Homocysteine in non-valvular atrial fibrillation: Role and clinical implications

Comparative analysis of the clinical features of nonvalvular atrial fibrillation among Tibetan, Han, and Hui patients in Qinghai Province, China

BACKGROUND

Global nonvalvular AF rises, impacting health severely. In Qinghai, China's diverse setting, studying AF among varied ethnic groups is crucial OBJECTIVES: The purpose of this study was to compares cardiac features in AF among Tibetan, Han, and Hui patients to develop tailored prevention and treatment strategies for this region, the goal was to enhance the understanding of AF and provide an empirical basis for developing prevention and treatment strategies specific to this region METHODS: This study included a total of 3445 Tibetan, Han, and Hui patients diagnosed with nonvalvular atrial fibrillation and treated at the Qinghai Cardiovascular and Cerebrovascular Specialist Hospital, China, between January 2019 and January 2021. We analyzed the differences in cardiac structure, comorbidities, and other influencing factors among the different ethnic groups RESULTS: We found significant differences in gender, age, smoking history, lone atrial fibrillation, left heart failure, dilated cardiomyopathy, and diabetes between Tibetan, Han, and Hui patients (P < 0.05). Tibetan, Han, and Hui patients also differed with regard to left ventricular end-diastolic volume, left ventricular ejection fraction, fractional shortening, NT-proBNP, glycated hemoglobin, red blood cell distribution width, platelet count, platelet hematocrit, platelet distribution width, homocysteine (Hcy), C-reactive protein, and superoxide dismutase (SOD) (P < 0.05) CONCLUSION: Our study revealed variations in comorbidities, cardiac structure, and blood indexes among Tibetan, Han, and Hui AF patients, highlighting distinct patterns in complications and biomarker levels across ethnic groups.

Sulfur-containing amino acids and their metabolites in atrial fibrosis

Atrial fibrosis, a symbol of atrial structural remodelling, is a complex process involved in the occurrence and maintenance of atrial fibrillation (AF). Atrial fibrosis is regulated by multiple factors. Sulfur containing amino acids and their metabolites, such as hydrogen sulfide (H2S) and taurine, can inhibit the process of atrial fibrosis and alleviate atrial remodeling. However, homocysteine can promote the activation of atrial fibroblasts and further promote atrial fibrosis. In this review, we will focus on the recent progress in atrial structural changes and molecular mechanisms of atrial fibrosis, as well as the regulatory roles and possible mechanisms of sulfur containing amino acids and their metabolites in atrial fibrosis. It is expected to provide new ideas for clarifying the mechanism of atrial fibrosis and finding targets to inhibit the progress of atrial fibrosis.

Homocysteine as a Predictor of Paroxysmal Atrial Fibrillation-Related Events: A Scoping Review of the Literature

High levels of homocysteine (Hcy) have been linked with adverse cardiovascular outcomes, such as arrhythmias and stroke. In the context of paroxysmal atrial fibrillation (PAF), hyperhomocysteinemia has been demonstrated to be an independent predictor of future events. The aim of this report was to address the potential value of Hcy levels in predicting future paroxysms of atrial fibrillation (AF), as well as to identify the potential mechanisms of action. We searched PubMed and the Cochrane Database on 16 January 2022. Keywords used were homocysteine or hyperhomocysteinemia paired with a total of 67 different keywords or phrases that have been implicated with the pathogenesis of AF. We included primary reports of clinical and non-clinical data in the English language, as well as systematic reviews with or without meta-analyses. We placed no time constraints on our search strategy, which yielded 3748 results. Following title review, 3293 reports were excluded and 455 reports were used for title and abstract review, after which 109 reports were finally used for full-text review. Our review indicates that Hcy levels seem to hold a predictive value in PAF. Herein, potential mechanisms of action are presented and special considerations are made for clinically relevant diagnostic procedures that could complement plasma levels in the prediction of future PAF events. Finally, gaps of evidence are identified and considerations for future clinical trial design are presented.

Homocysteine and atrial fibrillation: novel evidences and insights

Atrial fibrillation (AF) is one of the most prevalent rhythm disorders worldwide, with around 37.574 million cases around the globe (0.51 % global population).  Different studies showed a high informative value of different biomarkers, including such related to the systemic inflammation, biomechanical stress and fibrosis. In this review article we aimed to study only the relation of homocysteine to the AF development. Homocysteine is a sulfur-containing amino acid, that is produced in the process of methionine metabolism. Which is a non-canonical amino acid, that is derived from the food proteins. From the scientific point of view there is a relation between hyperhomocysteinemia and myocardial fibrosis, but these mechanisms are complicated and not sufficiently studied. Homocysteine regulates activity of the ion channels through their redox state. Elevated homocysteine level can condition electrical remodeling of the cardiomyocytes through the increase of sodium current and change in the function of rapid sodium channels, increase of inwards potassium current and decrease in amount of rapid potassium channels. High homocysteine concentration also leads to the shortening of the action potential, loss of the rate adaptation of the action potential and persistent circulation of the re-entry waves. In a series of experimental studies on mice there was an association found between the homocysteine level and activity of vascular inflammation. Elevation of homocysteine level is an independent factor of the thromboembolic events and AF relapses. Population studies showed, that homocysteine is an independent risk factor for AF. So, homocysteine is an interesting target for up-stream therapy.

Homocysteine (HCY) levels in patients with atrial fibrillation (AF): A meta-analysis

PURPOSE

Atrial fibrillation (AF) is one of the most common persistent arrhythmia, and its complications include cerebral embolism, arterial embolism and heart failure. Some studies have found that elevated Homocysteine (HCY) levels is a new risk factor for AF. Currently, there is no meta-analysis to explore whether the HCY levels is related to AF. Therefore, a meta-analysis was conducted to evaluate the relationship between the HCY levels and AF, in order to draw the attention of clinicians to the HCY levels.

METHODS

A meta-analysis was performed in the study to evaluated the association between the HCY levels and AF. In order to identify eligible original articles, The EMBASE, PubMed, and web of science were systematically searched until November 2020. All data were analyzed with Review Manager 5.3. The meta-analysis results were evaluated depending on standardized mean differences (SMD) with 95% confidence intervals (CI). Moreover, the subgroup analysis and sensitivity analysis were also analyzed.

RESULTS

The HCY levels was significantly associated with AF (WMD = 0.81, 95% CI: 0.58 to 1.03; P < .00001). In the analysis, there was a medium degree of heterogeneity (I² = 73%). Subgroup analysis showed that female < 60, BMI≥25, BMI <25, age ≥60 and publication year ≥2010 were identified as possible sources of heterogeneity. Sensitivity analysis showed that the main results remained unchanged after omitting any single study or converting the random effects model (REM) to fixed effects model (FEM).

CONCLUSIONS

The meta-analysis showed that there is a significant correlation between the HCY levels and AF, and the role of HCY in AF patients should not be ignored in clinical.

Adipocyte factor CTRP6 inhibits homocysteine-induced proliferation, migration, and dedifferentiation of vascular smooth muscle cells through PPARγ/NLRP3

NLRP3 and PPARγ play important roles in the development of atherosclerosis (AS). Studies have shown that PPARγ regulates the expression of NLRP3 in vascular diseases. In addition, the adipocyte factor CTRP6 can improve the activation of PPARγ in vascular diseases. However, the regulatory relationship between CTRP6, PPARγ, and NLRP3 in AS and its underlying mechanism have not been reported. Since proliferation, migration, and dedifferentiation of vascular smooth muscle cells (VSMCs) are key events in AS, in this study, we induced proliferation, migration, and dedifferentiation of VSCMs through homocysteine (HCY) to detect the specific effects of CTRP6, PPARγ, and NLRP3. Subsequently, CTRP6 was overexpressed and the PPARγ inhibitor GW9662 and agonist rosiglitazone were administered to HCY-induced VSCMs to investigate the mechanisms. The results show that the expression of CTRP6 decreased in HCY-induced VSMCs. In addition, CTRP6 overexpression inhibited the proliferation and migration of HCY-induced VSMCs, as well as cell cycle acceleration and dedifferentiation. Overexpression of CTRP6 increased HCY-induced PPARγ expression and inhibited NLRP3 expression. The addition of GW9662 and rosiglitazone further demonstrated that overexpression of CTRP6 inhibited HCY-induced VSMC proliferation, migration, and dedifferentiation through PPARγ/NLRP3 signaling. In conclusion, CTRP6 inhibited HCY-induced proliferation, migration, and dedifferentiation of VSMCs through PPARγ/NLRP3.

Appraising the Causal Association of Plasma Homocysteine Levels With Atrial Fibrillation Risk: A Two-Sample Mendelian Randomization Study

Background

Although several observational studies have suggested an association of elevated plasma homocysteine (Hcy) levels with increased risk of atrial fibrillation (AF), it remains unclear whether this association reflects causality. In this study, we aimed to investigate the causal association of plasma Hcy levels with AF risk.

Methods

A two-sample Mendelian randomization (MR) study was designed to investigate the causal association of Hcy with AF. Summary data on association of single nucleotide polymorphisms (SNPs) with Hcy were extracted from the hitherto largest genome-wide association study (GWAS) with up to 44,147 individuals, and statistics data on association of SNPs with AF were obtained from another recently published GWAS with up to 1,030,836 individuals. SNPs were selected at a genome-wide significance threshold (p < 5 × 10^–8). Fixed-effect inverse variance weighting (IVW) method was used to calculate the causal estimate. Other statistical methods and leave-one-out analysis were applied in the follow-up sensitivity analyses. MR-Egger intercept test was conducted to detect the potential directional pleiotropy.

Results

In total, nine SNPs were identified as valid instrumental variables in our two-sample MR analysis. Fixed-effect IVW analysis indicated no evidence of causal association of genetically predicted Hcy with AF. The odds ratio (OR) and 95% confidence interval (CI) of AF per standard deviation (SD) increase in Hcy were 1.077 (0.993, 1.168), p = 0.075. Similar results were observed in the sensitivity analyses. MR-Egger intercept test suggested no evidence of potential horizonal pleiotropy.

Conclusions

This two-sample MR analysis found no evidence to support causal association of Hcy with AF.

Hypertension-Mediated Organ Damage Correlates With Serum Homocysteine Level in Community-Dwelling Elderly Chinese: The North Shanghai Study

Introduction: Serum homocysteine (Hcy) level is associated with cardiocerebrovascular disease. However, the relationship between Hcy and hypertension-mediated organ damage (HMOD) in non-hospitalized residents has not been elucidated. We aimed to investigate the association of HMOD with Hcy in elderly Chinese.

Methods: One thousand seven hundred and forty-four community-dwelling elderly Chinese (age ≥65 years) participated in the Northern Shanghai Study from Jun. 2014 to Aug. 2015. Hyperhomocysteinemia (HHcy) was defined as serum Hcy ≥15 mmol/L, and HMOD was estimated as arterial stiffness [carotid-femoral pulse wave velocity (CF-PWV) and ankle-brachial index (ABI)], cardiac impairment [left ventricular (LV) hypertrophy and LV diastolic dysfunction], and renal dysfunction [estimated glomerular filtration rate (eGFR) and urinary albumin/creatinine ratio]. Linear and logistic regression models were built to explore the associations of HMOD with Hcy.

Results: Among 1,744 participants, 632 (36.2%) were diagnosed as HHcy. HHcy group had more men (61.2 vs. 35.3%), with higher age (73.7 ± 6.7 vs. 70.4 ± 5.3 years) and BMI (24.2 ± 3.4 vs. 23.7 ± 3.5 kg/m²). Linear regression analysis showed that serum Hcy level was positively associated CF-PWV and negatively associated with ABI and eGFR. By logistic regression, HHcy was significantly associated with abnormal CF-PWV [odds ratio (OR) = 1.53, 95% confidence interval (CI) 1.08–2.16] and ABI (OR = 1.55, 95% CI 1.17–2.04), and decreased eGFR (OR = 7.09, 95% CI 4.03–12.47) after adjustment for covariates. Moreover, similar associations of serum Hcy level with CF-PWV and eGFR were observed in subgroups by gender and hypertensive state.

Conclusion: HMOD, particularly renal dysfunction and arterial stiffening, was significantly and independently associated with increased serum Hcy level in the elderly Chinese.

Clinical Trial Registration: [ClinicalTrial.gov], identifier [NCT02368938].

No causal association between plasma homocysteine levels and atrial fibrillation: A Mendelian randomization study

BACKGROUND AND AIMS

Although several studies have shown an association between plasma homocysteine (Hcy) levels and atrial fibrillation (AF), the causality remains unclear. We undertook a Mendelian randomization (MR) study to investigate the causal association between Hcy and AF.

METHODS AND RESULTS

Single-nucleotide polymorphisms (SNPs) which genome-wide significantly associated with plasma Hcy levels were obtained from a genome-wide meta-analysis (N = 44 147). MR analyses including the random-effect inverse variance-weighted (IVW) meta-analysis, weighted median analysis, and MR-Egger regression were used to estimate the associations between the selected SNPs and AF based on a meta-analysis of genome-wide association study for AF (N = 588 190). The MR analyses revealed no causal role of genetically elevated plasma Hcy levels with AF risk (random-effect IVW, odds ratio per 1 SD increase in Hcy levels = 0.972, 95% confidence interval = 0.919 to 1.027, P = 0.308). The results were consistent with the weighted median method, MR-Egger and the analysis after excluding the pleiotropic SNPs. No heterogeneity and directional pleiotropy were observed in sensitivity analyses.

CONCLUSION

The findings suggested that plasma Hcy levels were not causally associated with AF.

Role of hyperhomocysteine, thyroid dysfunction and their interaction in ischemic stroke patients with non-valvular atrial fibrillation

The role of hyperhomocysteinemia (HHcy) and thyroid dysfunction in ischemic stroke with non-valvular atrial fibrillation (AF) remains controversial. Till now, the relationship between HHcy and thyroid dysfunction in ischemic stroke with non-valvular AF has not been reported. The aim of this study was to investigate the role and relationship of HHcy and thyroid dysfunction in ischemic stroke patients with non-valvular AF. Seven hundred and seventeen patients with acute ischemic stroke within the first 7 days of symptom onset were consecutively included in this study. Eligible patients were divided into AF group and without AF group. Variables including age, sex, smoke, drink, history of stroke were collected. Levels of homocysteine (Hcy), thyroid-stimulating hormone were evaluated at presentation. Multivariable logistic regression and spearman bivariate correlate analysis were used to evaluate the relationship of HHcy and thyroid dysfunction in ischemic stroke patients with AF. There were 122 patients with AF and 595 patients without AF. Two hundred and eighty-eight (40.2%) patients had HHcy and Three hundred and sixteen (44.1%) patients had thyroid dysfunction. There was significant difference of serum Hcy (P = 0.014) and thyroxine levels (P = 0.002) between patients with and without AF. Furthermore, the difference of serum Hcy (P = 0.007) and thyroxine levels (P = 0.004) between patients with and without AF was also significant in female subgroups. We did not find association between HHcy and thyroid dysfunction in AF group (P = 0.463). In conclusion, both HHcy and thyroid dysfunction were associated with AF in patients with acute ischemic stroke and in female subgroup patients. However, thyroid dysfunction had no relationship with HHcy in ischemic stroke patients with AF.

Elevated Homocysteine Levels Associated with Atrial Fibrillation and Recurrent Atrial Fibrillation

There is increasing evidence linking plasma homocysteine levels and atrial fibrillation (AF). The association between an elevated level of plasma homocysteine and AF was examined by meta-analysis in this study.The PubMed and ScienceDirect databases until August 2019 were utilized to collect previous literature on homocysteine and the potential relation to AF. The pooled effects were evaluated depending on standardized mean differences (SMDs) or odds ratios (ORs) with 95% confidence intervals (CIs), and the calculation was performed using Stata 12 software.A total of 11 validated articles were included in the meta-analysis. For pooled effect, the results confirmed that AF patients had higher homocysteine levels than control subjects (SMD: 0.58, 95%CI: 0.09-1.06). Compared with control subjects, homocysteine levels were higher in paroxysmal AF (SMD: 0.45, 95%CI: 0.18-0.72) and persistent AF patients (SMD: 1.21, 95%CI: 0.50-1.92). The pooled analysis suggested that patients with elevated homocysteine levels had markedly higher risk of AF compared with lower homocysteine levels in the categorical variable (OR: 2.21, 95%CI: 1.16-4.21) and continuous variable analyses (OR: 1.13, 95%CI: 1.00-1.27), respectively. In addition, the pooled analysis indicated that recurrent AF patients had significantly higher homocysteine levels than those without recurrence (SMD: 0.65, 95%CI: 0.42-0.88). The pooled analysis of the categorical variables indicated that elevated homocysteine levels were associated with increased risk of AF recurrence (OR: 3.81, 95%CI: 3.11-4.68). However, the association was weak in the pooled analysis of continuous variables (OR: 1.88, 95%CI: 0.74-4.81).Our meta-analysis identified that plasma homocysteine levels were significantly elevated in AF and recurrent AF patients. Elevated homocysteine is associated with increased risk of AF and AF recurrence.

Protective mechanism of SIRT1 on Hcy-induced atrial fibrosis mediated by TRPC3

High plasma levels of homocysteine (Hcy) are regarded as a risk factor for atrial fibrillation (AF), which is closely associated with the pathological consequence of atrial fibrosis and can lead to heart failure with a high mortality rate; here, we show that atrial fibrosis is mediated by the relationship between canonical transient receptor potential 3 (TRPC3) channels and sirtuin type 1 (SIRT1) under the stimulation of Hcy. The left atrial appendage was obtained from patients with either sinus rhythm (SR) or AF and used to evaluate the relationship between the concentration of Hcy and a potential mechanism of cardiac fibrosis mediated by TRPC3 and SIRT1. We next performed transverse aortic constriction (TAC) in mouse to investigate the relationship. The mechanisms underlying atrial fibrosis involving TRPC3 and SIRT1 proteins were explored by co‐IP, BLI and lentivirus transfection experiments. qPCR and WB were performed to analyse gene and protein expression, respectively. The higher level of atrial fibrosis was observed in the HH mouse group with a high Hcy diet. Such results suggest that AF patients may be more susceptible to atrial fibrosis and possess a high probability of progressing to hyperhomocysteinemia. Moreover, our findings are consistent with the hypothesis that TRPC3 channel up‐regulation leads to abnormal accumulation of collagen, with the down‐regulation of SIRT1 as an aetiological factor of high Hcy, which in turn predisposes to atrial fibrosis and strongly enhances the possibility of AF.

Serum folate and cobalamin levels and urinary dimethylarsinic acid in US children and adults

Nutritional status could affect arsenic metabolism and toxicity in the general population chronically exposed to low levels of inorganic arsenic. In this study, we examined the association of serum folate and cobalamin with urinary concentrations of dimethylarsinic acid (DMA), the most abundant metabolite of inorganic arsenic measured in urine, in children and adults who participated in the 2003-2006 US National Health and Nutrition Examination Surveys. A total of 1161 children (aged 6-19 years) and 1938 adults (aged 20-85 years) were analyzed for the association using multivariate general linear models, adjusting for potential confounders. We observed a positive association between serum levels of folate and cobalamin and creatinine-corrected urinary concentrations of DMA in both children and adults. Furthermore, serum levels of folate and cobalamin were inversely associated with homocysteine (Hcy). These results suggest that dietary intake of folate and cobalamin may exhibit protective functions against arsenic toxicity by increasing arsenic metabolism to the less toxic metabolite DMA and decreasing serum levels of Hcy.