The prognostic value of serum troponin T in unstable angina

Troponin Elevation in Asymptomatic Cancer Patients: Unveiling Connections and Clinical Implications

PURPOSE OF THE REVIEW

Elevated troponin levels are well established e.g., for the diagnosis of suspected acute coronary syndrome in symptomatic patients. In contrast, troponin elevations in asymptomatic cancer patients emerge as a complex phenomenon, challenging traditional perceptions of its association solely with cardiac events.

RECENT FINDINGS

Recent data support the predictive value of cardiac biomarker for all-cause mortality and cardiotoxicity in cancer patients. This review gives an overview about the current literature about cardiac troponins in prediction and identification of high-risk cancer patients. The overview is focusing on diagnostic challenges, biomarker significance, and gaps of knowledge. Latest publications highlight the relevance of cardiac troponin in risk analysis before cancer treatment as well as a potential diagnostic gatekeeper for further cardiological diagnostics and therapy.

Thymic Atrophy and Immune Dysregulation in Infants with Complex Congenital Heart Disease

Congenital heart disease (CHD) is the most common birth defect, and up to 50% of infants with CHD require cardiovascular surgery early in life. Current clinical practice often involves thymus resection during cardiac surgery, detrimentally affecting T-cell immunity. However, epidemiological data indicate that CHD patients face an elevated risk for infections and immune-mediated diseases, independent of thymectomy. Hence, we examined whether the cardiac defect impacts thymus function in individuals with CHD. We investigated thymocyte development in 58 infants categorized by CHD complexity. To assess the relationship between CHD complexity and thymic function, we analyzed T-cell development, thymic output, and biomarkers linked to cardiac defects, stress, or inflammation. Patients with highly complex CHD exhibit thymic atrophy, resulting in low frequencies of recent thymic emigrants in peripheral blood, even prior to thymectomy. Elevated plasma cortisol levels were detected in all CHD patients, while high NT-proBNP and IL-6 levels were associated with thymic atrophy. Our findings reveal an association between complex CHD and thymic atrophy, resulting in reduced thymic output. Consequently, thymus preservation during cardiovascular surgery could significantly enhance immune function and the long-term health of CHD patients.

Correlation between baseline immature platelets fraction levels and peak troponin in patients with acute myocardial infarction

INTRODUCTION

Elevated peak cardiac troponin levels have been linked with increased morbidity and mortality in patients with acute myocardial infarction (AMI). Immature Platelets are young and relatively large platelets that are hyper-reactive and pro-thrombotic compared to regular platelets. Increased immature platelet fraction (IPF) has been associated with an elevated risk of thrombotic events. We hypothesize that patients with higher IPF levels during AMI, will experience a more severe infarct, leading to elevated peak troponin levels.

METHODS

Clinical data from patients admitted to the cardiology division between 2018 and 2022, who were diagnosed with AMI and underwent an IPF testing. Univariate and multivariate regression analyses were performed to identify predictors of elevated peak troponin.

RESULTS

Among the 277 patients diagnosed with AMI who underwent IPF testing, 113 had (STEMI) and 164 had (NSTEMI). The median value of IPF of 4.2% was used as the threshold for defining elevated IPF. Notably, among STEMI patients, those with IPF ≥ 4.2% had significantly higher peak troponin levels ( P  = 0.021). Conversely, no significant difference in peak troponin levels was observed among NSTEMI patients ( P  = 0.348). Multivariate analysis identified patients with STEMI in the higher IPF group as one of the significant predictors for elevated peak troponin levels.

CONCLUSION

This study revealed a correlation between higher baseline IPF levels and increased peak troponin levels specifically in STEMI patients, while no such association was found in NSTEMI patients. Incorporating IPF levels above the median into risk stratification scores for STEMI patients may provide valuable support for adopting a more proactive therapeutic approach.

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.

Cardiac troponin release following coronary artery bypass grafting: mechanisms and clinical implications

The use of biomarkers is undisputed in the diagnosis of primary myocardial infarction (MI), but their value for identifying MI is less well studied in the postoperative phase following coronary artery bypass grafting (CABG). To identify patients with periprocedural MI (PMI), several conflicting definitions of PMI have been proposed, relying either on cardiac troponin (cTn) or the MB isoenzyme of creatine kinase, with or without supporting evidence of ischaemia. However, CABG inherently induces the release of cardiac biomarkers, as reflected by significant cTn concentrations in patients with uncomplicated postoperative courses. Still, the underlying (patho)physiological release mechanisms of cTn are incompletely understood, complicating adequate interpretation of postoperative increases in cTn concentrations. Therefore, the aim of the current review is to present these potential underlying mechanisms of cTn release in general, and following CABG in particular (Graphical Abstract). Based on these mechanisms, dissimilarities in the release of cTnI and cTnT are discussed, with potentially important implications for clinical practice. Consequently, currently proposed cTn biomarker cut-offs by the prevailing definitions of PMI might warrant re-assessment, with differentiation in cut-offs for the separate available assays and surgical strategies. To resolve these issues, future prospective studies are warranted to determine the prognostic influence of biomarker release in general and PMI in particular.

Cardiac troponins - a paradigm for diagnostic biomarker identification and development

The introduction of cardiac troponins into clinical diagnostics has not only improved diagnostic pathways for myocardial infarction but also profoundly influenced the definition of myocardial infarction. The term troponin appeared in the literature almost 60 years ago, i.e. shortly after this journal was founded. The development of cardiac troponins from proteins involved in muscle contraction, which were in the focus of few specialized research groups from physiology and biochemistry, to one of the most frequently measured protein biomarkers in medicine is a paradigmatic success story which is also reflected in almost 300 publications on the topic in this journal. From the viewpoint of biomarker development the critical success factors were medical need, timely generation of medical evidence, and the rapid development of robust and precise laboratory assays.

The influence of inflammation on cardiovascular disease in women

The onset of cardiovascular disease in women is almost a decade later than men, partly due to the protective effect of estrogen prior to menopause. Recently, it was noted that while there have been advances in improving the morbidity and mortality from CVD in women older than 55 years, the improvement in younger women has been stagnant. The mechanism behind this lag is unclear. This manuscript reviews the literature available on the sex-specific inflammatory response in the context of traditional and non-traditional cardiovascular disease risk factors. Our review suggests that women have a differential inflammatory response to various disease states that increases their risk for CVD and warrants a distinct prioritization from men when calculating cardiovascular disease risk.

Type 2 MI and Myocardial Injury in the Era of High-sensitivity Troponin

Troponin has been the cornerstone of the definition of MI since its introduction to clinical practice. High-sensitivity troponin has allowed clinicians to detect degrees of myocardial damage at orders of magnitude smaller than previously and is challenging the definitions of MI, with implications for patient management and prognosis. Detection and diagnosis are no doubt enhanced by the greater sensitivity afforded by these markers, but perhaps at the expense of specificity and clarity. This review focuses on the definitions, pathophysiology, prognosis, prevention and management of type 2 MI and myocardial injury. The five types of MI were first defined in 2007 and were recently updated in 2018 in the fourth universal definition of MI. The authors explore how this pathophysiological classification is used in clinical practice, and discuss some of the unanswered questions in this era of availability of high-sensitivity troponin.

Biomarker Development in Cardiology: Reviewing the Past to Inform the Future

Cardiac biomarkers have become pivotal to the clinical practice of cardiology, but there remains much to discover that could benefit cardiology patients. We review the discovery of key protein biomarkers in the fields of acute coronary syndrome, heart failure, and atherosclerosis, giving an overview of the populations they were studied in and the statistics that were used to validate them. We review statistical approaches that are currently in use to assess new biomarkers and overview a framework for biomarker discovery and evaluation that could be incorporated into clinical trials to evaluate cardiovascular outcomes in the future.

Outcomes associated with the high sensitivity cardiac troponin testing in patients presenting with non-cardiovascular disorders

There are limited data regarding the utility of troponin testing in patients presenting with non-cardiovascular (CV) symptoms as the primary manifestation. The study population comprised 2057 patients who presented to the emergency department (ED) of a US healthcare system with non-CV symptoms as the primary manifestation between January and September 2018. We compared the effect of high-sensitivity cardiac troponin T (hs-cTnT) (n = 901) after its introduction vs. 4th generation cTnT (n = 1156) on the following outcomes measures: ED length of stay (LOS), coronary tests/procedures (angiography or stress test), and long-term mortality. Mean age was 64 ± 17 yrs., and 47% were female. Primary non-CV manifestations included pneumonia, obstructive pulmonary disease, infection, abdominal-complaint, and renal failure. Mean follow up was 9 ± 4 months. Patients' demographics and medical history were clinically similar between the two troponin groups. A second cTn test was obtained more frequently in the hs-cTnT than cTnT (84% vs. 32%; p < 0.001), possibly leading to a longer ED stay (8.1 ± 8.2 h vs 5.6 ± 3.4 h, respectively; p < 0.001). Coronary tests/procedures were performed at a significantly higher rate in the hs-cTnT than cTnT following the introduction of the hs-cTnT test (28% vs. 22%, p < 0.001). Multivariate analysis showed that following the introduction of hs-cTnT testing, there was a significant 27% lower risk of long-term mortality from ED admission through follow-up (HR = 0.73, 95%CI 0.54-0.98; p = 0.035). In conclusion, we show that in patients presenting primarily with non-CV disorders, the implementation of the hs-cTnT was associated with a higher rate of diagnostic coronary procedures/interventions, possibly leading to improved long-term survival rates.

The Diagnostic Challenges Associated with Type 2 Myocardial Infarction

The diagnostic challenges associated with type 2 myocardial infarction (T2MI) evolve around an extensive evidence base. T2MI is a type of MI that occurs secondary to ischemia due to increased demand or decreased oxygen supply. This classification has been used for the last 5 years, yet there is little understanding of the characteristics and clinical outcomes. According to a survey, T2M1 can be caused mainly by different factors such as anemia (31%), sepsis (24%), and arrhythmia (17%). Other associated factors, such as age and gender, also play a part in the disease. The pathology behind T2MI is the rise and fall of cardiac troponin values with at least one value above the 99 percentile and evidence of an imbalance unrelated to coronary thrombosis. The diagnosis of the condition is evidence-based backed up with imaging techniques. The treatment of T2MI may involve blood pressure management, administration of blood products, heart rate control, and respiratory support. Depending on the clinical presentation, coronary evaluations can be used to assess the likelihood of coronary artery disease (CAD). If indicated, the MI guidelines may apply to CAD. If it shows, the MI guidelines may use electrocardiography findings of ST-segment elevation myocardial infarction (STEMI) or non-STEMI. However, the absence of CAD indicates that the benefits of cardiovascular risk reduction strategies with T2MI remain uncertain.

Mitochondrial DNA Methylation Is Higher in Acute Coronary Syndrome Than in Stable Coronary Artery Disease

BACKGROUND/AIM

Decreased mitochondrial DNA copy number (mtDNA-CN) has been associated with coronary artery disease (CAD). We aimed to clarify the difference between stable CAD (SCAD) and acute coronary syndrome (ACS) regarding mtDNA-CN and the DNA methylation ratio in regions influencing the regulation of mitochondrial biogenesis.

MATERIALS AND METHODS

Using quantitative real-time polymerase chain reaction, mtDNA-CN was measured in peripheral blood leukocytes sampled from 50 patients with SCAD and 50 with ACS. We then conducted bisulfite modification of DNA followed by methylation-specific polymerase chain reaction to quantify mtDNA methylation in the mitochondrial D-loop region (mtDLR) and nuclear DNA methylation in the promoter region of nuclear peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) gene.

RESULTS

Compared to patients with SCAD, those with ACS had significantly lower relative mtDNA-CN (0.89±0.24 vs. 1.00±0.28, p=0.013) and higher DNA methylation ratio of the mtDLR (1.11±0.24 vs. 1.00±0.25, p=0.027) Conclusion: Our findings suggest that increased DNA methylation in the mtDLR, which translates into reduced mtDNA content, may affect the clinical phenotype of CAD.

Development, validation, and implementation of biomarker testing in cardiovascular medicine state-of-the-art: proceedings of the European Society of Cardiology-Cardiovascular Round Table

Many biomarkers that could be used to assess ejection fraction, heart failure, or myocardial infarction fail to translate into clinical practice because they lack essential performance characteristics or fail to meet regulatory standards for approval. Despite their potential, new technologies have added to the complexities of successful translation into clinical practice. Biomarker discovery and implementation require a standardized approach that includes: identification of a clinical need; identification of a valid surrogate biomarker; stepwise assay refinement, demonstration of superiority over current standard-of-care; development and understanding of a clinical pathway; and demonstration of real-world performance. Successful biomarkers should improve efficacy or safety of treatment, while being practical at a realistic cost. Everyone involved in cardiovascular healthcare, including researchers, clinicians, and industry partners, are important stakeholders in facilitating the development and implementation of biomarkers. This article provides suggestions for a development pathway for new biomarkers, discusses regulatory issues and challenges, and suggestions for accelerating the pathway to improve patient outcomes. Real-life examples of successful biomarkers-high-sensitivity cardiac troponin, T2* cardiovascular magnetic resonance imaging, and echocardiography-are used to illustrate the value of a standardized development pathway in the translation of concepts into routine clinical practice.

Preoperative troponin levels and outcomes of coronary surgery following myocardial infarction

BACKGROUND

This study evaluates the impact of peak preoperative troponin level on outcomes of coronary artery bypass grafting (CABG) for non-ST-elevation myocardial infarction (NSTEMI).

METHODS

This was a retrospective review of patients undergoing isolated CABG from 2011 to 2018 with the presentation of NSTEMI. Patients were stratified into low- and high-risk groups based on median preoperative peak troponin (1.95 ng/dl). Major adverse cardiac and cerebrovascular events (MACCE) and mortality were compared. Multivariable analysis was performed to model risk factors for MACCE and mortality.

RESULTS

This study included 1211 patients, 607 low-risk (≤1.95 ng/dl) and 604 high-risk (>1.95 ng/dl). Patients were well-matched with respect to age and comorbidity. High-risk patients had lower median preoperative ejection fraction (46.5% [interquartile range {IQR}: 35.0%-55.0%] vs. 53.0% [IQR: 40.0%-58.0%]) and higher incidence of preoperative intra-aortic balloon pump (15.9% vs. 8.73%). Intensive care unit and hospital length of stay were longer in the high-risk group, but increasing troponin level was not associated with prolonged intensive care or hospital length of stay (>4 and >14 days, respectively) after risk adjustment. Postoperative complications and 30-day, 1- and 5-year rates of both MACCE and survival were similar between groups. Peak troponin greater than 1.95 ng/dl was not associated with increased hazards for MACCE, mortality, or readmission in multivariable modeling. In subanalysis, neither increasing troponin as a continuous variable nor peak troponin greater than 10.00 ng/ml were associated with increased hazards for these outcomes.

CONCLUSIONS

Preoperative troponin levels do not appear to be predictive of short- or long-term outcomes following CABG, and clinical decisions regarding surgical revascularization should not be dictated by these measurements.

Clinical Utility of Cardiac Troponin I and Cardiac Troponin T Measurements

The measurement of CK-MB remains the test of choice for confirmation or exclusion of AMI and probably will remain the test of choice for routine diagnosis in the near future. Nowadays determination of cardiac troponin T (cTnT) and cardiac troponin I (cTnI) as a method relatively expensive and time-consuming should be restricted to clinical settings that really require their high specificity.

Procalcitonin: Where Are We Now?

Procalcitonin is a biomarker that is generally elevated in bacterial infections. This review describes a conceptual framework for biomarkers using lessons from the history of troponin, applies this framework to procalcitonin with a review of observational studies and randomized trials in and out of the intensive care unit, and concludes with clinical recommendations and thoughts on how to test a test.

Prevalence and Clinical Implication of Wellens' Sign in Patients With Non-ST-Segment Elevation Myocardial Infarction

Background

Symmetrically inverted or biphasic T waves in anterior precordial leads, Wellens’ sign, have been shown to represent impending infarction of left anterior descending (LAD) territory among unstable angina patients in the studies published more than 3 decades ago, when non-ST-segment elevation myocardial infarction (NSTEMI) was not a recognized entity. The clinical implication of Wellens’ sign in the contemporary NSTEMI cohort has not been clarified.

Methods

We performed a retrospective analysis of all NSTEMI patients who underwent coronary angiography between January 2013 and June 2014. Wellens’ sign was defined as either symmetrically inverted T waves (≥ 0.10 mV) or biphasic T waves in both leads V2 and V3. Coronary angiograms were reviewed and culprit lesions were determined for each patient.

Results

A total of 274 patients were included in the final analysis, of whom 24 (8.8%) had Wellens’ sign. Among these 24 patients, 16 had a LAD culprit (eight proximal), two had a non-LAD culprit, and six had non-obstructive coronary artery disease. Patients with Wellens’ sign were more likely to have LAD culprit (66.7% vs. 19.6%, P < 0.001) and proximal LAD culprit (33.3% vs. 14.4%, P = 0.035) than those without it. Wellens’ sign had a sensitivity of 24.6% and a specificity of 96.2% to predict LAD culprit.

Conclusions

Our study revealed that: 1) Wellens’ sign was seen in 8.8% of the patients with NSTEMI; 2) Two-thirds of patients with Wellens’ sign had LAD culprit and one-third had proximal LAD culprit; and 3) Sensitivity and specificity of Wellens’ sign to predict LAD culprit were 24.6% and 96.2%, respectively.

Elevated High-Sensitivity Troponin I in the Stabilized Phase after an Acute Coronary Syndrome Predicts All-Cause and Cardiovascular Mortality in a Highly Admixed Population: A 7-Year Cohort

Background

High-sensitivity cardiac troponin I (hs-cTnI) has played an important role in the risk stratification of patients during the in-hospital phase of acute coronary syndrome (ACS), but few studies have determined its role as a long-term prognostic marker in the outpatient setting.

Objective

To investigate the association between levels of hs-cTnI measured in the subacute phase after an ACS event and long-term prognosis in a highly admixed population.

Methods

We measured levels of hs-cTnI in 525 patients 25 to 90 days after admission for an ACS event; these patients were then divided into tertiles according to hs-cTnI levels and followed for up to 7 years. We compared all-cause and cardiovascular mortality using Cox proportional hazards models and adopting a significance level of 5%.

Results

After a median follow-up of 51 months, patients in the highest tertile had a greater hazard ratio (HR) for all-cause mortality after adjustment for age, sex, known cardiovascular risk factors, medication use, and demographic factors (HR: 3.84, 95% CI: 1.92-8.12). These findings persisted after further adjustment for estimated glomerular filtration rate < 60 ml/min/1.73 m² and left ventricular ejection fraction < 0.40 (HR: 6.53, 95% CI: 2.12-20.14). Cardiovascular mortality was significantly higher in the highest tertile after adjustment for age and sex (HR: 5.65, 95% CI: 1.94-16.47) and both in the first (HR: 4.90, 95% CI: 1.35-17.82) and second models of multivariate adjustment (HR: 5.89, 95% CI: 1.08-32.27).

Conclusions

Elevated hs-cTnI levels measured in the stabilized phase after an ACS event are independent predictors of all-cause and cardiovascular mortality in a highly admixed population.

Relationship Between Preoperative Low-Density Lipoprotein Cholesterol and Periprocedural Myocardial Injury in Patients Following Elective Percutaneous Coronary Intervention in Southern China

BACKGROUND Periprocedural myocardial injury (PMI) is known to be a predictor of postprocedural cardiovascular morbidity and mortality following a percutaneous coronary intervention (PCI). However, the correlation between low-density lipoprotein cholesterol and periprocedural myocardial injury in patients following elective PCI in southern China remains unclear. Therefore, we aimed to investigate the association of preoperative low-density lipoprotein cholesterol (LDL-C) levels with PMI in patients following elective PCI. MATERIAL AND METHODS This study included 1942 consecutive patients who received elective PCI. Cardiac troponin I (cTnI) was used to assess perioperative myocardial injury. The peak cTnI was measured within 24 h after PCI, and the correlation between the cTnI value and the preoperative LDL level was studied. RESULTS The data suggest that the PCI patients with preprocedural LDL-C <100 mg/dl were strongly and independently correlated with less risk of PMI. Univariate logistic regression indicated that patients with preprocedural LDL-C of 70~99 mg/dl were correlated with lower risk of postprocedural cTnI elevation above 3×ULN (odds ratio [OR]: 0.762; 95% [CI]: 0.603-0.965; P<0.024) up to 20×ULN (OR: 0.730; 95% CI: 0.576-0.924; P<0.000) compared to those with preprocedural LDL-C ≥100 mg/dl. Moreover, patients with preprocedural LDL-C of <70 mg/dl were more strongly correlated with lower risk of postprocedural cTnI elevation above 3×ULN (OR: 0.641; 95% CI: 0.436-0.936; P<0.021) up to 20×ULN (OR: 0.476; 95% CI: 0.316-0.717; P<0.000). CONCLUSIONS Our study demonstrated that PCI patients with lower preprocedural LDL-C were correlated with a lower risk of PMI in southern China.

Elevated cardiac troponin T in cirrhotic patients with emergency care admissions: Associations with mortality

BACKGROUND AND AIM

Mortality of cirrhotic patients after emergency care admission is high, and prognostic factors can help in prioritizing patients. The aim of our study was to assess the association between levels of cardiac troponin T (cTnT) and 1-year mortality in patients with liver cirrhosis without known cardiac disease, who were admitted to the emergency department (ED).

METHODS

All patients with cirrhosis presented to the ED from October 2009 until August 2015 who had an initial cTnT value measured with the first lab panel were retrospectively analyzed with a follow-up of 365 days.

RESULTS

Of a total of 237 cirrhotic ED patients, cTnT measurements were available for 87 (63% men, mean age 58.9 ± 11.0 years, and median Model for End-stage Liver Disease score was 15 [25th-75th percentile: 10-19]). Chronic Liver Failure Consortium acute-on-chronic liver failure (CLIF-C-ACLF) score was 33. Forty-three patients (49%) had cTnT values above the normal range (14 ng/L), of which 19 (22%) had values over 30 ng/L. Two patients were lost to follow-up. In multivariable analysis, both CLIF-C-ACLF (hazard ratio 1.072 per point increase; 95% confidence interval 1.029-1.117; P < 0.001) and cTnT (hazard ratio 1.014 per ng/L increase; 95% confidence interval 1.004-1.024; P = 0.008) emerged as independently associated with mortality.

CONCLUSIONS

A large proportion of cirrhotic patients in the ED have elevated levels of cTnT even if there is no evidence of cardiac disease. Elevated cTnT is associated with increased mortality during 1 year after correcting for Model for End-stage Liver Disease and CLIF-C-ACLF scores.

Osteoprotegerin Is Associated With Major Bleeding But Not With Cardiovascular Outcomes in Patients With Acute Coronary Syndromes: Insights From the PLATO (Platelet Inhibition and Patient Outcomes) Trial

Background

Elevated levels of osteoprotegerin, a secreted tumor necrosis factor–related molecule, might be associated with adverse outcomes in patients with coronary artery disease. We measured plasma osteoprotegerin concentrations on hospital admission, at discharge, and at 1 and 6 months after discharge in a predefined subset (n=5135) of patients with acute coronary syndromes in the PLATO (Platelet Inhibition and Patient Outcomes) trial.

Methods and Results

The associations between osteoprotegerin and the composite end point of cardiovascular death, nonprocedural spontaneous myocardial infarction or stroke, and non–coronary artery bypass grafting major bleeding during 1 year of follow‐up were assessed by Cox proportional hazards models. Event rates of the composite end point per increasing quartile groups at baseline were 5.2%, 7.5%, 9.2%, and 11.9%. A 50% increase in osteoprotegerin level was associated with a hazard ratio (HR) of 1.31 (95% confidence interval [CI], 1.21–1.42) for the composite end point but was not significant in adjusted analysis (ie, clinical characteristics and levels of C‐reactive protein, troponin T, NT‐proBNP [N‐terminal pro‐B‐type natriuretic peptide], and growth differentiation factor‐15). The corresponding rates of non–coronary artery bypass grafting major bleeding were 2.4%, 2.2%, 3.8%, and 7.2%, with an unadjusted HR of 1.52 (95% CI, 1.36–1.69), and a fully adjusted HR of 1.26 (95% CI, 1.09–1.46). The multivariable association between the osteoprotegerin concentrations and the primary end point after 1 month resulted in an HR of 1.09 (95% CI, 0.89–1.33); for major bleeding after 1 month, the HR was 1.33 (95% CI, 0.91–1.96).

Conclusions

In patients with acute coronary syndrome treated with dual antiplatelet therapy, osteoprotegerin was an independent marker of major bleeding but not of ischemic cardiovascular events. Thus, high osteoprotegerin levels may be useful in increasing awareness of increased bleeding risk in patients with acute coronary syndrome receiving antithrombotic therapy.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00391872.

High sensitivity troponins in contemporary cardiology practice: are we turning a corner?

INTRODUCTION

Troponin is considered to be the gold standard biomarker for ruling out MI. There has been a drive to improve the diagnostic speed, and as such the high sensitivity cardiac troponin (hs-cTn) assays have been introduced into clinical practice and are now part of international guidelines. Their novel value in clinical practice more generally is becoming apparent. Areas covered: In this review we will evaluate the evidence for the use of hs-cTn assays in clinical practice, the issues with the assay and how the hs-cTn can be utilized in the future as a biomarker of cardiovascular risk. Expert commentary: The use of the hs-cTn assays as a 'rule out' test for MI is compelling, as a 'rule in' there are significant issues relating the specificity of the assay for MI. The future of the assay may lie in population screening and risk modeling.

Safety and efficacy of rivaroxaban for the secondary prevention following acute coronary syndromes among biomarker-positive patients: Insights from the ATLAS ACS 2-TIMI 51 trial

BACKGROUND:

Despite dual antiplatelet therapy, persistent thrombin generation and thrombin-mediated platelet activation account in part for the residual risk of atherothrombotic disease among patients with prior acute coronary syndrome (ACS). Inhibition of thrombin generation among high-risk ACS patients (biomarker-positive ACS) with the factor Xa inhibitor rivaroxaban may limit ongoing thrombus formation and myocardial necrosis and thereby improve clinical outcomes.

OBJECTIVES AND METHODS:

ATLAS ACS 2-TIMI 51 was a double-blind, placebo-controlled clinical trial that randomized ACS patients to either rivaroxaban 2.5 mg b.i.d., rivaroxaban 5 mg b.i.d., or placebo plus standard-of-care antiplatelet therapy for a mean of 13.1 months and up to 31 months ( N=15,526). This post-hoc analysis evaluates the safety and efficacy of rivaroxaban among biomarker-positive ACS patients with and without a history of prior stroke of transient ischemic attack in the ATLAS ACS 2-TIMI 51 trial.

RESULTS:

A total of 12,626 biomarker-positive ACS patients were included in this analysis. Among biomarker-positive patients without a prior history of stroke or transient ischemic attack, rivaroxaban 2.5 b.i.d. was associated with a reduction in the primary efficacy endpoint (composite of cardiovascular death, myocardial infarction, or stroke) as compared with placebo (hazard ratio=0.80, 95% confidence interval (0.68-0.94), p=0.007) at the expense of an increase in non-coronary-artery-bypass-graft-related Thrombolysis in Myocardial Infarction major bleeding (1.9% vs. 0.7%, p<0.0001), but not a significant increase in either intracranial hemorrhage (0.4% vs. 0.2%, p=0.11) or fatal bleeding (0.1% vs. 0.3%, p=0.16).

CONCLUSION:

Rivaroxaban 2.5 mg b.i.d. was associated with a significant reduction in the composite of cardiovascular death, myocardial infarction, or stroke with no increase in fatal bleeding. Biomarker-positive patients with no prior history of stroke or transient ischemic attack may be a optimal target population to receive "dual pathway" therapy with rivaroxaban plus dual antiplatelet therapy for secondary prevention following ACS.

Cardiac troponins: 25 years on the stage and still improving their clinical value

Twenty-five years ago, non-isotopic immunoassays for measuring the cardiac specific isoforms of troponin I (cTnI) and T (cTnT) were developed. Both biomarkers radically changed the diagnosis, prognosis, and therapy indication of acute coronary syndromes (ACS) and, particularly, of myocardial infarction (MI). However, cardiac troponins (cTn) rapidly demonstrated their usefulness in other cardiac and non-cardiac conditions, a part of the ischemic coronary diseases. Consequently, the number of patients to be tested for cTn and the number of tests requested to clinical laboratories sharply increased. Though the manufacturers continuously improved the analytical characteristics of the first cTn assays and produced different cTn assay "generations", the universal definition of myocardial infarction required less-than-available analytical imprecision at the cTn concentration used to assess MI (i.e. the 99th reference percentile). To address the clinical requirements, manufacturers developed the high-sensitivity cTn (hs-cTn) assays that allow to measure the 99th reference percentile with adequate precision, to detect cTn in many healthy subjects and, hence, to calculate the hs-cTn biological variation and especially to observe in very short time intervals serial differences in hs-cTn attributable to cardiac ischemia. Since the number of patients attending the emergency departments (ED) for a suspected ACS or MI is increasing, the improved properties of hs-cTn assays, allowing faster and safer patient assessment, will help to alleviate the sometimes overcrowded EDs. However, there are many biological, analytical, and clinical factors that can influence the true hs-cTn values of a patient. Clinicians and laboratory professionals should know about them for the best interpretation of the otherwise largely useful hs-cTn measurements. In conclusion, 25 years after their introduction for clinical use, "cTn are still on the stage and improving their clinical value".

Region and cell-type resolved quantitative proteomic map of the human heart

The heart is a central human organ and its diseases are the leading cause of death worldwide, but an in-depth knowledge of the identity and quantity of its constituent proteins is still lacking. Here, we determine the healthy human heart proteome by measuring 16 anatomical regions and three major cardiac cell types by high-resolution mass spectrometry-based proteomics. From low microgram sample amounts, we quantify over 10,700 proteins in this high dynamic range tissue. We combine copy numbers per cell with protein organellar assignments to build a model of the heart proteome at the subcellular level. Analysis of cardiac fibroblasts identifies cellular receptors as potential cell surface markers. Application of our heart map to atrial fibrillation reveals individually distinct mitochondrial dysfunctions. The heart map is available at maxqb.biochem.mpg.de as a resource for future analyses of normal heart function and disease.

The human heart is composed of distinct regions and cell types, but relatively little is known about their specific protein composition. Here, the authors present a region- and cell type-specific proteomic map of the healthy human heart, revealing functional differences and potential cell type markers.

Troponin Testing for Clinicians

The analytical performance of troponin assays has improved markedly in the last 2 decades. The variety of assays, their evolution over time, and their critical importance in influencing care, mandates the need for skills in their use. There are 3 critical elements necessary for optimal use of troponin testing in clinical care, as follows: 1) the analytical performance of the assay; 2) the clinical sensitivity and specificity of the test result; and 3) the clinical reasoning for ordering and the proper clinical context for interpreting the test result. This paper provides further explanation that will assist clinicians in their clinical decision making and interpretation of troponin test results. Schematic visual explanations are provided to help clinicians develop a more intuitive understanding of troponin testing.

Cardiac Biomarkers and the Diagnosis of Myocardial Infarction in Women

PURPOSE OF REVIEW

Women with suspected acute coronary syndrome are less likely to undergo investigation or receive treatment than men, and women consistently have poorer outcomes. This review summarises how the latest development in cardiac biomarkers could improve both diagnosis and outcomes in women.

RECENT FINDINGS

Novel high-sensitivity cardiac troponin assays have identified differences in the reference range and therefore diagnostic threshold for myocardial infarction in men and women. These differences are present across multiple populations with different ethnic backgrounds and for a range of assays. The use of a uniform threshold for cardiac troponin does not provide equivalent prediction in men and women, with lower thresholds needed for women to provide comparable risk stratification. Sex differences in cardiac troponin concentrations are not widely recognised in clinical practice and may be contributing to the under-diagnosis of myocardial infarction in women and discrepancies in patient care and outcomes.

Evaluation of Serial High Sensitivity Troponin T Levels in Individuals Without Overt Coronary Heart Disease Following Exercise Stress Testing

BACKGROUND

Detectable levels of high sensitivity (cardiac) troponin T (HsTnT), occur in the majority of patients with stable coronary heart disease (CHD), and often in 'healthy' individuals. Extreme physical activity may lead to marked elevations in creatine kinase MB and TnT levels. However, whether HsTnT elevations occur commonly after exercise stress testing (EST), and if so, whether this has clinical significance, needs clarification.

METHODS

To determine whether HsTnT levels become elevated after EST (Bruce protocol) to ≥95% of predicted maximum heart rate in presumed healthy subjects without overt CHD, we assayed HsTnT levels for ∼5h post-EST in 105 subjects (median age 37 years).

RESULTS

Pre-EST HsTnT levels <5 ng/L were present in 31/32 (97%) of females and 52/74 (70%) of males. Post-EST, 13 (12%) subjects developed HsTnT levels >14 ng/L, with troponin elevation occurring at least three hours post-EST. Additionally, a detectable ≥ 50% increase in HsTnT levels (4.9→9ng/L) occurred in 28 (27%) of subjects who during EST achieved ≥ 95% of their predicted target heart rate. The median age of the subjects with HsTnT elevations to > 14ng/L post-EST was higher than those without such elevation (42 and 36 years respectively; p=0.038). At a median follow-up of 13 months no adverse events were recorded.

CONCLUSION

The current study demonstrates that detectable elevations occur in HsTnT post-EST in 'healthy' subjects without overt CHD. Future studies should evaluate the clinical significance of detectable elevations in post-EST HsTnT with long-term follow-up for adverse cardiac events.

Cardiac Troponin I Increase After Successful Percutaneous Coronary Angioplasty: Predictors and Long-Term Prognostic Value

After successful percutaneous coronary interventions (PCI), elevations of cardiac enzymes are not rare, but it is still not clear whether those elevations are associated with adverse late outcome. The purpose of the study was to investigate the relation between cardiac troponin I (cTn-I) increase after successful percutaneous intervention and late outcome. The study consisted of 100 consecutive patients (mean age 56 ±9.8, 84% male) who had successful elective coronary balloon angioplasty with or without stent implantation. Patients with stable angina (n=54) and unstable angina (n=46) were included in the study. Blood samples for measurement of cTn-I were taken before and immediately after the procedure, and every 6 hours for the first 24 hours. Patients with preprocedural cTn-I elevation were excluded from the study. Postprocedural cTn-I elevation was detected in 34 patients (34%, troponin (+) group) and cTn-I levels were normal in 66 patients (66%, troponin (-) group). Logistic regression analysis showed that intervention in patients with unstable angina, stent implantation following balloon dilation, and maximal inflation pressure were the predictors of cTn-I elevation (p=0.035, p=0.038, and p=0.014, respectively). During the prospective follow-up period for 21 ±7.5 months, the incidence of major cardiac events including recurrent angina, acute myocardial infarction, death, and revascularization were not different in patients with and without cTn-I elevation. Overall, major cardiac events occurred in 9 patients (26%) in the troponin (+) group and in 13 patients (20%) in the troponin (-) group. Kaplan-Meier survival analysis showed that cTn-I elevation was not an important correlate of overall cardiac events (log-rank: 1.66, p=0.19). The authors conclude that postprocedural cTn-I elevation is related to unstable angina, stent implantation following predilation, and inflation pressure, and there is no association with minor myocardial injury occurring after successful percutaneous coronary intervention and late adverse cardiac events.

Therapy of unstable angina with the low molecular weight heparins

Unstable angina is in most cases caused by partial or complete coronary artery occlusion due to the disruption of an atherosclerotic plaque and to thrombus formation. An immediate antithrombotic approach is essential to prevent fatal and non-fatal myocardial infarction, and the combination of aspirin and unfractionated heparin has played a pivotal role in the past years. Low molecular weight heparins have improved pharmacokinetic and pharmaco-dynamic properties over unfractionated heparin that have resulted in greater efficacy and safety in the field of venous thromboembolism. Low molecular weight heparins can be administered by once or twice daily subcutaneous injections at fixed, weight-adjusted doses without the need for monitoring. Because of their potential, many recent clinical trials have evaluated their efficacy and safety in the management of patients with unstable angina. Three low molecular weight heparins have so far been tested: nadroparin, dalteparin and enoxaparin. The results of the published trials confirm that the newer compounds are at least as safe and effective as unfractionated heparin, and offer considerable therapeutic advantages. Nevertheless, the different properties of the three compounds and perhaps the different designs of the clinical trials have led to not entirely comparable findings.

How Well Do Laboratories Adhere to Recommended Clinical Guidelines for the Management of Myocardial Infarction: The CARdiac MArker Guidelines Uptake in Europe Study (CARMAGUE)

BACKGROUND

We undertook an assessment of current use of evidence-based guidelines for the use of cardiac biomarkers in Europe (EU) and North America (NA).

METHODS

In 2013–2014 a web-based questionnaire was distributed via NA and EU biochemical societies. Questions covered cardiac biomarkers measured, analytical methods used, decision thresholds, and use of decision-making protocols. Results were collated using a central database and analyzed using comparative and descriptive nonparametric statistics.

RESULTS

In EU, returns were obtained from 442 hospitals, 50% central or university hospitals, and 39% from local hospitals from 35 countries with 395/442 (89%) provided an acute service. In NA there were 91 responses (63.7% central or university hospitals, 19.8% community hospitals) with 76/91 (83.5%) providing an acute service. Cardiac troponin was the preferred cardiac biomarker in 99.5% (EU) and 98.7% (NA), and the first line marker in 97.7% (EU) and 97.4% (NA). There were important differences in the choice of decision limits and their derivations. The origin of the information was also significantly different, with EU vs NA as follows: package insert, 61.9% vs 40%; publications, 17.1% vs 15.0%; local clinical or analytical validation choice, 21.0% vs 45.0%; P = 0.0003.

CONCLUSIONS

There are significant differences between EU and NA use of cardiac biomarkers. This probably relates to different availability of assays between EU and NA (such as high-sensitivity troponin assays) and different laboratory practices on assay introduction (greater local evaluation of assay performance occurred in NA).

High-sensitivity cardiac troponin assays and unstable angina

The term unstable angina has been conventionally applied to patients with myocardial ischemia without myocardial necrosis. However, while the clinical context has remained constant over time, the biomarkers of myocardial injury and acute myocardial infarction have evolved. High-sensitivity cardiac troponin assays have several key analytical differences from prior cardiac troponin assay generations, which may alter the diagnosis and frequency of unstable angina, as well as affect our understanding of previously developed risk stratification strategies. This document reviews the current challenges in regards to unstable angina when using high-sensitivity cardiac troponin I and T assays.

Borderline Values of Troponin-T and High Sensitivity C-Reactive Protein Did Not Predict 2-Year Mortality in TnT Positive Chest-Pain Patients, Whereas Brain Natriuretic Peptide Did

Background

Troponin-T (TnT), high-sensitive C-reactive protein (hsCRP), and Brain Natriuretic Peptide (BNP) have been shown to be independent prognostic indicators of total and cardiac death during short- and long-term follow-up.

Methods

We investigated prospectively the prognostic value of admission samples of TnT, hsCRP, and BNP in 871 chest-pain patients from South-Western Norway and 982 patients from Northern Argentina, based on a similar protocol and database setup. Follow-up was 2 years for the pooled population. The prognostic value of the selected biomarkers was investigated in quartiles of 239 patients with TnT values greater than 0.01 and up to and including 0.1 ng/mL, with continuous TnT as a potential confounder.

Results

After 24 months, 69 patients had died, of whom 38 died from cardiac causes. In the selected range of TnT, this biomarker was not significantly different between patients who died and survived (mean 0.0452 and 0.0457, p = 0.887). The BNP levels were significantly higher among patients dying than in long-term survivors [340 (142–656) versus 157 (58–367) pg/mL (median, 25 and 75% percentiles), p < 0.001]. In a multivariable Cox regression model for death within 2 years, the hazard ratio (HR) for BNP in the highest quartile (Q4) as compared to the lowest (Q1) was significantly related to total mortality [HR 2.84 (95% confidence interval (CI), 1.13–7.17)], p = 0.027, in addition to age (p ≤ 0.001) and hypercholesterolemia (p = 0.043). For cardiac death, the HR for BNP was 5.18 (95% CI, 1.06–25.3), p = 0.042. Several other variables (age, congestive heart failure, ST elevation myocardial infarction, and study country) were also significantly related to cardiac death. In a multivariable Cox regression model, hsCRP rendered no significant prognostic information for all-cause mortality (p = 0.089) or for cardiac mortality (p = 0.524).

Conclusion

In patients with borderline TnT values (greater than 0.01 and up to and including 0.1 ng/mL), this biomarker as well as hsCRP did not render prognostic information, whereas BNP was found to be a strong prognostic indicator of 2-year total and cardiac mortality.

Discordant cardiac biomarker levels independently predict outcome in ST-segment elevation myocardial infarction

AIMS

To investigate the prognostic relevance of elevated Troponin T (cTnT) levels in patients with ST-segment elevation myocardial infarction (STEMI) without significant creatine kinase (CK) elevation on admission.

METHODS AND RESULTS

From January 1, 2002 to December 31, 2006 patients with STEMI without significant CK elevation (<2-fold) on admission treated with percutaneous coronary intervention (PCI) were included and stratified according to cTnT plasma levels. Univariate and multivariate regression analyses were used to find independent predictors for mortality. During the 5-year period 514 patients with STEMI and normal CK plasma levels were included. 308 (59.9 %) patients had cTnT levels <0.1 μg/l and 206 (40.1 %) patients had cTnT levels ≥0.1 μg/l. Multivariate logistic regression analysis identified cTnT levels ≥0.1 μg/l and 3-vessel disease as positive, and hemoglobin levels as negative independent predictors for long-term mortality. Discordantly elevated cTnT plasma levels independently predicted higher mortality rates in the first year (HR 3.9, 95 % CI 1.7-9.1, p = 0.002) and during 5 years (HR 2.3, 95 % CI 1.4-3.9, p = 0.002) after PCI for STEMI.

CONCLUSIONS

Discordant elevation of cTnT in the presence of normal CK plasma levels on admission is associated with increased mortality in STEMI patients undergoing primary PCI. This may be due to preceding microembolization.