Serum tenascin-C levels as a prognostic biomarker of heart failure events in patients with hypertrophic cardiomyopathy

Obstructive hypertrophic cardiomyopathy: from genetic insights to a multimodal therapeutic approach with mavacamten, aficamten, and beyond

BACKGROUND

A cardiac condition marked by excessive growth of heart muscle cells, hypertrophic cardiomyopathy (HCM) is a complex genetic disorder characterized by left ventricular hypertrophy, microvascular ischemia, myocardial fibrosis, and diastolic dysfunction. Obstructive hypertrophic cardiomyopathy (oHCM), a subset of HCM, involves significant obstruction in the left ventricular outflow tract (LVOT), leading to symptoms like dyspnea, fatigue, and potentially life-threatening cardiac events. With advancements in genetic understanding and the introduction of novel pharmacologic agents, including cardiac myosin inhibitors like mavacamten and aficamten, there is a paradigm shift in the therapeutic approach to oHCM.

MAIN BODY

The underlying mechanisms of HCM are closely tied to genetic mutations affecting sarcomere proteins, particularly those encoded by the MYH7 and MYBPC3 genes. These mutations lead to disrupted sarcomere function, resulting in hypertrophic changes and LVOT obstruction. While genetic heterogeneity is a hallmark of HCM, clinical diagnosis relies heavily on imaging techniques such as Echocardiography and cardiac magnetic resonance imaging to assess the extent of hypertrophy and obstruction. Current pharmacological management of obstructive HCM (oHCM) focuses on alleviating symptoms rather than modifying disease progression. Beta-blockers and calcium channel blockers are primary treatment options, although their effectiveness varies among patients. Recent clinical trials have highlighted the potential of novel cardiac myosin inhibitors, including mavacamten and aficamten, in enhancing exercise capacity, reducing LVOT obstruction, and improving overall cardiac function. These innovative agents represent a significant breakthrough in targeting the fundamental pathophysiological mechanisms driving oHCM. A comprehensive literature review was conducted, utilizing top-tier databases such as PubMed, Scopus, and Google Scholar, to compile an authoritative and up-to-date overview of the current advancements in the field. This review sheds light on the updated 2024 American Heart Association (AHA) guidelines for HCM management, emphasizing the treatment cascade and tailored management for each stage of oHCM. By introducing a new paradigm for personalized medicine in oHCM, this research leverages advanced genomics, biomarkers, and imaging techniques to optimize treatment strategies.

CONCLUSIONS

The introduction of cardiac myosin inhibitors heralds a new era in the management of oHCM. By directly targeting the molecular mechanisms underpinning the disease, these novel therapies offer improved symptom relief and functional outcomes. Ongoing research into the genetic basis of HCM and the development of targeted treatments holds promise for further enhancing patient care. Future studies should continue to refine these therapeutic strategies and explore their long-term benefits and potential in diverse patient populations. This review makes a significant contribution to the field by synthesizing the most recent AHA guidelines, emphasizing the crucial role of tailored management strategies in optimizing outcomes for patients with oHCM, and promoting the incorporation of cutting-edge genomics and imaging modalities to enhance personalized care.

Protein Biomarkers of Adverse Clinical Features and Events in Sarcomeric Hypertrophic Cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a heterogeneous condition that can lead to atrial fibrillation, heart failure, and sudden cardiac death in many individuals but mild clinical impact in others. The mechanisms underlying this phenotypic heterogeneity are not well defined. The aim of this study was to use plasma proteomic profiling to help illuminate biomarkers that reflect or inform the heterogeneity observed in HCM.

METHODS

The Olink antibody-based proteomic platform was used to measure plasma proteins in patients with genotype positive (sarcomeric) HCM participating in the HCM Registry. We assessed associations between plasma protein levels with clinical features, cardiac magnetic resonance imaging metrics, and the development of atrial fibrillation.

RESULTS

We measured 275 proteins in 701 patients with sarcomeric HCM. There were associations between late gadolinium enhancement with proteins reflecting neurohormonal activation (NT-proBNP [N-terminal pro-B-type natriuretic peptide] and ACE2 [angiotensin-converting enzyme 2]). Metrics of left ventricular remodeling had novel associations with proteins involved in vascular development and homeostasis (vascular endothelial growth factor-D and TM [thrombomodulin]). Assessing clinical features, the European Society of Cardiology sudden cardiac death risk score was inversely associated with SCF (stem cell factor). Incident atrial fibrillation was associated with mediators of inflammation and fibrosis (MMP2 [matrix metalloproteinase 2] and SPON1 [spondin 1]).

CONCLUSIONS

Proteomic profiling of sarcomeric HCM identified biomarkers associated with adverse imaging and clinical phenotypes. These circulating proteins are part of both established pathways, including neurohormonal activation and fibrosis, and less familiar pathways, including endothelial function and inflammatory proteins less well characterized in HCM. These findings highlight the value of plasma profiling to identify biomarkers of risk and to gain further insights into the pathophysiology of HCM.

Association of Tenascin-C Gene Polymorphisms with Risk of Acute Coronary Syndrome in South Indian Population: A Case-Control Genetic Association Study

Background: The extracellular matrix (ECM) glycoprotein changes are associated with the pathogenesis and complications of atherosclerosis, leading to acute coronary syndrome (ACS). Tenascin-C (TNC), an ECM protein, has been implemented in the pathogenesis, diagnosis, and prognosis of patients with cardiovascular disease. Aim: The study aimed to compare the genetic variants of the TNC gene (rs13321, rs2104772, and rs12347433) between South Indians with ACS and healthy participants. Materials and Methods: This case-control study recruited 150 ACS patients as cases and 150 healthy participants as controls. TNC genotyping was performed using TaqMan 5'-exonuclease allele discrimination assay. Serum TNC levels were measured by enzyme-linked immunosorbent assay. Results: Serum TNC levels were significantly higher in cases compared with controls. No significant difference was observed in allele and genotype frequencies of rs13321, rs2104772, and rs12347433 between cases and controls, which was confirmed by dominant, recessive, codominant, and homozygotic genetic models. The patients with heterozygous genotypes of rs13321, rs2104772, and rs12347433 had significantly lower serum TNC levels than patients with respective homozygous genotypes. Haplotype analyses revealed that the C-T-A haplotype in the block of rs13321-rs12347433-rs2104772 was associated with lower ACS risk (OR = 0.33, 95% CI: 0.15 - 0.75; p = 0.005). Also, the C-T-T and G-T-A haplotypes of the TNC gene were associated with higher and lower serum TNC levels, respectively. Conclusion: Our study demonstrated no genetic association between single nucleotide polymorphisms of the TNC gene and ACS risk; however, the C-T-A haplotype of the TNC gene might be associated with reduced ACS risk in South Indians.

Circulating Biomarkers in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is the most common genetic heart disease. Biomarkers, molecules measurable in the blood, could inform the clinician by aiding in diagnosis, directing treatment, and predicting outcomes. We present an updated review of circulating biomarkers in hypertrophic cardiomyopathy representing key pathologic processes including wall stretch, myocardial necrosis, fibrosis, inflammation, hypertrophy, and endothelial dysfunction, in addition to their clinical significance.

Tenascin-C in fibrosis in multiple organs: Translational implications

Systemic sclerosis (SSc, scleroderma) is a complex disease with a pathogenic triad of autoimmunity, vasculopathy, and fibrosis involving the skin and multiple internal organs [1]. Because fibrosis accounts for as much as 45% of all deaths worldwide and appears to be increasing in prevalence [2], understanding its pathogenesis and progression is an urgent scientific challenge. Fibroblasts and myofibroblasts are the key effector cells executing physiologic tissue repair on one hand, and pathological fibrogenesis leading to chronic fibrosing conditions on the other. Recent studies identify innate immune signaling via toll-like receptors (TLRs) as a key driver of persistent fibrotic response in SSc. Repeated injury triggers the in-situ generation of "damage-associated molecular patterns" (DAMPs) or danger signals. Sensing of these danger signals by TLR4 on resident cells elicits potent stimulatory effects on fibrotic gene expression and myofibroblast differentiation triggering the self-limited tissue repair response to self-sustained pathological fibrosis characteristic of SSc. Our unbiased survey for DAMPs associated with SSc identified extracellular matrix glycoprotein tenascin-C as one of the most highly up-regulated ECM proteins in SSc skin and lung biopsies [3,4]. Furthermore, tenascin C is responsible for driving sustained fibroblasts activation, thereby progression of fibrosis [3]. This review summarizes recent studies examining the regulation and complex functional role of tenascin C, presenting tenascin-TLR4 axis in pathological fibrosis, and novel anti-fibrotic approaches targeting their signaling.

Connecting different heart diseases through intercellular communication

Well-orchestrated intercellular communication networks are pivotal to maintaining cardiac homeostasis and to ensuring adaptative responses and repair after injury. Intracardiac communication is sustained by cell-cell crosstalk, directly via gap junctions (GJ) and tunneling nanotubes (TNT), indirectly through the exchange of soluble factors and extracellular vesicles (EV), and by cell-extracellular matrix (ECM) interactions. GJ-mediated communication between cardiomyocytes and with other cardiac cell types enables electrical impulse propagation, required to sustain synchronized heart beating. In addition, TNT-mediated organelle transfer has been associated with cardioprotection, whilst communication via EV plays diverse pathophysiological roles, being implicated in angiogenesis, inflammation and fibrosis. Connecting various cell populations, the ECM plays important functions not only in maintaining the heart structure, but also acting as a signal transducer for intercellular crosstalk. Although with distinct etiologies and clinical manifestations, intercellular communication derailment has been implicated in several cardiac disorders, including myocardial infarction and hypertrophy, highlighting the importance of a comprehensive and integrated view of complex cell communication networks. In this review, I intend to provide a critical perspective about the main mechanisms contributing to regulate cellular crosstalk in the heart, which may be considered in the development of future therapeutic strategies, using cell-based therapies as a paradigmatic example. This Review has an associated Future Leader to Watch interview with the author.

Current Use of Cardiac Biomarkers in Various Heart Conditions

Biomarkers are increasingly recognized to have significant clinical value in early identification and progression of various cardiovascular diseases. There are many heart conditions, such as congestive heart failure (CHF), ischemic heart diseases (IHD), and diabetic cardiomyopathy (DCM), and cardiac remodeling, in which the severity of the cardiac pathology can be mirrored through these cardiac biomarkers. From the emergency department (ED) evaluation of acute coronary syndromes (ACS) or suspected acute myocardial infarction (AMI) with cardiac marker Troponin to the diagnosis of chronic conditions like Heart Failure (HF) with natriuretic peptides, like B-type natriuretic peptide (BNP), N-terminal pro-B- type natriuretic peptide (Nt-proBNP) and mid regional pro-atrial natriuretic peptide (MR- proANP), their use is continuously increasing. Their clinical importance has led to the discovery of newer biomarkers, such as the soluble source of tumorigenicity 2 (sST2), galectin-3 (Gal-3), growth differentiation factor-15 (GDF-15), and various micro ribonucleic acids (miRNAs). Since cardiac pathophysiology involves a complex interplay between inflammatory, genetic, neurohormonal, and biochemical levels, these biomarkers could be enzymes, hormones, and biologic substances showing cardiac injury, stress, and malfunction. Therefore, multi-marker approaches with different combinations of novel cardiac biomarkers, and continual assessment of cardiac biomarkers are likely to improve cardiac risk prediction, stratification, and overall patient wellbeing. On the other hand, these biomarkers may reflect coexisting or isolated disease processes in different organ systems other than the cardiovascular system. Therefore, knowledge of cardiac biomarkers is imperative. In this article, we have reviewed the role of cardiac biomarkers and their use in the diagnosis and prognosis of various cardiovascular diseases from different investigations conducted in recent years.

Tenascin-C in Heart Diseases-The Role of Inflammation

Tenascin-C (TNC) is a large extracellular matrix (ECM) glycoprotein and an original member of the matricellular protein family. TNC is transiently expressed in the heart during embryonic development, but is rarely detected in normal adults; however, its expression is strongly up-regulated with inflammation. Although neither TNC-knockout nor -overexpressing mice show a distinct phenotype, disease models using genetically engineered mice combined with in vitro experiments have revealed multiple significant roles for TNC in responses to injury and myocardial repair, particularly in the regulation of inflammation. In most cases, TNC appears to deteriorate adverse ventricular remodeling by aggravating inflammation/fibrosis. Furthermore, accumulating clinical evidence has shown that high TNC levels predict adverse ventricular remodeling and a poor prognosis in patients with various heart diseases. Since the importance of inflammation has attracted attention in the pathophysiology of heart diseases, this review will focus on the roles of TNC in various types of inflammatory reactions, such as myocardial infarction, hypertensive fibrosis, myocarditis caused by viral infection or autoimmunity, and dilated cardiomyopathy. The utility of TNC as a biomarker for the stratification of myocardial disease conditions and the selection of appropriate therapies will also be discussed from a clinical viewpoint.

The Roles of Tenascins in Cardiovascular, Inflammatory, and Heritable Connective Tissue Diseases

Tenascins are a family of multifunctional extracellular matrix (ECM) glycoproteins with time- and tissue specific expression patterns during development, tissue homeostasis, and diseases. There are four family members (tenascin-C, -R, -X, -W) in vertebrates. Among them, tenascin-X (TNX) and tenascin-C (TNC) play important roles in human pathologies. TNX is expressed widely in loose connective tissues. TNX contributes to the stability and maintenance of the collagen network, and its absence causes classical-like Ehlers-Danlos syndrome (clEDS), a heritable connective tissue disorder. In contrast, TNC is specifically and transiently expressed upon pathological conditions such as inflammation, fibrosis, and cancer. There is growing evidence that TNC is involved in inflammatory processes with proinflammatory or anti-inflammatory activity in a context-dependent manner. In this review, we summarize the roles of these two tenascins, TNX and TNC, in cardiovascular and inflammatory diseases and in clEDS, and we discuss the functional consequences of the expression of these tenascins for tissue homeostasis.

Tenascin-C Function in Glioma: Immunomodulation and Beyond

First identified in the 1980s, tenascin-C (TNC) is a multi-domain extracellular matrix glycoprotein abundantly expressed during the development of multicellular organisms. TNC level is undetectable in most adult tissues but rapidly and transiently induced by a handful of pro-inflammatory cytokines in a variety of pathological conditions including infection, inflammation, fibrosis, and wound healing. Persistent TNC expression is associated with chronic inflammation and many malignancies, including glioma. By interacting with its receptor integrin and a myriad of other binding partners, TNC elicits context- and cell type-dependent function to regulate cell adhesion, migration, proliferation, and angiogenesis. TNC operates as an endogenous activator of toll-like receptor 4 and promotes inflammatory response by inducing the expression of multiple pro-inflammatory factors in innate immune cells such as microglia and macrophages. In addition, TNC drives macrophage differentiation and polarization predominantly towards an M1-like phenotype. In contrast, TNC shows immunosuppressive function in T cells. In glioma, TNC is expressed by tumor cells and stromal cells; high expression of TNC is correlated with tumor progression and poor prognosis. Besides promoting glioma invasion and angiogenesis, TNC has been found to affect the morphology and function of tumor-associated microglia/macrophages in glioma. Clinically, TNC can serve as a biomarker for tumor progression; and TNC antibodies have been utilized as an adjuvant agent to deliver anti-tumor drugs to target glioma. A better mechanistic understanding of how TNC impacts innate and adaptive immunity during tumorigenesis and tumor progression will open new therapeutic avenues to treat brain tumors and other malignancies.

Plasma Tenascin-C: a prognostic biomarker in heart failure with preserved ejection fraction

INTRODUCTION

Tenascin-C is a marker of interstitial fibrosis. We assessed whether plasma Tenascin-C differed between heart failure with preserved ejection fraction (HFpEF) and asymptomatic controls and related to clinical outcomes.

MATERIALS AND METHODS

Prospective, observational study of 172 age- and sex-matched subjects (HFpEF n = 130; controls n = 42, age 73 ± 9, males 50%) who underwent phenotyping with 20 plasma biomarkers, echocardiography, cardiac MRI and 6-minute-walk-testing. The primary endpoint was the composite of all-cause death/HF hospitalisation.

RESULTS

Tenascin-C was higher in HFpEF compared to controls (13.7 [10.8-17.3] vs (11.1 [8.9-12.9] ng/ml, p < 0.0001). Tenascin-C correlated positively with markers of clinical severity (NYHA, E/E', BNP) and plasma biomarkers reflecting interstitial fibrosis (ST-2, Galectin-3, GDF-15, TIMP-1, TIMP-4, MMP-2, MMP-3, MMP-7, MMP-8), cardiomyocyte stress (BNP, NTpro-ANP), inflammation (MPO, hs-CRP, TNFR-1, IL6) and renal dysfunction (urea, cystatin-C, NGAL); p < 0.05 for all. During follow-up (median 1428 days), there were 61 composite events (21 deaths, 40 HF hospitalizations). In multivariable Cox regression analysis, Tenascin-C (adjusted hazard ratio [HR] 1.755, 95% confidence interval [CI] 1.305-2.360; p < 0.0001) and indexed extracellular volume (HR 1.465, CI 1.019-2.106; p = 0.039) were independently associated with adverse outcomes.

CONCLUSIONS

In HFpEF, plasma Tenascin-C is higher compared to age- and sex-matched controls and a strong predictor of adverse outcomes. Trial registration: ClinicalTrials.gov: NCT03050593.

Tenascin-C promotes chronic pressure overload-induced cardiac dysfunction, hypertrophy and myocardial fibrosis

AIMS

Left ventricular (LV) hypertrophy is characterized by cardiomyocyte hypertrophy and interstitial fibrosis ultimately leading to increased myocardial stiffness and reduced contractility. There is substantial evidence that the altered expression of matrix metalloproteinases (MMP) and Tenascin-C (TN-C) are associated with the progression of adverse LV remodeling. However, the role of TN-C in the development of LV hypertrophy because of chronic pressure overload as well as the regulatory role of TN-C on MMPs remains unknown.

METHODS AND RESULTS

In a knockout mouse model of TN-C, we investigated the effect of 10 weeks of pressure overload using transverse aortic constriction (TAC). Cardiac function was determined by magnetic resonance imaging. The expression of MMP-2 and MMP-9, CD147 as well as myocardial fibrosis were assessed by immunohistochemistry. The expression of TN-C was assessed by RT-qPCR and ELISA. TN-C knockout mice showed marked reduction in fibrosis (P < 0.001) and individual cardiomyocytes size (P < 0.01), in expression of MMP-2 (P < 0.05) and MMP-9 (P < 0.001) as well as preserved cardiac function (P < 0.01) in comparison with wild-type mice after 10 weeks of TAC. In addition, CD147 expression was markedly increased under pressure overload (P < 0.01), irrespectively of genotype. TN-C significantly increased the expression of the markers of hypertrophy such as ANP and BNP as well as MMP-2 in H9c2 cells (P < 0.05, respectively).

CONCLUSION

Our results are pointed toward a novel signaling mechanism that contributes to LV remodeling via MMPs upregulation, cardiomyocyte hypertrophy as well as myocardial fibrosis by TN-C under chronic pressure overload.

Comparative proteomic analysis of mouse models of pathological and physiological cardiac hypertrophy, with selection of biomarkers of pathological hypertrophy by integrative Proteogenomics

To determine fundamental characteristics of pathological cardiac hypertrophy, protein expression profiles in two widely accepted models of cardiac hypertrophy (swimming-trained mouse for physiological hypertrophy and pressure-overload-induced mouse for pathological hypertrophy) were compared using a label-free quantitative proteomics approach. Among 3955 proteins (19,235 peptides, false-discovery rate < 0.01) identified in these models, 486 were differentially expressed with a log2 fold difference ≥ 0.58, or were detected in only one hypertrophy model (each protein from 4 technical replicates, p < .05). Analysis of gene ontology biological processes and KEGG pathways identified cellular processes enriched in one or both hypertrophy models. Processes unique to pathological hypertrophy were compared with processes previously identified in cardiac-hypertrophy models. Individual proteins with differential expression in processes unique to pathological hypertrophy were further confirmed using the results of previous targeted functional analysis studies. Using a proteogenomic approach combining transcriptomic and proteomic analyses, similar patterns of differential expression were observed for 23 proteins and corresponding genes associated with pathological hypertrophy. A total of 11 proteins were selected as early-stage pathological-hypertrophy biomarker candidates, and the results of western blotting for five of these proteins in independent samples confirmed the patterns of differential expression in mouse models of pathological and physiological cardiac hypertrophy.

The role of human urotensin-II in patients with hypertrophic cardiomyopathy

OBJECTIVE

Hypertrophic cardiomyopathy (HCM) is a genetic condition with the hallmark feature of left ventricular hypertrophy. Human Urotensin-II (hUT-II) is regarded as a cardiovascular autacoid/hormone, and it has cardiac inotropic and hypertrophic properties. Aims of this study were to elucidate the clinical significance of serum hUT-II levels as a potential new biomarker in patients with HCM.

METHODS

This study included 40 HCM patients (60% males and 40% females) and were compared to 30 healthy control subjects (47% males and 53% females. All patients underwent extensive clinical, laboratory, and echocardiographic. Blood samples were taken to test for serum hUT-II levels by commercial ELISA Kit.

RESULTS

Serum hUT-II was significantly higher (p < 0.01) in patients with HCM (15.8 ± 2.1 pmol/L) compared with healthy controls (3.3 ± 1.7 pmol/L). With regard to HCM patient, Serum hUT-II levels were significantly higher in the female with 16.3 ± 1.9 pmol/L than the male with 15.4 ± 2.2 pmol/L (p < 0.05). Among echocardiographic parameters, hUT-II was negatively associated with ejection fraction (r = -0.160, p = 0.324).

CONCLUSION

Results of the first study indicated that serum hUT-II levels were markedly elevated in patients with HCM. Serum hUT-II is a novel biomarker parameter that has clinical use in patients with the severity of LVH.

Internal Affairs: Tenascin-C as a Clinically Relevant, Endogenous Driver of Innate Immunity

To protect against danger, the innate immune system must promptly and accurately sense alarm signals, and mount an appropriate response to restore homeostasis. One endogenous trigger of immunity is tenascin-C, a large hexameric protein of the extracellular matrix. Upregulated upon tissue injury and cellular stress, tenascin-C is expressed during inflammation and tissue remodeling, where it influences cellular behavior by interacting with a multitude of molecular targets, including other matrix components, cell surface proteins, and growth factors. Here, we discuss how these interactions confer upon tenascin-C distinct immunomodulatory capabilities that make this matrix molecule necessary for efficient tissue repair. We also highlight in vivo studies that provide insight into the consequences of misregulated tenascin-C expression on inflammation and fibrosis during a wide range of inflammatory diseases. Finally, we examine how its unique expression pattern and inflammatory actions make tenascin-C a viable target for clinical exploitation in both diagnostic and therapeutic arenas.

Matricellular proteins in drug delivery: Therapeutic targets, active agents, and therapeutic localization

Extracellular matrix is composed of a complex array of molecules that together provide structural and functional support to cells. These properties are mainly mediated by the activity of collagenous and elastic fibers, proteoglycans, and proteins such as fibronectin and laminin. ECM composition is tissue-specific and could include matricellular proteins whose primary role is to modulate cell-matrix interactions. In adults, matricellular proteins are primarily expressed during injury, inflammation and disease. Particularly, they are closely associated with the progression and prognosis of cardiovascular and fibrotic diseases, and cancer. This review aims to provide an overview of the potential use of matricellular proteins in drug delivery including the generation of therapeutic agents based on the properties and structures of these proteins as well as their utility as biomarkers for specific diseases.

Tenascin-C in cardiovascular remodeling: potential impact for diagnosis, prognosis estimation and targeted therapy

Fetal variants of tenascin-C are not expressed in healthy adult myocardium. But, there is a relevant re-occurrence during pathologic cardiac tissue and vascular remodeling. Thus, these molecules, in particular B and C domain containing tenascin-C, might qualify as promising novel biomarkers for diagnosis and prognosis estimation. Since a stable extracellular deposition of fetal tenascin-C variants is present in diseased cardiac tissue, the molecules are excellent target structures for antibody-based delivery of diagnostic (e.g., radionuclides) or therapeutic (bioactive payloads) agents directly to the site of disease. Against the background that fetal tenascin-C variants are functionally involved in cardiovascular tissue remodeling, therapeutic functional blocking strategies could be experimentally tested in the future.

Emerging biomarkers for heart failure: an update

A growing array of biological pathways underpins the syndrome we recognize as heart failure. These include both deleterious pathways promoting its development and progression, as well as compensatory cardioprotective pathways. Components of these pathways can be utilized as biomarkers of this condition to aid diagnosis, prognostication and potentially guide management. As our understanding of the pathophysiology of heart failure deepens further candidate biomarkers are being identified. We provide an overview of the more recently emerging biomarkers displaying potential promise for future clinical use.

Clinical significance of left ventricular apical aneurysms in hypertrophic cardiomyopathy patients: the role of diagnostic electrocardiography

OBJECTIVES

Some patients with hypertrophic cardiomyopathy (HCM) develop left ventricular apical aneurysm, leading to serious cardiovascular complications. The aims of this study were to identify the incidence and clinical course of HCM patients with apical aneurysms in Japan, and to evaluate the role of electrocardiography (ECG) as a screening test to detect apical aneurysms in HCM patients.

METHODS AND RESULTS

In a retrospective, single center analysis of a population of 247 HCM patients, 21 patients (8.5%) had left ventricular apical aneurysms. Their mean age was 60 ± 14 years (range: 23-77 years) at study entry. Over 4.7 ± 3.3 years of follow-up, 10 patients (47.6%) experienced an adverse clinical event (annual event rate: 10.1%/y), including five implantable cardioverter-defibrillator (ICD) implantations for ventricular tachycardia/ventricular fibrillation (VT/VF), an appropriate discharge of ICD for VT/VF, and four nonfatal thromboembolic strokes. Two patients developed systolic dysfunction (ejection fraction <50%). No sudden cardiac death or progressive heart failure was detected. Fourteen patients showed ST-segment elevation (≥ 1 mm) in V3 through V5 of ECG. In four patients, progression of the ST-segment elevation was recognized. When the ST-segment elevation was used to identify apical aneurysms in HCM patients, the sensitivity was 66.7%, and the specificity was 98.7%.

CONCLUSION

Apical aneurysms in HCM patients in Japan are not rare, and are associated with serious cardiovascular complications. The early diagnosis of apical aneurysms can be achieved by serial ECG.

Prognostic difference between paroxysmal and non-paroxysmal atrial fibrillation in patients with hypertrophic cardiomyopathy

BACKGROUND

The association of atrial fibrillation (AF) with sudden death and the difference in prognostic significance between paroxysmal and non-paroxysmal AF remains unclear in patients with hypertrophic cardiomyopathy (HCM). Our aim was to investigate the clinical significance of AF, and to assess the prognostic difference between paroxysmal and non-paroxysmal AF in HCM patients.

METHODS

The study included 430 HCM patients. Documentation of AF was based on electrocardiograms obtained either after the acute onset of symptoms or fortuitously during routine examination of asymptomatic patients.

RESULTS

AF was detected in 120 patients (27.9%). In the patients with AF, syncope and non-sustained ventricular tachycardia were more frequent and the left atrial dimension was larger. Multivariate analysis showed that AF was an independent determinant of the outcome, including the risk of HCM-related death (adjusted hazard ratio 3.57, p<0.001) and sudden death (adjusted hazard ratio 2.61, p=0.038). When patients with AF were divided into subgroups with paroxysmal AF (n=75) or non-paroxysmal AF (n=45), only paroxysmal AF was identified as an independent determinant of the outcome, including the risk of HCM-related death (adjusted hazard ratio 5.24, p<0.001) and sudden death (adjusted hazard ratio 4.67, p=0.002).

CONCLUSIONS

AF is a common supraventricular arrhythmia in HCM and has an adverse influence on the prognosis. In addition, each type of AF had a different clinical impact, with paroxysmal AF being a significant independent determinant of an adverse outcome, including sudden death.

Assessment of tenascin-C levels in ventricular noncompaction/hypertrabeculation patients: a cross-sectional study

PURPOSE

Ventricular noncompaction/hypertrabeculation (NC/HT) is a rare form of congenital cardiomyopathy. We aimed to investigate the presence of serum tenascin-C (TN-C) in adult patients with NC/HT and evaluate its value.

METHODS AND RESULTS

Serum TN-C levels were measured by ELISA in 50 NC/HT patients both with/without systolic dysfunction and in 23 normal controls. Systolic dysfunction was defined as ejection fraction (EF) ≤ 40. Mann-Whitney U-test and ROC curve analysis were done. Of 49 NC/HT patients, 24 (49%) patients had systolic dysfunction (mean age 36 ± 15) and 25 patients (51%) had normal systolic function (mean age 36 ± 17). The ages between groups were not different. The mean levels of serum TN-C in patients with or without systolic dysfunction were 26 ± 10 ng/mL and 26 ± 8 ng/mL respectively, compared to normal controls, 7 ± 2 ng/mL (P < 0.001). No significance was observed between 2 groups of NC/HT patients regarding TN-C levels (P = 0.8). The ROC curve analysis revealed that a TN-C value of 11.7 ng/mL identified patients with NC/HT with 100% sensitivity and specifity.

CONCLUSION

High serum TN-C levels are present in adult NC/HT cardiomyopathy even when left ventricular systolic function remains normal. Also, serum TN-C levels could be regarded as a candidate biomarker in the diagnosis of NC/HT which needs to be tested in larger prospective studies.

Clinical characteristics and outcomes of dilated phase of hypertrophic cardiomyopathy: report from the registry data in Japan

BACKGROUND

A subset of patients with hypertrophic cardiomyopathy (HCM) has been reported to progress into dilated-HCM (D-HCM), characterized by left ventricular (LV) systolic dysfunction and cavity dilatation, resembling idiopathic dilated cardiomyopathy (DCM). We compared the characteristics, treatments, and outcomes in patients with heart failure (HF) due to D-HCM vs. DCM by using national registry data in Japan.

METHODS AND RESULTS

The Japanese Cardiac Registry of Heart Failure in Cardiology (JCARE-CARD) is a prospective observational study of patients hospitalized due to worsening HF with an average of 2.2 years of follow-up. Patients with D-HCM (n=41) were more likely to be male, have prior stroke, atrial fibrillation, and sustained ventricular tachycardia or ventricular fibrillation compared with DCM (n=486). Echocardiography demonstrated that D-HCM patients had smaller LV end-systolic diameter, higher ejection fraction, and greater wall thickness. Treatments for HF including angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, β-blocker, and spironolactone were similar between groups except for higher use of amiodarone, warfarin, and implantable cardioverter-defibrillator for D-HCM. Mortality was significantly higher in patients with D-HCM (29.7% vs. 14.4%; p<0.05). Sudden death tended to be higher also in D-HCM (8.1% vs. 2.6%; p=0.06), which, however, did not reach statistical significance.

CONCLUSIONS

HF patients with D-HCM had higher mortality risk than those with DCM. Effective management strategies are critically needed to be established for D-HCM.