomarkers representing different pathological pathways improve prediction of atherosclerotic cardiovascular disease (ACVD) and coronary artery disease (CAD). In parallel, coronary computed tomography angiography (CCTA) has become the most widely used imaging modality for the evaluation of patients with possible angina. CCTA now allows for the quantification of coronary calcification, atherosclerotic plaque volume and different plaque characteristics, enabling the identification high-risk features and inflammation. In the future, the use of CCTA is likely to extend to risk stratification for the prevention of ACVD. As such, how to integrate these diagnostic and prognostic circulating and imaging biomarkers is a topic of considerable interest. This review aims to describe current status and future possibilities for the integration of CCTA and cardiac biomarker testing to improve the identification and treatment of individuals with coronary heart disease and heightened cardiovascular risk.

Association of Cardiac Troponin T With Coronary Atherosclerosis in Asymptomatic Primary Prevention People With HIV

Background

Coronary plaque is common among people with HIV (PWH) with low-to-moderate traditional atherosclerotic cardiovascular disease (ASCVD) risk.

Objectives

The purpose of this study was to determine the association of high-sensitivity cardiac troponin T (hs-cTnT) levels with coronary plaque characteristics and evaluate if hs-cTnT improves identification of these features beyond traditional ASCVD risk factors among PWH.

Methods

Among PWH receiving stable antiretroviral therapy with low-to-moderate ASCVD risk and no known history of ASCVD, hs-cTnT levels and measures of plaque by coronary computed tomography angiography were assessed. Primary outcomes included the association of hs-cTnT level with the presence of any plaque, vulnerable plaque, coronary artery calcium (CAC) score, and Leaman score. Assessment of model discrimination of hs-cTnT for plaque characteristics was also performed.

Results

The cohort included 708 U.S. participants with a mean age of 51 ± 6 years, 119 (17%) females, a median ASCVD risk score of 4.4% (Q1-Q3: 2.5%-6.6%), and a median hs-cTnT level of 6.7 ng/L (detectable level ≥6 ng/L in 61%). Any plaque was present in 341 (48%), vulnerable plaque in 155 (22%), CAC>100 in 68 (10%), and a Leaman score >5 in 105 (15%). After adjustment for ASCVD risk score, participants with hs-cTnT >9.6 ng/L (highest category) versus an undetectable level (<6 ng/L) had a greater relative risk for any plaque (1.37, 95% CI: 1.12-1.67), vulnerable plaque (1.47, 95% CI: 1.16-1.87), CAC>100 (2.58, 95% CI: 1.37-4.83), and Leaman score >5 (2.13, 95% CI: 1.32-3.46). The addition of hs-cTnT level modestly improved the discrimination of ASCVD risk score to identify critical plaque features.

Conclusions

In PWH without known ASCVD, hs-cTnT levels were strongly associated with and improved prediction of subclinical coronary plaque. (Evaluating the Use of Pitavastatin to Reduce the Risk of Cardiovascular Disease in HIV-Infected Adults [REPRIEVE]; NCT02344290).

Exploration of the Potential Biomarker FNDC5 for Discriminating Heart Failure in Patients with Coronary Atherosclerosis

Coronary atherosclerosis leading to ischemic artery disease is one of the etiological factors to develop heart failure (HF). This study aimed to investigate potential biomarkers for discriminating HF in atherosclerotic patients. This study included 40 consecutive atherosclerotic patients who underwent angiography. Concentrations of B-type natriuretic peptide (BNP), fibronectin type III domain containing 5 (FNDC5), and Phosphodiesterase 9A (PDE9A) were measured in 20 atherosclerotic patients with HF symptoms/signs and 20 without HF symptoms/signs. Circulating BNP levels were elevated, while FNDC5 levels were reduced in atherosclerotic patients with HF symptoms/signs compared to those without HF symptoms/signs. Pearson correlation analysis showed a significant correlation between FNDC5 and BNP. Receiver Operating Characteristics analysis indicated that both FNDC5 and BNP were able to discriminate HF in atherosclerotic patients. Our findings suggest that FNDC5, along with BNP, has independent value as a biomarker for discriminating HF in patients with coronary atherosclerosis.

Clinical Implications of High-Sensitivity Troponin Elevation Levels in Non-ST-Segment Elevation Myocardial Infarction Patients: Beyond Diagnostics

Standard troponin has long been pivotal in diagnosing coronary syndrome, especially Non-ST-Segment Elevation Myocardial Infarction (NSTEMI). The recent introduction of high-sensitivity troponin (hs-cTnI) has elevated it to the gold standard. Yet, its nuanced role in predicting angiographic lesions and clinical outcomes, notably in specific populations like obesity, remains underexplored. Aim: To evaluate the association between hs-cTnI magnitude in NSTEMI patients and angiographic findings, progression to acute heart failure, and its performance in obesity. Methods: Retrospective study of 208 NSTEMI patients at a large university center (2020-2023). Hs-cTnI values were assessed for angiographic severity, acute heart failure, and characteristics in the obese population. Data collected and diagnostic performance were evaluated using manufacturer-specified cutoffs. Results: 97.12% of patients had a single culprit vessel. Hs-cTnI elevation correlated with angiographic stenosis severity. Performance for detecting severe coronary disease was low, with no improvement using a higher cutoff. No association was found between hs-cTnI and the culprit vessel location. Hs-cTnI did not predict acute heart failure progression. In the obese population, hs-cTnI levels were higher, but acute heart failure occurred less frequently than in non-obese counterparts. Conclusions: In NSTEMI, hs-cTnI elevation is associated with significant stenosis, but not with location or acute heart failure. Obesity correlates with higher hs-cTnI levels but a reduced risk of acute heart failure during NSTEMI.

Cardiac Troponin Serum Concentration Measurement Is Useful Not Only in the Diagnosis of Acute Cardiovascular Events

Cardiac troponin serum concentration is the primary marker used for the diagnosis of acute coronary syndrome. Moreover, the measurement of cardiac troponin concentration is important for risk stratification in patients with pulmonary embolism. The cardiac troponin level is also a general marker of myocardial damage, regardless of etiology. The purpose of this study is to conduct a literature review and present the most important information regarding the current state of knowledge on the cardiac troponin serum concentration in patients with chronic cardiovascular disease (CVD), as well as on the relationships between cardiac troponin serum concentration and features of subclinical cardiovascular dysfunction. According to research conducted to date, patients with CVDs, such as chronic coronary syndrome, chronic lower extremities' ischemia, and cerebrovascular disease, are characterized by higher cardiac troponin concentrations than people without a CVD. Moreover, the literature data indicate that the concentration of cardiac troponin is correlated with markers of subclinical dysfunction of the cardiovascular system, such as the intima-media thickness, pulse wave velocity, ankle-brachial index, coronary artery calcium index (the Agatston score), and flow-mediated dilation. However, further research is needed in various patient subpopulations and in different clinical contexts.

Development and validation of a simple model to predict functionally significant coronary artery disease in Chinese populations: A two-center retrospective study

Objectives

This study sought to derive and validate a simple model combining traditional clinical risk factors with biomarkers and imaging indicators easily obtained from routine preoperative examinations to predict functionally significant coronary artery disease (CAD) in Chinese populations.

Methods

We developed five models from a derivation cohort of 320 patients retrospective collected. In the derivation cohort, we assessed each model discrimination using the area under the receiver operating characteristic curve (AUC), reclassification using the integrated discrimination improvement (IDI) and net reclassification improvement (NRI), calibration using the Hosmer-Lemeshow test, and clinical benefit using decision curve analysis (DCA) to derive the optimal model. The optimal model was internally validated by bootstrapping, and external validation was performed in another cohort including 96 patients.

Results

The optimal model including 5 predictors (age, sex, hyperlipidemia, hs-cTnI and LVEF) achieved an AUC of 0.807 with positive NRI and IDI in the derivation cohort. Moreover, the Hosmer-Lemeshow test showed a good fit, and the DCA demonstrated good clinical net benefit. The C-statistic calculated by bootstrapping internal validation was 0.798, and the calibration curve showed adequate calibration (Brier score = 0.179). In the external validation cohort, the optimal model performance was acceptable (AUC = 0.704; Brier score = 0.20). Finally, a nomogram based on this model was constructed to facilitate its use in clinical practice.

Conclusions

A simple model combined clinical risk factors with hs-cTnI and LVEF improving the prediction of functionally significant CAD in Chinese populations. This attractive model may be a choice for clinicians to risk stratification for CAD.

Can high-sensitive troponin levels within the normal range predict positivity in treadmill test?

BACKGROUND

This study aimed to determine whether a high level of high-sensitivity troponin T (hsTnT) predicts a positive treadmill test in patients with suspected stable ischemic heart disease (SIHD).

METHODS

In all, 366 patients with suspected SIHD were included in the study. We measured the serum hsTnT levels before the treadmill test. The treadmill test was performed according to the Bruce protocol.

RESULTS

Of the 366 patients, 97 had positive treadmill tests. The hsTnT levels were significantly higher in the positive group than in the negative group. In the binary logistic regression analysis, hsTnT, pretest probability, metabolic equivalents (METs), target heart rate (THR) percentage, and Duke treadmill score (DTS) were independent predictors of a positive treadmill test [hsTnT odds ratio (OR): 2.178, P  < 0.001; pretest probability OR: 1.036, P  = 0.007; METs OR: 0.755, P  = 0.008; THR OR: 0.773, P  < 0.001; DTS OR: 2.661, P  = 0.012]. In the receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) value of the model with the combined parameters of hsTnT, pretest probability, METs, THR, and DTS was statistically significant in predicting a positive treadmill test [combined model AUC: 0.945 (0.922-0.968), P  < 0.001].

CONCLUSIONS

In sum, high pretest hsTnT levels predicted a positive treadmill test in patients with suspected SIHD. Analysis of the hsTnT levels before the treadmill test can increase the sensitivity and specificity of the treadmill test. The methods for measuring hsTnT levels are cheap and easily accessible and can be used before the treadmill test in patients with suspected SIHD.

Association between high-sensitive cardiac troponin level and coronary artery disease: A systematic review and meta-analysis

Background and objectives

Previous studies suggest a link between high-sensitive cardiac troponin (hs-cTn) levels and coronary artery disease (CAD). However, the nature of this relationship is disputed. To address this, we conducted a study to gather and assess evidence on the association between hs-cTn and CAD prediction.

Data sources

Studies were systematically searched and collected from four databases and different types of gray literature to cover all available evidence. After the screening, the selected articles' quality and risk of bias assessment were evaluated.

Synthesis method

Meta-analysis calculated std. mean difference on the extracted data. Furthermore, heterogeneity, sensitivity, subgroups, and publication bias analyses were assessed.

Results

Twenty-two studies were included in this systematic review, with a total of 844 cases and 2101 control people. The results of the meta-analysis on nine studies showed a significant and positive association between hs-cTn levels and CAD (pooled std. mean difference = 0.44; 95% confidence interval = 0.14-0.73; p < 0.003), with no publication bias (p = 0.9170). Among subgroups, std. mean differences were notably different only when the data were stratified by region or risk of bias; however, subgroup analysis could not determine the source of heterogeneity.

Conclusions

Available prospective studies indicate a strong association of hs-cTn with the risk of CAD and significant improvements in CAD prediction. Further investigations in both molecular and clinical fields with proper methodology and more detailed information are needed to discover more evidence and underlying mechanisms to clear the interactive aspects of hs-cTn level in CAD patients.

Biomarkers for Non-Invasive Stratification of Coronary Artery Disease and Prognostic Impact on Long-Term Survival in Patients with Stable Coronary Heart Disease

Knowledge about cardiac and inflammatory biomarkers in patients with stable coronary artery disease (CAD) is limited. To address this, we analyzed 3072 patients (36% female) with a median follow-up of 10 years in the Leipzig LIFE Heart Study with suspected CAD with coronary angiography. Selected biomarkers included troponin T (hsTNT), N-terminal pro B-type natriuretic peptide (NT-proBNP), copeptin, C-reactive protein (hsCRP), and interleukin-6 (IL-6). Patients were stratified by CAD severity: CAD0 (no sclerosis), CAD1 (non-obstructive, i.e., stenosis < 50%), and CAD2 (≥one stenosis ≥ 50%). Group comparison (GC) included GC1: CAD0 + 1 vs. CAD2; GC2: CAD0 vs. CAD1 + 2. CAD0, CAD1, and CAD2 were apparent in 1271, 631, and 1170 patients, respectively. Adjusted for classical risk factors, hs-cTnT, NT-proBNP, and IL-6 differed significantly in both GC and hsCRP only in GC2. After multivariate analysis, hs-cTnT, NT-proBNP, and IL-6 remained significant in GC1. In GC2, hs-cTnT (p < 0.001) and copeptin (p = 0.014) reached significance. Ten-year survival in groups CAD0, CAD1, and CAD2 was 88.3%, 77.3%, and 72.4%. Incorporation of hs-cTnT, NT-proBNP, copeptin, and IL-6 improved risk prediction (p < 0.001). The studied cardiac and inflammatory biomarkers enable fast and precise non-invasive identification of mortality risk in CAD patients, allowing the tailoring of primary and secondary CAD prevention.

Coronary Atherosclerosis, Cardiac Troponin, and Interleukin-6 in Patients With Chest Pain

BACKGROUND

Increased inflammation and myocardial injury can be observed in the absence of myocardial infarction or obstructive coronary artery disease (CAD).

OBJECTIVES

The authors determined whether biomarkers of inflammation and myocardial injury-interleukin (IL)-6 and high-sensitivity cardiac troponin (hs-cTn)-were associated with the presence and extent of CAD and were independent predictors of major adverse cardiovascular events (MACEs) in stable chest pain.

METHODS

Using participants from the PROMISE trial, the authors measured hs-cTn I and IL-6 concentrations and analyzed computed tomography angiography (CTA) images in the core laboratory for CAD characteristics: significant stenosis (≥70%), high-risk plaque (HRP), Coronary Artery Disease Reporting and Data System (CAD-RADS) categories, segment involvement score (SIS), and coronary artery calcium (CAC) score. The primary endpoint was a composite MACE (death, myocardial infarction, or unstable angina).

RESULTS

The authors included 1,796 participants (age 60.2 ± 8.0 years; 47.5% men, median follow-up 25 months). In multivariable linear regression adjusted for atherosclerotic cardiovascular disease (ASCVD) risk, hs-cTn was associated with HRP, stenosis, CAD-RADS, and SIS. IL-6 was only associated with stenosis and CAD-RADS. hs-cTn above median (1.5 ng/L) was associated with MACEs in univariable analysis (HR: 2.1 [95% CI: 1.3-3.6]; P = 0.006), but not in multivariable analysis adjusted for ASCVD and CAD. IL-6 above median (1.8 ng/L) was associated with MACEs in multivariable analysis adjusted for ASCVD and HRP (HR: 1.9 [95% CI: 1.1-3.3]; P = 0.03), CAC (HR: 1.9 [95% CI: 1.0-3.4]; P = 0.04), and SIS (HR: 1.8 [95% CI: 1.0-3.2]; P = 0.04), but not for stenosis or CAD-RADS. In participants with nonobstructive CAD (stenosis 1%-69%), the presence of both hs-cTn and IL-6 above median was strongly associated with MACEs (HR: 2.5-2.7 after adjustment for CAD characteristics).

CONCLUSIONS

Concentrations of hs-cTn and IL-6 were associated with CAD characteristics and MACEs, indicating that myocardial injury and inflammation may each contribute to pathways in CAD pathophysiology. This association was most pronounced among participants with nonobstructive CAD representing an opportunity to tailor treatment in this at-risk group. (PROspective Multicenter Imaging Study for Evaluation of Chest Pain [PROMISE]; NCT01174550).

Cardiac troponin I and T for ruling out coronary artery disease in suspected chronic coronary syndrome

To compare the performance of high-sensitivity cardiac troponin I and T (hs-cTnI; hs-cTnT) in diagnosing obstructive coronary artery disease (CAD₅₀) in patients with suspected chronic coronary syndrome (CCS). A total of 706 patients with suspected CCS, referred for Coronary Computed Tomography Angiography, were included. cTn concentrations were measured using the Singulex hs-cTnI (limit of detection [LoD] 0.08 ng/L) and Roche hs-cTnT (LoD 3 ng/L) assays. Obstructive coronary artery disease (CAD₅₀) was defined as ≥ 50% coronary stenosis. Cardiovascular risk was determined by the NORRISK2-score. Median age of the patients was 65 (range 28-87) years, 35% were women. All patients had hs-cTnI concentrations above the LoD (median 1.9 [Q1-3 1.2-3.6] ng/L), 72% had hs-cTnT above the LoD (median 5 [Q1-3 2-11] ng/L). There was a graded relationship between hs-cTn concentrations and coronary artery calcium. Only hs-cTnI remained associated with CAD₅₀ in adjusted analyses (OR 1.20 95% Confidence Interval [1.05-1.38]), p = 0.009). The C-statistics for hs-cTnI and hs-cTnT were 0.65 (95% CI [0.60-0.69]) and 0.60 (0.56-0.64). The highest specificity and negative predictive values for CAD₅₀ were in the lowest NORRISK2-tertile. hs-cTn concentrations provide diagnostic information in patients with suspected CCS, with superior performance of hs-cTnI compared to hs-cTnT in regard to CAD₅₀. The diagnostic performance appeared best in those with low cardiovascular risk.

Highly sensitive troponin I assay in the diagnosis of coronary artery disease in patients with suspected stable angina

BACKGROUND

Evaluation of suspected stable angina patients with probable coronary artery disease (CAD) in the community is challenging. In the United Kingdom, patients with suspected stable angina are referred by community physicians to be assessed by specialists within the hospital system in rapid access chest pain clinics (RACPC). The role of a highly sensitive troponin I (uscTnI) assay in the diagnosis of suspected CAD in a RACPC in a “real-life” setting in a non-academic hospital has not been explored.

AIM

To examine the diagnostic value of uscTnI (detection limit 0.12 ng/L, upper reference range 8.15 ng/L, and detected uscTnI in 96.8% of the reference population), in the evaluation of stable CAD in a non-selected patient group, with several co-morbidities, who presented to the RACPC.

METHODS

One hundred and seventy two RACPC patients were assigned to either functional or anatomical testing according to the hospital protocol.

RESULTS

The investigations offered to patients were exercise tolerance test 7.6%, 24 h ECG 1.2%, Echocardiogram 14.5%, stress echocardiogram 8.1%, coronary computed tomography angiography (CCTA) 12.8%, coronary angiogram 13.4%, 17.4% were diagnosed with non-cardiac chest pain, 3.5% treated as stable angina, 8.2% reviewed by cardiologists, electronic medical records were not available in 10.4%. Receiver operating characteristic curves for CAD used uscTnI values measured in patients who underwent functional testing, angiogram or CCTA. Values > 0.52 ng/L showed 100% sensitivity and at > 11.6 ng/L showed 100% specificity. In the range > 0.52-11.6 ng/L, uscTnI may not have the same diagnostic potential. In patients assigned to coronary angiogram higher concentrations of uscTnI was associated with severe CAD. Low levels of uscTnI and low pre-test probability of CAD (QRISK3) may decrease patient numbers assigned to CCTA.

CONCLUSION

The uscTnI diagnostic cut-off values in a RACPC will depend on patient population and their presenting co-morbidity. In the presence of clinical comorbidities and previous CAD the uscTnI needs to be used in conjunction with clinical assessment.

Troponin-Guided Coronary Computed Tomographic Angiography After Exclusion of Myocardial Infarction

BACKGROUND

Patients with suspected acute coronary syndrome in whom myocardial infarction has been excluded are at risk of future adverse cardiac events.

OBJECTIVES

This study evaluated the usefulness of high-sensitivity cardiac troponin I (hs-cTnI) to select patients for further investigation after myocardial infarction has been excluded.

METHODS

This is a prospective cohort study of patients presenting to the emergency department with suspected acute coronary syndrome and hs-cTnI concentrations below the sex-specific 99th percentile. Patients were recruited in a 2:1 fashion, stratified by peak hs-cTnI concentration above and below the risk stratification threshold of 5 ng/L. All patients underwent coronary computed tomography angiography (CCTA) after hospital discharge.

RESULTS

Overall, 250 patients were recruited (61.4 ± 12.2 years 31% women) in whom 62.4% (156 of 250 patients) had coronary artery disease (CAD). Patients with intermediate hs-cTnI concentrations (between 5 ng/L and the sex-specific 99th percentile) were more likely to have CAD than those with hs-cTnI concentrations <5 ng/L (71.9% [120 of 167 patients] vs 43.4% [36 of 83 patients]; odds ratio: 3.33; 95% CI: 1.92-5.78). Conversely, there was no association between anginal symptoms and CAD (63.2% [67 of 106 patients] vs 61.8% [89 of 144 patients]; odds ratio: 0.92; 95% CI: 0.48-1.76). Most patients with CAD did not have a previous diagnosis (53.2%; 83 of 156 patients) and were not on antiplatelet and statin therapies (63.5%; 99 of 156 patients) before they underwent CCTA.

CONCLUSIONS

In patients who had myocardial infarction excluded, CAD was 3× more likely in those with intermediate hs-cTnI concentrations compared with low hs-cTnI concentrations. In such patients, CCTA could help to identify those with occult CAD and to target preventative treatments, thereby improving clinical outcomes.

Estimating the real-world performance of the PROMISE minimal-risk tool

BACKGROUND

Stable chest pain is a common indication for cardiac catheterization. We assessed the prognostic value of the Prospective Multicenter Imaging Study for Evaluation (PROMISE) Minimal-Risk Tool in identifying patients who are at very low risk of obstructive coronary artery disease (CAD) or downstream cardiovascular adverse outcomes.

METHODS

We applied the PROMISE Minimal-Risk Tool to consecutive patients without known CAD who underwent elective cardiac catheterization for stable angina from January 1, 2000 to December 31, 2014 in the Duke Databank for Cardiovascular Disease (DDCD). Patients with scores >0.46 (top decile of lowest-risk from the PROMISE cohort) were classified as low-risk. Logistic regression modeling compared likelihood of freedom from obstructive coronary artery disease on index angiography, 2-year survival, and 2-year survival free of myocardial infarction (MI) and MI/revascularization between low- and non low-risk patients. Alternative cut points to define low- risk patients were also explored.

RESULTS

Among 6251 patients undergoing cardiac catheterization for stable chest pain, 1082 (17.3%) were low-risk per the PROMISE minimal-risk tool. Among low risk patients, obstructive coronary artery disease was observed in 14.9% and left main disease (≥ 50% Stenosis) was rare (0.9%). Compared with other patients, low risk patients had a higher likelihood of freedom from obstructive coronary disease on index catheterization (85.1% vs. 44.2%, OR 4.84, 95% CI 4.06-5.77). Low risk patients had significantly higher survival (98.2% vs. 94.4%, OR 3.18, 95% CI 1.99-5.08), MI-free survival (97.2% vs. 91.9%, OR 3.03, 95% CI 2.07-4.45), and MI/revascularization-free survival (86.2 vs. 59.9%, OR 4.19, 95% CI 3.48-5.05) at 2 years than non-low risk patients. Operating characteristics for predicting the outcomes of interest varied modestly depending on the low-risk cut-point used but the positive predictive value for 2 year freedom from death was >98% regardless.

CONCLUSION

The PROMISE minimal-risk tool identifies 17% of stable chest pain patients referred to cardiac catheterization as low risk. These patients have a low prevalence of obstructive CAD and better survival than non-low risk patients. While this suggests that these patients are unlikely to benefit from catheterization, further research is needed to confirm a favorable downstream prognosis with medical management alone.

Discrimination capability of pretest probability of stable coronary artery disease: a systematic review and meta-analysis suggesting how to improve validation procedures

OBJECTIVE

Externally validated pretest probability models for risk stratification of subjects with chest pain and suspected stable coronary artery disease (CAD), determined through invasive coronary angiography or coronary CT angiography, are analysed to characterise the best validation procedures in terms of discriminatory ability, predictive variables and method completeness.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Global Health (Ovid), Healthstar (Ovid) and MEDLINE (Ovid) searched on 22 April 2020.

ELIGIBILITY CRITERIA

We included studies validating pretest models for the first-line assessment of patients with chest pain and suspected stable CAD. Reasons for exclusion: acute coronary syndrome, unstable chest pain, a history of myocardial infarction or previous revascularisation; models referring to diagnostic procedures different from the usual practices of the first-line assessment; univariable models; lack of quantitative discrimination capability.

METHODS

Eligibility screening and review were performed independently by all the authors. Disagreements were resolved by consensus among all the authors. The quality assessment of studies conforms to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). A random effects meta-analysis of area under the receiver operating characteristic curve (AUC) values for each validated model was performed.

RESULTS

27 studies were included for a total of 15 models. Besides age, sex and symptom typicality, other risk factors are smoking, hypertension, diabetes mellitus and dyslipidaemia. Only one model considers genetic profile. AUC values range from 0.51 to 0.81. Significant heterogeneity (p<0.003) was found in all but two cases (p>0.12). Values of I² >90% for most analyses and not significant meta-regression results undermined relevant interpretations. A detailed discussion of individual results was then carried out.

CONCLUSIONS

We recommend a clearer statement of endpoints, their consistent measurement both in the derivation and validation phases, more comprehensive validation analyses and the enhancement of threshold validations to assess the effects of pretest models on clinical management.

PROSPERO REGISTRATION NUMBER

CRD42019139388.

Nourin-Dependent miR-137 and miR-106b: Novel Biomarkers for Early Diagnosis of Myocardial Ischemia in Coronary Artery Disease Patients

Background: Although cardiovascular imaging techniques are widely used to diagnose myocardial ischemia in patients with suspected stable coronary artery disease (CAD), they have limitations related to lack of specificity, sensitivity and “late” diagnosis. Additionally, the absence of a simple laboratory test that can detect myocardial ischemia in CAD patients, has led to many patients being first diagnosed at the time of the development of myocardial infarction. Nourin is an early blood-based biomarker rapidly released within five minutes by “reversible” ischemic myocardium before progressing to necrosis. Recently, we demonstrated that the Nourin-dependent miR-137 (marker of cell damage) and miR-106b-5p (marker of inflammation) can diagnose myocardial ischemia in patients with unstable angina (UA) and also stratify severity of ischemia, with higher expression in acute ST-segment elevation myocardial infarction (STEMI) patients compared to UA patients. Minimal baseline-gene expression levels of Nourin miRNAs were detected in healthy subjects. Objectives: To determine: (1) whether Nourin miRNAs are elevated in chest pain patients with myocardial ischemia suspected of CAD, who also underwent dobutamine stress echocardiography (DSE) or ECG/Treadmill stress test, and (2) whether the elevated levels of serum Nourin miRNAs correlate with results of ECHO/ECG stress test in diagnosing CAD patients. Methods: Serum gene expression levels of miR-137, miR-106b-5p and their corresponding molecular pathway network were measured blindly in 70 enrolled subjects using quantitative real time PCR (qPCR). Blood samples were collected from: (1) patients with chest pain suspected of myocardial ischemia (n = 38) both immediately “pre-stress test” and “post-stress test” 30 min. after test termination; (2) patients with acute STEMI (n = 16) functioned as our positive control; and (3) healthy volunteers (n = 16) who, also, exercised on ECG/Treadmill stress test for Nourin baseline-gene expression levels. Results: (1) strong correlation was observed between Nourin miRNAs serum expression levels and results obtained from ECHO/ECG stress test in diagnosing myocardial ischemia in CAD patients; (2) positive “post-stress test” patients with CAD diagnosis showed upregulation of miR-137 by 572-fold and miR-106b-5p by 122-fold, when compared to negative “post-stress test” patients (p < 0.001); (3) similarly, positive “pre-stress test” CAD patients showed upregulation of miR-137 by 1198-fold and miR-106b-5p by 114-fold, when compared to negative “pre-stress test” patients (p < 0.001); and (4) healthy subjects had minimal baseline-gene expressions of Nourin miRNAs. Conclusions: Nourin-dependent miR-137 and miR-106b-5p are promising novel blood-based biomarkers for early diagnosis of myocardial ischemia in chest pain patients suspected of CAD in outpatient clinics. Early identification of CAD patients, while patients are in the stable state before progressing to infarction, is key to providing crucial diagnostic steps and therapy to limit adverse cardiac events, improve patients’ health outcome and save lives.

Extracellular Vesicles in Diagnosing Chronic Coronary Syndromes the Bumpy Road to Clinical Implementation

Coronary artery disease (CAD), comprising both acute coronary syndromes (ACS) and chronic coronary syndromes (CCS), remains one of the most important killers throughout the entire world. ACS is often quickly diagnosed by either deviation on an electrocardiogram or elevated levels of troponin, but CCS appears to be more complicated. The most used noninvasive strategies to diagnose CCS are coronary computed tomography and perfusion imaging. Although both show reasonable accuracy (80-90%), these modalities are becoming more and more subject of debate due to costs, radiation and increasing inappropriate use in low-risk patients. A reliable, blood-based biomarker is not available for CCS but would be of great clinical importance. Extracellular vesicles (EVs) are lipid-bilayer membrane vesicles containing bioactive contents e.g., proteins, lipids and nucleic acids. EVs are often referred to as the "liquid biopsy" since their contents reflect changes in the condition of the cell they originate from. Although EVs are studied extensively for their role as biomarkers in the cardiovascular field during the last decade, they are still not incorporated into clinical practice in this field. This review provides an overview on EV biomarkers in CCS and discusses the clinical and technological aspects important for successful clinical application of EVs.

SCOT-HEART trial: reshuffling our approach to stable ischemic heart disease

The role of diagnostic testing in triaging patients with stable ischemic heart disease continues to evolve towards recognizing the benefits of coronary CT angiography (CCTA) over functional testing. The SCOT-HEART (Scottish Computed Tomography of the HEART) trial highlights this paradigm shift finding a significant reduction of death from coronary heart disease or non-fatal myocardial infarction without a significant increased rate of invasive coronary angiography over a 5 year follow-up period when implementing CCTA with standard care vs standard care alone. The better negative predictive value and ability to identify nonobstructive coronary artery disease to optimize medical therapy highlight the benefits of a CCTA first strategy. With the advent of noninvasive fractional flow reserve (FFR) and widespread availability and ease of CT, CCTA continues to establish itself as a pivotal diagnostic exam for patients with stable ischemic heart disease. In this commentary, we review the SCOT-HEART trial and its impact on CCTA for patients with stable ischemic heart disease.

Using High-Sensitivity Cardiac Troponin for the Exclusion of Inducible Myocardial Ischemia in Symptomatic Patients: A Cohort Study

BACKGROUND

The optimal noninvasive method for surveillance in symptomatic patients with stable coronary artery disease (CAD) is unknown.

OBJECTIVE

To apply a novel approach using very low concentrations of high-sensitivity cardiac troponin I (hs-cTnI) for exclusion of inducible myocardial ischemia in symptomatic patients with CAD.

DESIGN

Prospective diagnostic cohort study. (ClinicalTrials.gov: NCT01838148).

SETTING

University hospital.

PATIENTS

1896 consecutive patients with CAD referred with symptoms possibly related to inducible myocardial ischemia.

MEASUREMENTS

Presence of inducible myocardial ischemia was adjudicated using myocardial perfusion imaging with single-photon emission computed tomography, as well as coronary angiography and fractional flow reserve measurements where available. Staff blinded to adjudication measured circulating hs-cTn concentrations. An hs-cTnI cutoff of 2.5 ng/L, derived previously in mostly asymptomatic patients with CAD, was assessed. Predefined target performance criteria were at least 90% negative predictive value (NPV) and at least 90% sensitivity for exclusion of inducible myocardial ischemia. Sensitivity analyses were based on measurements with an hs-cTnT assay and an alternative hs-cTnI assay with even higher analytic sensitivity (limit of detection, 0.1 ng/L).

RESULTS

Overall, 865 patients (46%) had inducible myocardial ischemia. The hs-cTnI cutoff of 2.5 ng/L provided an NPV of 70% (95% CI, 64% to 75%) and a sensitivity of 90% (CI, 88% to 92%) for exclusion of inducible myocardial ischemia. No hs-cTnI cutoff reached both performance characteristics predefined as targets. Similarly, using the alternative assays for hs-cTnI or hs-cTnT, no cutoff achieved the target performance: hs-cTnT concentrations less than 5 ng/L yielded an NPV of 66% (CI, 59% to 72%), and hs-cTnI concentrations less than 2 ng/L yielded an NPV of 68% (CI, 62% to 74%).

LIMITATION

Data were generated in a large single-center diagnostic study using central adjudication.

CONCLUSION

In symptomatic patients with CAD, very low hs-cTn concentrations, including hs-cTnI concentrations less than 2.5 ng/L, do not generally allow users to safely exclude inducible myocardial ischemia.

PRIMARY FUNDING SOURCE

European Union, Swiss National Science Foundation, Kommission für Technologie und Innovation (Innosuisse), Swiss Heart Foundation, Cardiovascular Research Foundation Basel, University of Basel, University Hospital Basel, Roche, Abbott, and Singulex.

Integrated diagnostics: the future of laboratory medicine?

The current scenario of in vitro and in vivo diagnostics can be summarized using the “silo metaphor”, where laboratory medicine, pathology and radiology are three conceptually separated diagnostic disciplines, which will increasingly share many comparable features. The substantial progresses in our understanding of biochemical-biological interplays that characterize many human diseases, coupled with extraordinary technical advances, are now generating important multidisciplinary convergences, leading the way to a new frontier, called integrated diagnostics. This new discipline, which is currently defined as convergence of imaging, pathology and laboratory tests with advanced information technology, has an enormous potential for revolutionizing diagnosis and therapeutic management of human diseases, including those causing the largest number of worldwide deaths (i.e. cardiovascular disease, cancer and infectious diseases). However, some important drawbacks should be overcome, mostly represented by insufficient information technology infrastructures, costs and enormous volume of different information that will be integrated and delivered. To overcome these hurdles, some specific strategies should be defined and implemented, such as planning major integration of exiting information systems or developing innovative ones, combining bioinformatics and imaging informatics, using health technology assessment for assessing cost and benefits, providing interpretative comments in integrated reports, developing and using expert systems and neural networks, overcoming cultural and political boundaries for generating multidisciplinary teams and integrated diagnostic algorithms.

The role of coronary CT angiography for acute chest pain in the era of high-sensitivity troponins

Accurate and efficient diagnostic triage for acute chest pain (ACP) remains one of the most challenging problems in the emergency department (ED). While the proportion of patients that present with myocardial infarction (MI), aortic dissection, or pulmonary embolism is relatively low, a missed diagnosis can be life threatening. Coronary computed tomography angiography (CCTA) has developed into a robust diagnostic tool in the triage of ACP over the past decade, with several trials showing that it can reliably identify patients at low risk of major adverse cardiovascular events, shorten the length of stay in the ED, and reduce cost associated with the triage of patients with undifferentiated chest pain. Recently, however, high-sensitivity troponin assays have been increasingly incorporated as a rapid and efficient diagnostic test in the triage of ACP due to their higher sensitivity and negative predictive value of myocardial infarction. As more EDs adopt high-sensitivity troponin assays into routine clinical practice, the role of CCTA will likely change. In this review, we provide an overview of CCTA and high-sensitivity troponins for evaluation of patients with suspected ACS in the ED. Moreover, we discuss the changing role of CCTA in the era of high-sensitivity troponins.

Clinical determinants of plasma cardiac biomarkers in patients with stable chest pain

OBJECTIVE

Troponin and B-type natriuretic peptide (BNP) concentrations are associated with cardiovascular risk in stable patients. Understanding their determinants and identifying modifiable clinical targets may improve outcomes. We aimed to establish clinical and cardiac determinants of these biomarkers.

METHODS

This was a prespecified substudy from the randomised Scottish Computed Tomography of the Heart trial, which enrolled patients 18-75 years with suspected stable angina between 2010 and 2014 (NCT01149590). We included patients from six centres in whom high-sensitivity troponin I and BNP were measured (Singulex Erenna). Patients with troponin >99th centile upper reference limit (10.2 ng/L) or BNP ≥400 ng/L were excluded to avoid inclusion of patients with myocardial injury or heart failure. Multivariable linear regression models were constructed with troponin and BNP as dependent variables.

RESULTS

In total, 885 patients were included; 881 (99%) and 847 (96%) had troponin and BNP concentrations above the limit of detection, respectively. Participants had a slight male preponderance (n=513; 56.1%), and the median age was 59.0 (IQR 51.0-65.0) years. The median troponin and BNP concentrations were 1.4 (IQR 0.90-2.1) ng/L and 29.1 (IQR 14.0-54.0) ng/L, respectively. Age and atherosclerotic burden were independent predictors of both biomarkers. Male sex, left ventricular mass and systolic blood pressure were independent predictors of increased troponin. In contrast, female sex and left ventricular volume were independent predictors of increased BNP.

CONCLUSIONS

Troponin and BNP are associated with coronary atherosclerosis but have important sex differences and distinct and contrasting associations with CT-determined left ventricular mass and volume.

CLINICAL TRIAL REGISTRATION

NCT01149590; Post-results.

Laboratory comparison between cell cytotoxicity neutralization assay and ultrasensitive single molecule counting technology for detection of Clostridioides difficile toxins A and B, PCR, enzyme immunoassays, and multistep algorithms

Diagnostic tests for Clostridioides difficile infection (CDI) lack either specificity (nucleic acid amplification tests) or sensitivity (enzyme immunoassays; EIAs). The performance of the Singulex Clarity® C. diff toxins A/B assay was compared to cell cytotoxicity neutralization assay. Testing was also performed using an EIA for glutamate dehydrogenase (GDH) and C. difficile toxins A and B (C. Diff Quik Chek Complete®), polymerase chain reaction (PCR) (BD MAX™ Cdiff Assay), and 2 multistep algorithms: algorithm 1 (discordant GDH/toxin results arbitrated by PCR) and algorithm 2 (PCR-positive samples tested with toxin EIA). The Clarity assay and PCR both had 97% sensitivity, while specificity was 100% for Clarity and 79% for PCR. Algorithm 1 yielded 41% discordant results, and both toxin EIA and algorithm 2 had 58% sensitivity. Median toxin concentrations, as measured by the Clarity C. difficile toxin assay, were 3590, 11.5, 0.4, and 0 pg/mL for GDH+/toxin+, GDH+/toxin-/PCR+, GDH+/toxin-/PCR-, and GDH-/toxin- samples, respectively (P < 0.001). The Clarity assay may offer a single-test solution for CDI.

High-sensitive cardiac Troponin T and exercise stress test for evaluation of angiographically significant coronary disease

BACKGROUND

Exercise stress test (EST) has a moderate precision for diagnosis of CAD and could potentially obtain improved accuracy if adding a reliable cardiac biomarker to the test.

OBJECTIVE

We aimed to investigate resting levels and change in hs-cTnT during EST in patients with and without angiographically significant CAD. Moreover, we intended to explore the additive value of hs-cTnT to EST results in diagnosis of stable CAD. We hypothesized that hs-cTnT would be higher in CAD patients and increase diagnostic precision of EST.

METHOD

Patients presenting with symptoms of stable CAD, performed a maximal EST on a bicycle ergometer. Venous blood samples were taken at rest and within 5 min post-exercise. All patients underwent coronary angiography. Significant CAD was defined as having ≥75% stenosis in one or more segments of the coronary arteries.

RESULTS

Out of the 297 participants, significant CAD was found in 111 (37%) patients. Patients with significant CAD compared to without, had higher resting levels of hs-cTnT (median 8.1 vs 5.0 ng/L) and no significant difference in exercise-induced change (median 0.5 vs 0.3 ng/L), p < 0.001 and p = 0.086 respectively. Combined resting hs-cTnT with EST had higher predictive value for significant CAD than EST alone, AUC = 0.751 vs. AUC = 0.637. In an adjusted multivariable regression analysis, resting hs-cTnT >6.0 ng/L was predictive for having significant CAD, OR 2.55 (CI 95% 1.40, 4.65 p = 0.002).

CONCLUSION

In patients with suspected stable CAD, hs-cTnT has a predictive value alone, as well as added to a diagnostic EST for CAD.

Identifying Myocardial Ischemia due to Coronary Microvascular Dysfunction in the Emergency Department: Introducing a New Paradigm in Acute Chest Pain Evaluation

Chest pain stands as one of the most frequent patient presentations in the emergency department (ED). Despite established diagnostic algorithms for identifying several important causes of chest pain, such as acute myocardial infarction (AMI), aortic dissection, and pulmonary embolism, guidance on managing patients with recurrent chest pain, one of the top 3 reasons for repeated hospitalization in the United States, is less defined. The assessment of symptoms, serial ECG, and necrosis biomarkers plays a major role in patient management. Notably, the recently introduced high-sensitivity troponin T (hs-TnT) assay is helping to identify ischemia in patients previously undiagnosed by conventional testing. In Europe, with the use of this assay for over a decade, the identification of patients with AMI has substantially increased, particularly of patients with type 2 AMI, which is seen in the absence of atherosclerotic obstruction of the epicardial coronaries on angiography. Use of hs-TnT is in particular relevant in women, in whom the use of a sex-specific threshold for elevated hs-TnT has almost doubled the diagnosis of AMI. With the advent of the hs-TnT assay in the United States in 2017, a similar phenomenon is expected. Thus, it is important to learn from the European experience and to develop sex-specific nuanced algorithms for the evaluation of additional causes of myocardial ischemia/necrosis, such as coronary artery vasomotor disorders and coronary microvascular dysfunction. The latter has a high prevalence among symptomatic women presenting to the ED, a group in whom recurrent chest pain is common. This commentary describes the tools available for diagnosing epicardial- and non-epicardial-related myocardial ischemia in patients with recurrent chest pain in the ED setting. A sex-specific, nuanced approach applied to select groups of patients being observed in the ED has the potential to reduce admissions and to allow for the initiation of timely, appropriate medical treatment and outpatient follow-up in an at-risk population. The costs and availability of advanced diagnostics may pose some limitation to the widespread adoption of such protocols.

Comparison between High-Sensitivity Cardiac Troponin T and Cardiac Troponin I in a Large General Population Cohort

BACKGROUND

Few data compare cardiac troponin T (cTnT) and cardiac troponin I (cTnI) in a general population. We sought to evaluate the distribution and association between cTnT, cTnI, and cardiovascular risk factors in a large general population cohort.

METHODS

High-sensitivity cTnT and cTnI were measured in serum from 19501 individuals in the Generation Scotland Scottish Family Health Study. Associations with cardiovascular risk factors were compared using age- and sex-adjusted regression. Observed age- and sex-stratified 99th centiles were compared with 99th centiles for cTnT (men, 15.5 ng/L; women, 9.0 ng/L) and cTnI (men, 34.2 ng/L; women, 15.6 ng/L) used in clinical practice.

RESULTS

cTnT and cTnI concentrations were detectable in 53.3% and 74.8% of participants, respectively, and were modestly correlated in unadjusted analyses (R ² = 21.3%) and only weakly correlated after adjusting for age and sex (R ² = 9.5%). Cardiovascular risk factors were associated with both troponins, but in age- and sex-adjusted analyses, cTnI was more strongly associated with age, male sex, body mass index, and systolic blood pressure (P < 0.0001 for all vs cTnT). cTnT was more strongly associated with diabetes (P < 0.0001 vs cTnI). The observed 99th centiles were broadly consistent with recommended 99th centiles in younger men and women. After the age of 60 years, observed 99th centiles increased substantially for cTnT, and beyond 70 years of age, the 99th centiles approximately doubled for both troponins.

CONCLUSIONS

In the general population, cTnT and cTnI concentrations are weakly correlated and are differentially associated with cardiovascular risk factors. The 99th centiles currently in use are broadly appropriate for men and women up to but not beyond the age of 60 years.