Circulating biomarkers of hypertrophy and fibrosis in patients with hypertrophic cardiomyopathy assessed by cardiac magnetic resonance

Cardiac Fibrosis in heart failure: Focus on non-invasive diagnosis and emerging therapeutic strategies

Heart failure is a leading cause of mortality and hospitalization worldwide. Cardiac fibrosis, resulting from the excessive deposition of collagen fibers, is a common feature across the spectrum of conditions converging in heart failure. Eventually, either reparative or reactive in nature, in the long-term cardiac fibrosis contributes to heart failure development and progression and is associated with poor clinical outcomes. Despite this, specific cardiac antifibrotic therapies are lacking, making cardiac fibrosis an urgent unmet medical need. In this context, a better patient phenotyping is needed to characterize the heterogenous features of cardiac fibrosis to advance toward its personalized management. In this review, we will describe the different phenotypes associated with cardiac fibrosis in heart failure and we will focus on the potential usefulness of imaging techniques and circulating biomarkers for the non-invasive characterization and phenotyping of this condition and for tracking its clinical impact. We will also recapitulate the cardiac antifibrotic effects of existing heart failure and non-heart failure drugs and we will discuss potential strategies under preclinical development targeting the activation of cardiac fibroblasts at different levels, as well as targeting additional extracardiac processes.

Evaluation of global and regional myocardial work in hypertrophic cardiomyopathy patients by left ventricular pressure-strain loop

OBJECTIVE

This study aimed to investigate the value of left ventricular (LV) press-strain loop (PSL) in evaluating global and regional myocardial work (MW) in hypertrophic cardiomyopathy (HCM) patients.

METHODS

A total of 30 HCM patients with interventricular septum hypertrophy (HCM group) and 35 healthy subjects (control group) were selected from First Hospital of Qinhuangdao. The general clinical data and conventional ultrasound parameters of two groups were acquired. The MW parameters were analyzed using LV PSL. The regional MW parameters in the HCM group were compared between ventricular septum and the free walls of left ventricle.

RESULTS

The epicardial adipose tissue thickness of the HCM group was significantly greater than that of the control group (P < 0.05). Global work efficiency was significantly reduced, while global wasted work was increased in patients with HCM compared with controls (all P < 0.05). The HCM group was compared in the group, to be specific, in the HCM group, the work index, the work efficiency, and the longitudinal strain on the interventricular septum were lower than those on the free wall (all P < 0.05).

CONCLUSION

PSL is more effective than LVEF in assessing left ventricular systolic function in HCM and is able to quantify regional myocardial work in the ventricular septum in HCM patients with preserved LVEF, suggesting a novel idea for clinical diagnosis and assessment.

Increase in skeletal muscle extracellular volume as an under-recognised change detected at cardiac MRI in hypertrophic cardiomyopathy

AIM

To explore skeletal muscle change and its correlation with the myocardium in hypertrophic cardiomyopathy (HCM) using cardiac magnetic resonance imaging (cMRI) with T1 mapping and late gadolinium enhancement (LGE).

MATERIALS AND METHODS

This retrospective study enrolled 50 HCM patients and 35 healthy controls. The extracellular volume (ECV) of the skeletal muscle and myocardium, the presence and absence of LGE of the myocardium, and cardiac troponin T (cTnT), were assessed. In the HCM group, the elevated ECV_skeletal group was defined as ECV_skeletal >2 standard deviations (SD) above the mean value of the controls. Statistical analyses included Student's t-test, the Mann-Whitney U-test, and linear regression.

RESULTS

ECV_skeletal in the HCM group was higher than in the control group (mean 13.0 versus 10.9%; p<0.001), with 20 (40%) HCM patients having elevated ECV_skeletal (ECV_skeletal ≥13.7%). In the HCM group, ECV_skeletal had a positive linear correlation with global myocardial ECV (r=0.37, p=0.009). In addition, the elevated ECV_skeletal group had a higher cTnT than the non-elevated group (log cTnT, mean 1.55 versus 1.16, p=0.045). Furthermore, segmental myocardial ECV in the elevated ECV_skeletal group was higher than in the non-elevated group, despite the presence or absence of myocardial LGE (median 30.1 versus 27.2%; 26.5 versus 24.6%, both p<0.001) or hypertrophy (median 29.0 versus 26.0%; 26.8 versus 24.8%, both p<0.001).

CONCLUSION

In the HCM patients, ECV_skeletal was higher than in the healthy controls. Furthermore, some ECV_skeletal changes had corresponding changes in the cTnT and myocardium.

Integrating Cardiac MRI Imaging and Multidisciplinary Clinical Care is Associated With Improved Outcomes in Patients With Fabry Disease

Given the inherent complexities of Fabry disease (FD) and evolving landscape of cardiovascular clinical management, there is no established ideal clinical care model for these patients. We identified clinical factors predictive of increased risk of major adverse cardiac events (MACE) in patients with FD targeted to improve clinical outcomes. Ninety-five patients studied over a median follow-up time of 6.3 years, and 26 patients reached the composite endpoint with a high prevalence of heart failure and cerebrovascular events and no cardiac-related mortality. Patients with MACE had worse health-related quality of life scores. Hypertrophy and presence of myocardial fibrosis increase risk of MACE by 4-5 times, and dyslipidemia increases risk of MACE by 3 times. Early Fabry-specific treatment and close monitoring of comorbidities reduce cardiac complications and mortality. These findings highlight the importance of comprehensive multidisciplinary management to help improve outcomes in FD patients.

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.

Association of NT-proBNP and hs-cTnT with Imaging Markers of Diastolic Dysfunction and Focal Myocardial Fibrosis in Hypertrophic Cardiomyopathy

Serum biomarkers such as N-terminal prohormone of the brain natriuretic peptide (NT-proBNP) and cardiac troponins are elevated in patients with hypertrophic cardiomyopathy (HCM). At present, it is not clear if these markers are associated with distinct clinical alterations in HCM, such as left ventricular hypertrophy, outflow tract obstruction, myocardial fibrosis and/or diastolic dysfunction (DD), which are associated with adverse cardiovascular outcome. Here we evaluate the association of NT-proBNP and high sensitivity cardiac troponin T (hs-cTnT) to a variety of cardiac imaging parameters in HCM patients in a multivariable regression analysis. This retrospective cross-sectional study included 366 HCM patients who underwent transthoracic echocardiography (TTE), 218 of whom also obtained cardiovascular magnetic resonance (CMR) to assess focal myocardial fibrosis by LGE. Multivariable regression analyses revealed the strongest association of the DD parameters E/E′ mean and E/E′ septal with NT-proBNP (b = 0.06, 95%-CI [0.05−0.07], p < 0.001, R2 = 0.28; b = 0.08, 95%-CI [0.06−0.1], p < 0.001, R2 = 0.25) and LGE size showed the strongest association with hs-cTnT (b = 0.20, 95%-CI [0.15−0.24], p < 0.001, R2 = 0.28). This study indicates that NT-proBNP and hs-cTnT are associated with structural and functional alterations in HCM. NT-proBNP is a stronger predictor for DD, while hs-cTnT is associated with the extent of focal myocardial fibrosis. Both biomarkers might be useful in the diagnostic procedure in addition to imaging parameters.

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.

Comprehensive Proteomics Profiling Identifies Patients With Late Gadolinium Enhancement on Cardiac Magnetic Resonance Imaging in the Hypertrophic Cardiomyopathy Population

Introduction

In hypertrophic cardiomyopathy (HCM), late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR) represents myocardial fibrosis and is associated with sudden cardiac death. However, CMR requires particular expertise and is expensive and time-consuming. Therefore, it is important to specify patients with a high pre-test probability of having LGE as the utility of CMR is higher in such cases. The objective was to determine whether plasma proteomics profiling can distinguish patients with and without LGE on CMR in the HCM population.

Materials and Methods

We performed a multicenter case-control (LGE vs. no LGE) study of 147 patients with HCM. We performed plasma proteomics profiling of 4,979 proteins. Using the 17 most discriminant proteins, we performed logistic regression analysis with elastic net regularization to develop a discrimination model with data from one institution (the training set; n = 111) and tested the discriminative ability in independent samples from the other institution (the test set; n = 36). We calculated the area under the receiver-operating-characteristic curve (AUC), sensitivity, and specificity.

Results

Overall, 82 of the 147 patients (56%) had LGE on CMR. The AUC of the 17-protein model was 0.83 (95% confidence interval [CI], 0.75–0.90) in the training set and 0.71 in the independent test set for validation (95% CI, 0.54–0.88). The sensitivity of the training model was 0.72 (95% CI, 0.61–0.83) and the specificity was 0.78 (95% CI, 0.66–0.90). The sensitivity was 0.71 (95% CI, 0.49–0.92) and the specificity was 0.74 (95% CI, 0.54–0.93) in the test set. Based on the discrimination model derived from the training set, patients in the test set who had high probability of having LGE had a significantly higher odds of having LGE compared to those who had low probability (odds ratio 29.6; 95% CI, 1.6–948.5; p = 0.03).

Conclusions

In this multi-center case-control study of patients with HCM, comprehensive proteomics profiling of 4,979 proteins demonstrated a high discriminative ability to distinguish patients with and without LGE. By identifying patients with a high pretest probability of having LGE, the present study serves as the first step to establishing a panel of circulating protein biomarkers to better inform clinical decisions regarding CMR utilization.

Long non-coding RNA THRIL is upregulated in coronary heart disease and binds to microRNA-424 to upregulate TXNIP in mice

Cardiovascular disease, particularly coronary heart disease (CHD), is one of the diseases with the highest fatality. The close correlation between long non-coding RNAs (lncRNAs) and the occurrence and development of myocardial injury has been highlighted recently. This article mainly focused on the regulation of THRIL on myocardial injury caused by CHD in mice. After establishment of a mouse model with CHD, a lncRNA microarray analysis was performed on mouse myocardial tissues to detect differentially expressed lncRNAs, followed by RT-qPCR validation. CHD was induced in mice by high-fat diet feeding and THRIL was silenced using si-THRIL. The results showed that treating CHD mice with si-THRIL attenuated myocardial damage by restoring LVEF, LVFS, and HDL-C levels, while lowering HMI, LVMI, TC, TG, LDL-C, CK-MB, and cTnI levels. Meanwhile, mechanistical studies using bioinformatics prediction, dual-luciferase and subcellular fractionation assays revealed that THRIL bound to microRNA (miR)-424, inhibited miR-424 interaction with TXNIP and promoted TXNIP expression in the myocardial tissues. The cardioprotective effects of si-THRIL on mice were attenuated when miR-424 was downregulated. Moreover, TXNIP exerted its effects on myocardial injury by mediating the p53 pathway. Taken together, this study demonstrated that THRIL inhibition alleviates myocardial injury in CHD possibly through the miR-424/TXNIP/p53 axis.

Circulating miR-19b-3p as a Novel Prognostic Biomarker for Acute Heart Failure

Background Circulating microRNAs are emerging biomarkers for heart failure (HF). Our study aimed to assess the prognostic value of microRNA signature that is differentially expressed in patients with acute HF. Methods and Results Our study comprised a screening cohort of 15 patients with AHF and 5 controls, a PCR-discovery cohort of 50 patients with AHF and 26 controls and a validation cohort of 564 patients with AHF from registered study DRAGON-HF (Diagnostic, Risk Stratification and Prognostic Value of Novel Biomarkers in Patients With Heart Failure). Through screening by RNA-sequencing and verification by reverse-transcription quantitative polymerase chain reaction, 9 differentially expressed microRNAs were verified (miR-939-5p, miR-1908-5p, miR-7706, miR-101-3p, miR-144-3p, miR-4732-3p, miR-3615, miR-484 and miR-19b-3p). Among them, miR-19b-3p was identified as the microRNA signature with the highest fold-change of 8.4 and the strongest prognostic potential (area under curve with 95% CI, 0.791, 0.654-0.927). To further validate its prognostic value, in the validation cohort, the baseline level of miR-19b-3p was measured. During a follow-up period of 19.1 (17.7, 20.7) months, primary end point comprising of all-cause mortality or readmission due to HF occurred in 48.9% patients, while patients in the highest quartile of miR-19b-3p level presented the worst survival (Log-rank P<0.001). Multivariate Cox model showed that the level of miR-19b-3p could independently predict the occurrence of primary end point (adjusted hazard ratio,1.39; 95% CI, 1.18-1.64). In addition, miR-19b-3p positively correlated with soluble suppression of tumorigenicity 2 and echocardiographic indexes of left ventricular hypertrophy. Conclusions Circulating miR-19b-3p could be a valuable prognostic biomarker for AHF. In addition, a high level of circulating miR-19b-3p might indicate ventricular hypertrophy in AHF subjects. Registration URL: https://www.clinicaltrials.gov. Unique Identifier: NCT03727828.

Correlation between serum miR-122 and myocardial damage and ventricular function in patients with essential hypertension

Background

Myocardial damage and decreased ventricular function are risk factors leading to a bad prognosis in patients with essential hypertension (EH). MicroRNAs play important roles in myocardial function impairment in patients with hypertension. The purpose of our research was to investigate the correlation between serum miR-122 and myocardial damage and ventricular functions in EH patients.

Methods

The clinic data of EH patients (group A, n=60) and healthy individuals (group B, n=60) from December 2016 to December 2019 in our hospital were collected and analyzed. Serum miR-122, myocardial damage markers [B-type brain natriuretic peptide (BNP), homocysteine (Hcy), cardiac troponin T (cTnT) and creatine kinase MB isoenzyme (CK-MB)] and cardiac function indicators [ejection fraction (EF), left ventricular septal thickness (IVST), left ventricular isovolumic relaxation time (IVRT), left ventricular end-diastolic diameter (LVEDD), left ventricular posterior wall thickness (LVPWT), and left ventricular end-systolic diameter (LVESD)] were assessed in both groups. The correlation between serum miR-122 and myocardial damage markers and ventricular function indicators was analyzed.

Results

(I) The mean serum miR-122 concentration in group A and group B was 6.86±1.23 and 3.36±1.87 µmol/L, respectively. The serum miR-122 concentration in group A was evidently increased compared with that in group B. (II) The levels of BNP, Hcy, cTnT, and CK-MB in the peripheral blood in group A were evidently increased compared with those in group B (P<0.05). (III) EF and IVRT were evidently decreased in group A compared with that in group B (P<0.05). (IV) Serum miR-122 concentration was positively correlated with the myocardial damage markers BNP, Hcy, cTnT and CK-MB, and serum miR-122 concentration was negatively correlated with the ventricular function indicators EF and IVRT but not significantly correlated with other ventricular function indicators (IVST, LVEDD, LVPWT and LVESD).

Conclusions

The serum miR-122 concentration in EH patients was higher than that in healthy individuals, and miR-122 concentration was positively correlated with myocardial damage markers. Serum miR-122 level was negatively correlated with the ventricular function indicators EF and IVRT but was not significantly correlated with other ventricular function indicators (IVST, LVEDD, LVPWT, and LVESD).

Increased ratio of sST2/LVMI predicted cardiovascular mortality and heart failure rehospitalization in heart failure with reduced ejection fraction patients: a prospective cohort study

Background

Inflammation is one of the principal triggering mechanisms for left ventricular fibrosis and remodeling in heart failure, leading to adverse clinical outcomes. Soluble suppression of tumorigenicity 2 (sST2), a member of the interleukin-1 receptor family, is assumed to play a significant role in the fibrotic response to inflammation. Left ventricular mass index (LVMI) is a parameter of the prefibrotic inflammatory phase of heart failure preceding remodeling. The present study aimed to investigate the prognostic value of the sST2/LVMI ratio in heart failure with reduced ejection fraction.

Methods

This was a prospective cohort study. A total of 45 consecutive patients with heart failure with reduced ejection fraction, treated between September 2015 and December 2016, were enrolled. The sST2/LVMI ratio was measured at baseline. The primary endpoint was a composite of cardiovascular mortality and readmission for heart failure. The prognostic impact of the sST2/LVMI ratio was evaluated using a multivariable Cox proportional hazards regression model.

Results

Forty-five patients were enrolled in this study. Their average age was 48 ± 14 years, and approximately 20% of them were men. Patients were followed for 9 months, during which the primary outcome occurred in 15 patients. Kaplan–Meier analysis showed that patients with a high sST2/LVMI ratio (≥ 0.39) had shorter event-free survival than those with intermediate (between 0.39 and 0.24) and low ratios (< 0.24) (log-rank, P = 0.022). The fully adjusted multivariable Cox regression analysis showed that the sST2/LVMI ratio was positively associated with the composite outcome in patients with heart failure with reduced ejection fraction after adjusting for confounders (hazard ratio 1.64, 95% confidence interval 1.06 to 2.54). By subgroup analysis, a stronger association was found with age between 40 and 55 years, systolic blood pressure < 115 or ≥ 129 mmHg, diastolic blood pressure < 74 mmHg, hematocrit < 44.5%, and interventricular septum thickness ≥ 8.5 mm.

Conclusion

In patients with heart failure with reduced ejection fraction, the relationship between the sST2/LVMI ratio and the composite outcome was linear. A higher baseline ratio of sST2/LVMI was associated with an increased risk of cardiovascular mortality and heart failure rehospitalization in the short-term follow-up.

Predictive values of multiple non-invasive markers for myocardial fibrosis in hypertrophic cardiomyopathy patients with preserved ejection fraction

Myocardial fibrosis assessed by late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR) is associated with cardiovascular outcomes in hypertrophic cardiomyopathy (HCM) patients, but little is known about the utility of non-invasive markers for detecting LGE. This study aims to explore the association between cardiac-specific biomarkers, CMR myocardial strain, left ventricular (LV) hypertrophy and LGE in HCM patients with preserved ejection fraction (EF) and investigate the predictive values of these indexes for LGE. We recruited 33 healthy volunteers and 86 HCM patients with preserved EF to undergo contrast-enhanced CMR examinations. In total, 48 of 86 HCM patients had the presence of LGE. The LGE-positive patients had significant higher serum high-sensitivity cardiac troponin I (hs-cTnI) and N-terminal pro b-type natriuretic peptide (Nt-proBNP) levels and lower global longitudinal (GLS) and circumferential (GCS) strains than the LGE-negative group. The LGE% was independently associated with the Nt-proBNP levels, GCS, LV end-diastolic maximum wall thickness (MWT) and beta-blocker treatment. In the receiver operating characteristic curve analysis, the combined parameters of Nt-proBNP ≥ 108.00 pg/mL and MWT ≥ 17.30 mm had good diagnostic performance for LGE, with a specificity of 81.25% and sensitivity of 70.00%. These data indicate that serum Nt-proBNP is a potential biomarker associated with LGE% and, combined with MWT, were useful for identifying myocardial fibrosis in HCM patients with preserved EF. Additionally, LV GCS may be a more sensitive indicator for reflecting the presence of myocardial fibrosis than GLS.

Growth differentiation factor 15 as mortality predictor in heart failure patients with non-reduced ejection fraction

Aims

The prognostic value of biomarkers in patients with heart failure (HF) and mid‐range (HFmrEF) or preserved ejection fraction (HFpEF) has not been widely addressed. The aim of this study was to assess whether the prognostic value of growth differentiation factor 15 (GDF‐15) is superior to that of N‐terminal pro‐brain natriuretic peptide (NT‐proBNP) in patients with HFmrEF or HFpEF.

Methods and results

Heart failure patients with either HFpEF or HFmrEF were included in the study. During their first visit to the HF unit, serum samples were obtained and stored for later assessment of GDF‐15 and NT‐proBNP concentrations. Patients were followed up by the HF unit. The main endpoint was all‐cause mortality. A total of 311 patients, 90 (29%) HFmrEF and 221 (71%) HFpEF, were included. Mean age was 72 ± 13 years, and 136 (44%) were women. No differences were found in GDF‐15 or NT‐proBNP concentrations between both HF groups. During a median follow‐up of 15 months (Q1–Q3: 9–30 months), 98 patients (32%) died, most (71%) of cardiovascular causes. Patients who died had higher median concentrations of GDF‐15 (4085 vs. 2270 ng/L, P < 0.0001) and NT‐proBNP (1984 vs. 1095 ng/L, P < 0.0001). A Cox multivariable model identified New York Heart Association Functional Class III (P = 0.04), systolic blood pressure (P = 0.01), left atrial diameter (P = 0.03), age >65 years (P < 0.0001), and GDF‐15 concentrations (P = 0.01) but not NT‐proBNP as independent predictors of all‐cause mortality. The area under the curve was 0.797 for the basic model including NT‐proBNP, and the area under the curve comparing the overall model was 0.819, P = 0.016 (DeLong's test). Integrated discrimination improvement index after the inclusion of GDF‐15 in the model with the mortality risk factors was 0.033; that is, the ability to predict death increased by 3.3% (P = 0.004). Net reclassification improvement was 0.548 (P < 0.001); that is, the capacity to improve the classification of the event (mortality) was 54.8%. GDF‐15 concentrations were divided in tertiles (<1625, 1625–4330, and >4330 ng/L), and survival curves were evaluated using the Kaplan–Meier technique. Patients in the highest tertile had the poorest 5 year survival, at 16%, whereas the lowest tertile had the best survival, of 78% (P < 0.001).

Conclusions

Growth differentiation factor 15 was superior to NT‐proBNP for assessing prognosis in patients with HFpEF and HFmrEF. GDF‐15 emerges as a strong, independent biomarker for identifying HFmrEF and HFpEF patients with worse prognosis.

Effect of feline characteristics on plasma N-terminal-prohormone B-type natriuretic peptide concentration and comparison of a point-of-care test and an ELISA test

BACKGROUND

Increased plasma concentration of N-terminal-prohormone B-type natriuretic peptide (NT-proBNP) can be detected in cats with cardiac disease. Potential effects of feline characteristics on NT-proBNP concentration may influence clinical usefulness.

OBJECTIVES

To evaluate potential effects of feline characteristics on NT-proBNP plasma concentration and to compare NT-proBNP plasma concentrations in healthy cats with results in hypertrophic cardiomyopathy (HCM) cats with or without left atrial enlargement (LAE) using an ELISA and a point-of-care test (POCT), and assess if POCT results reflect ELISA results.

ANIMALS

One hundred healthy cats of 3 breeds and 39 HCM cats were included.

METHODS

Diseases other than HCM were excluded by physical examination, blood pressure measurement, echocardiography, hematology, and serum biochemistry.

RESULTS

Higher NT-proBNP concentrations were found in males than in females in healthy (P = .005) and in HCM cats (P = .0021), but breed had no effect on NT-proBNP concentrations. Using ≥100 pmol/L as a cutoff for abnormal samples, ELISA and POCT had similar sensitivity (SE; 72 and 74%) and specificity (SP; 97 and 98%) for detecting cats with HCM, cats with HCM and LAE (SE, both 100%; SP, 97 versus 98%), and cats with HCM without LAE (SE, both 69%; SP, 97 versus 98%), respectively, when compared to healthy cats.

CONCLUSIONS AND CLINICAL IMPORTANCE

Breed had no effect on plasma NT-proBNP concentrations, but higher concentrations were found in male than in female cats. The ELISA and POCT had similar SE and SP for detecting HCM. Both tests could identify all HCM cats with LAE but not all HCM cats without LAE.

Mechanisms of cardiac collagen deposition in experimental models and human disease

The inappropriate deposition of extracellular matrix within the heart (termed cardiac fibrosis) is associated with nearly all types of heart disease, including ischemic, hypertensive, diabetic, and valvular. This alteration in the composition of the myocardium can physically limit cardiomyocyte contractility and relaxation, impede electrical conductivity, and hamper regional nutrient diffusion. Fibrosis can be grossly divided into 2 types, namely reparative (where collagen deposition replaces damaged myocardium) and reactive (where typically diffuse collagen deposition occurs without myocardial damage). Despite the widespread association of fibrosis with heart disease and general understanding of its negative impact on heart physiology, it is still not clear when collagen deposition becomes pathologic and translates into disease symptoms. In this review, we have summarized the current knowledge of cardiac fibrosis in human patients and experimental animal models, discussing the mechanisms that have been deduced from the latter in relation to the former. Because assessment of the extent of fibrosis is paramount both as a research tool to further understanding and as a clinical tool to assess patients, we have also summarized the current state of noninvasive/minimally invasive detection systems for cardiac fibrosis. Albeit not exhaustive, our aim is to provide an overview of the current understanding of cardiac fibrosis, both clinically and experimentally.