Importance of Biomarkers for Long-Term Mortality Prediction in Acutely Dyspneic Patients

Multi-Marker Approach in Patients with Acute Chest Pain in the Emergency Department

BACKGROUND

Chest pain is a prevalent reason for emergency room referrals and presents diagnostic challenges. The physician must carefully differentiate between cardiac and noncardiac causes, including various vascular and extracardiovascular conditions. However, it is crucial not to overlook serious conditions such as acute coronary syndrome (ACS). Diagnosis of acute myocardial infarction (AMI) and early discharge management become difficult when traditional clinical criteria, ECG, and troponin values are insufficient. Recently, the focus has shifted to a "multi-marker" approach to improve diagnostic accuracy and prognosis in patients with chest pain.

METHODS

This observational, prospective, single-center study involved, with informed consent, 360 patients presenting to the emergency department with typical chest pain and included a control group of 120 healthy subjects. In addition to routine examinations, including tests for hsTnI (Siemens TNIH kit), according to the 0-1 h algorithm, biochemical markers sST2 (tumorigenicity suppression-2) and suPAR (soluble urokinase plasminogen activator receptor) were also evaluated for each patient. A 12-month follow-up was conducted to monitor outcomes and adverse events.

RESULTS

We identified two groups of patients: a positive one (112 patients) with high levels of hsTnI, sST2 > 24.19 ng/mL, and suPAR > 2.9 ng/mL, diagnosed with ACS; and a negative one (136 patients) with low levels of hsTnI, suPAR < 2.9 ng/mL, and sST2 < 24.19 ng/mL. During the 12-month follow-up, no adverse events were observed in the negative group. In the intermediate group, patients with hsTnI between 6 ng/L and the ischemic limit, sST2 > 29.1 ng/mL and suPAR > 2.9 ng/mL, showed the highest probability of adverse events during follow-up, while those with sST2 < 24.19 ng/mL and suPAR < 2.9 ng/mL had a better outcome with no adverse events at 12 months.

CONCLUSION

Our data suggest that sST2 and suPAR, together with hsTnI, may be useful in the prognosis of cardiovascular patients with ACS, providing additional information on endothelial damage. These biomarkers could guide the clinical decision on further diagnostic investigations. In addition, suPAR and sST2 emerge as promising for event prediction in patients with chest pain. Their integration into the standard approach in PS could facilitate more efficient patient management, allowing safe release or timely admission based on individual risk.

Global historical retrospect and future prospects on biomarkers of heart failure: A bibliometric analysis and science mapping

Introduction

Heart failure is a rapidly growing public health problem and has become a major cause of hospitalization in middle-aged and older adults. Biomarkers are clinically important in managing heart failure and have attracted more attention from researchers in recent years. This study aimed to evaluate the global research of heart failure biomarkers by bibliometrics and to identify the hot spots and perspectives for further advancement.

Methods

Selection of relevant documents was from the Web of Science Core Collection. Microsoft Excel, VOSviewer, SciMA, and CiteSpace software were used for bibliometric analysis.

Results

As of October 29, 2021, 5,978 documents for heart failure biomarkers have been identified from 1989 to 2021. European Journal of Heart Failure and Circulation respectively ranked first in terms of the number of publications and the number of co-citations. A total of 5,698 institutions from 90 countries participated in these publications, with the USA leading with 2,045 documents. The most productive institution was Harvard University. Januzzi, J.L. and Maisel, A.S. were the most productive and most cited authors respectively. Natriuretic peptide, copeptin, valsartan, ferric carboxymaltose, empagliflozin, preserved ejection fraction, myocardial fibrosis, and heart transplantation were hot themes.

Conclusions

Extensive national and inter-institutional collaboration should be enhanced to bridge the gap between developed and less developed countries in heart failure biomarkers research. The research in this field seems to have reached a relatively mature stage, with a decrease in research fervor in recent years. The study of the natriuretic peptide family still has high centrality, with advances in the study of expression products and inflammatory markers. Cardiac fibrosis, cardiac remodeling, and therapies regarding heart failure have become hot spots.

Biomarkers in heart failure clinical trials. A review from the Biomarkers Working Group of the Heart Failure Association of the European Society of Cardiology

The approval of new heart failure (HF) therapies has slowed over the past two decades in part due to the high costs of conducting large randomized clinical trials that are needed to adequately power major clinical endpoint studies. Several biomarkers have been identified reflecting different elements of HF pathophysiology, with possible applications in diagnosis, risk stratification, treatment monitoring, and even in the design of clinical trials. Biomarkers could potentially be used to refine study inclusion criteria to enable enrolment of patients who are more likely to respond to a therapeutic intervention, despite being at sufficient risk to meet pre-determined study endpoint rates. When there is a close relationship between biomarker levels and clinical endpoints, changes in biomarker levels after a given treatment can act as a surrogate endpoint, potentially reducing the duration and cost of a clinical trial. Natriuretic peptides have been widely used in clinical trials with a variable amount of added value, which such variation being probably due to the absence of a close pathophysiological connection to the study drug. Notable exceptions to this include sacubitril/valsartan and vericiguat. Future studies should seek to adopt unbiased approaches for discovery of true companion diagnostics; with -omics-based tools, biomarkers might be more precisely selected for use in clinical trials to identify responses that closely reflect the biological effects of the drug under investigation. Finally, biomarkers associated with cardiac damage and remodelling, such as cardiac troponin, could be employed as safety endpoints provided that standardization between different assays is achieved.

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.

Natriuretic Peptides as Inclusion Criteria in Clinical Trials: A JACC: Heart Failure Position Paper

This study investigated the use of natriuretic peptides as inclusion criteria and to develop recommendations regarding their use. B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are commonly used as inclusion criteria for heart failure (HF) clinical trials, but no consensus exists regarding their optimal use for this purpose. A comprehensive search of the Aggregate Analysis of ClincalTrials.gov database identified 3,446 HF trials. Of these, 365 recently completed or ongoing HF clinical trials (10.6%) used either BNP or NT-proBNP as inclusion criteria. A panel of experts discussed current practices and a path forward for the use of natriuretic peptides as inclusion criteria for HF trials. Significant variations existed across trials regarding which natriuretic peptide and which cutoff value were used. Overall, 43% used both natriuretic peptides, 33% used only NT-proBNP, and 24% used only BNP in determining eligibility. Studies using BNP and NT-proBNP concentrations as inclusion criteria had higher cardiovascular event rates and higher concentrations for study entry and were generally associated with higher event rates. Areas of uncertainty included use in certain patient populations in which natriuretic peptides are historically lower (e.g., black patients, obese patients, patients with HF with preserved ejection fraction) or higher (older patients, patients with atrial fibrillation). This paper discusses best practices regarding use of BNP or NT-proBNP in clinical trials and identification of gaps in medical literature, including importance of documentation in ClinicalTrials.gov studies to inform future research efforts.

Established and Emerging Roles of Biomarkers in Heart Failure

Heart failure (HF) is a complex syndrome with an enormous societal burden in terms of cost, morbidity, and mortality. Natriuretic peptide testing is now widely used to support diagnosis, prognostication, and management of patients with HF and are incorporated into HF clinical practice guidelines. Beyond the natriuretic peptides, novel biomarkers may supplement traditional clinical and laboratory testing to improve understanding of the complex disease process of HF and possibly to personalize care for those affected through better individual phenotyping. In this review, we will discuss natriuretic peptides and the more novel biomarkers by dividing them into categories based on the major pathophysiologic pathways they represent. Given the complex physiology in HF, it is reasonable to expect that the future of biomarker testing lies in the application of multimarker testing panels, precision medicine to improve HF care delivery, and the use of biomarkers in proteomics and metabolomics to further improve HF care.

Relationship between Hypoalbuminemia on Admission and Long-term Mortality in Patients with Acute Decompensated Heart Failure

Objective Although several studies have reported the relationship between hypoalbuminemia and the clinical outcome, it remains disputable in patients with acute decompensated heart failure (ADHF). We therefore investigated the relationship between hypoalbuminemia on admission and long-term mortality in hospitalized patients following ADHF. Methods We examined a cohort of 751 consecutive patients who were admitted to the cardiac intensive-care unit between 2007 and 2011 with a diagnosis of ADHF. These patients were divided into 2 groups according to the presence or absence of hypoalbuminemia on admission, which was defined as a serum albumin ≤3.4 g/dL. A propensity score (PS) was calculated to evaluate the effects of variables related to the presence or absence of hypoalbuminemia. The association between hypoalbuminemia and mortality was assessed using two Cox regression models-namely, conventional adjustment and matching patients with and without hypoalbuminemia using the PS. Results Among the pre-match patients (n=551), 311 (56%) were classified as exhibiting hypoalbuminemia on admission. There were 152 deaths (27.5%), and the median follow-up was 1.9 years. The presence of hypoalbuminemia on admission tended to be associated with increased mortality in the unadjusted model [hazard ratio (HR) 1.32, 95% confidence interval (95% CI) 0.95-1.84; p=0.098] but not in the conventional adjusted model (HR 0.98, 95% CI 0.64-1.52; p=0.938). Even in post-match patients, no association between hypoalbuminemia and mortality was observed (HR 1.09, 95% CI 0.68-1.76; p=0.722). Conclusion Hypoalbuminemia on admission was not associated with long-term mortality in patients with ADHF, even if PS matching was used.

Biological markers and cardiac remodelling following the myocardial infarction

AIM

To assess growth stimulating factor ST2 and N-terminal pro b-type natriuretic peptide (NT-proBNP) levels in the sera of myocardial infraction (MI) patients, and their correlation with the adaptive and maladaptive variants of cardiac remodelling.

METHODS

87 patients (65 male, 22 females; 67±8.36 years) with ST-elevated MI were included in this study, and 67 patients had an adaptive, physiological, while 20 patients had a maladaptive, pathological variant of myocardium remodelling.

RESULTS

On day 1, ST2 and NT-proBNP levels were shown to increase 2.4 and 4.5 folds, respectively, compared with those in the control. ST2 levels in patients with maladaptive remodelling were 1.5-fold higher than those in the adaptive remodelling group. On day 12, a decrease in ST2 levels was observed in both groups. NT-proBNP levels increased 1.8 folds in both groups on day 1, compared with those in the controls. Increased ST2 levels on day 1 after MI were shown to increase the risk of maladaptive remodelling 4.5 folds, while high NT-proBNP levels increased this risk 2.3 times.

CONCLUSIONS

ST2 level determination allows us to predict the risk of maladaptive remodelling with a higher sensitivity and specificity than using NT-proBNP levels.

Association between C-reactive protein levels at hospital admission and long-term mortality in patients with acute decompensated heart failure

The C-reactive protein (CRP) levels obtained at hospital admission are associated with the prognosis of several cardiovascular diseases, including acute coronary syndrome. Although the admission CRP level is associated with in-hospital mortality in patients with acute decompensated heart failure (ADHF), there are limited data on the association between the admission CRP level and long-term mortality in patients with ADHF. This study included consecutive ADHF patients admitted to our institution from 2007 to 2011. Eligible patients were divided into four groups based on quartiles of admission CRP levels. The association between the admission CRP level and long-term mortality was assessed by multivariable Cox proportional analysis, including other independent variables with p values < 0.1 in the univariable analyses. Overall, 527 eligible patients were examined. There were 142 deaths (27%) during a median follow-up period of 2.0 years. In the multivariable analysis, the hazard ratio (HR) significantly increased with admission CRP levels in a dose-dependent manner for mortality (p for trend = 0.034). Multivariable analysis also showed a significant association between the admission CRP level, when treated as a natural logarithm-transformed continuous variable, and increased mortality (HR 1.16, p = 0.030). In patients with ADHF, the admission CRP level was associated with an increased risk of long-term mortality.

Critical Appraisal of Multivariable Prognostic Scores in Heart Failure: Development, Validation and Clinical Utility

Optimal management of heart failure requires accurate risk assessment. Many prognostic risk models have been proposed for patient with chronic and acute heart failure. Methodological critical issues are the data source, the outcome of interest, the choice of variables entering the model, the validation of the model in external population. Up to now, the proposed risk models can be a useful tool to help physician in the clinical decision-making. The availability of big data and of new methods of analysis may lead to developing new models in the future.

Routine blood tests are associated with short term mortality and can improve emergency department triage: a cohort study of >12,000 patients

BACKGROUND

Prioritization of acutely ill patients in the Emergency Department remains a challenge. We aimed to evaluate whether routine blood tests can predict mortality in unselected patients in an emergency department and to compare risk prediction with a formalized triage algorithm.

METHODS

A prospective observational cohort study of 12,661 consecutive admissions to the Emergency Department of Nordsjælland University Hospital during two separate periods in 2010 (primary cohort, n = 6279) and 2013 (validation cohort, n = 6383). Patients were triaged in five categories by a formalized triage algorithm. All patients with a full routine biochemical screening (albumin, creatinine, c-reactive protein, haemoglobin, lactate dehydrogenase, leukocyte count, potassium, and sodium) taken at triage were included. Information about vital status was collected from the Danish Central Office of Civil registration. Multiple logistic regressions were used to predict 30-day mortality. Validation was performed by applying the regression models on the 2013 validation cohort.

RESULTS

Thirty-day mortality was 5.3%. The routine blood tests had a significantly stronger discriminative value on 30-day mortality compared to the formalized triage (AUC 88.1 [85.7;90.5] vs. 63.4 [59.1;67.5], p < 0.01). Risk stratification by routine blood tests was able to identify a larger number of low risk patients (n = 2100, 30-day mortality 0.1% [95% CI 0.0;0.3%]) compared to formalized triage (n = 1591, 2.8% [95% CI 2.0;3.6%]), p < 0.01.

CONCLUSIONS

Routine blood tests were strongly associated with 30-day mortality in acutely ill patients and discriminatory ability was significantly higher than with a formalized triage algorithm. Thus routine blood tests allowed an improved risk stratification of patients presenting in an emergency department.

Rationale and design of the ICON-RELOADED study: International Collaborative of N-terminal pro-B-type Natriuretic Peptide Re-evaluation of Acute Diagnostic Cut-Offs in the Emergency Department

OBJECTIVES

The objectives were to reassess use of amino-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations for diagnosis and prognosis of acute heart failure (HF) in patients with acute dyspnea.

BACKGROUND

NT-proBNP facilitates diagnosis, prognosis, and treatment in patients with suspected or proven acute HF. As demographics of such patients are changing, previous diagnostic NT-proBNP thresholds may need updating. Additionally, value of in-hospital NT-proBNP prognostic monitoring for HF is less understood.

METHODS

In a prospective, multicenter study in the United States and Canada, patients presenting to emergency departments with acute dyspnea were enrolled, with demographic, medication, imaging, and clinical course information collected. NT-proBNP analysis will be performed using the Roche Diagnostics Elecsys proBNPII immunoassay in blood samples obtained at baseline and at discharge (if hospitalized). Primary end points include positive predictive value of previously established age-stratified NT-proBNP thresholds for the adjudicated diagnosis of acute HF and its negative predictive value to exclude acute HF. Secondary end points include sensitivity, specificity, and positive and negative likelihood ratios for acute HF and, among those with HF, the prognostic value of baseline and predischarge NT-proBNP for adjudicated clinical end points (including all-cause death and hospitalization) at 30 and 180days.

RESULTS

A total of 1,461 dyspneic subjects have been enrolled and are eligible for analysis. Follow-up for clinical outcome is ongoing.

CONCLUSIONS

The International Collaborative of N-terminal pro-B-type Natriuretic Peptide Re-evaluation of Acute Diagnostic Cut-Offs in the Emergency Department study offers a contemporary opportunity to understand best diagnostic cutoff points for NT-proBNP in acute HF and validate in-hospital monitoring of HF using NT-proBNP.

Impact on Clinical Outcomes of Periodic Leg Movements During Sleep in Hospitalized Patients Following Acute Decompensated Heart Failure

BACKGROUND

Periodic leg movements during sleep (PLM) are characterized by regularly recurring movement of the legs during sleep. Although PLM is common and a predictor of death in patients with chronic heart failure, the clinical significance of PLM in hospitalized patients with a reduced left ventricular ejection fraction (LVEF) following acute decompensated heart failure (ADHF) remains unknown.Methods and Results:After initial improvement of acute signs and symptoms of ADHF, 94 consecutive patients with reduced LVEF who underwent polysomnography were enrolled. They were divided into 2 groups based on the presence or absence of severe PLM defined as PLM index ≥30. The risks for clinical events, composite of all-cause death and rehospitalization, were assessed using a stepwise multivariable Cox proportional model including variables showing P<0.10 in univariate analyses. Severe PLM was observed in 21 patients (22%). At a median follow-up of 5.2 months, 30 patients experienced clinical events (32%). In the multivariable analysis, the presence of severe PLM was significantly associated with increasing clinical events (hazard ratio, 2.16; 95% confidence interval, 1.03-4.54; P=0.042) independent of hemoglobin level and the severity of sleep-disordered breathing.

CONCLUSIONS

In hospitalized patients with systolic dysfunction following ADHF, severe PLM was prevalent and significantly associated with increased risk of death and/or rehospitalization.

Dynamic Changes in High-Sensitivity Cardiac Troponin I Are Associated with Dynamic Changes in Sum Absolute QRST Integral on Surface Electrocardiogram in Acute Decompensated Heart Failure

BACKGROUND

A three-dimensional electrocardiographic (ECG) metric, the sum absolute QRST integral (SAI QRST), predicts ventricular arrhythmias in heart failure (HF) patients with implantable cardioverter defibrillator and mechanical response to cardiac resynchronization therapy. We hypothesized that there is an association between patient-specific changes in SAI QRST and myocardial injury as measured by high-sensitivity troponin I (hsTnI).

METHODS

Sum absolute integral QRST on resting 12-lead ECG and hsTnI were measured simultaneously, every 3 hours, and during 12-hour observation period in a prospective cohort of emergency department patients (n = 398; mean age 57.8 ± 13.2 years; 54% female, 64% black), diagnosed with acute coronary syndrome (ACS, n = 28), acutely decompensated HF (acute decompensated heart failure, n = 35), cardiac non-ACS (n = 19), or noncardiac condition (n = 316). Random-effects linear regression analysis assessed the association of SAI QRST and myocardial injury, with adjustment for demographics (age, sex, race), prevalent cardiovascular disease (myocardial infarction, history of revascularization, stroke, and HF), risk factors (diabetes, smoking, hypercholesterolemia, hypertension, and cocaine use), and left bundle branch block.

RESULTS

Within the entire cohort, SAI QRST decreased by 3 (95%CI -5 to -1) mV*ms every 3 hours. A 10-fold increase in hsTnI was associated with a 7.7 (0.6-14.9) mV*ms increase in SAI QRST. In the subgroup of acutely decompensated HF patients (n = 35), a 10-fold increase in hsTnI was associated with a 61.0 (5.9-116.1) mV*ms increase in SAI QRST.

CONCLUSION

Patient-specific time-varying changes in the surface ECG scalar measure of global electrical heterogeneity, as measured by SAI QRST, and in myocardial injury as measured by hsTnI, are independently and directly associated with each other, likely reflecting a common underlying mechanism.

Role of Soluble ST2 as a Marker for Rejection after Heart Transplant

Background and Objectives

Endomyocardial biopsy is obligatory during the first year after heart transplant (HTx) for the surveillance of acute rejection. Previous attempts using cardiac biomarkers for the detection of rejection failed to show enough evidence to substitute endomyocardial biopsy. Therefore, this study sought the possibility of using soluble ST2 (sST2), a novel cardiovascular marker, as a surrogate marker for acute allograft rejection after HTx.

Subjects and Methods

A total of 494 blood samples acquired at the time of endomyocardial biopsy were analyzed in 67 HTx cases from September 2006 to August 2014. Significant rejection was defined as International Society of Heart and Lung Transplant (ISHLT) score ≥2R and humoral rejection accompanied by hemodynamic instability.

Results

Twenty cases of HTx with 22 blood samples showed significant rejection in endomyocardial biopsy at 4.0 (2.0-9.0) months after HTx. The level of sST2 showed positive correlation with cardiac troponin I, and N-terminal pro-B-type natriuretic peptide (all p<0.001), and negative correlation with post-HTx months (p<0.001). The levels of sST2 according to the ISHLT scores were 36 (19-98), 28 (18-62), 15 (16-37), and 191 (85-343) ng/mL, consecutively 0R, 1R, 2R, and 3R+ (3R plus hemodynamically-unstable humoral rejection) (p=0.003). However, when we studied within-subject effects of sST2 using a mixed model, the sST2 level according to the predefined time point was not different according to the presence of significant rejection (p for interaction=0.94).

Conclusion

Although sST2 is known as a promising predictor for cardiovascular events, its role in HTx patients to predict acute allograft rejection seems to be limited.

ST2 Predicts Mortality and Length of Stay in a Critically Ill Noncardiac Intensive Care Unit Population

OBJECTIVES

The biomarker suppression of tumorigenicity 2 (ST2) is a well-established clinical biomarker of cardiac strain and is frequently elevated in a variety of cardiac conditions. Here, we sought to evaluate the prognostic value of ST2 in critically ill medical intensive care unit (MICU) patients without primary cardiac illness.

METHODS

We measured ST2 and high-sensitivity troponin T (hsTnT) on plasma specimens collected on 441 patients following admission to a noncardiac MICU and evaluated the prognostic power of ST2 both alone and in multivariate models.

RESULTS

Of these critically ill patients, 96% exhibited ST2 concentrations above the reference interval. ST2 concentrations were highly predictive of intensive care unit and hospital length of stay, as well as in-hospital mortality, with high concentrations predicting a poor prognosis. Rates of in-hospital mortality were more than four times higher in patients with ST2 concentrations in the highest compared with the lowest quartile. In multivariate analysis, ST2 remained an important predictor of death after adjustment for age, hsTnT, and common diagnoses.

CONCLUSIONS

ST2 is increased and predictive of prognosis in critically ill patients without primary cardiac disease, suggesting that critically ill patients may often have unrecognized cardiac injury. Clinical decision support algorithms incorporating ST2 and hsTnT results may be useful in patient risk stratification.

Biomarkers of Heart Failure with Preserved and Reduced Ejection Fraction

Biomarkers are increaingly being used in the management of heart failure not only for the purpose of screening, diagnosis, and risk stratification, but also as a guide to evaluate the response to treatment in the individual patient and as an entry criterion and/or a surrogate marker of efficacy in clinical trials testing novel drugs. In this chapter, we review the role of established biomarkers for heart failure management, according to the main classification of HF phenotypes, based on the measurement of left ventricular ejection fraction, including heart failure with reduced (<40%), preserved (≥50%), and, as recently proposed, mid-range (40-49%) ejection fraction.

Current Management of Heart Failure: When to Refer to Heart Failure Specialist and When Hospice is the Best Option

Heart failure is a common syndrome caused by different abnormalities of the cardiovascular system that result in impairment of the ventricles in filling or ejecting blood. It is one of the most common causes of hospitalization in the United States, with a very high cost to the health care system. This article focuses on the causes of left ventricle dysfunction and the presentation and management of heart failure, both acute and chronic.

Using ST2 in cardiovascular patients: a review

Biomarkers have emerged as indispensable tools for diagnosis and prognostication in a variety of cardiovascular diseases, and several are now standard of care. New markers are constantly being developed, but few are able to significantly improve upon already established markers. ST2 is a marker of cardiomyocyte stress and fibrosis, which provides incremental value to natriuretic peptides for risk stratification of patients across a wide spectrum of cardiovascular diseases. Based upon the totality of data, measurement of ST2 is now recommended for additive risk stratification in patients with acute or ambulatory heart failure in the 2013 American College of Cardiology Foundation and American Heart Association joint guidelines. Looking forward, ST2 levels may be useful for tailoring medical therapy in those with or at risk for developing heart failure. This paper provides an up-to-date overview of the clinical studies that led to the endorsement of ST2 as a cardiovascular prognostic marker, and provides insight into the application of ST2 now and in the future.

Serial ST2 testing in hospitalized patients with acute heart failure

Biomarkers, particularly natriuretic peptides (NP), complement clinical assessment in patients with heart failure (HF) and may serve as a target level to aid titration of treatment. NP levels that decrease with treatment for acute HF may identify patients at lower risk, but irrespective of the decrease, higher levels at discharge still portend worse outcomes. Beyond NPs, other biomarkers including ST2 have been shown to provide incremental value for prognosis. Although presentation ST2 values are prognostic, admission to discharge change in ST2 and the final ST2 concentration both independently predict patient outcomes in a stronger fashion. Although prognostic thresholds in the hospitalized patient are considerably higher than those used in the office-based setting, a minimum ST2 value of 35 ng/ml is a reasonable starting point for prognosis, noting that many patients will have considerably higher value than this value; as with the NPs, a decreasing value by discharge is desirable, and lower is always better. In conclusion, ST2 values are complementary to NP concentrations, and one can make a good case for serial testing of both biomarkers in the acutely hospitalized patient with HF.

Soluble ST2--analytical considerations

Suppression of tumorigenicity 2 (ST2, also known as interleukin [IL]-1 receptor-like-1) is an IL-1 receptor family member with transmembrane (ST2L) and soluble isoforms (sST2). ST2L is a membrane-bound receptor, and IL-33 is the functional ligand for ST2L. sST2, a soluble truncated form of ST2L, is secreted into the circulation and functions as a "decoy" receptor for IL-33, inhibiting IL-33/ST2L signaling. Blood concentrations of sST2 are increased in inflammatory diseases and heart disease and are considered a valuable prognostic marker in both conditions. In multiple clinical trials, sST2 has emerged as a clinically useful prognostic biomarker in patients with cardiac diseases. Interestingly, sST2 even provides prognostic information in low-risk community-based populations. In this review, we will discuss analytical considerations of measuring circulating sST2 including pre-analytical issues, such as in vitro stability of sST2, biological variation of sST2, and postanalytical issues, such as reference ranges and comparisons to diseased cohorts.

Novel Biomarkers in Heart Failure Beyond Natriuretic Peptides - The Case for Soluble ST2

Despite more effective management of heart failure over the past few decades, its burden as a chronic disease has grown and is expected to continue to rise, representing a major health problem for years to come. Having reliable tools for early diagnosis and risk stratification can help managing the condition more efficiently. In this context, the interest for biomarkers has increased considerably in the last years following the useful clinical role of B-type natriuretic peptides. These biomarkers have been extensively studied and have become established diagnostic and prognostic biomarkers in heart failure. Despite their usefulness, limitations still remain a problem in clinical practice and the search for new biomarkers has therefore continued. Amongst the most promising newer biomarkers, soluble ST2 deserves further consideration. The present review will focus on the role of this new biomarker in the context of heart failure.

Which biomarkers do clinicians need for diagnosis and management of heart failure with reduced ejection fraction?

While there have been significant recent advances in the medical management of chronic HF (including the use of beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, and aldosterone blockers), the ability to characterize, monitor, and predict a patient's response to HF therapy is poor. Risk stratification is important in patients with chronic heart failure and enables informed decisions about treatment and end-of-life care. Clinical parameters, such as advanced age, higher NYHA functional class, reduced left ventricular ejection fraction, lower body mass index, renal dysfunction, and anemia have all been associated with poor outcomes in HF. More recently, heart failure biomarkers have considerably changed the way we take care of our HF patients. BNP and NT-proBNP are endorsed by current guidelines and are now the gold standard biomarkers to confirm the diagnosis and to evaluate the prognosis of heart failure. Studies on natriuretic peptide-guided HF therapy look promising. Novel biomarkers, such soluble ST2, growth differentiation factor-15, highly sensitive troponins and Galectin-3, show potential in assessing prognosis beyond the established natriuretic peptides, but their role in the clinical care of the patient is still partially defined and more studies are needed.

Soluble ST2 in heart failure

In addition to routine clinical laboratory tests (including natriuretic peptides and cardiac troponins), other biomarkers are gaining attention for their utility in heart failure (HF) management. Among them, soluble ST2 (sST2) a novel biomarker integrating inflammation, fibrosis, and cardiac stress has been included in the 2013 ACCF/AHA guideline for additive risk stratification of patients with acute and chronic HF. sST2 is an interleukin-1 (IL-1) receptor family member, is secreted into the circulation and functions as a "decoy" receptor for IL-33, inhibiting IL-33/ST2 signaling. Blood concentrations of sST2 are increased in various diseases such as inflammatory diseases and heart diseases and are considered a valuable prognostic marker in both conditions. sST2 lacks disease specificity and, therefore, is not a valuable marker for the diagnosis of HF. In acute and chronic HF, however, sST2 is strongly associated with measures of HF severity and poor outcome. Several studies in patients with HF indicate that serial measurement of sST2 has prognostic value and could have a potential role in future biomarker-directed therapy. In this review, the role of sST2 as a HF biomarker will be discussed, specifically addressing analytical considerations of measuring sST2 as well as the clinical applications of measurement of sST2 for the diagnosis, prognosis and monitoring of acute and chronic HF.

A novel cardiac bio-marker: ST2: a review

Cardiovascular diseases (CVD) are the major cause of death worldwide. The identification of markers able to detect the early stages of such diseases and/or their progression is fundamental in order to adopt the best actions in order to reduce the worsening of clinical condition. Brain natriuretic peptide (BNP) and NT-proBNP are the best known markers of heart failure (HF), while troponins ameliorated the diagnosis of acute and chronic coronary artery diseases. Nevertheless, many limitations reduce their accuracy. Physicians have tried to develop further detectable molecules in order to improve the detection of the early moments of CVD and prevent their development. Soluble ST2 (suppression of tumorigenicity 2) is a blood protein confirmed to act as a decoy receptor for interleukin-33. It seems to be markedly induced in mechanically overloaded cardiac myocytes. Thus, HF onset or worsening of a previous chronic HF status, myocardial infarct able to induce scars that make the myocardium unable to stretch well, etc, are all conditions that could be detected by measuring blood levels of soluble ST2. The aim of this review is to explore the possible role of ST2 derived-protein as an early marker of cardiovascular diseases, above all in heart failure and ischemic heart diseases.