Surrogate markers of gut dysfunction are related to heart failure severity and outcome-from the BIOSTAT-CHF consortium.

BACKGROUND: The contribution of gut dysfunction to heart failure (HF) pathophysiology is not routinely assessed. We sought to investigate whether biomarkers of gut dysfunction would be useful in assessment of HF (eg, severity, adverse outcomes) and risk stratification. METHODS: A panel of gut-related biomarkers including metabolites of the choline/carnitine- pathway (acetyl-L-carnitine, betaine, choline, γ-butyrobetaine, L-carnitine and trimethylamine-N-oxide [TMAO]) and the gut peptide, Trefoil factor-3 (TFF-3), were investigated in 1,783 patients with worsening HF enrolled in the systems BIOlogy Study to TAilored Treatment in Chronic Heart Failure (BIOSTAT-CHF) cohort and associations with HF severity and outcomes, and use in risk stratification were assessed. RESULTS: Metabolites of the carnitine-TMAO pathway (acetyl-L-carnitine, γ-butyrobetaine, L-carnitine, and TMAO) and TFF-3 were associated with the composite outcome of HF hospitalization or all-cause mortality at 3 years (hazards ratio [HR] 2.04-2.93 [95% confidence interval {CI} 1.30-4.71] P≤ .002). Combining the carnitine-TMAO metabolites with TFF-3, as a gut dysfunction panel, showed a graded association; a greater number of elevated markers was associated with higher New York Heart Association class (P< .001), higher plasma concentrations of B-type natriuretic peptide (P< .001), and worse outcome (HR 1.90-4.58 [95% CI 1.19-6.74] P≤ 0.008). Addition of gut dysfunction biomarkers to the contemporary BIOSTAT HF risk model also improved prediction for the aforementioned composite outcome (C-statistics P≤ .011, NRI 13.5-21.1 [95% CI 2.7-31.9] P≤ .014). CONCLUSIONS: A panel of biomarkers of gut dysfunction showed graded association with severity of HF and adverse outcomes. Biomarkers as surrogate markers are potentially useful for assessment of gut dysfunction to HF pathophysiology and in risk stratification.

Association of gut-related metabolites with outcome in acute heart failure.

BACKGROUND: Trimethylamine N-oxide (TMAO), a gut-related metabolite, is associated with heart failure (HF) outcomes. However, TMAO is the final product of a complex metabolic pathway (ie, choline/carnitine) that has never been entirely investigated in HF. The present study investigates a panel of metabolites involved in the TMAO-choline/carnitine metabolic pathway for their associations with outcome in acute HF patients. METHODS: In total, 806 plasma samples from acute HF patients were analyzed for TMAO, trimethyllysine, L-carnitine, acetyl-L-carnitine, γ-butyrobetaine, crotonobetaine, trimethylamine, betaine aldehyde, choline, and betaine using a developed liquid chromatography-tandem mass spectrometry method. Associations with outcome of all-cause mortality (death) and a composite of all-cause mortality and/or rehospitalization caused by HF (death/HF) at 30 days and 1 year were investigated. RESULTS: TMAO, trimethyllysine, L-carnitine, acetyl-L-carnitine, and γ-butyrobetaine were associated with death and death/HF at 30 days (short term; hazard ratio 1.30-1.49, P≤ .021) and at 1 year (long term; hazard ratio 1.15-1.25, P≤ .026) when adjusted for cardiac risk factors. L-carnitine and acetyl-L-carnitine were superior for short-term outcomes whereas TMAO was the superior metabolite for association with long-term outcomes. Furthermore, acetyl-L-carnitine and L-carnitine were superior for in-hospital mortality and improved risk stratification when combined with current clinical risk scores (ie, Acute Decompensated HEart Failure National REgistry, Organized Program To Initiate Lifesaving Treatment In Hospitalized Patients With Heart Failure, and Get With The Guidelines-Heart Failure; odds ratio (OR) ≥ 1.52, P≤ .020). CONCLUSIONS: Carnitine-related metabolites show associations with adverse outcomes in acute HF, in particular L-carnitine and acetyl-L-carnitine for short-term outcomes, and TMAO for long-term outcomes. Further studies are warranted to investigate the role and implications of carnitine metabolites including intervention in the pathogenesis of HF.

Exercise Intolerance in Heart Failure with Preserved Ejection Fraction.

Exercise intolerance represents a typical feature of heart failure with preserved ejection fraction (HFpEF), and is associated with a poor quality of life, frequent hospitalizations, and increased all-cause mortality. The cardiopulmonary exercise test is the best method to quantify exercise intolerance, and allows detection of the main mechanism responsible for the exercise limitation, influencing treatment and prognosis. Exercise training programs improve exercise tolerance in HFpEF. However, studies are needed to identify appropriate type and duration. This article discusses the pathophysiology of exercise limitation in HFpEF, describes methods of determining exercise tolerance class, and evaluates prognostic implications and potential therapeutic strategies.

Matrix-assisted laser desorption ionisation (MALDI) mass spectrometry (MS): basics and clinical applications.

Background Matrix-assisted laser desorption ionisation (MALDI) mass spectrometry (MS) has been used for more than 30 years. Compared with other analytical techniques, it offers ease of use, high throughput, robustness, cost-effectiveness, rapid analysis and sensitivity. As advantages, current clinical techniques (e.g. immunoassays) are unable to directly measure the biomarker; rather, they measure secondary signals. MALDI-MS has been extensively researched for clinical applications, and it is set for a breakthrough as a routine tool for clinical diagnostics. Content This review reports on the principles of MALDI-MS and discusses current clinical applications and the future clinical prospects for MALDI-MS. Furthermore, the review assesses the limitations currently experienced in clinical assays, the advantages and the impact of MALDI-MS to transform clinical laboratories. Summary MALDI-MS is widely used in clinical microbiology for the screening of microbial isolates; however, there is scope to apply MALDI-MS in the diagnosis, prognosis, therapeutic drug monitoring and biopsy imaging in many diseases. Outlook There is considerable potential for MALDI-MS in clinic as a tool for screening, profiling and imaging because of its high sensitivity and specificity over alternative techniques.

The Gut Axis Involvement in Heart Failure: Focus on Trimethylamine N-oxide.

A novel pathophysiological model of interest is the association between heart failure (HF) and the gastrointestinal system, the 'gut hypothesis'. The choline and carnitine metabolic by-product, Trimethylamine N-oxide (TMAO) is one of the more prominent molecules associated with the link between HF and the gut. Indeed, TMAO levels are increased in HF populations and higher TMAO levels are associated with poor prognosis, whereas low TMAO levels either at baseline/follow up confer better prognosis. Considering that TMAO levels seem not to be affected by guideline-HF treatment, this model could represent a novel and independent therapeutic target for HF.

Proteomic Biomarkers of Heart Failure.

Heart failure (HF) is associated with significant morbidity and mortality. Biomarkers are used to assist clinicians with timely diagnosis, prognosis, and risk prediction of patients for personalized treatment. Using modern proteomic methods such as mass spectrometry, an increasing number of novel biomarkers have been identified that further aid clinicians in the early diagnosis and outcome prediction of HF. This article focuses on the array of common and novel protein-based biomarkers that provide diagnostic and prognostic information in HF.

Biomarkers in Acute Myocarditis and Chronic Inflammatory Cardiomyopathy: An Updated Review of the Literature.

Myocarditis is a disease caused by cardiac inflammation that can progress to dilated cardiomyopathy, heart failure, and eventually death. Several etiologies, including autoimmune, drug-induced, and infectious, lead to inflammation, which causes damage to the myocardium, followed by remodeling and fibrosis. Although there has been an increasing understanding of pathophysiology, early and accurate diagnosis, and effective treatment remain challenging due to the high heterogeneity. As a result, many patients have poor prognosis, with those surviving at risk of long-term sequelae. Current diagnostic methods, including imaging and endomyocardial biopsy, are, at times, expensive, invasive, and not always performed early enough to affect disease progression. Therefore, the identification of accurate, cost-effective, and prognostically informative biomarkers is critical for screening and treatment. The review then focuses on the biomarkers currently associated with these conditions, which have been extensively studied via blood tests and imaging techniques. The information within this review was retrieved through extensive literature research conducted on major publicly accessible databases and has been collated and revised by an international panel of experts. The biomarkers discussed in the article have shown great promise in clinical research studies and provide clinicians with essential tools for early diagnosis and improved outcomes.

Endothelial Dysfunction and Heart Failure with Preserved Ejection Fraction-An Updated Review of the Literature.

Heart failure (HF) is a clinical syndrome consisting of typical symptoms and signs due to structural and/or functional abnormalities of the heart, resulting in elevated intracardiac pressures and/or inadequate cardiac output. The vascular system plays a crucial role in the development and progression of HF regardless of ejection fraction, with endothelial dysfunction (ED) as one of the principal features of HF. The main ED manifestations (i.e., impaired endothelium-dependent vasodilation, increased oxidative stress, chronic inflammation, leukocyte adhesion, and endothelial cell senescence) affect the systemic and pulmonary haemodynamic and the renal and coronary circulation. The present review is aimed to discuss the contribution of ED to HF pathophysiology-in particular, HF with preserved ejection fraction-ED role in HF patients, and the possible effects of pharmacological and non-pharmacological approaches. For this purpose, relevant data from a literature search (PubMed, Scopus, EMBASE, and Medline) were reviewed. As a result, ED, assessed via venous occlusion plethysmography or flow-mediated dilation, was shown to be independently associated with poor outcomes in HF patients (e.g., mortality, cardiovascular events, and hospitalization due to worsening HF). In addition, SGLT2 inhibitors, endothelin antagonists, endothelial nitric oxide synthase cofactors, antioxidants, and exercise training were shown to positively modulate ED in HF. Despite the need for future research to better clarify the role of the vascular endothelium in HF, ED represents an interesting and promising potential therapeutic target.

The Gut Axis Involvement in Heart Failure: Focus on Trimethylamine N-oxide.

A novel pathophysiological model of interest is the association between heart failure (HF) and the gastrointestinal system, the 'gut hypothesis'. The choline and carnitine metabolic by-product, Trimethylamine N-oxide (TMAO) is one of the more prominent molecules associated with the link between HF and the gut. Indeed, TMAO levels are increased in HF populations and higher TMAO levels are associated with poor prognosis, whereas low TMAO levels either at baseline/follow up confer better prognosis. Considering that TMAO levels seem not to be affected by guideline-HF treatment, this model could represent a novel and independent therapeutic target for HF.

The effects of substrate composition and topography on the characteristics and growth of cell cultures of cochlear fibrocytes.

Spiral ligament fibrocytes of the cochlea play homoeostatic roles in hearing and their degeneration contributes to hearing loss. Culturing fibrocytes in vitro provides a way to evaluate their functional characteristics and study possible therapies for hearing loss. We investigated whether in vivo characteristics of fibrocytes could be recapitulated in vitro by modifying the culture substrates and carried out proof of concept studies for potential transplantation of culture cells into the inner ear. Fibrocytes cultured from 4 to 5-week old CD/1 mice were grown on 2D substrates coated with collagen I, II, V or IX and, after harvesting, onto or into 3D substrates (hydrogels) of collagen I alone or mixed collagen I and II at a 1:1 ratio. We also assessed magnetic nanoparticle (MNP) uptake. Cell counts, immunohistochemical and ultrastructural studies showed that fibrocytes grown on 2D substrates proliferated, formed both small spindle-shaped and large flat cells that avidly took up MNPs. Of the different collagen coatings, only collagen II had an effect, causing a reduced size of the larger cells. On hydrogels, the cells were plump/rounded with extended processes, resembling native cells. They formed networks over the surface and became incorporated into the gel. In all culture formats, the majority co-expressed caldesmon, aquaporin 1, S-100 and sodium potassium ATPase, indicating a mixed or uncharacterised phenotype. Time-course experiments showed a decrease to ∼50% of the starting population by 4d after seeding on collagen I hydrogels, but better survival (∼60%) was found on collagen I + II gels, whilst TEM revealed the presence of apoptotic cells. Cells grown within gels additionally showed necrosis. These results demonstrate that fibrocytes grown in 3D recapitulate in vivo morphology of native fibrocytes, but have poorer survival, compared with 2D. Therefore hydrogel cultures could be used to study fibrocyte function and might also offer avenues for cell-replacement therapies, but need more optimization for therapeutic use. Fibrocyte function could be modified using MNPs in combination, for example, with gene transfection.

Plasma desmosine for prediction of outcomes after acute myocardial infarction.

Background: Elastin degradation is implicated in the pathology of vulnerable plaque. Recent studies show promising results for plasma desmosine (pDES), an elastin-specific degradation product, as a marker of cardiovascular disease (CVD) outcomes. The aim of this study was to investigate the potential role of pDES as a marker of clinical outcome in patients with acute myocardial infarction (AMI). Materials and methods: In this case-control study, we studied 236 AMI patients: 79 patients who had death and/or myocardial infarction (MI) at 2 years, and 157 patients who did not have an event at 2 years. pDES was measured using a validated liquid chromatography-tandem mass spectrometry method. Association of pDES with adverse outcomes, and the incremental value of pDES to global registry of acute coronary events (GRACE) score for risk stratification was assessed. Results: pDES levels were elevated in patients with the composite outcome of death/MI at 2 years (p = 0.002). Logistic regression analyses showed pDES to be associated with death/MI at 2 years [Odds ratio (OR) 5.99 (95% CI 1.81-19.86) p = 0.003]. pDES remained a significant predictor of death/MI at 2 years even after adjustment for age, sex, history of CVD, revascularisation, blood pressure, medications on discharge, Troponin I, and NT-proBNP levels.[OR 5.60 (95% CI 1.04-30.04) p = 0.044]. In another multivariable model including adjustment for eGFR, pDES was significantly associated with the composite outcome at 6 months, but not at 2 years follow up. DES was also able to reclassify risk stratification for death/MI at 6 months, when added to the GRACE risk model [Net Reclassification Index (NRI) 41.2 (95% CI 12.0-70.4) p = 0.006]. Conclusion: pDES concentrations predict clinical outcomes in patients with AMI, demonstrating its potential role as a prognostic marker in AMI.

Association of gut-related metabolites with respiratory symptoms in COVID-19: A proof-of-concept study.

Gut-related metabolites have been linked with respiratory disease. The crosstalk between the gut and lungs suggests that gut health may be compromised in COVID-19. The aims of the present study were to analyze a panel of gut-related metabolites (acetyl-L-carnitine, betaine, choline, L-carnitine, trimethylamine, and trimethylamine N-oxide) in patients with COVID-19, matched with healthy individuals and patients with non-COVID-19 respiratory symptoms. As results, metabolites from this panel were impaired in patients with COVID-19 and were associated with the symptoms of breathlessness and temperature, and it was possible to differentiate between COVID-19 and asthma. Preliminary results showed that lower levels of betaine appeared to be associated with poor outcomes in patients with COVID-19, suggesting betaine as a marker of gut microbiome health.

Effects of Exercise on Heart Failure with Preserved Ejection Fraction: An Updated Review of Literature.

Heart failure with preserved ejection fraction (HFpEF) represents the most common HF phenotype of patients aged > 65 years, with an incidence and a prevalence that are constantly growing. The HFpEF cardinal symptom is exercise intolerance (EI), defined as the impaired ability to perform physical activity and to reach the predicted age-related level of exercise duration in the absence of symptoms­such as fatigue or dyspnea­and is associated with a poor quality of life, a higher number of hospitalizations, and poor outcomes. The evidence of the protective effect between exercise and adverse cardiovascular outcomes is numerous and long-established. Regular exercise is known to reduce cardiovascular events and overall mortality both in apparently healthy individuals and in patients with established cardiovascular disease, representing a cornerstone in the prevention and treatment of many cardio-metabolic conditions. Several studies have investigated the role of exercise in HFpEF patients. The present review aims to dwell upon the effects of exercise on HFpEF. For this purpose, the relevant data from a literature search (PubMed, EMBASE, and Medline) were reviewed. The analysis of these studies underlines the fact that exercise training programs improve the cardiorespiratory performance of HFpEF patients in terms of the increase in peak oxygen uptake, the 6 min walk test distance, and the ventilatory threshold; on the other hand, diastolic or systolic functions are generally unchanged or only partially modified by exercise, suggesting that multiple mechanisms contribute to the improvement of exercise tolerance in HFpEF patients. In conclusion, considering that exercise training programs are able to improve the cardiorespiratory performance of HFpEF patients, the prescription of exercise training programs should be encouraged in stable HFpEF patients, and further research is needed to better elucidate the pathophysiological mechanisms underpinning the beneficial effects described.

Ethnic differences in association of outcomes with trimethylamine N-oxide in acute heart failure patients.

AIMS: The aim of this study was to investigate whether ethnicity influences the associations between trimethylamine N-oxide (TMAO) levels and heart failure (HF) outcomes. METHODS AND RESULTS: Trimethylamine N-oxide levels were measured in two cohorts with acute HF at two sites. The UK Leicester cohort consisted mainly of Caucasian (n = 842, 77%) and South Asian (n = 129, 12%) patients, whereas patients in the Japanese cohort (n = 116, 11%) were all Japanese. The primary endpoint was the measurement of all-cause mortality and/or HF rehospitalization within 1 year post-admission. Association of TMAO levels with outcome was compared in the entire population and between ethnic groups after adjustment for clinical parameters. TMAO levels were significantly higher in Japanese patients [median (interquartile range): 9.9 µM (5.2-22.8)] than in Caucasian [5.9 µM (3.6-10.8)] and South Asian [4.5 µM (3.1-8.4)] (P < 0.001) patients. There were no differences in the rate of mortality and/or HF rehospitalization between the ethnic groups (P = 0.096). Overall, higher TMAO levels showed associations with mortality and/or rehospitalization after adjustment for confounders ( P = 0.002). Despite no differences between ethnicity and association with mortality/HF after adjustment (P = 0.311), only in Caucasian patients were TMAO levels able to stratify for a mortality/HF event (P < 0.001). CONCLUSIONS: Differences were observed in the association of mortality and/or rehospitalization based on circulating TMAO levels. Elevated TMAO levels in Caucasian patients showed increased association with adverse outcomes, but not in non-Caucasian patients.

Biomarkers in Cardiovascular Disease: The Dilemma of Racial Differences.

See Article Hackler et al.