Serum Markers of Collagen Turnover Predict Future Shocks in Implantable Cardioverter-Defibrillator Recipients With Dilated Cardiomyopathy on Optimal Treatment

Cardiac and Renal Fibrosis, the Silent Killer in the Cardiovascular Continuum: An Up-to-Date

Cardiovascular disease (CVD) and chronic kidney disease (CKD) often coexist and have a major impact on patient prognosis. Organ fibrosis plays a significant role in the pathogenesis of cardio-renal syndrome (CRS), explaining the high incidence of heart failure and sudden cardiac death in these patients. Various mediators and mechanisms have been proposed as contributors to the alteration of fibroblasts and collagen turnover, varying from hemodynamic changes to the activation of the renin-angiotensin system, involvement of FGF 23, and Klotho protein or collagen deposition. A better understanding of all the mechanisms involved has prompted the search for alternative therapeutic targets, such as novel inhibitors of the renin-angiotensin-aldosterone system (RAAS), serelaxin, and neutralizing interleukin-11 (IL-11) antibodies. This review focuses on the molecular mechanisms of cardiac and renal fibrosis in the CKD and heart failure (HF) population and highlights the therapeutic alternatives designed to target the responsible pathways.

Biomarkers of Collagen Metabolism Are Associated with Left Ventricular Function and Prognosis in Dilated Cardiomyopathy: A Multi-Modal Study

BACKGROUND

Collagen cross-linking is a fundamental process in dilated cardiomyopathy (DCM) and occurs when collagen deposition exceeds degradation, leading to impaired prognosis. This study investigated the associations of collagen-metabolism biomarkers with left ventricular function and prognosis in DCM.

METHODS

DCM patients who underwent endomyocardial biopsy, blood sampling, and cardiac MRI were included. The primary endpoint included death, heart failure hospitalization, or life-threatening arrhythmias, with a follow-up of 6 years (5-8).

RESULTS

In total, 209 DCM patients were included (aged 54 ± 13 years, 65% male). No associations were observed between collagen volume fraction, circulating carboxy-terminal propeptide of procollagen type-I (PICP), or collagen type I carboxy-terminal telopeptide [CITP] and matrix metalloproteinase [MMP]-1 ratio and cardiac function parameters. However, CITP:MMP-1 was significantly correlated with global longitudinal strain (GLS) in the total study sample (R = -0.40, p < 0.0001; lower CITP:MMP-1 ratio was associated with impaired GLS), with even stronger correlations in patients with LVEF > 40% (R = -0.70, p < 0.0001). Forty-seven (22%) patients reached the primary endpoint. Higher MMP-1 levels were associated with a worse outcome, even after adjustment for clinical and imaging predictors (1.026, 95% CI 1.002-1.051, p = 0.037), but CITP and CITP:MMP-1 were not. Combining MMP-1 and PICP improved the goodness-of-fit (LHR36.67, p = 0.004).

CONCLUSION

The degree of myocardial cross-linking (CITP:MMP-1) is associated with myocardial longitudinal contraction, and MMP-1 is an independent predictor of outcome in DCM patients.

The combination of carboxy-terminal propeptide of procollagen type I blood levels and late gadolinium enhancement at cardiac magnetic resonance provides additional prognostic information in idiopathic dilated cardiomyopathy - A multilevel assessment of myocardial fibrosis in dilated cardiomyopathy

Aims

To determine the prognostic value of multilevel assessment of fibrosis in dilated cardiomyopathy (DCM) patients.

Methods and results

We quantified fibrosis in 209 DCM patients at three levels: (i) non‐invasive late gadolinium enhancement (LGE) at cardiac magnetic resonance (CMR); (ii) blood biomarkers [amino‐terminal propeptide of procollagen type III (PIIINP) and carboxy‐terminal propeptide of procollagen type I (PICP)], (iii) invasive endomyocardial biopsy (EMB) (collagen volume fraction, CVF). Both LGE and elevated blood PICP levels, but neither PIIINP nor CVF predicted a worse outcome defined as death, heart transplantation, heart failure hospitalization, or life‐threatening arrhythmias, after adjusting for known clinical predictors [adjusted hazard ratios: LGE 3.54, 95% confidence interval (CI) 1.90–6.60; P < 0.001 and PICP 1.02, 95% CI 1.01–1.03; P = 0.001]. The combination of LGE and PICP provided the highest prognostic benefit in prediction (likelihood ratio test P = 0.007) and reclassification (net reclassification index: 0.28, P = 0.02; and integrated discrimination improvement index: 0.139, P = 0.01) when added to the clinical prediction model. Moreover, patients with a combination of LGE and elevated PICP (LGE+/PICP+) had the worst prognosis (log‐rank P < 0.001). RNA‐sequencing and gene enrichment analysis of EMB showed an increased expression of pro‐fibrotic and pro‐inflammatory pathways in patients with high levels of fibrosis (LGE+/PICP+) compared to patients with low levels of fibrosis (LGE‐/PICP‐). This would suggest the validity of myocardial fibrosis detection by LGE and PICP, as the subsequent generated fibrotic risk profiles are associated with distinct cardiac transcriptomic profiles.

Conclusion

The combination of myocardial fibrosis at CMR and circulating PICP levels provides additive prognostic value accompanied by a pro‐fibrotic and pro‐inflammatory transcriptomic profile in DCM patients with LGE and elevated PICP.

Role of collagen turnover biomarkers in the noninvasive assessment of myocardial fibrosis: an update

The pro-fibrotic milieu, as the result of the extracellular matrix remodeling, is a central feature in the pathophysiology of heart disease and contributes to its high morbidity and mortality. Fibrosis is a recognized risk factor for development of heart failure and arrythmias and is usually detected by cardiac magnetic resonance or endomyocardial biopsy. Collagen type I and type III are major components of the collagen network, and the assessment of their derived biomarkers could serve as estimate of the myocardial fibrotic content. This review summarizes data from numerous studies in which these biomarkers have proven their diagnostic and prognostic utility, setting the stage for further randomized clinical trials that might translate into early implementation of antifibrotic therapies.

Predictors of cardiac arrhythmic events in non coronary artery disease patients

Arrhythmic sudden cardiac death (SCD) represents a major worldwide public health problem accounting for 15–20% of deaths. Risk stratification to identify patients at risk of SCD is crucial in order to implement preventive measures in the general population. Several biomarkers have been tested exploring different pathophysiological mechanisms of cardiac conditions. Conflicting results have been described limiting so far their use in clinical practice. The use of new biomarkers such as microRNAs and sex hormones and the emerging role of genetic on risk prediction of SCD is a current research topic showing promising results.

This review outlines the role of plasma biomarkers to predict ventricular arrhythmias and SCD in non coronary artery disease with a special focus on their relationship with the genetic biomarkers.

Sudden death mechanisms in nonischemic cardiomyopathies: Insights gleaned from clinical implantable cardioverter-defibrillator trials

Sudden cardiac death (SCD) represents a major cause of death among patients with heart failure. Although scar-based, macroreentrant ventricular tachycardia/ventricular fibrillation is the primary etiology for SCD among patients with ischemic cardiomyopathy, a more diverse set of mechanisms and substrates is likely at play for the diverse group of patients characterized by nonischemic dilated cardiomyopathy (NICM). These causes may include scar-based reentry, but also neurohormonal stimulation (sympathetic, parasympathetic, renin-angiotensin-aldosterone), inflammation, and nonarrhythmic processes occurring in the context of a genetic predisposition. In addition to basic and translational science, observations from large randomized clinical trials of implantable cardioverter-defibrillators (ICDs) can also offer insight and support for specific mechanisms of SCD in these patients. This review will discuss the background of SCD in NICM, its potential mechanisms based on experimental and theoretical models, and the evidence for these mechanisms that can be derived from clinical trials of ICD therapy.

Personalizing Risk Stratification for Sudden Death in Dilated Cardiomyopathy: The Past, Present, and Future

Results from the DANISH Study (Danish Study to Assess the Efficacy of ICDs in Patients With Non-Ischemic Systolic Heat Failure on Mortality) suggest that for many patients with dilated cardiomyopathy (DCM), implantable cardioverter-defibrillators do not increase longevity. Accurate identification of patients who are more likely to die of an arrhythmia and less likely to die of other causes is required to ensure improvement in outcomes and wise use of resources. Until now, left ventricular ejection fraction has been used as a key criterion for selecting patients with DCM for an implantable cardioverter-defibrillator for primary prevention purposes. However, registry data suggest that many patients with DCM and an out-of-hospital cardiac arrest do not have a markedly reduced left ventricular ejection fraction. In addition, many patients with reduced left ventricular ejection fraction die of nonsudden causes of death. Methods to predict a higher or lower risk of sudden death include the detection of myocardial fibrosis (a substrate for ventricular arrhythmia), microvolt T-wave alternans (a marker of electrophysiological vulnerability), and genetic testing. Midwall fibrosis is identified by late gadolinium enhancement cardiovascular magnetic resonance imaging in ≈30% of patients and provides incremental value in addition to left ventricular ejection fraction for the prediction of sudden cardiac death events. Microvolt T-wave alternans represents another promising predictor, supported by large meta-analyses that have highlighted the negative predictive value of this test. However, neither of these strategies have been routinely adopted for risk stratification in clinical practice. More convincing data from randomized trials are required to inform the management of patients with these features. Understanding of the genetics of DCM and how specific mutations affect arrhythmic risk is also rapidly increasing. The finding of a mutation in lamin A/C, the cause of ≈6% of idiopathic DCM, commonly underpins more aggressive management because of the malignant nature of the associated phenotype. With the expansion of genetic sequencing, the identification of further high-risk mutations appears likely, leading to better-informed clinical decision making and providing insight into disease mechanisms. Over the next 5 to 10 years, we expect these techniques to be integrated into the existing algorithm to form a more sensitive, specific, and cost-effective approach to the selection of patients with DCM for implantable cardioverter-defibrillator implantation.

Cardiac Fibrosis and Arrhythmogenesis

Myocardial injury, mechanical stress, neurohormonal activation, inflammation, and/or aging all lead to cardiac remodeling, which is responsible for cardiac dysfunction and arrhythmogenesis. Of the key histological components of cardiac remodeling, fibrosis either in the form of interstitial, patchy, or dense scars, constitutes a key histological substrate of arrhythmias. Here we discuss current research findings focusing on the role of fibrosis, in arrhythmogenesis. Numerous studies have convincingly shown that patchy or interstitial fibrosis interferes with myocardial electrophysiology by slowing down action potential propagation, initiating reentry, promoting after-depolarizations, and increasing ectopic automaticity. Meanwhile, there has been increasing appreciation of direct involvement of myofibroblasts, the activated form of fibroblasts, in arrhythmogenesis. Myofibroblasts undergo phenotypic changes with expression of gap-junctions and ion channels thereby forming direct electrical coupling with cardiomyocytes, which potentially results in profound disturbances of electrophysiology. There is strong evidence that systemic and regional inflammatory processes contribute to fibrogenesis (i.e., structural remodeling) and dysfunction of ion channels and Ca2+ homeostasis (i.e., electrical remodeling). Recognizing the pivotal role of fibrosis in the arrhythmogenesis has promoted clinical research on characterizing fibrosis by means of cardiac imaging or fibrosis biomarkers for clinical stratification of patients at higher risk of lethal arrhythmia, as well as preclinical research on the development of antifibrotic therapies. At the end of this review, we discuss remaining key questions in this area and propose new research approaches. © 2017 American Physiological Society. Compr Physiol 7:1009-1049, 2017.

Association between matrix metalloproteinase-9 and worsening heart failure events in patients with chronic heart failure

AIMS

Matrix metalloproteinase (MMP) is up-regulated during heart failure (HF) and influences ventricular remodeling. We hypothesized that disparity between MMP-9 and tissue inhibitors of MMP-1 (TIMP-1) results in clinical manifestations and is related to prognostic risk in patients with chronic HF.

METHODS AND RESULTS

Plasma levels of MMP-9, TIMP-1, and brain natriuretic peptide (BNP) were measured in 173 patients with chronic HF. Combined endpoints of worsening HF events were assessed during follow-up (median 109 months). MMP-9 and TIMP-1 levels and the MMP-9/TIMP-1 ratio increased with increasing severity of the New York Heart Association class (P for trend = 0.003, 0.011, and 0.005, respectively). Patients with HF events (n = 35) had significantly higher MMP-9 than those without HF events (P = 0.004). Kaplan-Meier analysis demonstrated a higher probability of HF events with high MMP-9 values (>23.2 ng/mL; P = 0.005). A multivariate Cox proportional hazard model showed that high MMP-9 values were an independent predictor of HF events (hazard ratio, 3.73; 95% confidence interval (CI), 1.03-13.46; P = 0.043). In patients with lower BNP levels (≤210 pg/mL), the adjusted hazard ratio for HF events was 3.63 (95% CI, 1.20-11.02; P = 0.023) among patients with high MMP-9 values compared with patients with low BNP and low MMP-9 values.

CONCLUSIONS

MMP-9 and TIMP-1 levels correlate with the severity of chronic HF. MMP-9 is a strong predictor of HF events, suggesting that a disparity between MMP-9 and TIMP-1 levels and increased MMP-9 levels may help predict HF events.

Myocardial fibrosis predicts ventricular tachyarrhythmias

Myocardial fibrosis is a common pattern in the setting of different heart diseases, and promotes ventricular tachyarrhythmias by creating a vulnerable substrate for reentrant activity and by favoring the emergence of triggers. Currently, late gadolinium enhancement (LGE) cardiac magnetic resonance is considered the reference method for the noninvasive assessment of ventricular fibrosis. Several studies and meta-analyses have shown that ventricular fibrosis detected by LGE is a powerful predictor of ventricular tachyarrhythmic events in ischemic, non-ischemic dilated cardiomyopathy and hypertrophic cardiomyopathy patients. Both the presence and extension of ventricular fibrosis were shown to correlate with the occurrence of ventricular arrhythmias and sudden cardiac death, irrespective of the grade of left ventricular dysfunction. Based on these results, the assessment of ventricular fibrosis has been suggested as a candidate marker to improve the decision making for implantable cardioverter-defibrillator therapy in patients with left ventricular dysfunction. These points will be discussed in the review.

Neutrophil to lymphocyte ratio predicts appropriate therapy in idiopathic dilated cardiomyopathy patients with primary prevention implantable cardioverter defibrillator

OBJECTIVES

To investigate whether an inflammatory marker of neutrophil to lymphocyte ratio (NLR) predicts appropriate implantable cardioverter defibrillator (ICD) therapy (shock or anti tachycardia pacing) in idiopathic dilated cardiomyopathy (IDC) patients.

METHODS

We retrospectively examined IDC patients (mean age: 58.3 ± 11.8 years, 81.5% male) with ICD who admitted to outpatient clinic for pacemaker control at 2 tertiary care hospitals in Ankara and Edirne, Turkey from January 2013-2015. All ICDs were implanted for primary prevention. Hematological and biochemical parameters were measured prior procedure. Results: Over a median follow-up period of 43 months (Range 7-125), 68 (33.1%) patients experienced appropriate ICD therapy. The NLR was increased in patients that received appropriate therapy (4.39 ± 2.94 versus 2.96 ± 1.97, p less than 0.001).To identify independent risk factors for appropriate therapy, a multivariate linear regression model was conducted and age (β=0.163, p=0.013), fasting glucose (β=0.158, p=0.017), C-reactive protein (CRP) (β=0.289, p less than 0.001) and NLR (β=0.212, p less than 0.008) were found to be independent risk factors for appropriate ICD therapy. Conclusions: Before ICD implantation by using NLR and CRP, arrhythmic episodes may be predictable and better antiarrhythmic medical therapy optimization may protect these IDC patients from unwanted events.

Changes in collagen metabolism account for ventricular functional recovery following beta-blocker therapy in patients with chronic heart failure

While beta blockade improves left ventricular (LV) function in patients with chronic heart failure (CHF), the mechanisms are not well known. This study aimed to examine whether changes in myocardial collagen metabolism account for LV functional recovery following beta-blocker therapy in 62 CHF patients with reduced ejection fraction (EF). LV function was echocardiographically measured at baseline and 1, 6, and 12 months after bisoprolol therapy along with serum markers of collagen metabolism including C-terminal telopeptide of collagen type I (CITP) and matrix metalloproteinase (MMP)-2. Deceleration time of mitral early velocity (DcT) increased even in the early phase, but LVEF gradually improved throughout the study period. Heart rate (HR) was reduced from the early stage, and CITP gradually decreased. LVEF and DcT increased more so in patients with the larger decreases in CITP (r = -0.33, p < 0.05; r = -0.28, p < 0.05, respectively), and HR (r = -0.31, p < 0.05; r = -0.38, p < 0.05, respectively). In addition, there were greater decreases in CITP, MMP-2 and HR from baseline to 1, 6, or 12 months in patients with above-average improvement in LVEF than in those with below-average improvement in LVEF. Similar results were obtained in terms of DcT. There was no significant correlation between the changes in HR and CITP. In conclusion, improvement in LV systolic/diastolic function was greatest in patients with the larger inhibition of collagen degradation. Changes in myocardial collagen metabolism are closely related to LV functional recovery somewhat independently from HR reduction.

Stratification of the risk of sudden death in nonischemic heart failure

Despite significant therapeutic advancements, heart failure remains a highly prevalent clinical condition associated with significant morbidity and mortality. In 30%-40% patients, the etiology of heart failure is nonischemic. The implantable cardioverter-defibrillator (ICD) is capable of preventing sudden death and decreasing total mortality in patients with nonischemic heart failure. However, a significant number of patients receiving ICD do not receive any kind of therapy during follow-up. Moreover, considering the situation in Brazil and several other countries, ICD cannot be implanted in all patients with nonischemic heart failure. Therefore, there is an urgent need to identify patients at an increased risk of sudden death because these would benefit more than patients at a lower risk, despite the presence of heart failure in both risk groups. In this study, the authors review the primary available methods for the stratification of the risk of sudden death in patients with nonischemic heart failure.

Osteopontin and galectin-3 predict the risk of ventricular tachycardia and fibrillation in heart failure patients with implantable defibrillators

BACKGROUND

Myocardial extracellular matrix remodelling provides electrical heterogeneity entailing ventricular tachycardia/fibrillation (VT/VF) in heart failure (HF) patients. Osteopontin (OPN) and Galectin-3 (Gal-3) are fibrosis markers and may reflect the extension of the arrhythmogenic substrate. We assessed whether plasma OPN and Gal-3 predict the risk of sustained VT/VF in a cohort of HF patients with implantable cardioverter-defibrillator (ICD).

METHODS

A total of 75 HF patients underwent pre-ICD implantation clinical evaluation and assessment of plasma OPN and Gal-3. The primary endpoint was the time to the occurrence of the first sustained VT/VF. Hazard ratios (HR) were derived from Cox proportional-hazards analysis.

RESULTS

Patients with coronary artery disease (CAD) had higher plasma OPN (79.8 ± 44.0 ng/mL vs. 66.0 ± 31.8 ng/mL; P = 0.04). Both Gal-3 (r = -0.38; P = 0.01) and OPN (r = -0.27; p = 0.01) were negatively related to estimated glomerular filtration rate. After 29 ± 17 months, 20 patients (27%) reached the primary endpoint. Patients with VT/VF had higher plasma OPN and Gal-3 (97.4 ± 51.7 ng/mL vs. 65.9 ± 31.3 ng/mL; P = 0.002 and 19.7 ± 8.5 ng/mL vs. 16.2 ± 6.2 ng/mL; P = 0.05). In univariate analysis, OPN (log-OPN, HR: 32.4; 95%CI: 3.9-264.7; P = 0.001) and Gal-3 (HR: 1.05; 95%CI: 1.00-1.11; P = 0.04) predicted sustained VT/VF. In multivariable analysis, both OPN (HR: 41.4; 95%CI: 3.8-441.9; P = 0.002) and Gal-3 (HR: 1.06; 95%CI: 1.00-1.12; P = 0.03) retained their prognostic power after correction for age, sex, history of MI, EF, NYHA class, eGFR, use of ACE-I, and amiodarone.

CONCLUSIONS

Plasma OPN and Gal-3 predict sustained VT/VF in HF patients at high risk for SCD. Larger prospective studies should outline the role of these biomarkers in predicting SCD on top of conventional risk stratification.

The need to modify patient selection to improve the benefits of implantable cardioverter-defibrillator for primary prevention of sudden death in non-ischaemic dilated cardiomyopathy

Left ventricular ejection fraction (LVEF) ≤35% is a major determinant for implantable cardioverter-defibrillator (ICD) therapy for primary prevention of sudden death (SD) in patients with non-ischaemic dilated cardiomyopathy (DCM). However, as a risk marker for SD, low LVEF has limited sensibility and specificity. Selecting patients according to the current guidelines shows that most DCM patients do not actually benefit from ICD implantation and may suffer collateral effects and that many patients who are at risk of SD are not identified because a large proportion of SD patients exhibit only mildly depressed LVEF. Identifying patients who are at risk of SD on the sole basis of LVEF appears to be an over-simplification which does not maximize the benefit of ICD therapy. Owing to the complexity of the substrates underlying SD, multiple risk factors used in combination could probably predict the risk of SD better than any individual risk marker. Among non-invasive tests, microvolt T-wave alternans and cardiac magnetic resonance with late gadolinium enhancement may contribute to a better SD risk stratification by their high negative predictive value. Genetics may further contribute because approximately one-third of DCM patients have evidence of familial disease, and mutations in some known disease genes, including LMNA, have been associated with a high risk of SD. In this review, we critically analyse the current indications for ICD implantation and we explore existing knowledge about potentially predicting markers for selecting DCM patients who are at high and low risk of SD.

Experimental biomarkers in heart failure: an update

Over the past 5 years, researchers have examined the utility of many experimental heart failure biomarkers that are not yet widely adopted clinically, to complement the role of B-type natriuretic peptide and its precursor. Candidate biomarkers have been identified from several different pathophysiologic categories, including markers of inflammation, myocyte necrosis, renal dysfunction, neurohumoral activation, oxidative stress and raised intracardiac pressure. Indeed, some biomarkers provide prognostic information that is independent of information obtained from conventional clinical and biomarker assessment. Moreover, some biomarkers studied help to identify dominant pathology that may predict responsiveness to specific therapies. Preliminary data also suggest a potential role for the development of comprehensive biomarker profiling models, integrating biomarkers from several categories to refine risk assessment.

Serum markers of deranged myocardial collagen turnover: their relation to malignant ventricular arrhythmias in cardioverter-defibrillator recipients with heart failure

BACKGROUND

Pathologic collagen remodeling has been involved in the occurrence of ventricular arrhythmias and sudden cardiac death in heart failure. The aim of the study was to investigate the relationship between malignant ventricular arrhythmias and cardiac collagen turnover indexes, expressing specific types of derangement in collagen physiology, in stable patients with an implantable cardioverter-defibrillator (ICD).

METHODS

Seventy-four patients with an ICD and heart failure were studied. They had coronary artery disease (n = 42) or dilated cardiomyopathy, New York Heart Association classes I and II, and left ventricular ejection fraction 29% ± 1%. An ICD had been implanted for secondary (n = 36) or primary prevention of sudden cardiac death. We assessed (1) markers of collagen types I and III synthesis and their ratio: procollagen type I carboxyterminal peptide (PICP), procollagen type III aminoterminal peptide (PIIINP), and PICP/PIIINP; (2) markers of collagen degradation, degradation inhibition, and their ratio: matrix metalloproteinase 9 (MMP-9), tissue inhibitor of matrix metalloproteinase (TIMP) 1 (TIMP-1), and MMP-9/TIMP-1. Patients were prospectively followed up for 1 year. The number of episodes necessitating appropriate interventions for ventricular tachyarrhythmias (>170 beat/min) was related to the assessed parameters.

RESULTS

Multivariate analysis revealed a significant relation between the number of tachyarrhythmic episodes and MMP-9/TIMP-1 (P = .007), PICP/PIIINP (P = .007), and ejection fraction (P = .04). No other significant relation was observed between arrhythmias and the remaining parameters.

CONCLUSION

In heart failure, biochemical markers indicative of a deranged equilirium in myocardial collagen deposition/degradation and collagen I/III synthesis are related to ventricular arrhythmogenesis. Further studies are needed to investigate their predictive ability.

New paradigms in the prevention of sudden cardiac arrest and heart failure treatment

Congestive heart failure is a very real public health issue not only in the United States, but worldwide. Mortality in patients with congestive heart failure is typically either sudden cardiac death or pump failure. Paradoxically, patients with less severe heart failure are at higher relative risk of sudden cardiac death. Defining which patients are best treated with implantable defibrillators and resynchronization is the purpose of this review.

Diagnosing destabilized heart failure in the emergency setting: current and future biomarker tests

Acute or destabilized heart failure (DHF) is characterized by new or worsening signs and symptoms of heart failure leading to admission to an emergency department. Biomarkers may support the diagnosis, the prognosis and the management of DHF patients. The aim of this review article is to discuss and evaluate the clinical usefulness of both recognized and potential new biomarker tests for use in heart failure.

Emerging biomarkers in heart failure

BACKGROUND

Until recently, biomarker testing in heart failure (HF) syndromes has been viewed as an elective supplement to diagnostic evaluation of patients suspected to suffer from this condition. This approach to the use of biomarker testing contrasts with other cardiovascular diagnoses such as acute myocardial infarction, for which biomarkers are integral to disease process definition, risk stratification, and in some cases treatment decision making.

CONTENT

In this review we consider various perspectives on the evaluation of biomarkers in HF. In addition, we examine recent advances in the understanding of established biomarkers in HF (such as the natriuretic peptides), the elucidation of novel biomarkers potentially useful for the evaluation and management of patients with HF, and the growing understanding of important and relevant comorbidities in HF. We also review candidate biomarkers from a number of classes: (a) myocyte stretch, (b) myocyte necrosis, (c) systemic inflammation, (d) oxidative stress, (e) extracellular matrix turnover, (f) neurohormones, and (g) biomarkers of extracardiac processes, such as renal function.

SUMMARY

Novel applications of established biomarkers of HF as well as elucidation and validation of emerging assays for HF syndromes have collectively led to a growing interest in the more widespread use of such testing in patients affected by the diagnosis.

An isolated cryptic peptide influences osteogenesis and bone remodeling in an adult mammalian model of digit amputation

Biologic scaffolds composed of extracellular matrix (ECM) have been used successfully in preclinical models and humans for constructive remodeling of functional, site-appropriate tissue after injury. The mechanisms underlying ECM-mediated constructive remodeling are not completely understood, but scaffold degradation and site-directed recruitment of progenitor cells are thought to play critical roles. Previous studies have identified a cryptic peptide derived from the C-terminal telopeptide of collagen IIIα that has chemotactic activity for progenitor cells. The present study characterized the osteogenic activity of the same peptide in vitro and in vivo in an adult murine model of digit amputation. The present study showed that the cryptic peptide increased calcium deposition, alkaline phosphatase activity, and osteogenic gene expression in human perivascular stem cells in vitro. Treatment with the cryptic peptide in a murine model of mid-second phalanx digit amputation led to the formation of a bone nodule at the site of amputation. In addition to potential therapeutic implications for the treatment of bone injuries and facilitation of reconstructive surgical procedures, cryptic peptides with the ability to alter stem cell recruitment and differentiation at a site of injury may serve as powerful new tools for influencing stem cell fate in the local injury microenvironment.

Recruitment of progenitor cells by an extracellular matrix cryptic peptide in a mouse model of digit amputation

Biologic scaffolds composed of extracellular matrix (ECM) have been used successfully in preclinical models and humans for constructive remodeling of functional, site-appropriate tissue after injury. The mechanisms underlying ECM-mediated constructive remodeling are not completely understood, but scaffold degradation and site-directed recruitment of both differentiated and progenitor cells are thought to play critical roles. Previous studies have shown that degradation products of ECM scaffolds can recruit a population of progenitor cells both in vitro and in vivo. The present study identified a single cryptic peptide derived from the α subunit of the collagen III molecule that is chemotactic for a well-characterized perivascular stem cell in vitro and causes the site-directed accumulation of progenitor cells in vivo. The oligopeptide was additionally chemotactic for human cortical neural stem cells, rat adipocyte stem cells, C2C12 myoblast cells, and rat Schwann cells in vitro. In an adult murine model of digit amputation, treatment with this peptide after mid-second phalanx amputation resulted in a greater number of Sox2+ and Sca1+,Lin- cells at the site of injury compared to controls. Since progenitor cell activation and recruitment are key prerequisites for epimorphic regeneration in adult mammalian tissues, endogenous site-directed recruitment of such cells has the potential to alter the default wound healing response from scar tissue toward regeneration.