Biomarkers of Myocardial Fibrosis:

One-step detection of procollagen type III N-terminal peptide as a fibrosis biomarker using fluorescent immunosensor (quenchbody)

BACKGROUND

Procollagen type III N-terminal peptide (P-III-NP) is a fibrosis biomarker associated with liver and cardiac fibrosis. Despite the value of P-III-NP as a biomarker, its analysis currently relies on enzyme-linked immunosorbent assays (ELISA) and radioimmunoassays (RIA), which require more than 3 h. To facilitate early diagnosis and treatment through rapid biomarker testing, we developed a one-step immunoassay for P-III-NP using a quenchbody, which is a fluorescence-labeled immunosensor for immediate signal generation.

RESULTS

To create quenchbodies, the total mRNA of P-III-NP antibodies was extracted from early-developed hybridoma cells, and genes of variable regions were obtained through cDNA synthesis, inverse PCR, and sequencing. A single-chain variable fragment (scFv) with an N-terminal Cys-tag was expressed in E. coli Shuffle T7, resulting in a final yield of 9.8 mg L-1. The fluorescent dye was labeled on the Cys-tag of the anti-P-III-NP scFv using maleimide-thiol click chemistry, and the spacer arm lengths between the maleimide-fluorescent dyes were compared. Consequently, a TAMRA-C6-labeled quenchbody exhibited antigen-dependent fluorescence signals and demonstrated its ability to detect P-III-NP at concentrations as low as 0.46 ng mL-1 for buffer samples, 1.0 ng mL-1 for 2 % human serum samples.

SIGNIFICANCE

This one-step P-III-NP detection method provides both qualitative and quantitative outcomes within a concise 5-min timeframe. Furthermore, its application can be expanded using a 96-well platform and human serum, making it a high-throughput and sensitive method for testing fibrotic biomarkers.

Pericardial Fluid Accumulates microRNAs That Regulate Heart Fibrosis after Myocardial Infarction

Pericardial fluid (PF) has been suggested as a reservoir of molecular targets that can be modulated for efficient repair after myocardial infarction (MI). Here, we set out to address the content of this biofluid after MI, namely in terms of microRNAs (miRs) that are important modulators of the cardiac pathological response. PF was collected during coronary artery bypass grafting (CABG) from two MI cohorts, patients with non-ST-segment elevation MI (NSTEMI) and patients with ST-segment elevation MI (STEMI), and a control group composed of patients with stable angina and without previous history of MI. The PF miR content was analyzed by small RNA sequencing, and its biological effect was assessed on human cardiac fibroblasts. PF accumulates fibrotic and inflammatory molecules in STEMI patients, namely causing the soluble suppression of tumorigenicity 2 (ST-2), which inversely correlates with the left ventricle ejection fraction. Although the PF of the three patient groups induce similar levels of fibroblast-to-myofibroblast activation in vitro, RNA sequencing revealed that PF from STEMI patients is particularly enriched not only in pro-fibrotic miRs but also anti-fibrotic miRs. Among those, miR-22-3p was herein found to inhibit TGF-β-induced human cardiac fibroblast activation in vitro. PF constitutes an attractive source for screening diagnostic/prognostic miRs and for unveiling novel therapeutic targets in cardiac fibrosis.

The sclerotic component of metabolic syndrome: Fibroblast activities may be the central common denominator driving organ function loss and death

Fibrosis is a common feature of more than 50 different diseases and the cause of more than 35% of deaths worldwide, of which liver, kidney, skin, heart and, recently, lungs are receiving the most attention. Tissue changes, resulting in loss of organ function, are both a cause and consequence of disease and outcome. Fibrosis is caused by an excess deposition of extracellular matrix proteins, which over time results in impaired organ function and organ failure, and the pathways leading to increased fibroblast activation are many. This narrative review investigated the common denominator of fibrosis, fibroblasts, and the activation of fibroblasts, in response to excess energy consumption in liver, kidney, heart, skin and lung fibrosis. Fibroblasts are the main drivers of organ function loss in lung, liver, skin, heart and kidney disease. Fibroblast activation in response to excess energy consumption results in the overproduction of a range of collagens, of which types I, III and VI seem to be the essential drivers of disease progression. Fibroblast activation may be quantified in serum, enabling profiling and selection of patients. Activation of fibroblasts results in the overproduction of collagens, which deteriorates organ function. Patient profiling of fibroblast activities in serum, quantified as collagen production, may identify an organ death trajectory, better enabling identification of the right treatment for use in different metabolic interventions. As metabolically activated patients have highly elevated risk of kidney, liver and heart failure, it is essential to identify which organ to treat first and monitor organ status to correct treatment regimes. In direct alignment with this, it is essential to identify the right patients with the right organ deterioration trajectory for enrolment in clinical studies.

Galectin-3 (Gal-3) and the tissue inhibitor of matrix metalloproteinase (TIMP-2) as potential biomarkers for the clinical evolution of chronic Chagas cardiomyopathy

BACKGROUND

Chronic Chagas cardiomyopathy (CCC) is responsible for the highest morbidity and worst prognosis in Chagas disease patients. However, predicting factors that correlate with disease progression, morbidity, and mortality is challenging. It is necessary to have simple, quantitative, and economical risk biomarkers that add value to conventional methods and assist in the diagnosis and prognosis of patients with CCC or in evolution.

OBJECTIVES

We evaluated molecules related to cardiac remodeling and fibrosis, such as MMP-2, MMP-9, TIMP-2, TIMP-1, PICP, CTXI, and Gal-3, and correlated these biomarkers with echocardiographic variables (LVDD, LVEF, and E/e' ratio).

METHODS

Blood samples from Chagasic patients without apparent cardiopathy (WAC), CCC patients, and healthy individuals were used to perform plasma molecule dosages using Luminex or ELISA.

RESULTS

MMP-2 and TIMP-2 presented higher levels in CCC; in these patients, the inhibitory role of TIMP-2 over MMP-2 was reinforced. The ratio of MMP-2/TIMP-2 in WAC patients showed a bias in favor of the gelatinase pathway. MMP-9 and TIMP-1 showed higher levels in Chagas patients compared to healthy subjects. PICP and CTXI are not associated with cardiac deterioration in Chagas disease. Increased levels of Gal-3 are associated with worse cardiac function in CCC. Receiver operating characteristic (ROC) curve analysis identified Gal-3 and TIMP-2 as putative biomarkers to discriminate WAC from cardiac patients.

CONCLUSIONS

Among the molecules evaluated, Gal-3 and TIMP-2 have the potential to be used as biomarkers of cardiac remodeling and progressive myocardial fibrosis in Chagas disease.

CT for the evaluation of myocardial extracellular volume with MRI as reference: a systematic review and meta-analysis

OBJECTIVE

Myocardial extracellular volume (ECV) fraction is an important imaging biomarker in clinical decision-making. CT-ECV is a potential alternative to MRI for ECV quantification. We conducted a meta-analysis to comprehensively assess the reliability of CT for ECV quantification with MRI as a reference.

METHODS

We systematically searched PubMed, EMBASE, and the Cochrane Library for relevant articles published since the establishment of the database in July 2022. The articles comparing CT-ECV with MRI as a reference were included. Meta-analytic methods were applied to determine the pooled weighted bias, limits of agreement (LOA), and correlation coefficient (r) between CT-ECV and MRI-ECV.

RESULTS

Seventeen studies with a total of 459 patients and 2231 myocardial segments were included. The pooled mean difference (MD), LOA, and r for ECV quantification at the per-patient level was (0.07%; 95% LOA: - 0.42 to 0.55%) and 0.89 (95% CI: 0.86-0.91), respectively, while on the per-segment level was (0.44%; 95% LOA: 0.16-0.72%) and 0.84 (95% CI: 0.82-0.85), respectively. The pooled r from studies with the ECViodine method for ECV quantification was significantly higher compared to those with the ECVsub method (0.94 (95% CI: 0.91-0.96) vs. 0.84 (95% CI: 0.80-0.88), respectively, p = 0.03). The pooled r from septal segments was significantly higher than those from non-septal segments (0.88 (95% CI: 0.86-0.90) vs. 0.76 (95% CI: 0.71-0.90), respectively, p = 0.009).

CONCLUSION

CT showed a good agreement and excellent correlation with MRI for ECV quantification and is a potentially attractive alternative to MRI.

CLINICAL RELEVANCE STATEMENT

The myocardial extracellular volume fraction can be acquired using a CT scan, which is not only a viable alternative to myocardial extracellular volume fraction derived from MRI but is also less time-consuming and costly for patients.

KEY POINTS

• Noninvasive CT-ECV is a viable alternative to MRI-ECV for ECV quantification. • CT-ECV using the ECViodine method showed more accurate myocardial ECV quantification than ECVsub. • Septal myocardial segments showed lower measurement variability than non-septal segments for the ECV quantification.

Collagenase treatment reduces the anisotropy of ultrasonic backscatter in rat myocardium by reducing collagen crosslinks

Dysregulation of collagen deposition, degradation, and crosslinking in the heart occur in response to increased physiological stress. Collagen content has been associated with ultrasonic backscatter (brightness), and we have shown that the anisotropy of backscatter can be used to measure myofiber alignment, that is, variation in the brightness of a left ventricular short-axis ultrasound. This study investigated collagen's role in anisotropy of ultrasonic backscatter; female Sprague-Dawley rat hearts were treated with a collagenase-containing solution, for either 10 or 30 min, or control solution for 30 min. Serial ultrasound images were acquired at 2.5-min intervals throughout collagenase treatment. Ultrasonic backscatter was assessed from anterior and posterior walls, where collagen fibrils are predominately aligned perpendicular to the angle of insonification, and the lateral and septal walls, where collagen is predominately aligned parallel to the angle of insonification. Collagenase digestion reduced backscatter anisotropy within the myocardium. Collagen remains present in the myocardium throughout collagenase treatment, but crosslinking is altered within 10 min. These data suggest that crosslinking of collagen modulates the anisotropy of ultrasonic backscatter. An Anisotropy Index, derived from differences in backscatter from parallel and perpendicularly aligned fibers, may provide a noninvasive index to monitor the progression and state of myocardial fibrosis.

Geniposide alleviates pressure overload in cardiac fibrosis with suppressed TGF-β1 pathway

BACKGROUND

Cardiac fibrosis is one of the main contributors to the pathogenesis of heart failure. Geniposide (GE), a major iridoid in gardenia fruit extract, has recently been reported to improve skeletal muscle fibrosis through the modulation of inflammation response. This investigation aimed to illuminate the cardio-protective effect and the potential mechanism of GE in cardiac fibrosis.

MATERIAL AND METHODS

A transverse aortic contraction (TAC) induction mice model was established and GE (0 mg/kg; 10 mg/kg; 20 mg/kg; 40 mg/kg) was administered by oral gavage daily for 4 weeks. Hemodynamic parameters, Masson's trichrome stain, and hematoxylin-eosin (HE) staining were estimated and cardiomyocyte fibrosis, interstitial collagen levels, and hypertrophic markers were analyzed using qPCR and western blot. In vitro, H9C2 cells were exposed to the Ang II (1 μM) pretreated with GE (0.1 μM, 1 μM, and 10 μM). Cardiomyocyte apoptosis was detected. Moreover, the transforming growth factor β1 (TGF-β1)/Smad2 pathway was assessed in vivo and in vitro.

RESULTS

GE significantly ameliorated TAC-induced cardiac hypertrophy, ventricular remodeling, myocardial fibrosis, and improved cardiac function in vivo, and it inhibited Ang II-induced cardiomyocyte apoptosis in vitro. We further observed that the inflammatory channel TGF-β1/Smad2 pathway was suppressed by GE both in vivo and in vitro.

CONCLUSION

These results indicate that GE inhibited myocardial fibrosis and improved hypertrophic cardiomyocytes with attenuated the TGF-β1/Smad2 pathway and proposed to be an important therapeutic of cardiac fibrosis reduced by TAC.

Imaging in atrial fibrillation: A way to assess atrial fibrosis and remodeling to assist decision-making

The 2020 ESC atrial fibrillation (AF) guidelines suggest the novel 4S-AF scheme for the characterization of AF. Imaging techniques could be helpful for this objective in everyday clinical practice, and information derived from these techniques reflects basic aspects of the pathophysiology of AF, which may facilitate treatment decision-making, and optimal management of AF patients. The aim of this review is to provide an overview of the mechanisms associated with atrial fibrosis and to describe imaging techniques that may help the management of AF patients in clinical practice. Transthoracic echocardiography is the most common procedure given its versatility, safety, and simplicity. Transesophageal echocardiography provides higher resolution exploration, and speckle tracking echocardiography can provide incremental functional and prognostic information over conventional echocardiographic parameters. In addition, LA deformation imaging, including LA strain and strain rate, are related to the extent of fibrosis. On the other hand, multidetector-row computed tomography and cardiac magnetic resonance provide higher resolution data and more accurate assessment of the dimensions, structure, and spatial relationships of the LA. Imaging is central when deciding on catheter ablation or cardioversion, and helps in selecting those patients who will really benefit from these procedures. Moreover, imaging enhances the understanding of the underlying mechanisms of atrial remodeling and might assists in refining the risk of stroke, which help to select the best medical therapies/interventions. In summary, evaluation of LA enlargement, LA remodeling and fibrosis with imaging techniques adds clinical and prognostic information and should be assessed as a part of routine comprehensive AF evaluation.

Correlations between serum laminin level and severity of heart failure in patients with chronic heart failure

Objective

This study aimed to investigate the correlation between serum laminin (LN) levels and clinical stages of heart failure in patients with chronic heart failure.

Methods

A total of 277 patients with chronic heart failure were selected from September 2019 to June 2020 in the Department of Cardiology, Second Affiliated Hospital of Nantong University. Based on stages of heart failure, the patients were divided into four groups: stage A, stage B, stage C, and stage D, with 55, 54, 77, and 91 cases, respectively. At the same time, 70 healthy people in this period were selected as the control group. Baseline data were recorded and serum Laminin (LN) levels were measured. The research compared, the differences in baseline data among the four groups of HF and normal controls, and analyzed the correlation between N-terminal pro-brain natriuretic peptide (NT-proBNP) and left ventricular ejection fraction (LVEF). The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of LN in the C-D stage of heart failure. Logistic multivariate ordered analysis was applied to screen the independent related factors of clinical stages of heart failure.

Results

Serum LN levels in patients with chronic heart failure were significantly higher than those in healthy people, which were 33.2 (21.38, 101.9) ng/ml and 20.45 (15.53, 23.04) ng/ml, respectively. With the progression of clinical stages of HF, serum LN and NT-proBNP levels increased, while LVEF gradually decreased (P < 0.05). Correlation analysis showed that LN was positively correlated with NT-proBNP (r = 0.744, P = 0.000) and negatively correlated with LVEF (r = -0.568, P = 0.000). The area under the ROC curve of LN for predicting C and D stages of heart failure was 0.913, 95% confidence interval was 0.882-0.945, P = 0.000, specificity 94.97%, and sensitivity 77.38%. Multivariate Logistic analysis showed that LN, Total bilirubin, NT-proBNP and HA were all independent correlates of heart failure staging.

Conclusion

Serum LN levels in patients with chronic heart failure are significantly increased and are independently correlated with the clinical stages of heart failure. It could potentially be an early warning index of the progression and severity of heart failure.

Circulating Biomarkers of Fibrosis Formation in Patients with Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is a progressive inheritable disease which is characterized by a gradual fibro-(fatty) replacement of the myocardium. Visualization of diffuse and patchy fibrosis patterns is challenging using clinically applied cardiac imaging modalities (e.g., late gadolinium enhancement, LGE). During collagen synthesis and breakdown, carboxy–peptides are released into the bloodstream, specifically procollagen type-I carboxy-terminal propeptides (PICP) and collagen type-I carboxy-terminal telopeptides (ICTP). We collected the serum and EDTA blood samples and clinical data of 45 ACM patients (age 50.11 ± 15.53 years, 44% female), divided into 35 diagnosed ACM patients with a 2010 ARVC Task Force Criteria score (TFC) ≥ 4, and 10 preclinical variant carriers with a TFC < 4. PICP levels were measured using an enzyme-linked immune sorbent assay and ICTP levels with a radio immunoassay. Increased PICP/ICTP ratios suggest a higher collagen deposition. We found significantly higher PICP and PICP/ICTP levels in diagnosed patients compared to preclinical variant carriers (p < 0.036 and p < 0.027). A moderate negative correlation existed between right ventricular ejection fractions (RVEF) and the PICP/ICTP ratio (r = −0.46, p = 0.06). In addition, significant correlations with left ventricular function (LVEF r = −0.53, p = 0.03 and end-systolic volume r = 0.63, p = 0.02) were found. These findings indicate impaired contractile performance due to pro-fibrotic remodeling. Follow-up studies including a larger number of patients should be performed to substantiate our findings and the validity of those levels as potential promising biomarkers in ACM.

Dynamic and static biomechanical traits of cardiac fibrosis

Cardiac fibrosis is a common pathology in cardiovascular diseases which are reported as the leading cause of death globally. In recent decades, accumulating evidence has shown that the biomechanical traits of fibrosis play important roles in cardiac fibrosis initiation, progression and treatment. In this review, we summarize the four main distinct biomechanical traits (i.e., stretch, fluid shear stress, ECM microarchitecture, and ECM stiffness) and categorize them into two different types (i.e., static and dynamic), mainly consulting the unique characteristic of the heart. Moreover, we also provide a comprehensive overview of the effect of different biomechanical traits on cardiac fibrosis, their transduction mechanisms, and in-vitro engineered models targeting biomechanical traits that will aid the identification and prediction of mechano-based therapeutic targets to ameliorate cardiac fibrosis.

Comparison of serum biomarkers of myocardial fibrosis with cardiac magnetic resonance in patients operated for tetralogy of Fallot

BACKGROUND

Serum biomarkers of myocardial fibrosis are considered markers of adverse outcome in adults with heart disease. Associations between biomarkers and clinical parameters in tetralogy of Fallot (TOF) has been understudied. We compared serum biomarker profiles with clinical and cardiac magnetic resonance (CMR) parameters of ventricular remodeling in patients with repaired TOF.

METHODS

Serum biomarkers [metalloproteinases MMP1 and MMP9, galectin-3, micro-RNA21 (miR21)), ST2, procollagen type I carboxy-terminal propeptide (PICP), and NTproBNP] were measured in TOF patients undergoing CMR. Associations between biomarkers and clinical and CMR variables were assessed using correlation coefficients, and linear and logistic regression.

RESULTS

Sixty patients were investigated, of which 47% were male. Age at CMR and TOF repair was 15 years [interquartile range (IQR) 9, 22] and 3.2 months (IQR 0.8, 6.2), respectively. Twelve (20%) had prior pulmonary valve replacement (PVR). MMP1 values were higher among those with prior PVR (16.7 (IQR 7.9, 25.5) vs 14.4 (IQR 9.9, 24.9), p = 0.02). When stratifying MMP1 into low and high groups, higher MMP1 was associated with higher indexed right (RV) and left ventricular (LV) mass and RV mass:volume ratios after adjusting for PVR. No other associations between biomarkers and CMR parameters were identified.

CONCLUSIONS

Only MMP1 was associated with markers of RV remodeling after TOF repair. As an enzyme involved in extracellular matrix degradation, MMP1 could be associated with fibrotic processes underlying RV remodeling, including dilation and hypertrophy. The additional biomarkers may not be specific towards cardiac remodeling. These findings merit further correlations with myocardial fibrosis measurements by CMR.

Clinical Phenotypes of Heart Failure With Preserved Ejection Fraction to Select Preclinical Animal Models

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To better define HFpEF clinically, patients are nowadays often clustered into phenogroups, based on their comorbidities and symptoms

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Many animal models claim to mimic HFpEF, but phenogroups are not yet regularly used to cluster them

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HFpEF animals models often lack reports of clinical symptoms of HF, therefore mainly presenting as extended models of LVDD, clinically seen as a prestate of HFpEF

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We investigated if clinically relevant phenogroups can guide selection of animal models aiming at better defined animal research

At least one-half of the growing heart failure population consists of heart failure with preserved ejection fraction (HFpEF). The limited therapeutic options, the complexity of the syndrome, and many related comorbidities emphasize the need for adequate experimental animal models to study the etiology of HFpEF, as well as its comorbidities and pathophysiological changes. The strengths and weaknesses of available animal models have been reviewed extensively with the general consensus that a “1-size-fits-all” model does not exist, because no uniform HFpEF patient exists. In fact, HFpEF patients have been categorized into HFpEF phenogroups based on comorbidities and symptoms. In this review, we therefore study which animal model is best suited to study the different phenogroups—to improve model selection and refinement of animal research. Based on the published data, we extrapolated human HFpEF phenogroups into 3 animal phenogroups (containing small and large animals) based on reports and definitions of the authors: animal models with high (cardiac) age (phenogroup aging); animal models focusing on hypertension and kidney dysfunction (phenogroup hypertension/kidney failure); and models with hypertension, obesity, and type 2 diabetes mellitus (phenogroup cardiometabolic syndrome). We subsequently evaluated characteristics of HFpEF, such as left ventricular diastolic dysfunction parameters, systemic inflammation, cardiac fibrosis, and sex-specificity in the different models. Finally, we scored these parameters concluded how to best apply these models. Based on our findings, we propose an easy-to-use classification for future animal research based on clinical phenogroups of interest.

Relation of Serum Albumin Levels to Myocardial Extracellular Volume in Patients With Severe Aortic Stenosis

Severe aortic stenosis (AS) is often characterized by myocardial interstitial fibrosis. Myocardial interstitial fibrosis, classically measured by magnetic resonance imaging, was also shown to be accurately measured by computed tomography (CT)-derived extracellular volume fraction (ECVF). Serum albumin (SA) level (g/dl) has been shown to correlate with ECVF among patients with heart failure and preserved ejection fraction. Our objective was to evaluate the association between SA and ECVF among patients with severe symptomatic AS. Patients with symptomatic severe AS who were evaluated as candidates for intervention between 2016 and 2018 were enrolled prospectively. All patients underwent precontrast and postcontrast CT for estimating myocardial ECVF. Valid ambulatory SA within 6 weeks of the cardiac CT were obtained and classified as (tertiles) <3.8, 3.8 to 4.19, and ≥4.2 g/dl. Patients with acute systemic illness at the time of the albumin test were excluded. The study included 68 patients, mean age 81 ± 6 years, 53% women. Patients with lower SA were more likely to have chronic renal failure, previous percutaneous coronary interventions, and a reduced functional class. The mean ECVF (%) in the study cohort was 41 ± 12%, significantly higher among the patients in the lower SA level groups (50 ± 12% vs 38 ± 7% vs 33 ± 9% in the <3.8 g/dl, 3.8 to 4.19 g/dl and ≥4.2 g/dl groups respectively, p for trend <0.001). A statistically significant inverse correlation was found between SA levels and ECVF (r -0.7, p <0.001). Multivariable analysis showed significant independent association between low SA and ECVF. In conclusion, the SA level is inversely associated with CT-derived ECVF in patients with severe AS.

Exploring the Correlation Between Fibrosis Biomarkers and Clinical Disease Severity in PLN p.Arg14del Patients

Background: Pathogenic variants in phospholamban (PLN, like p. Arg14del), are found in patients diagnosed with arrhythmogenic (ACM) and dilated cardiomyopathy (DCM). Fibrosis formation in the heart is one of the hallmarks in PLN p.Arg14del carriers. During collagen synthesis and breakdown, propeptides are released into the circulation, such as procollagen type I carboxy-terminal propeptide (PICP) and C-terminal telopeptide collagen type I (ICTP).

Aim: To investigate if PICP/ICTP levels in blood are correlative biomarkers for clinical disease severity and outcome in PLN p.Arg14del variant carriers.

Methods: Serum and EDTA blood samples were collected from 72 PLN p.Arg14del carriers (age 50.5 years, 63% female) diagnosed with ACM (n = 12), DCM (n = 14), and preclinical variant carriers (n = 46). PICP levels were measured with an enzyme-linked immune sorbent assay and ICTP with a radio immuno-assay. Increased PICP/ICTP ratios suggest a higher collagen deposition. Clinical data including electrocardiographic, and imaging results were adjudicated from medical records.

Results: No correlation between PICP/ICTP ratios and late gadolinium enhancement (LGE) was found. Moderate correlations were found between the PICP/ICTP ratio and end-diastolic/systolic volume (both rs = 0.40, n = 23, p = 0.06). PICP/ICTP ratio was significantly higher in patients with T wave inversion (TWI), especially in leads V4–V6, II, III, and aVF (p &lt; 0.022) and in patients with premature ventricular contractions (PVCs) during an exercise tolerance test (p = 0.007).

Conclusion: High PICP/ICTP ratios correlated with clinical parameters, such as TWI and PVCs. Given the limited size and heterogeneity of the patient group, additional studies are required to substantiate the incremental prognostic value of these fibrosis biomarkers in PLN p.Arg14del patients.

Fufang Xueshuantong Improves Diabetic Cardiomyopathy by Regulating the Wnt/β-Catenin Pathway

Diabetic cardiomyopathy (DCM) is one of the main complications of diabetic patients and the major reason for the high prevalence of heart failure in diabetic patients. Fufang Xueshuantong (FXST) is a traditional Chinese medicine formula commonly used in the treatment of diabetic retinopathy and stable angina pectoris. However, the role of FXST in DCM has not yet been clarified. This study was conducted to investigate the effects of FXST on diabetic myocardial lesions and reveal its molecular mechanism. The rats were intraperitoneally injected with 65 mg/kg streptozotocin (STZ) to induce diabetes mellitus (DM). DM rats were given saline or FXST. The rats in the control group were intraperitoneally injected with an equal amount of sodium citrate buffer and gavaged with saline. After 12 weeks, echocardiography, heart weight index (HWI), and myocardial pathological changes were determined. The expression of transforming growth factor-beta1 (TGF-β1), collagen I, and collagen III was examined using immunofluorescence staining and western blot. The expressions of Wnt/β-catenin signaling pathway-related proteins and mRNA were detected by western blot and real-time PCR. The results showed that FXST significantly improved cardiac function, ameliorated histopathological changes, and decreased HWI in the DM rats. FXST significantly inhibited the expression of myocardial TGF-β1, collagen I, and collagen III in DM rats. Furthermore, FXST significantly inhibited the Wnt/β-catenin pathway. Taken together, FXST has a protective effect on DCM, which might be mediated by suppressing the Wnt/β-catenin pathway.

Arrhythmogenic cardiomyopathy: pathogenesis, pro-arrhythmic remodelling, and novel approaches for risk stratification and therapy

Arrhythmogenic cardiomyopathy (ACM) is a life-threatening cardiac disease caused by mutations in genes predominantly encoding for desmosomal proteins that lead to alterations in the molecular composition of the intercalated disc. ACM is characterized by progressive replacement of cardiomyocytes by fibrofatty tissue, ventricular dilatation, cardiac dysfunction, and heart failure but mostly dominated by the occurrence of life-threatening arrhythmias and sudden cardiac death (SCD). As SCD appears mostly in apparently healthy young individuals, there is a demand for better risk stratification of suspected ACM mutation carriers. Moreover, disease severity, progression, and outcome are highly variable in patients with ACM. In this review, we discuss the aetiology of ACM with a focus on pro-arrhythmic disease mechanisms in the early concealed phase of the disease. We summarize potential new biomarkers which might be useful for risk stratification and prediction of disease course. Finally, we explore novel therapeutic strategies to prevent arrhythmias and SCD in the early stages of ACM.

8-Gingerol Ameliorates Myocardial Fibrosis by Attenuating Reactive Oxygen Species, Apoptosis, and Autophagy via the PI3K/Akt/mTOR Signaling Pathway

8-gingerol (8-Gin) is the series of phenolic substance that is extracted from ginger. Although many studies have revealed that 8-Gin has multiple pharmacological properties, the possible underlying mechanisms of 8-Gin against myocardial fibrosis (MF) remains unclear. The study examined the exact role and potential mechanisms of 8-Gin against isoproterenol (ISO)-induced MF. Male mice were intraperitoneally injected with 8-Gin (10 and 20 mg/kg/d) and concurrently subcutaneously injected with ISO (10 mg/kg/d) for 2 weeks. Electrocardiography, pathological heart morphology, myocardial enzymes, reactive oxygen species (ROS) generation, degree of apoptosis, and autophagy pathway-related proteins were measured. Our study observed 8-Gin significantly reduced J-point elevation and heart rate. Besides, 8-Gin caused a marked decrease in cardiac weight index and left ventricle weight index, serum levels of creatine kinase and lactate dehydrogenase (CK and LDH, respectively), ROS generation, and attenuated ISO-induced pathological heart damage. Moreover, treatment with 8-Gin resulted in a marked decrease in the levels of collagen types I and III and TGF-β in the heart tissue. Our results showed 8-Gin exposure significantly suppressed ISO-induced autophagosome formation. 8-Gin also could lead to down-regulation of the activities of matrix metalloproteinases-9 (MMP-9), Caspase-9, and Bax protein, up-regulation of the activity of Bcl-2 protein, and alleviation of cardiomyocyte apoptosis. Furthermore, 8-Gin produced an obvious increase in the expressions of the PI3K/Akt/mTOR signaling pathway-related proteins. Our data showed that 8-Gin exerted cardioprotective effects on ISO-induced MF, which possibly occurred in connection with inhibition of ROS generation, apoptosis, and autophagy via modulation of the PI3K/Akt/mTOR signaling pathway.

Arrhythmogenic Cardiomyopathy-Current Treatment and Future Options

Arrhythmogenic cardiomyopathy (ACM) is an inheritable heart muscle disease characterised pathologically by fibrofatty myocardial replacement and clinically by ventricular arrhythmias (VAs) and sudden cardiac death (SCD). Although, in its original description, the disease was believed to predominantly involve the right ventricle, biventricular and left-dominant variants, in which the myocardial lesions affect in parallel or even mostly the left ventricle, are nowadays commonly observed. The clinical management of these patients has two main purposes: the prevention of SCD and the control of arrhythmic and heart failure (HF) events. An implantable cardioverter defibrillator (ICD) is the only proven lifesaving treatment, despite significant morbidity because of device-related complications and inappropriate shocks. Selection of patients who can benefit the most from ICD therapy is one of the most challenging issues in clinical practice. Risk stratification in ACM patients is mostly based on arrhythmic burden and ventricular dysfunction severity, although other clinical features resulting from electrocardiogram and imaging modalities such as cardiac magnetic resonance may have a role. Medical therapy is crucial for treatment of VAs and the prevention of negative ventricular remodelling. In this regard, the efficacy of novel anti-HF molecules and drugs acting on the inflammatory pathway in patients with ACM is, to date, unknown. Catheter ablation represents an effective strategy to treat ventricular tachycardia relapses and recurrent ICD shocks. The present review will address the current strategies for prevention of SCD and treatment of VAs and HF in patients with ACM.

Single-source dual energy CT to assess myocardial extracellular volume fraction in aortic stenosis before transcatheter aortic valve implantation (TAVI)

PURPOSE

To assess myocardial extracellular volume fraction (ECV) measurement provided by a single-source dual-energy computed tomography (SSDE-CT) acquisition added at the end of a routine CT examination before transcatether aortic valve implantation (TAVI) compared to cardiac magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Twenty-one patients (10 men, 11 women; mean age, 86±4.9 years [SD]; age range: 71-92 years) with severe aortic stenosis underwent standard pre-TAVI CT with additional cardiac SSDE-CT acquisition 7minutes after intravenous administration of iodinated contrast material and myocardial MRI including pre- and post-contrast T1-maps. Myocardial ECV and standard deviation (σECV) were calculated in the 16-segments model. ECV provided by SSDE-CT was compared to ECV provided by MRI, which served as the reference. Analyses were performed on a per-segment basis and on a per-patient involving the mean value of the 16-segments.

RESULTS

ECV was slightly overestimated by SSDE-CT (29.9±4.6 [SD] %; range: 20.9%-48.3%) compared to MRI (29.1±3.9 [SD] %; range: 22.0%-50.7%) (P<0.0001) with a bias and limits of agreement of +2.3% (95%CI: -16.1%-+20.6%) and +2.5% (95%CI: -2.1%-+7.1%) for per-segment and per-patient-analyses, respectively. Good (r=0.81 for per-segment-analysis) to excellent (r=0.97 for per-patient-analysis) linear relationships (both P<0.0001) were obtained. The σECV was significantly higher at SSDE-CT (P<0.0001). Additional radiation dose from CT was 1.89±0.38 (SD) mSv (range: 1.48-2.47 mSv).

CONCLUSION

A single additional SSDE-CT acquisition added at the end of a standard pre-TAVI CT protocol can provide ECV measurement with good to excellent linear relationship with MRI.

Diffuse myocardial fibrosis: mechanisms, diagnosis and therapeutic approaches

Diffuse myocardial fibrosis resulting from the excessive deposition of collagen fibres through the entire myocardium is encountered in a number of chronic cardiac diseases. This lesion results from alterations in the regulation of fibrillary collagen turnover by fibroblasts, facilitating the excessive deposition of type I and type III collagen fibres within the myocardial interstitium and around intramyocardial vessels. The available evidence suggests that, beyond the extent of fibrous deposits, collagen composition and the physicochemical properties of the fibres are also relevant in the detrimental effects of diffuse myocardial fibrosis on cardiac function and clinical outcomes in patients with heart failure. In this regard, findings from the past 20 years suggest that various clinicopathological phenotypes of diffuse myocardial fibrosis exist in patients with heart failure. In this Review, we summarize the current knowledge on the mechanisms and detrimental consequences of diffuse myocardial fibrosis in heart failure. Furthermore, we discuss the validity and usefulness of available imaging techniques and circulating biomarkers to assess the clinicopathological variation in this lesion and to track its clinical evolution. Finally, we highlight the currently available and potential future therapeutic strategies aimed at personalizing the prevention and reversal of diffuse myocardial fibrosis in patients with heart failure.

The protective effect of isosteviol sodium on cardiac function and myocardial remodelling in transverse aortic constriction rat

Pathological hypertrophy contributes to heart failure and there is not quite effective treatment to invert this process. Isosteviol has been shown to protect the heart against ischaemia-reperfusion injury and isoproterenol-induced cardiac hypertrophy, but its effect on pressure overload-induced cardiac hypertrophy is still unknown. Pressure overload induced by transverse aortic constriction (TAC) causes cardiac hypertrophy in rats to mimic the pathological condition in human. This study examined the effects of isosteviol sodium (STVNa) on cardiac hypertrophy by the TAC model and cellular assays in vitro. Cardiac function test, electrocardiogram analysis and histological analysis were conducted. The effects of STVNa on calcium transient of the adult rat ventricular cells and the proliferation of neonatal rat cardiac fibroblasts were also studied in vitro. Cardiac hypertrophy was observed after 3-week TAC while the extensive cardiac dysfunction and electronic remodelling were observed after 9-week TAC. Both STVNa and sildenafil (positive drug) treatment reversed the two process, but STVNa appeared to be more superior in some aspects and did not change calcium transient considerably. STVNa also reversed TAC-induced cardiac fibrosis in vivo and TGF-β1-induced fibroblast proliferation in vitro. Moreover, STVNa, but not sildenafil, reversed impairment of the autonomic nervous system induced by 9-week TAC.

Myocardial Interstitial Fibrosis in Nonischemic Heart Disease, Part 3/4: JACC Focus Seminar

Myocardial interstitial fibrosis (MIF) is a histological hallmark of several cardiac diseases that alter myocardial architecture and function and are associated with progression to heart failure. MIF is a diffuse and patchy process, appearing as a combination of interstitial microscars, perivascular collagen fiber deposition, and increased thickness of mysial collagen strands. Although MIF arises mainly because of alterations in fibrillar collagen turnover leading to collagen fiber accumulation, there are also alterations in other nonfibrillar extracellular matrix components, such as fibronectin and matricellular proteins. Furthermore, in addition to an excess of collagen, qualitative changes in collagen fibers also contribute to the detrimental impact of MIF. In this part 3 of a 4-part JACC Focus Seminar, we review the evidence on the complex mechanisms leading to MIF, as well as its contribution to systolic and diastolic cardiac dysfunction and impaired clinical outcomes in patients with nonischemic heart disease.

GLP-1 receptor agonist ameliorates experimental lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fatal lung disease. This disease is characterized by an excessive accumulation of extracellular matrix deposition that modify normal lung physiology. Up to date, there are not efficient therapeutic tools to fight IPF. Glucagon-like peptide-1 receptor (GLP-1R) activation plays an essential role in lung functions in normal and in pathological conditions. The aim of the present study was to study the possible beneficial effects of the administration of the GLP-1R agonist, liraglutide, in the pathogenesis of the fibrotic process in an animal model of pulmonary fibrosis induced by bleomycin. We observed that liraglutide decreased mRNA expression of collagen, hydroxyproline and key enzymes for the synthesis of collagen. In addition, GLP-1R activation restored the ACE2 mRNA levels modulating the activities of the RAS components, increased the production of surfactant proteins (SFTPa1, SFTPb, SFTPc) and promoted an improvement in pulmonary and cardiac functionality, including a partial restoration of lung alveolar structure. Liraglutide effects are shown at both the pro-inflammatory and fibrosis phases of the experimental disease. For these reasons, GLP-1 might be regarded as a promising drug for treating pulmonary fibrosis.

Association of Circulating Tissue Inhibitor of Metalloproteinases-1 and Procollagen Type III Aminoterminal Peptide Levels With Incident Heart Failure and Chronic Kidney Disease

Background Tissue inhibitor of metalloproteinases-1 ( TIMP -1) and procollagen type III aminoterminal peptide are established circulating markers of extracellular matrix remodeling and associated with cardiovascular disease. The association of both biomarkers with incident congestive heart failure and chronic kidney disease ( CKD ) in the community is not well studied. Methods and Results We measured plasma total TIMP -1 and procollagen type III aminoterminal peptide levels in 922 Framingham participants (mean age, 57 years; 57% women) and related both biomarkers to the risk of incident CKD and congestive heart failure in multivariable-adjusted Cox regression models. Plasma total TIMP -1 levels were positively associated with risk of incident CKD (164 events; hazard ratio per 1 SD in log-biomarker, 1.90; 95% CI , 1.53-2.37) in multivariable models, including adjustments for left ventricular mass, C-reactive protein, and B-type natriuretic peptide levels. The association of total TIMP -1 with risk of congestive heart failure was statistically significant in an age- and sex-adjusted model, but was attenuated upon adjustment for conventional risk factors. Blood procollagen type III aminoterminal peptide levels were not related to the risk of CKD or congestive heart failure. Conclusions Higher baseline levels of total TIMP -1 conferred an increased risk for incident CKD , independent of conventional risk factors and circulating biomarkers of chronic systemic inflammation and neurohormonal activation. Our prospective observations in a large community-based sample support the role of matrix remodeling in the pathogenesis of CKD .

Development of endomyocardial fibrosis model using a cell patterning technique: In vitro interaction of cell coculture of 3T3 fibroblasts and RL-14 cardiomyocytes

Cardiac functions can be altered by changes in the microstructure of the heart, i.e., remodeling of the cardiac tissue, which may activate pathologies such as hypertrophy, dilation, or cardiac fibrosis. Cardiac fibrosis can develop due to an excessive deposition of extracellular matrix proteins, which are products of the activation of fibroblasts. In this context, the anatomical-histological change may interfere with the functioning of the cardiac tissue, which requires specialized cells for its operation. The purpose of the present study was to determine the cellular interactions and morphological changes in cocultures of 3T3 fibroblasts and RL-14 cardiomyocytes via the generation of a platform an in vitro model. For this purpose, a platform emulating the biological characteristics of endomyocardial fibrosis was generated using a cell patterning technique to study morphological cellular changes in compact and irregular patterns of fibrosis. It was found that cellular patterns emulating the geometrical distributions of endomyocardial fibrosis generated morphological changes after interaction of the RL-14 cardiomyocytes with the 3T3 fibroblasts. Through this study, it was possible to evaluate biological characteristics such as cell proliferation, adhesion, and spatial distribution, which are directly related to the type of emulated endomyocardial fibrosis. This research concluded that fibroblasts inhibited the proliferation of cardiomyocytes via their interaction with specific microarchitectures. This behavior is consistent with the histopathological distribution of cardiac fibrosis; therefore, the platform developed in this research could be useful for the in vitro assessment of cellular microdomains. This would allow for the experimental determination of interactions with drugs, substrates, or biomaterials within the engineering of cardiac tissues.

Myocardial interstitial fibrosis in the era of precision medicine. Biomarker-based phenotyping for a personalized treatment

Myocardial interstitial fibrosis is a constant pathological finding in structural heart diseases of various etiologies that evolve with heart failure. Although fibrosis facilitates heart failure progression, until now no therapeutic strategy has been developed that ensures its reversal. A possible explanation for this may lie in the vision of myocardial interstitial fibrosis as a homogeneous lesion instead of a heterogeneous lesion in which different phenotypes can be distinguished using appropriate criteria. In addition, the notion that the heterogeneity of myocardial interstitial fibrosis may be cardiac disease-specific must be also considered when approaching this entity. Therefore, we propose that myocardial interstitial fibrosis represents a true challenge for transitioning from usual care to biomarker-based personalized treatment and precision medicine in heart failure. As a proof-of-concept, in this review we discuss the phenotyping of myocardial interstitial fibrosis in patients with heart failure attributable to hypertensive heart disease based on its histomolecular alterations and provide evidence of the prognostic relevance of the resulting stratification. Furthermore, we discuss the available information on some circulating biomarkers and certain pharmacological agents useful for noninvasive identification and personalized treatment, respectively, of those phenotypes.

Procollagen type I carboxy-terminal propeptide (PICP) and MMP-2 are potential biomarkers of myocardial fibrosis in patients with hypertrophic cardiomyopathy

BACKGROUND

Whether current proposed biomarkers of myocardial fibrosis (BMFs) actually reflect the changes in fibrous characteristics of myocardial tissue remains unclear. The relation between peripheral BMFs and histological myocardial fibrosis in patients with hypertrophic cardiomyopathy (HCM) has been unknown.

METHODS AND RESULTS

We studied 52 HCM patients who underwent a transaortic extended septal myectomy. Complete medical history was collected, and related examinations were performed. Echocardiography and cardiovascular magnetic resonance were employed to characterize cardiac morphology and function. Procollagen type I carboxy-terminal propeptide (PICP), C-terminal telopeptide of type I collagen (CITP), matrix metalloproteinases (total MMP-2 and total MMP-9), and tissue inhibitor of metalloproteinase 1 (TIMP-1) levels in both plasma and myocardial tissues were determined and compared. Myocardial fibrosis was detected with Masson's trichrome staining, and collagen volume fraction (CVF) was calculated. There was a significant correlation between plasma PICP levels and myocardial PICP contents (r=0.382, P=.007). Besides, plasma PICP (r=0.332, P=.020) levels correlated positively with CVF. In addition, plasma TIMP-1 levels were significantly correlated with myocardial TIMP-1 contents (r=0.282, P=.043). Plasma MMP-2 levels correlated positively with CVF (r=0.379, P=.006). Patients who took calcium channel blockers (CCBs; diltiazem or verapamil) had significantly lower plasma PICP levels, myocardial PICP content, and CVF in comparison with those who did not take CCBs.

CONCLUSIONS

In patients with HCM, plasma PICP and MMP-2 levels quantitatively reflect myocardial fibrosis, suggesting that PICP and MMP-2 may be used as reliable BMFs. CCBs may attenuate cardiac fibrosis in patients with HCM.

The Role of Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases in Duchenne Muscular Dystrophy Cardiomyopathy

BACKGROUND

Cardiomyopathy is the leading cause of death in Duchenne muscular dystrophy (DMD). Standard cardiac biomarkers are poor indicators of DMD cardiovascular disease. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) regulate collagen turnover. Given the cardiac fibrosis seen in DMD, we hypothesized that MMPs and TIMPs correlate with severity of DMD cardiomyopathy.

METHODS AND RESULTS

Prospectively enrolled DMD subjects (n = 42) underwent cardiac magnetic resonance imaging for function and late gadolinium enhancement (LGE), including LGE severity from 0 (no LGE) to 4 (severe). Serum from DMD and healthy male control subjects (n = 15) analyzed for MMPs 1, 2, 3, 7, 9, and 10 and TIMPs 1-4. MMP1, MMP7, and MMP10 were higher in DMD than in control (respectively, median 5080 pg/mL vs 2120 pg/mL [P = .007], 2170 pg/mL vs 1420 pg/mL [P < .001], and 216 pg/mL vs 140pg/mL [P = .040]); TIMP4 was lower in DMD (124 pg/mL vs 263 pg/mL; P = .046). Within DMD, MMP7 correlated inversely with left ventricular ejection fraction (r = -0.40; P = .012) and directly with strain (r = 0.54; P = .001) and LGE severity (r = 0.47; P = .003). MMP7 was higher in DMD patients with LGE compared with those without LGE and control subjects (P < .001).

CONCLUSIONS

Multiple MMPs are elevated in DMD compared with control subjects. MMP7 is related to DMD cardiac dysfunction and myocardial fibrosis, possibly through remodeling of the extracellular matrix.

Atrial Fibrillation, Ventricular Arrhythmia, and Left Ventricular Remodeling in the ICU – First Results of the Single- Center RHYTHM-ACC Registry

The aim of this study was to investigate the association between left ventricular remodeling, atrial fibrillation (AF), and the severity of ventricular tachycardia (VT) in patients with ventricular rhythm disturbances admitted in a level 3 facility of acute cardiac care. Material and Methods: The RHYTHM-ACC registry was a single-center observational study, including 150 consecutive patients with sustained or non-sustained ventricular tachycardia (sVT and nsVT, respectively) admitted in an intensive cardiac care unit (ICCU), separated in: group 1 - 29 patients (21.01%) with dilated cardiomyopathy (DCM), and group 2 - 109 patients (78.99%) with normal ventricular performance. We investigated the difference between clinical characteristics of patients with sVT versus those with nsVT in each study group, and the association between AF and different forms of ventricular arrhythmia in 38 (25.33%) patients with AF and 112 (74.66%) patients in sinus rhythm. Results: There were no significant differences between the study groups with respect to type of ventricular arrhythmia: sVT (46.87% vs. 36.44%, p = 0.2), nsVT (43.75% vs. 55.93%, p = 0.2), or ventricular fibrillation (VF) (9.37% vs. 7.62%, p = 0.7). However, patients with DCM presented a significantly higher incidence of AF (43.75% vs. 20.33%, p = 0.01) and bundle branch block (37.5% vs. 11.86%, p = 0.0007). VF occurred more frequently in patients with AF compared to those in sinus rhythm (18.42% vs. 4.46%, p = 0.006). Multivariate analysis identified the co-existence of AF (OR = 4.8, p = 0.01) and the presence of a bundle branch block (BBB) (OR = 3.9, p = 0.03) as the most powerful predictors for the degeneration of VT into VF in patients admitted with sVT or nsVT in an ICCU unit. Conclusions: In patients with any type of VT admitted in an ICCU, the presence of ventricular remodeling is associated with a higher incidence of AF and conduction abnormalities, but not with a more severe pattern of ventricular arrhythmia. At the same time, AF and BBB seem to represent the most powerful predictors for degeneration of VT into VF, independent of the type of VT.

Effect of Substrate Stiffness on Mechanical Coupling and Force Propagation at the Infarct Boundary

Heterogeneous intercellular coupling plays a significant role in mechanical and electrical signal transmission in the heart. Although many studies have investigated the electrical signal conduction between myocytes and nonmyocytes within the heart muscle tissue, there are not many that have looked into the mechanical counterpart. This study aims to investigate the effect of substrate stiffness and the presence of cardiac myofibroblasts (CMFs) on mechanical force propagation across cardiomyocytes (CMs) and CMFs in healthy and heart-attack-mimicking matrix stiffness conditions. The contractile forces generated by the CMs and their propagation across the CMFs were measured using a bio-nanoindenter integrated with fluorescence microscopy for fast calcium imaging. Our results showed that softer substrates facilitated stronger and further signal transmission. Interestingly, the presence of the CMFs attenuated the signal propagation in a stiffness-dependent manner. Stiffer substrates with CMFs present attenuated the signal ∼24-32% more compared to soft substrates with CMFs, indicating a synergistic detrimental effect of increased matrix stiffness and increased CMF numbers after myocardial infarction on myocardial function. Furthermore, the beating pattern of the CMF movement at the CM-CMF boundary also depended on the substrate stiffness, thereby influencing the waveform of the propagation of CM-generated contractile forces. We performed computer simulations to further understand the occurrence of different force transmission patterns and showed that cell-matrix focal adhesions assembled at the CM-CMF interfaces, which differs depending on the substrates stiffness, play important roles in determining the efficiency and mechanism of signal transmission. In conclusion, in addition to substrate stiffness, the degree and type of cell-cell and cell-matrix interactions, affected by the substrate stiffness, influence mechanical signal conduction between myocytes and nonmyocytes in the heart muscle tissue.

Prevalence and prognosis of ventricular tachycardia/ventricular fibrillation in patients with post-infarction left ventricular aneurysm: Analysis of 575 cases

BACKGROUND

We investigated the prevalence of ventricular tachycardia/ventricular fibrillation (VT/VF) in Post-infarction left ventricular aneurysm (PI-LVA) patients and analyze clinical outcomes in patients presenting with VT/VF.

METHODS

575 PI-LVA patients were enrolled and investigated by logistic regression analysis. Patients with VT/VF were followed up, the composite primary endpoint was cardiac death and appropriate ICD/external shocks.

RESULTS

The incidence of sustained VT/VF was 11%. Logistical regression analysis showed male gender, enlarged LV end diastolic diameter (LVEDD) and higher NYHA class were correlated with VT/VF development. During follow up of 46 ± 15 months, 19 out of 62(31%) patients reached study end point. Multivariate Cox regression analysis revealed that enlarged LVEDD and moderate/severe mitral regurgitation (MR) were independently predictive of clinical outcome.

CONCLUSIONS

Male gender, enlarged LVEDD and higher NYHA class associated with risk of sustained VT/VF in PI-LVA patients. Among VT/VF positive patients, enlarged LVEDD and moderate/severe MR independently predicted poor clinical prognosis.

Connective tissue growth factor dependent collagen gene expression induced by MAS agonist AR234960 in human cardiac fibroblasts

Perspectives on whether the functions of MAS, a G protein-coupled receptor, are beneficial or deleterious in the heart remain controversial. MAS gene knockout reduces coronary vasodilatation leading to ischemic injury. G protein signaling activated by MAS has been implicated in progression of adaptive cardiac hypertrophy to heart failure and fibrosis. In the present study, we observed increased expression of MAS, connective tissue growth factor (CTGF) and collagen genes in failing (HF) human heart samples when compared to non-failing (NF). Expression levels of MAS are correlated with CTGF in HF and NF leading to our hypothesis that MAS controls CTGF production and the ensuing expression of collagen genes. In support of this hypothesis we show that the non-peptide MAS agonist AR234960 increases both mRNA and protein levels of CTGF via ERK1/2 signaling in HEK293-MAS cells and adult human cardiac fibroblasts. MAS-mediated CTGF expression can be specifically blocked by MAS inverse agonist AR244555 and also by MEK1 inhibition. Expression of CTGF gene was essential for MAS-mediated up-regulation of different collagen subtype genes in HEK293-MAS cells and human cardiac fibroblasts. Knockdown of CTGF by RNAi disrupted collagen gene regulation by the MAS-agonist. Our data indicate that CTGF mediates the profibrotic effects of MAS in cardiac fibroblasts. Blocking MAS-CTGF-collagen pathway should be considered for pharmacological intervention for HF.

Fibrosis imaging: Current concepts and future directions

Fibrosis plays an important role in many different pathologies. It results from tissue injury, chronic inflammation, autoimmune reactions and genetic alterations, and it is characterized by the excessive deposition of extracellular matrix components. Biopsies are routinely employed for fibrosis diagnosis, but they suffer from several drawbacks, including their invasive nature, sampling variability and limited spatial information. To overcome these limitations, multiple different imaging tools and technologies have been evaluated over the years, including X-ray imaging, computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI), positron emission tomography (PET) and single-photon emission computed tomography (SPECT). These modalities can provide anatomical, functional and molecular imaging information which is useful for fibrosis diagnosis and staging, and they may also hold potential for the longitudinal assessment of therapy responses. Here, we summarize the use of non-invasive imaging techniques for monitoring fibrosis in systemic autoimmune diseases, in parenchymal organs (such as liver, kidney, lung and heart), and in desmoplastic cancers. We also discuss how imaging biomarkers can be integrated in (pre-) clinical research to individualize and improve anti-fibrotic therapies.

Non-invasive quantification of collagen turnover in renal transplant recipients

Kidney allograft failure due to chronic injury/rejection remains the main cause of graft loss in renal transplant recipients (RTR). Here, we investigated whether specific biomarkers of extracellular matrix (ECM) turnover are associated with allograft function and chronic kidney disease (CKD) stage in RTR. Seventy-eight patients who attended the University Medical Center Groningen for a routine check-up after kidney transplantation were enrolled in the study. Plasma and/or 24h-urine samples were collected and specific matrix-metalloproteinase-generated neo-epitope fragments of collagens were measured by enzyme-linked immunosorbent assay. Our results demonstrated that urinary levels of C3M, a marker for collagen type III degradation, correlated with estimated glomerular filtration rate (eGFR; r = 0.58, p<0.0001), with lower levels detected in the urine of patients with advanced CKD. In addition, plasma levels of Pro-C6, a marker for collagen type VI formation, significantly increased with disease progression and correlated with eGFR (r = -0.72, p<0.0001). Conversely, plasma C3M and urinary Pro-C6 levels showed no correlation with renal function. We identified two neo-epitope biomarkers of tissue turnover associated with ECM remodeling and fibrosis that can stratify patients by CKD stage. This is as promising first step towards non-invasive monitoring of ECM turnover in the kidneys.

Myocardial T1 and T2 Mapping: Techniques and Clinical Applications

Cardiac magnetic resonance (CMR) imaging is widely used in various medical fields related to cardiovascular diseases. Rapid technological innovations in magnetic resonance imaging in recent times have resulted in the development of new techniques for CMR imaging. T1 and T2 image mapping sequences enable the direct quantification of T1, T2, and extracellular volume fraction (ECV) values of the myocardium, leading to the progressive integration of these sequences into routine CMR settings. Currently, T1, T2, and ECV values are being recognized as not only robust biomarkers for diagnosis of cardiomyopathies, but also predictive factors for treatment monitoring and prognosis. In this study, we have reviewed various T1 and T2 mapping sequence techniques and their clinical applications.

Effect of High Thoracic Sympathetic Nerve Block on Serum Collagen Biomarkers in Patients with Chronic Heart Failure

OBJECTIVES

The impact of high thoracic sympathetic block (HTSB) on myocardial fibrosis in chronic heart failure (HF) is unclear. Myocardial collagen synthesis can be assessed by measuring circulating biomarkers. We observed the effect of HTSB on serum collagen biomarkers in HF.

METHODS

Forty-four patients were randomized to a control and a HTSB group. They received routine medications. Repeated epidural injections were given to the HTSB group for 4 weeks. Echocardiography and measurements of serum carboxy-terminal propeptide of procollagen type I (PICP) and amino-terminal propeptide of procollagen type III (PIIINP) were performed at baseline and 4 weeks later.

RESULTS

There were significant reductions in left atrial diameter, left ventricular (LV) diameter and volume, LV weight index (LVWI) and serum PICP and PIIINP levels in the HTSB group (p < 0.05). The changes in LV end-systolic volume and ejection fraction (LVEF) were greater in the HTSB group than in the control group (p < 0.05). In the HTSB group, the decreases in PICP and PIIINP were correlated with the decrease in LVWI (PICP: r = 0.695, p = 0.000; PIIINP: r = 0.642, p = 0.001), and the decrease in PICP was negatively associated with the rise in LVEF (r = -0.813, p = 0.000).

CONCLUSION

HTSB reduces myocardial fibrosis in HF, which may accompany the improvement of LV hypertrophy and dysfunction.

Procollagen C-Proteinase Enhancer 1 (PCPE-1) as a Plasma Marker of Muscle and Liver Fibrosis in Mice

Current non-invasive diagnostic methods of fibrosis are limited in their ability to identify early and intermediate stages of fibrosis and assess the efficacy of therapy. New biomarkers of fibrosis are therefore constantly sought for, leading us to evaluate procollagen C-proteinase enhancer 1 (PCPE-1), a fibrosis-related extracellular matrix glycoprotein, as a plasma marker of fibrosis. A sandwich ELISA that permitted accurate measurements of PCPE-1 concentrations in mouse plasma was established. Tissue fibrosis was assessed using histochemical, immunofluorescence, and immunoblotting analyses for type I collagen and PCPE-1. The normal plasma concentration of PCPE-1 in 6 weeks to 4 months old mice was ~200 ng/ml (189.5 ± 11.3 to 206.8 ± 13.8 ng/ml). PCPE-1 plasma concentrations in four and 8.5 months old mdx mice displaying fibrotic diaphragms increased 27 and 40% respectively relatively to age-matched control mice, an increase comparable to that of the N-propeptide of procollagen type III (PIIINP), a known blood marker of fibrosis. PCPE-1 plasma levels in mice with CCl4-induced liver fibrosis increased 34 to 50% relatively to respective controls and reflected the severity of the disease, namely increased gradually during the progression of fibrosis and went down to basal levels during recovery, in parallel to changes in the liver content of collagen I and PCPE-1. The results favor PCPE-1 as a potential new clinically valuable fibrosis biomarker.

Effects of atorvastatin on atrial remodeling in a rabbit model of atrial fibrillation produced by rapid atrial pacing

Background

Accumulating evidence suggests that myeloperoxidase (MPO) is involved in atrial remodeling of atrial fibrillation (AF). Statins could reduce the MPO levels in patients with cardiovascular diseases. This study evaluated the effects of atorvastatin on MPO level and atrial remodeling in a rabbit model of pacing-induced AF.

Methods

Eighteen rabbits were randomly divided into sham, control and atorvastatin groups. Rabbits in the control and atorvastatin groups were subjected to rapid atrial pacing (RAP) at 600 bpm for 3 weeks, and treated with placebo or atorvastatin (2.5 mg/kg/d), respectively. Rabbits in the sham group did not receive RAP. After 3 weeks of pacing, atrial structural and functional changes were assessed by echocardiography, atrial effective refractory period (AERP) and AF inducibility were measured by atrial electrophysiological examination, and histological changes were evaluated by Masson trichrome-staining. The L-type calcium channel α1c (Cav1.2), collagen I and III, MPO, matrix metalloproteinase (MMP)-2 and MMP-9 were analyzed by real time polymerase chain reaction and/or western blot.

Results

All rabbits were found to have maintained sinus rhythm after 3 weeks of RAP. Atrial burst stimulation induced sustained AF (>30 min) in 5, 4, and no rabbits in the control, atorvastatin, and sham groups, respectively. The AERP shortened and Cav1.2 mRNA level decreased in the control group, but these changes were suppressed in the atorvastatin group. Obvious left atrial enlargement and dysfunction was found in both control and atorvastatin groups. Compared with the control group, these echocardiograhic indices of left atrium did not differ in the atorvastatin group. Prominent atrial fibrosis and increased levels of collagen I and III were observed in the control group but not in the atorvastatin group. The mRNA and protein levels of MPO, MMP-2 and MMP-9 significantly increased in the control group, but these changes were prevented in the atorvastatin group.

Conclusion

Treatment with atorvastatin prevented atrial remodeling in a rabbit model of RAP-induced AF. The reduction of levels of atrial MPO, MMP-2 and MMP-9 may contribute to the prevention of atorvastatin on atrial remodeling.

The Role of Imaging in Aortic Valve Disease

PURPOSE OF REVIEW

Aortic valve disease is the most common form of heart valve disease in developed countries. Imaging remains central to the diagnosis and risk stratification of patients with both aortic stenosis and regurgitation and has traditionally been performed with echocardiography. Indeed, echocardiography remains the cornerstone of aortic valve imaging as it is cheap, widely available and provides critical information concerning valve hemodynamics and ventricular function.

RECENT FINDINGS

Whilst diagnostic in the vast majority of patients, echocardiography has certain limitations including operator variability, potential for measurement errors and internal inconsistencies in severity grading. In particular, low-gradient severe aortic stenosis is common and challenging to diagnose. Aortic valve imaging may therefore be improved with alternative and complimentary multimodality approaches.

SUMMARY

This review investigates established and novel techniques for imaging both the aortic valve and the myocardial remodelling response including echocardiography, computed tomography, cardiovascular magnetic resonance and positron emission tomography. Moreover, we examine how the complementary information provided by each modality may be used in both future clinical practice and the research arena.

Superiority of the extracellular volume fraction over the myocardial T1 value for the assessment of myocardial fibrosis in patients with non-ischemic cardiomyopathy

PURPOSE

This study aimed to assess the efficacies of the myocardial T1 value and the extracellular volume fraction (ECV) for determining the severity of myocardial fibrosis in patients with non-ischemic cardiomyopathy.

MATERIALS AND METHODS

Myocardial fibrosis is considered the most important indicator of cardiac damage associated with non-ischemic cardiomyopathy. Recently, modified Look-Locker inversion recovery imaging (MOLLI) has been used for T1 mapping and measurement of the ECV for the assessment of myocardial fibrosis. The present study included 22 patients (mean age, 61.5±12.7; 21 male) with non-ischemic heart failure. Motion corrected myocardial T1 mapping was automatically performed using a MOLLI sequence, and the ECV was estimated from the pre- and post-contrast blood and myocardial T1 values corrected for the hematocrit level. All endomyocardial biopsy specimens were obtained from the inferoposterior left ventricular wall. The percentage of myocardial fibrosis (%F) was determined after Elastica Masson-Goldner staining as follows: (fibrosis area/[fibrosis area+myocardial area])×100.

RESULTS

No correlation was noted between the %F and the pre- (r=0.290, p=0.191) or post-contrast T1 values (r=-0.190, p=0.398); however, a significant correlation was noted between the %F and ECV (r=0.750, p<0.001).

CONCLUSIONS

In this study, the ECV reflected the extent of myocardial fibrosis, but the pre- and post-contrast T1 values did not. The ECV may be used to estimate the severity of myocardial fibrosis in patients with non-ischemic cardiomyopathy.

Retinoic acid and sodium butyrate suppress the cardiac expression of hypertrophic markers and proinflammatory mediators in Npr1 gene-disrupted haplotype mice

The objective of the present study was to examine the genetically determined differences in the natriuretic peptide receptor-A (NPRA) gene (Npr1) copies affecting the expression of cardiac hypertrophic markers, proinflammatory mediators, and matrix metalloproteinases (MMPs) in a gene-dose-dependent manner. We determined whether stimulation of Npr1 by all-trans retinoic acid (RA) and histone deacetylase (HDAC) inhibitor sodium butyric acid (SB) suppress the expression of cardiac disease markers. In the present study, we utilized Npr1 gene-disrupted heterozygous (Npr1(+/-), 1-copy), wild-type (Npr1(+/+), 2-copy), gene-duplicated (Npr1(++/+), 3-copy) mice, which were treated intraperitoneally with RA, SB, and a combination of RA/SB, a hybrid drug (HB) for 2 wk. Untreated 1-copy mice showed significantly increased heart weight-body weight (HW/BW) ratio, blood pressure, hypertrophic markers, including beta-myosin heavy chain (β-MHC) and proto-oncogenes (c-fos and c-jun), proinflammatory mediator nuclear factor kappa B (NF-κB), and MMPs (MMP-2, MMP-9) compared with 2-copy and 3-copy mice. The heterozygous (haplotype) 1-copy mice treated with RA, SB, or HB, exhibited significant reduction in the expression of β-MHC, c-fos, c-jun, NF-κB, MMP-2, and MMP-9. In drug-treated animals, the activity and expression levels of HDAC were significantly reduced and histone acetyltransferase activity and expression levels were increased. The drug treatments significantly increased the fractional shortening and reduced the systolic and diastolic parameters of the Npr1(+/-) mice hearts. Together, the present results demonstrate that a decreased Npr1 copy number enhanced the expression of hypertrophic markers, proinflammatory mediators, and MMPs, whereas an increased Npr1 repressed the cardiac disease markers in a gene-dose-dependent manner.

Assessment of myocardial fibrosis with T1 mapping MRI

Myocardial fibrosis can arise from a range of pathological processes and its presence correlates with adverse clinical outcomes. Cardiac magnetic resonance (CMR) can provide a non-invasive assessment of cardiac structure, function, and tissue characteristics, which includes late gadolinium enhancement (LGE) techniques to identify focal irreversible replacement fibrosis with a high degree of accuracy and reproducibility. Importantly the presence of LGE is consistently associated with adverse outcomes in a range of common cardiac conditions; however, LGE techniques are qualitative and unable to detect diffuse myocardial fibrosis, which is an earlier form of fibrosis preceding replacement fibrosis that may be reversible. Novel T1 mapping techniques allow quantitative CMR assessment of diffuse myocardial fibrosis with the two most common measures being native T1 and extracellular volume (ECV) fraction. Native T1 differentiates normal from infarcted myocardium, is abnormal in hypertrophic cardiomyopathy, and may be particularly useful in the diagnosis of Anderson-Fabry disease and amyloidosis. ECV is a surrogate measure of the extracellular space and is equivalent to the myocardial volume of distribution of the gadolinium-based contrast medium. It is reproducible and correlates well with fibrosis on histology. ECV is abnormal in patients with cardiac failure and aortic stenosis, and is associated with functional impairment in these groups. T1 mapping techniques promise to allow earlier detection of disease, monitor disease progression, and inform prognosis; however, limitations remain. In particular, reference ranges are lacking for T1 mapping values as these are influenced by specific CMR techniques and magnetic field strength. In addition, there is significant overlap between T1 mapping values in healthy controls and most disease states, particularly using native T1, limiting the clinical application of these techniques at present.

Effects of Heterogeneous Diffuse Fibrosis on Arrhythmia Dynamics and Mechanism

Myocardial fibrosis is an important risk factor for cardiac arrhythmias. Previous experimental and numerical studies have shown that the texture and spatial distribution of fibrosis may play an important role in arrhythmia onset. Here, we investigate how spatial heterogeneity of fibrosis affects arrhythmia onset using numerical methods. We generate various tissue textures that differ by the mean amount of fibrosis, the degree of heterogeneity and the characteristic size of heterogeneity. We study the onset of arrhythmias using a burst pacing protocol. We confirm that spatial heterogeneity of fibrosis increases the probability of arrhythmia induction. This effect is more pronounced with the increase of both the spatial size and the degree of heterogeneity. The induced arrhythmias have a regular structure with the period being mostly determined by the maximal local fibrosis level. We perform ablations of the induced fibrillatory patterns to classify their type. We show that in fibrotic tissue fibrillation is usually of the mother rotor type but becomes of the multiple wavelet type with increase in tissue size. Overall, we conclude that the most important factor determining the formation and dynamics of arrhythmia in heterogeneous fibrotic tissue is the value of maximal local fibrosis.

Prognostic value of collagen turnover biomarkers in cardiac resynchronization therapy: A subanalysis of the TRUST CRT randomized trial population

BACKGROUND

A substantial proportion of patients do not respond to cardiac resynchronization therapy (CRT). Various echocardiographic and biochemical markers including collagen turnover biomarkers were suggested to predict CRT results. However, pathological significance of collagen turnover biomarkers in CRT remains controversial.

OBJECTIVE

The aim of the present study was to evaluate the relationship between levels of collagen turnover biomarkers (amino-terminal propeptide of procollagen type I and amino-terminal propeptide of procollagen type III [PIIINP]), N-terminal of the prohormone brain natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein, and matrix metalloproteinases (metalloproteinase-2 and metalloproteinase-9) and echocardiographic response to CRT and clinical outcomes.

METHODS

The study population consisted of patients enrolled in the Triple Site Versus Standard Cardiac Resynchronization Therapy trial. Blood samples were obtained before implantation of a CRT with defibrillator. The levels of PIIINP, amino-terminal propeptide of procollagen type I, metalloproteinase-2, and metalloproteinase-9 were determined using commercially available ELISA kits. High-sensitivity C-reactive protein and NT-proBNP levels were determined in a standard way.

RESULTS

Samples were collected from 74 of 100 enrolled patients. The multivariate logistic regression analysis demonstrated that low PIIINP levels (odds ratio [OR] 3.56; 95% confidence interval [CI] 1.23-10.24; P = .017) and baseline ejection fraction (OR 2.14; 95% CI 1.11-4.11; P = .02) were favorably associated with echocardiographic response. PIIINP and NT-proBNP levels appeared to be independent predictors of all-cause mortality (PIIINP: OR 3.11; 95% CI 1.21-7.89; P = .033; NT-proBNP: OR 2.05; 95% CI 1.11-4.96; P = .039) and risk of major cardiac adverse event (PIIINP: OR 3.56; 95% CI 1.53-9.15; P = .007; NT-proBNP: OR 4.51; 95% CI 1.75-11.6; P = .001). PIIINP levels showed significant additive value in predicting mortality as compared with NT-proBNP levels, but they were not superior to ejection fraction in predicting response. Survival analysis with cutoff values identified by receiver operating characteristic analysis confirmed a significant benefit associated with low baseline PIIINP levels.

CONCLUSION

Low PIIINP levels are associated with favorable echocardiographic response and long-term survival in CRT recipients.

Cardiac Remodeling: Concepts, Clinical Impact, Pathophysiological Mechanisms and Pharmacologic Treatment

Cardiac remodeling is defined as a group of molecular, cellular and interstitial changes that manifest clinically as changes in size, mass, geometry and function of the heart after injury. The process results in poor prognosis because of its association with ventricular dysfunction and malignant arrhythmias. Here, we discuss the concepts and clinical implications of cardiac remodeling, and the pathophysiological role of different factors, including cell death, energy metabolism, oxidative stress, inflammation, collagen, contractile proteins, calcium transport, geometry and neurohormonal activation. Finally, the article describes the pharmacological treatment of cardiac remodeling, which can be divided into three different stages of strategies: consolidated, promising and potential strategies.

Mitigation of myocardial fibrosis by molecular cardiac surgery-mediated gene overexpression

OBJECTIVE

Heart failure is accompanied by up-regulation of transforming growth factor beta signaling, accumulation of collagen and dysregulation of sarcoplasmic reticulum calcium adenosine triphosphatase cardiac isoform 2a (SERCA2a). We examined the fibrotic response in small and large myocardial infarct, and the effect of overexpression of the SERCA2a gene.

METHODS

Ischemic cardiomyopathy was induced via creation of large or small infarct in 26 sheep. Animals were divided into 4 groups: small infarct; large infarct with heart failure; gene-treated (large infarct with heart failure followed by adeno-associated viral vector, serotype 1.SERCA2a gene construct transfer by molecular cardiac surgery with recirculating delivery); and control.

RESULTS

Heart failure was significantly less pronounced in the gene-treated and small-infarct groups than in the large-infarct group. Expression of transforming growth factor beta signaling components was significantly higher in the large-infarct group, compared with the small-infarct and gene-treated groups. Both the angiotensin II type 1 receptor and angiotensin II were significantly elevated in the small- and large-infarct groups, whereas gene treatment diminished this effect. Active fibrosis with de novo collagen synthesis was evident in the large-infarct group; the small-infarct and gene-treated groups showed less fibrosis, with a lower ratio of de novo to mature collagen.

CONCLUSIONS

The data presented provide evidence that progression of fibrosis is mediated through increased transforming growth factor beta and angiotensin II signaling, which is mitigated by increased SERCA2a gene expression.