Asymmetric and Symmetric Dimethylarginine Predict Outcomes in Patients With Atrial Fibrillation: An ARISTOTLE Substudy

Cellular and molecular biology of posttranslational modifications in cardiovascular disease

Cardiovascular disease (CVD) has now become the leading cause of death worldwide, and its high morbidity and mortality rates pose a great threat to society. Although numerous studies have reported the pathophysiology of CVD, the exact pathogenesis of all types of CVD is not fully understood. Therefore, much more research is still needed to explore the pathogenesis of CVD. With the development of proteomics, many studies have successfully identified the role of posttranslational modifications in the pathogenesis of CVD, including key processes such as apoptosis, cell metabolism, and oxidative stress. In this review, we summarize the progress in the understanding of posttranslational modifications in cardiovascular diseases, including novel protein posttranslational modifications such as succinylation and nitrosylation. Furthermore, we summarize the currently identified histone deacetylase (HDAC) inhibitors used to treat CVD, providing new perspectives on CVD treatment modalities. We critically analyze the roles of posttranslational modifications in the pathogenesis of CVD-related diseases and explore future research directions related to posttranslational modifications in cardiovascular diseases.

Symmetric Dimethylarginine Predicts Previously Undetected Atrial Fibrillation in Patients With Ischemic Stroke

BACKGROUND

Atrial fibrillation (AF) is a stroke risk factor that often remains undetected at hospital admission. Long-term Holter monitoring helps to identify patients with previously unrecognized AF. Asymmetric (ADMA) and symmetric dimethylarginine (SDMA) are elevated in AF in cross-sectional studies. We analyzed ADMA, SDMA, and other L-arginine metabolites to assess their association with AF in the Find-AF trial.

METHODS AND RESULTS

We included 280 patients presenting with acute cerebral ischemia. Patients presenting in sinus rhythm received 7-day Holter-ECG. Biomarkers were quantified by ultra-performance liquid chromatography-tandem mass spectrometry. We also analyzed protein methylation and L-arginine-related metabolites in human induced pluripotent stem cell-derived cardiomyocytes in vitro. ADMA and SDMA were elevated in 44 patients who presented with AF. SDMA, but not ADMA, was significantly elevated in patients newly diagnosed with AF in Holter-ECG as compared with those in sinus rhythm. SDMA plasma concentration >0.571 μmol/L significantly predicted presence of AF in Holter-ECG (area under the curve=0.676 [0.530-0.822]; P=0.029; sensitivity 0.786, specificity 0.572). SDMA levels further increased in patients with AF during the first 24 hours in hospital, and ADMA levels remained stable. In vitro, induced pluripotent stem cell-derived cardiomyocytes showed increased symmetric protein methylation and elevated SDMA during rapid pacing (2.0 Hz versus 0.5 Hz), whereas asymmetric protein methylation and ADMA were unchanged.

CONCLUSIONS

SDMA at admission was significantly elevated in stroke patients presenting with AF and showed a moderate but significant prospective association with previously unrecognized AF. Thus, stroke patients with elevated SDMA concentration at admission may specifically benefit from extended Holter-ECG monitoring.

Associations of plasma arginine, homoarginine, and ADMA/SDMA levels with risk of ischemic stroke: A nested case-control study

BACKGROUND AND AIMS

Previous studies have linked aberrant nitric oxide (NO) metabolism with vascular diseases. Although arginine, homoarginine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) are involved in NO metabolic pathways, their associations with ischemic stroke (IS) remain unclear.

METHODS AND RESULTS

We conducted a case-control study nested within the Prospective Follow-up Study on Cardiovascular Morbidity and Mortality in China (PFS-CMMC) (2013-2018, n = 16,457; median follow-up time: 5.3 y), which included 321 incident cases of IS and 321 controls matched by age and sex. Plasma arginine, homoarginine, ADMA/SDMA were measured by ultrahigh performance liquid chromatography-tandem mass spectrometry. Conditional logistic regression analyses were used to calculate odds ratios (ORs) and their 95% confidence intervals (CIs) for the association between the plasma metabolites and IS risk. After adjustment for body mass index, educational attainment, smoking, hypertension, hyperlipidemia, diabetes, and family history of stroke, the OR of IS risk for the highest versus the lowest quartile was 2.46 (95% CI: 1.39-4.35, P trend = 0.004) for homoarginine and 2.22 (95% CI: 1.24-3.97, P trend = 0.003) for ADMA/SDMA. Spline regression analyses indicated positive dose-response relationships of homoarginine and ADMA/SDMA with the IS risk (both P for linearity <0.05). No significant association was observed between plasma arginine and IS risk.

CONCLUSIONS

Elevated plasma levels of homoarginine and ADMA/SDMA were associated with a higher risk of IS. Our novel findings suggest a role of NO metabolism in the pathogenesis of IS.

Asymmetric dimethylarginine correlates with indicators of prethrombotic state in patients with nonvalvular atrial fibrillation

OBJECTIVE

The mechanism of asymmetric dimethylarginine (ADMA) in thrombosis in patients with nonvalvular atrial fibrillation (NVAF) is still unclear. Our aim was to investigate the relationship between ADMA and indicators of prethrombotic state in NVAF patients and to analyze the predictive role of ADMA in NVAF thrombosis.

METHODS

A total of 192 NVAF patients were continuously selected from January 2023 to October 2023. Plasma ADMA levels were measured by high-performance liquid chromatography. P-selectin (P-sel), von Willebrand factor (vWF), D-dimer (D-D), and plasminogen activator inhibitor-1 (PAI-1) levels were measured by enzyme-linked immunosorbent assay (ELISA). Nitric oxide (NO) levels were measured by the nitrate reductase assay for plasma nitrite/nitrate, then the Griess method (Shanghai Hailian Biotechnology Co., Shanghai, China) was used to calculate plasma NO levels.

RESULTS

In our study, ADMA levels were significantly elevated and positively correlated with P-sel, vWF, D-D, and PAI-1, whereas NO levels were significantly negatively correlated with these prethrombotic factors in NVAF. Furthermore, multifactorial logistic regression analysis showed that ADMA and LA diameter were independent predictors of high thrombosis risk (CHA2DS2-VASc ≥2 score) in patients with NVAF.

CONCLUSIONS

Our findings suggested that ADMA correlated with the prethrombotic state in NVAF and that reduction of ADMA levels in NVAF patients may be a novel therapeutic strategy for thrombosis risk reduction.

High ADMA Is Associated with Worse Health Profile in Heart Failure Patients Hospitalized for Episodes of Acute Decompensation

Background and Objectives: episodes of acute decompensation in chronic heart failure (ADHF), a common health problem for the growing elderly population, pose a significant socio-economic burden on the public health systems. Limited knowledge is available on both the endothelial function in and the cardio-metabolic health profile of old adults hospitalized due to ADHF. This study aimed to investigate the connection between asymmetric dimethylarginine (ADMA)-a potent inhibitor of nitric oxide-and key health biomarkers in this category of high-risk patients. Materials and Methods: this pilot study included 83 individuals with a known ADHF history who were admitted to the ICU due to acute cardiac decompensation. Selected cardiovascular, metabolic, haemogram, renal, and liver parameters were measured at admission to the ICU. Key renal function indicators (serum creatinine, sodium, and potassium) were determined again at discharge. These parameters were compared between patients stratified by median ADMA (114 ng/mL). Results: high ADMA patients showed a significantly higher incidence of ischemic cardiomyopathy and longer length of hospital stay compared to those with low ADMA subjects. These individuals exhibited significantly higher urea at admission and creatinine at discharge, indicating poorer renal function. Moreover, their lipid profile was less favorable, with significantly elevated levels of total cholesterol and HDL. However, no significant inter-group differences were observed for the other parameters measured. Conclusions: the present findings disclose multidimensional, adverse ADMA-related changes in the health risk profile of patients with chronic heart failure hospitalized due to recurrent decompensation episodes.

Relationship Between Fibrosis, Endocardial Endothelial Damage, and Thrombosis of Left Atrial Appendage in Atrial Fibrillation

BACKGROUND

Left atrial appendage (LAA) thrombus (LAAT) and ischemic stroke are considered important in atrial cardiomyopathy with progressive atrial fibrosis and endocardial endothelial damage.

OBJECTIVES

This study aimed to obtain histological evidence to clarify the association between LAA fibrosis and endocardial endothelial damage with LAAT, ischemic stroke, and clinical risk factors.

METHODS

Ninety-six patients with atrial fibrillation (AF) scheduled to undergo LAA excision during surgery were enrolled. They underwent transesophageal echocardiography before the surgery to validate the LAA function/morphology and LAAT presence or absence. The resected LAAs were subjected to Azan-Mallory staining and CD31 immunohistochemistry to quantify the degree of fibrosis and endocardial endothelial damage staged as F1-F4 and E1-E4 per the quantiles.

RESULTS

Patients with an LAAT and/or ischemic stroke history had higher fibrosis degrees (18.4% ± 9.9% vs 10.4% ± 7.0%, P < 0.0001) and lower CD31 expressions (0.27 [IQR: 0.05-0.57] vs 1.02 [IQR: 0.49-1.65]; P < 0.0001). Also, higher CHADS₂ was associated with a higher degree of fibrosis and lower CD31 expression. Multivariate logistic regression analysis revealed that endothelial damage (E4) was associated with an LAAT and/or ischemic stroke history independent of AF type (paroxysmal or nonparoxysmal) with an OR of 3.47. Among patients with nonparoxysmal AF, fibrosis (F4, OR: 3.66), endothelial damage (E4, OR: 4.62), and LAA morphology (non-chicken-wing, OR: 3.79) were independently associated with LAAT and/or stroke. The degree of fibrosis correlated significantly with endothelial damage (R = -0.38, P = 0.0001).

CONCLUSIONS

These histological findings may be essential in considering the pathophysiology of LAAT and stroke within the atrial cardiomyopathy context.

Biomarkers of Atrial Fibrillation Recurrence in Patients with Paroxysmal or Persistent Atrial Fibrillation Following External Direct Current Electrical Cardioversion

Atrial fibrillation (AF) is associated with atrial remodeling, cardiac dysfunction, and poor clinical outcomes. External direct current electrical cardioversion is a well-developed urgent treatment strategy for patients presenting with recent-onset AF. However, there is a lack of accurate predictive serum biomarkers to identify the risks of AF relapse after electrical cardioversion. We reviewed the currently available data and interpreted the findings of several studies revealing biomarkers for crucial elements in the pathogenesis of AF and affecting cardiac remodeling, fibrosis, inflammation, endothelial dysfunction, oxidative stress, adipose tissue dysfunction, myopathy, and mitochondrial dysfunction. Although there is ample strong evidence that elevated levels of numerous biomarkers (such as natriuretic peptides, C-reactive protein, galectin-3, soluble suppressor tumorigenicity-2, fibroblast growth factor-23, turn-over collagen biomarkers, growth differential factor-15) are associated with AF occurrence, the data obtained in clinical studies seem to be controversial in terms of their predictive ability for post-cardioversion outcomes. Novel circulating biomarkers are needed to elucidate the modality of this approach compared with conventional predictive tools. Conclusions: Biomarker-based strategies for predicting events after AF treatment require extensive investigation in the future, especially in the presence of different gender and variable comorbidity profiles. Perhaps, a multiple biomarker approach exerts more utilization for patients with different forms of AF than single biomarker use.

microRNAs as Biomarkers of Endothelial Dysfunction and Therapeutic Target in the Pathogenesis of Atrial Fibrillation

The pathophysiology of atrial fibrillation (AF) may involve atrial fibrosis/remodeling and dysfunctional endothelial activities. Despite the currently available treatment approaches, the progression of AF, its recurrence rate, and the high mortality risk of related complications underlay the need for more advanced prognostic and therapeutic strategies. There is increasing attention on the molecular mechanisms controlling AF onset and progression points to the complex cell to cell interplay that triggers fibroblasts, immune cells and myofibroblasts, enhancing atrial fibrosis. In this scenario, endothelial cell dysfunction (ED) might play an unexpected but significant role. microRNAs (miRNAs) regulate gene expression at the post-transcriptional level. In the cardiovascular compartment, both free circulating and exosomal miRNAs entail the control of plaque formation, lipid metabolism, inflammation and angiogenesis, cardiomyocyte growth and contractility, and even the maintenance of cardiac rhythm. Abnormal miRNAs levels may indicate the activation state of circulating cells, and thus represent a specific read-out of cardiac tissue changes. Although several unresolved questions still limit their clinical use, the ease of accessibility in biofluids and their prognostic and diagnostic properties make them novel and attractive biomarker candidates in AF. This article summarizes the most recent features of AF associated with miRNAs and relates them to potentially underlying mechanisms.

Ischemia with Nonobstructive Coronary Artery Disease and Atrial Cardiomyopathy-Two Sides of the Same Story?

Ischemia with nonobstructive coronary artery disease (INOCA) is increasingly recognized as a significant cause of angina, myocardial remodeling, and eventually heart failure (HF). Coronary microvascular dysfunction (CMD) is a major endotype of INOCA, and it is caused by structural and functional alterations of the coronary microcirculation. At the same time, atrial cardiomyopathy (ACM) defined by structural, functional, and electrical atrial remodeling has a major clinical impact due to its manifestations: atrial fibrillation (AF), atrial thrombosis, stroke, and HF symptoms. Both these pathologies share similar risk factors and have a high comorbidity burden. CMD causing INOCA and ACM frequently coexist. Thus, questions arise whether there is a potential link between these pathologies. Does CMD promote AF or the reverse? Which are the mechanisms that ultimately lead to CMD and ACM? Are both part of a systemic disease characterized by endothelial dysfunction? Lastly, which are the therapeutic strategies that can target endothelial dysfunction and improve the prognosis of patients with CMD and ACM? This review aims to address these questions by analyzing the existing body of evidence, offering further insight into the mechanisms of CMD and ACM, and discussing potential therapeutic strategies.

Perhexiline Therapy in Patients with Type 2 Diabetes: Incremental Insulin Resistance despite Potentiation of Nitric Oxide Signaling

Perhexiline (Px) inhibits carnitine palmitoyltransferase 1 (CPT1), which controls uptake of long chain fatty acids into mitochondria. However, occasional cases of hypoglycaemia have been reported in Px-treated patients, raising the possibility that Px may also increase sensitivity to insulin. Furthermore, Px increases anti-aggregatory responses to nitric oxide (NO), an effect which may theoretically parallel insulin sensitization. We therefore sought to examine these relationships in patients with stable Type 2 diabetes (T2D) and cardiovascular disease (n = 30). Px was initiated, and dosage was titrated, to reach the therapeutic range and thus prevent toxicity. Investigations were performed before and after 2 weeks, to examine changes in insulin sensitivity and, utilizing aggregometry in whole blood, platelet responsiveness to the anti-aggregatory effects of the NO donor sodium nitroprusside (SNP). Other parameters that affect may affect NO signalling were also evaluated. Px substantially potentiated inhibition of platelet aggregation by SNP (from 16.7 ± 3.0 to 27.3 ± 3.7%; p = 0.005). Px did not change fasting blood glucose concentrations but reduced insulin sensitivity (HOMA-IR score increased from median of 4.47 to 6.08; p = 0.028), and increased fasting plasma insulin concentrations (median 16.5 to 19.0 mU/L; p = 0.014). Increases in SNP responses tended (r = −0.30; p = 0.11) to be reciprocally related to increases in HOMA-IR, and increases in HOMA-IR were greater (p = 0.002) in patients without NO-sensitizing effects. No patient developed symptomatic hypoglycaemia, nor was there any other short-term toxicity of Px. Thus, in patients with stable T2D and cardiovascular disease, Px increases anti-aggregatory responsiveness to NO, but is not an insulin sensitizer, and does not induce hypoglycaemia. Absence of NO-sensitizing effect occurs in approximately 30% of Px-treated patients with T2D, and is associated with induction of insulin resistance in these patients.

Asymmetric Dimethylarginine Protects Neurons from Oxygen Glucose Deprivation Insult by Modulating Connexin-36 Expression

Background

Asymmetric dimethylarginine (ADMA) is a nonselective nitric oxide synthase inhibitor. ADMA is thought to inhibit the production of nitric oxide (NO) by neurons after oxygen-glucose deprivation (OGD). The gap junction protein Connexin-36 (cx-36) is involved in the pathophysiology of stroke. We investigated whether ADMA could protect neurons from OGD insults by regulating the expression of cx-36.

Methods

Cultured rat cortical neuronal cells were used. Neurons were treated with OGD with or without ADMA pretreatment. The lactate dehydrogenase (LDH) release rate was used to assess neuronal injury. Intracellular NO levels were determined using 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate. Western blotting was performed to detect cx-36 expression.

Results

The LDH release rate increased in the supernatant of neurons after the OGD insult, whereas ADMA treatment reduced the LDH release rate. Intracellular NO levels increased following OGD treatment, and this increase was not inhibited by ADMA treatment. Expression of cx-36 was upregulated in neurons under OGD conditions, and treatment with ADMA downregulated the expression of cx-36.

Conclusions

ADMA protects neurons from OGD insult, and cx-36 downregulation may be a possible pathway involved in ADMA-mediated neuronal protection.

Arginine catabolism metabolites and atrial fibrillation or heart failure risk: 2 case-control studies within the Prevención con Dieta Mediterránea (PREDIMED) trial

BACKGROUND

Arginine-derived metabolites are involved in oxidative and inflammatory processes related to endothelial functions and cardiovascular risks.

OBJECTIVES

We prospectively examined the associations of arginine catabolism metabolites with the risks of atrial fibrillation (AF) or heart failure (HF), and evaluated the potential modifications of these associations through Mediterranean diet (MedDiet) interventions in a large, primary-prevention trial.

METHODS

Two nested, matched, case-control studies were designed within the Prevención con Dieta Mediterránea (PREDIMED) trial. We selected 509 incident cases and 547 matched controls for the AF case-control study and 326 cases and 402 matched controls for the HF case-control study using incidence density sampling. Fasting blood samples were collected at baseline and arginine catabolism metabolites were measured using LC-tandem MS. Multivariable conditional logistic regression models were applied to test the associations between the metabolites and incident AF or HF. Interactions between metabolites and intervention groups (MedDiet groups compared with control group) were analyzed with the likelihood ratio test.

RESULTS

Inverse association with incident AF was observed for arginine (OR per 1 SD, 0.83; 95% CI: 0.73-0.94), whereas a positive association was found for N1-acetylspermidine (OR for Q4 compared with Q1 1.58; 95% CI: 1.13-2.25). For HF, inverse associations were found for arginine (OR per 1 SD, 0.82; 95% CI: 0.69-0.97) and homoarginine (OR per 1 SD, 0.81; 95% CI: 0.68-0.96), and positive associations were found for the asymmetric dimethylarginine (ADMA) and symmetric dimethlyarginine (SDMA) ratio (OR per 1 SD, 1.19; 95% CI: 1.02-1.41), N1-acetylspermidine (OR per 1 SD, 1.34; 95% CI: 1.12-1.60), and diacetylspermine (OR per 1 SD, 1.20; 95% CI: 1.02-1.41). In the stratified analysis according to the dietary intervention, the lower HF risk associated with arginine was restricted to participants in the MedDiet groups (P-interaction = 0.044).

CONCLUSIONS

Our results suggest that arginine catabolism metabolites could be involved in AF and HF. Interventions with the MedDiet may contribute to strengthen the inverse association between arginine and the risk of HF. This trial was registered at controlled-trials.com as ISRCTN35739639.

Endothelial function and atrial fibrillation: A missing piece of the puzzle?

Endothelial dysfunction, a term used to describe both the physical damage and dysregulated physiology of this endothelial lining, is an increasingly recognized pathophysiological state shared by many cardiovascular diseases. Historically, the role of endothelial dysfunction in atrial fibrillation (AF) was thought to be limited to mediating atrial thromboembolism. However, there is emerging evidence that endothelial dysfunction both promotes and maintains atrial arrhythmic substrate, predicts adverse outcomes, and identifies patients at high risk of recurrence following cardioversion and ablation therapy. Treatments targeted at improving endothelial function also represent a promising new therapeutic paradigm in AF. This review summarizes the current understanding of endothelial function in AF.

Evaluation of Different Blood Parameters From Endurance Horses Competing at 160 km

The purpose of this study was to assess a change in different blood parameters before and after a 160 km endurance race and to evaluate differences in cardiac biomarkers between horses that completed the race and horses that did not. The study population consisted of 52 healthy endurance horses. Horses participating in the study were assigned to three groups: horses that successfully completed the race ("finishers"), horses that failed to qualify at the veterinary check for primarily metabolic reasons ("metabolic") and horses that failed to qualify at the veterinary check for primarily gait related reasons ("gait related"). The latter two groups were combined to form a final group of "non-finishers" that were excluded for either "gait related" or "metabolic" disorders. Venous blood samples were taken before and after the endurance race. Serum and EDTA-plasma were analyzed for cardiac troponin I (cTNI), heart fatty acid binding protein (HFABP), alpha-hydroxybutyrate dehydrogenase (α-HBDH), atrial natriuretic peptide (ANP), lactate dehydrogenase (LDH), symmetric dimethylarginine (SDMA) and asymmetric dimethylarginine (ADMA). Lactate dehydrogenase (P = .001), SDMA (P= .001) and ADMA (P= .002) increased significantly after the endurance race in the finisher group. A significant increase in cTNI and α-HBDH concentration after the endurance race compared to the values before the endurance race was detected in the finisher (P= .001, P= .001) and gait related group (P= .002, P= .007). The longer the distance completed, the more these five blood parameters increased. No differences between the groups could be found and none of the measured blood parameters showed significant differences among groups before or after racing.

Asymmetric Dimethylarginine: a Key Player in the Pathophysiology of Endothelial Dysfunction, Vascular Inflammation and Atherosclerosis in Rheumatoid Arthritis?

Patients with rheumatoid arthritis (RA), a chronic and disabling autoimmune condition that is characterized by articular and extra-articular manifestations and a pro-inflammatory and pro-oxidant state, suffer from premature atherosclerosis and excessive cardiovascular disease burden. A key step in the pathogenesis of atherosclerosis is impaired synthesis of the endogenous messenger nitric oxide (NO) by endothelial cells which, in turn, alters local homeostatic mechanisms and favors vascular damage and plaque deposition. While the exact mechanisms of endothelial dysfunction in RA remain to be established, there is good evidence that RA patients have relatively high circulating concentrations of the methylated arginine asymmetric dimethylarginine (ADMA), a potent endogenous inhibitor of endothelial NO synthase (eNOS). This review discusses the biological and pathophysiological role of ADMA, the interplay between ADMA, inflammation and oxidative stress, and the available evidence on the adverse impact of ADMA on endothelial function and atherosclerosis and potential ADMA-lowering therapies in RA patients.

A systematic review of the correlation between serum asymmetric dimethylarginine, carotid atherosclerosis and ischaemic stroke

OBJECTIVE

To investigate the correlation between serum asymmetric dimethylarginine (ADMA) and the risk of ischaemic stroke and carotid atherosclerosis in adults.

METHODS

We systematically searched PubMed, EMBASE, Web of Science and other databases for relevant studies on serum ADMA and ischaemic stroke or carotid atherosclerosis, which were published from December 1980 to December 2019. The quality of the included studies was evaluated according to the Cochrane system evaluation standard. The difference in serum ADMA level between ischaemic stroke and control group was selected as the effect size (standardized mean difference, SMD). The pooled analysis was performed using Review Manager (V.5.3).

RESULTS

According to the selection criteria, thirteen studies were included in the meta-analysis after screening. Nine studies compared ADMA levels between the ischaemic stroke group and healthy control group, involving a total of 1315 and 880 subjects in the two groups, respectively. Pooled effect sizes were calculated using the random-effects model due to the high heterogeneity (I²  = 93%, P < .00001). The level of serum ADMA in patients with ischaemic stroke was significantly higher than that in healthy people (SDM = 0.69, 95% CI [0.32, 1.06], P = .0002). Seven of the thirteen articles compared ADMA levels between the carotid arteriosclerosis group and the healthy control group, with 559 and 330 subjects in the two groups, respectively. The random-effects model was applied due to the high heterogeneity (I²  = 91%, P < .00001). The level of serum ADMA in patients with carotid arteriosclerosis was significantly higher than that in healthy people (SDM = 1.03, 95% CI [0.49, 1.57], P = .0002).

CONCLUSION

The serum ADMA may be related to ischaemic stroke, and it is a risk factor for carotid atherosclerosis.

Metabolic Signature of Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is a genetic-based cardiac disease accompanied by severe ventricular arrhythmias and a progressive substitution of the myocardium with fibro-fatty tissue. ACM is often associated with sudden cardiac death. Due to the reduced penetrance and variable expressivity, the presence of a genetic defect is not conclusive, thus complicating the diagnosis of ACM. Recent studies on human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs) obtained from ACM individuals showed a dysregulated metabolic status, leading to the hypothesis that ACM pathology is characterized by an impairment in the energy metabolism. However, despite efforts having been made for the identification of ACM specific biomarkers, there is still a substantial lack of information regarding the whole metabolomic profile of ACM patients. The aim of the present study was to investigate the metabolic profiles of ACM patients compared to healthy controls (CTRLs). The targeted Biocrates AbsoluteIDQ^® p180 assay was used on plasma samples. Our analysis showed that ACM patients have a different metabolome compared to CTRLs, and that the pathways mainly affected include tryptophan metabolism, arginine and proline metabolism and beta oxidation of fatty acids. Altogether, our data indicated that the plasma metabolomes of arrhythmogenic cardiomyopathy patients show signs of endothelium damage and impaired nitric oxide (NO), fat, and energy metabolism.

The Influences of Tai Chi on Balance Function and Exercise Capacity among Stroke Patients: A Meta-Analysis

Objective

This study aims to explore the influences of Tai Chi on the balance function and exercise capacity among stroke patients.

Methods

Databases including PubMed, Embase, WOS (Web of Science), the Cochrane Library, CNKI (China National Knowledge Infrastructure), Wanfang Data, VIP (VIP database), and CBM (China Biology Medicine disc) were retrieved to gather the figures of randomized controlled trials on the balance function and exercise capacity among stroke patients. Then relevant data were input and analyzed in Review Manager 5.3.

Results

Nineteen papers were included and analyzed in this study. According to the combined effect size, the balance function of stroke patients improved significantly: the Berg Balance Function Scale score [MD = 7.67, 95% CI (3.44, 11.90)]; standing and walking test scores [MD = 3.42, 95% CI (4.22, −2.63)]; gravity swing area [MD = 0.79, 95% CI (1.48, 0.10)]; and gravity swing speed [MD = −5.43, 95% CI (−7.79, 3.08)]. In addition, the exercise capacity improved significantly as well: the FMA (Fugl-Meyer Assessment Scale) scale score [MD = 4.15, 95% CI (1.68, 6.63)]. There are no significant influences or changes of other related results.

Conclusions

Stroke patients are able to improve their balance functions and exercise capacities prominently when they do Tai Chi exercise once or twice a week and ≥5 times/week and >30 ≤ 60 min/time.

Asymmetric dimethylarginine-A potential cardiac biomarker in horses

INTRODUCTION/OBJECTIVES

Asymmetric dimethylarginine (ADMA) is a cardiac biomarker in humans, symmetric dimethylarginine (SDMA) a renal biomarker in humans, cats, and dogs. The purpose of this prospective study was to investigate if measuring serum ADMA and SDMA concentrations via ELISA allows detection of cardiac disease in horses in a routine laboratory setting. In this context, reference values in horses were established.

ANIMALS, MATERIALS, AND METHODS

Seventy-eight horses with no known medical history were compared to 23 horses with confirmed structural cardiac disease with/or without arrhythmias. Horses underwent physical examination, electrocardiography, echocardiography and venous blood sampling and were staged based on the severity of cardiac disease from 0 to II. Asymmetric dimethylarginine and SDMA were measured via ELISA and crosschecked using liquid chromatograph triple quadrupole mass spectrometry. Reference intervals with 90th percent confidence intervals were evaluated and standard software was used to test for significant differences in ADMA, SDMA, and the l-arginine/ADMA ratio between groups.

RESULTS

The reference ranges were 1.7-3.8 μmol/L and 0.3-0.8 μmol/L for ADMA and SDMA, respectively. Serum ADMA was higher in horses with heart disease compared to healthy horses (p < 0.01) and highest in horses with stage II heart disease (p = 0.02). The l-Arginine/ADMA ratio was significantly higher in healthy animals than those with cardiac disease (p = 0.001).

CONCLUSIONS

Reference values for serum ADMA and SDMA using ELISA methods are presented in horses. This study confirms the association between heart disease and increased serum ADMA concentration as well as a decreased l-Arginine/ADMA ratio in horses.

Treatment-related biomarkers in pulmonary hypertension patients on oral therapies

Background

Multiple classes of oral therapy are available for the treatment of pulmonary arterial hypertension (PAH), but there is little to guide clinicians in choosing a specific regimen or therapeutic class. We aimed to investigate whether treatment-relevant blood biomarkers can predict therapy response in prevalent PAH patients.

Methods

This prospective cohort study longitudinally assessed biomarkers along the endothelin-1 (ET-1) and nitric oxide (cGMP, ADMA, SDMA, nitrite, and S-nitrosohemoglobin) pathways along with the cGMP/NT-proBNP ratio over 12 months in patients with WHO Group 1 PAH on oral PAH-specific therapies. The relationship between biomarkers and 6MWD at the same and future visits was examined using mixed linear regression models adjusted for age. As cGMP can be elevated when NT-proBNP is elevated, we also tested the relationship between 6MWD and the cGMP/NT-pro BNP ratio. Patients with PAH with concomitant heart or lung disease or chronic thromboembolic pulmonary hypertension (CTEPH) were included in a sensitivity analysis.

Results

The study cohort included 58 patients with PAH treated with either an endothelin receptor antagonist (27.6%), phosphodiesterase-5 inhibitor (25.9%) or a combination of the two (43.1%). Among biomarkers along the current therapeutic pathways, ET-1 and the cGMP/NT-proBNP ratio associated with same visit 6MWD (p = 0.02 and p = 0.03 respectively), and ET-1 predicted future 6MWD (p = 0.02). ET-1 (p = 0.01) and cGMP/NT-proBNP ratio (p = 0.04) also predicted future 6MWD in the larger cohort (n = 108) of PAH patients with concomitant left heart disease (n = 17), lung disease (n = 20), or CTEPH (n = 13). Finally, in the larger cohort, SDMA associated with 6MWD at the same visit (p = 0.01) in all subgroups and ADMA associated with 6MWD in PAH patients with concomitant lung disease (p = 0.03) and PAH patients on ERA therapy (p = 0.01).

Conclusions

ET-1, cGMP/NTproBNP ratio, and dimethylarginines ADMA and SDMA are mediators along pathways targeted by oral PAH therapies that associate with or predict 6MWD.

Prognostic Value of Asymmetric Dimethylarginine in Patients with Heart Failure: A Systematic Review and Meta-analysis

Objective

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthesis, is reported to be a risk factor for cardiovascular disease. The purpose of the present study is to investigate whether ADMA is an independent predictor for future mortality and adverse clinical events among patients with heart failure (HF).

Methods

Electronic literature databases (Central, MEDLINE, and Embase) were searched for relevant observational studies on the prognostic value of ADMA in HF patients published before January 2019. Pooled hazard ratios (HRs) or odds ratio and the corresponding 95% confidence interval (CI) were calculated for risk evaluation.

Results

10 studies with 2195 participants were identified and analyzed. The pooled HR of composite clinical events for the highest vs. lowest quartiles from categorical variable results was 1.34 (95% CI: 1.15-1.57, P < 0.001, I² = 0%), which is 1.31 (95% CI: 1.10-1.55, P < 0.005, I² = 0%) in the subgroup of acute decompensated HF. The pooled HR of composite clinical events from continuous variable results was 1.41 (95% CI: 1.21-1.63, P < 0.001, I² = 21.9%), with 0.1 μM increment accounting for the increasing 25% risk for composite adverse clinical events. The pooled HR for all-cause mortality was 2.38 (95% CI: 1.48-3.82, P < 0.001, I² = 0%) after sensitivity analysis. Two studies reporting the HR of inhospital mortality in HF patients regarded it as a prognostic indicator, with categorical variable HR as 1.26 (95% CI: 1.07-1.84, P < 0.05) and continuous variable OR as 2.15 (95% CI: 1.17–4.29, P < 0.05).

Conclusions

ADMA is an independent predictor for composite clinical outcomes among HF patients with both short-term and long-term prognostic value.

Elevated plasma levels of asymmetric dimethylarginine and the risk for arrhythmic death in ischemic and non-ischemic, dilated cardiomyopathy - A prospective, controlled long-term study

INTRODUCTION

Elevated plasma levels of asymmetric dimethylarginine (ADMA), an inhibitor of NO synthase, are associated with adverse outcome. There is no data available, whether ADMA levels are associated with arrhythmic death (AD) in patients with ischemic cardiomyopathy (ICM) or non-ischemic, dilated cardiomyopathy (DCM).

METHODS AND RESULTS

A total of 110 ICM, 52 DCM and 30 control patients were included. Primary outcome parameter of this prospective study was arrhythmic death (AD) or resuscitated cardiac arrest (RCA). Plasma levels of ADMA were significantly higher in ICM (p < 0.001) and in DCM (p < 0.001) patients compared to controls. During a median follow-up of 7.0 years, 62 (32.3%) patients died. AD occurred in 26 patients and RCA was observed in 22 patients. Plasma levels of ADMA were not associated with a significantly increased risk of AD or RCA in ICM (hazard ratio (HR) = 1.37, p = 0.109) or in DCM (HR = 1.06, p = 0.848) patients. No significant association was found with overall mortality in ICM (HR = 1.39, p = 0.079) or DCM (HR = 1.10, p = 0.666) patients. Stratified Kaplan-Meier curves for ADMA levels in the upper tertile (>0.715 µmol/l) or the two lower tertiles (≤0.715 µmol/l) did not show a higher risk for AD or RCA (p = 0.221) or overall mortality (p = 0.548). In patients with left ventricular ejection fraction ≤ 35%, ADMA was not associated with AD or RCA (HR = 1.35, p = 0.084) or with overall mortality (HR = 1.24, p = 0.162).

CONCLUSIONS

Plasma levels of ADMA were elevated in patients with ICM or DCM as compared to controls, but were not significantly predictive for overall mortality or the risk for arrhythmic death.

Nitroxyl: A Novel Strategy to Circumvent Diabetes Associated Impairments in Nitric Oxide Signaling

Diabetes is associated with an increased mortality risk due to cardiovascular complications. Hyperglycemia-induced oxidative stress underlies these complications, leading to an impairment in endogenous nitric oxide (NO•) generation, together with reductions in NO• bioavailability and NO• responsiveness in the vasculature, platelets and myocardium. The latter impairment of responsiveness to NO•, termed NO• resistance, compromises the ability of traditional NO•-based therapeutics to improve hemodynamic status during diabetes-associated cardiovascular emergencies, such as acute myocardial infarction. Whilst a number of agents can ameliorate (e.g. angiotensin converting enzyme [ACE] inhibitors, perhexiline, statins and insulin) or circumvent (e.g. nitrite and sGC activators) NO• resistance, nitroxyl (HNO) donors offer a novel opportunity to circumvent NO• resistance in diabetes. With a suite of vasoprotective properties and an ability to enhance cardiac inotropic and lusitropic responses, coupled with preserved efficacy in the setting of oxidative stress, HNO donors have intact therapeutic potential in the face of diminished NO• signaling. This review explores the major mechanisms by which hyperglycemia-induced oxidative stress drives NO• resistance, and the therapeutic potential of HNO donors to circumvent this to treat cardiovascular complications in type 2 diabetes mellitus.

Effect of fish oil on circulating asymmetric dimethylarginine and adiponectin in overweight or obese patients with atrial fibrillation

Obesity and adipose-derived peptides might be involved in the pathogenesis of atrial fibrillation (AF). Adiponectin plays a major role in the modulation of several metabolic pathways, and asymmetric dimethylarginine (ADMA) has been suggested to be predictive of AF and associated adverse events. The aim of this study was to investigate the effect of fish oil supplementation on circulating adiponectin and ADMA in overweight or obese patients with persistent AF. In this randomized, double-blind, placebo-controlled trial, 80 overweight or obese (body mass index (BMI) ≥ 25 kg/m2) patients with persistent AF were randomly assigned to two groups to receive either 2 g/day fish oil or placebo, for 8 weeks. Serum levels of adiponectin and ADMA, and anthropometric indexes were measured. This study showed that serum adiponectin concentrations increased significantly following fish oil supplementation compared with the placebo group (13.15 ± 7.33 vs. 11.88 ± 6.94 µg/ml; p = .026). A significant reduction was also observed in serum ADMA levels in the fish oil compared with the placebo group following the intervention (0.6 ± 0.13 vs. 0.72 ± 0.15 µmol/L; p = .001). The changes in serum adiponectin and ADMA concentrations remained significant after adjustments for baseline values, age, sex, and changes of BMI and waist circumference (p = .011 and p = .001, respectively). In conclusion,  8 weeks supplementation with fish oil increased serum adiponectin and decreased ADMA concentrations in overweight or obese patients with persistent AF. As adiponectin and ADMA are suggested to be involved in many pathways associated with AF, the current findings might be promising in the clinical management of this disease, an issue that needs further investigations.

Arginine Derivatives in Cerebrovascular Diseases: Mechanisms and Clinical Implications

The amino acid L-arginine serves as substrate for the nitric oxide synthase which is crucial in vascular function and disease. Derivatives of arginine, such as asymmetric (ADMA) and symmetric dimethylarginine (SDMA), are regarded as markers of endothelial dysfunction and have been implicated in vascular disorders. While there is a variety of studies consolidating ADMA as biomarker of cerebrovascular risk, morbidity and mortality, SDMA is currently emerging as an interesting metabolite with distinct characteristics in ischemic stroke. In contrast to dimethylarginines, homoarginine is inversely associated with adverse events and mortality in cerebrovascular diseases and might constitute a modifiable protective risk factor. This review aims to provide an overview of the current evidence for the pathophysiological role of arginine derivatives in cerebrovascular ischemic diseases. We discuss the complex mechanisms of arginine metabolism in health and disease and its potential clinical implications in diverse aspects of ischemic stroke.

Markers of endothelial pathology to support detection of atrial fibrillation in embolic stroke of undetermined source

A relevant part of embolic strokes of undetermined source (ESUS) is assumed to be cardiogenic. As shown previously, certain biomarkers of endothelial pathology are related to atrial fibrillation (AF). In this long-term follow-up study, we aimed to investigate whether these biomarkers are associated with subsequently diagnosed AF and with atrial cardiopathy. In 98 patients who suffered ischemic stroke of known and unknown origin L-arginine, Asymmetric (ADMA) and Symmetric Dimethylarginine (SDMA) have been measured on follow-up at least one year after index stroke. Stroke-diagnostics were available for all patients, including carotid Intima-Media-Thickness (CIMT) and comprehensive echocardiography studies. CIMT was larger in AF- compared with ESUS-patients (P < 0.001), independently from CHA2DS2VASC in the regression analysis (P = 0.004). SDMA-values were stable over time (P < 0.001; r = 0.788), whereas for ADMA moderate correlation with the initial values could be found (P = 0.007; r = 0.356). According to Kaplan-Meier-analyses, AF-detection rates were associated with CIMT (P = 0.003) and SDMA (P < 0.001). SDMA correlated with left atrial volume-index within the whole collective (P = 0.003, r = 0.322) and within the ESUS-subgroup (P = 0.003; r = 0.446). These associations were independent from CHA2DS2VASC and renal function in the regression analysis (P = 0.02 and P = 0.005, respectively). In conclusion, these results highlight SDMA and CIMT as potential markers of atrial cardiopathy and AF in ESUS-patients.

Comparative thromboembolic risk in atrial fibrillation with and without a secondary precipitant-Danish nationwide cohort study

OBJECTIVES

We compared long-term outcomes in patients with atrial fibrillation (AF) with and without a secondary precipitant.

DESIGN AND SETTING

Retrospective cohort study based on Danish nationwide registries.

PARTICIPANTS

Patients with AF with and without secondary precipitants (1996-2015) were matched 1:1 according to age, sex, calendar year, CHA₂DS₂-VASc score and oral anticoagulation therapy (OAC), resulting in a cohort of 39 723 patients with AF with a secondary precipitant and the same number of patients with AF without a secondary precipitant. Secondary precipitants included alcohol intoxication, thyrotoxicosis, myocardial infarction, surgery and infection in conjunction with AF.

PRIMARY AND SECONDARY OUTCOMES

The primary outcome in this study was thromboembolic events. Secondary outcomes included AF rehospitalisation and death. Long-term risks of outcomes were examined by multivariable Cox regression analysis.

RESULTS

The most common precipitants were infection (55.0%), surgery (13.2%) and myocardial infarction (12.0%). The 5-year absolute risk of thromboembolic events (taking death into account as a competing risk) in patients with AF grouped according to secondary precipitants were 8.3% (alcohol intoxication), 8.5% (thyrotoxicosis), 12.1% (myocardial infarction), 11.6% (surgery), 12.2% (infection), 10.1% (>1 precipitant) and 12.3% (no secondary precipitant). In the multivariable analyses, AF with a secondary precipitant was associated with the same or an even higher thromboembolic risk than AF without a secondary precipitant. One exception was patients with AF and thyrotoxicosis: those not initiated on OAC therapy carried a lower thromboembolic risk the first year of follow-up than matched patients with AF without a secondary precipitant and no OAC therapy.

CONCLUSIONS

In general, AF with a secondary precipitant was associated with the same thromboembolic risk as AF without a secondary precipitant. Consequently, this study highlights the need for more research regarding the long-term management of patients with AF associated with a secondary precipitant.

Association of Asymmetric Dimethylarginine and Diastolic Dysfunction in Patients with Hypertrophic Cardiomyopathy

Despite genetic heterogeneity, early manifestation of diastolic dysfunction (DD) is common in hypertrophic cardiomyopathy (HCM). Nitric oxide (NO) may contribute to myocardial relaxation. NO synthases (NOS) use l-arginine (Arg) as a substrate, as asymmetric dimethylarginine (ADMA) is a direct endogenous inhibitor of NOS. This study aimed to analyze the association of Arg and its derivates, i.e., l-homoarginine (hArg), ADMA and symmetric dimethylarginine (SDMA), with DD in HCM patients. In 215 HCM patients (mean age 54 ± 15 years, 58% male) transmitral and mitral annulus velocities were echocardiographically analyzed. Plasma concentrations of Arg derivatives were measured by liquid chromatography tandem-mass spectrometry. In 143 (70%) patients suffering from DD, ADMA showed the strongest association with DD (0.66 ± 0.16, 0.72 ± 0.24, and 0.76 ± 0.26 µmol/L, p < 0.01 for trend). In linear regression analyses, positive association per standard deviation increase of ADMA was found with E-wave (beta coefficient (95% confidence interval): 4.72 (0.43–9.01); p < 0.05) and mean E/E’ (1.76 (0.73–2.79) p < 0.001). Associations were adjusted for age, sex, body mass index (BMI), diabetes mellitus, coronary artery disease, and arterial hypertension. Elevated ADMA is associated with the severity of DD in HCM. Higher ADMA level might lead to decreased NO production and thus an impaired myocardial relaxation pattern.

Genetic regulation of dimethylarginines and endothelial dysfunction in rheumatoid arthritis

Rheumatoid Arthritis (RA) confers an increased cardiovascular disease (CVD) risk which accounts for much of the premature morbidity and mortality observed in this population. Alterations in vascular function and morphology leading to increased atherosclerotic burden are considered the main drivers of CVD in RA individuals with systemic inflammation playing a key role in the dysregulation of endothelial homeostasis and initiation of vascular injury. Dimethylarginines are endogenous inhibitors of nitric oxide (NO) synthase and have emerged as novel, independent biomarkers of CVD in a wide range of conditions associated with vascular pathology. In RA several reports have demonstrated abnormal dimethylarginine metabolism attributable to various factors such as systemic inflammation, decreased degradation or upregulated synthesis. Although a causal relationship between dimethylarginines and vascular damage in RA has not been established, the tight interrelations between inflammation, dimethylarginines and endothelial dysfunction suggest that determination of dimethylarginine regulators may shed more light in the pathophysiology of the atherosclerotic process in RA and may also provide new therapeutic targets. The Alanine-Glyoxylate Aminotransferase 2 (AGTX2)-dependent pathway is a relatively recently discovered alternative pathway of dimethylarginine catabolism and its role on RA-related atherosclerotic disease is yet to be established. As factors affecting dimethylarginine concentrations linked to CVD risk and endothelial dysfunction are of prominent clinical relevance in RA, we present preliminary evidence that gene variants of AGTX-2 may influence dimethylarginine levels in RA patients and provide the rationale for larger studies in this field.