Role of homocysteine for thromboembolic complication in patients with non-valvular atrial fibrilation

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.

Hyperhomocysteinemia and Ischemic Stroke: A Potential Dose-Response Association-A Systematic Review and Meta-analysis

Background and Purpose  Previous studies suggest an association between increased homocysteine (Hcy) and risk of ischemic stroke. Yet, it remains unknown whether a dose-response association exists between Hcy levels and risk of ischemic stroke. Methods  Systematic literature searches were performed in PubMed, Embase, Scopus, and Web of Science. Inclusion criteria were studies investigating ischemic stroke risk in an adult population with measured Hcy levels. We computed odds ratios (ORs) for a 5 µmol/L increase in Hcy levels using a random effects meta-analysis. Results  In total, 108 studies met the inclusion criteria of which 22 were rated as high-quality studies, and 20 studies included a dose-response analysis. Hcy levels were analyzed either as a continuous or categorical variable. The majority of the studies found an increased risk of ischemic stroke when comparing the highest-to-lowest Hcy strata. A graded association was observed over the Hcy strata, indicating a dose-response association, with the most apparent effect when Hcy levels exceeded approximately 15 µmol/L. No studies explored a potential nonlinear association between Hcy levels and ischemic stroke. Six studies were included in a meta-analysis, showing an OR of 1.43 (95% confidence interval [CI]: 1.28-1.61) per 5 µmol/L increase in Hcy levels. Conclusion  This review and meta-analysis indicate a dose-response association between Hcy levels and ischemic stroke. An evident increase in effect measures was observed when Hcy levels exceeded 15 µmol/L, indicating a nonlinear association between ischemic stroke and Hcy levels. This nonlinear association warrants further study. This study is registered with clinical trial ( https://www.crd.york.ac.uk/prospero/ ; unique identifier: CRD42019130371).

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.

Association of homocysteine and smoking with cerebral microemboli in patients with mechanical heart valves: a transcranial Doppler study

Objectives

Microembolic signals (MES) on transcranial Doppler (TCD) predict stroke and cognitive decline. Plasma levels of total homocysteine (tHcy), a prothrombotic factor, are higher in patients with microemboli in carotid stenosis and in patients with paradoxical embolism. In this study we assessed the association between the level of tHcy and the number of MES in patients with mechanical heart valves (MHVs).

Methods

TCD monitoring was performed to detect MES before and after breathing 100% oxygen and repeated every 2-4 weeks up to six times.

Results

Twenty-five patients with MHVs (mean age: 63.60±10.15 years) participated in this study; 15 were men (66.47±7.25 years) and 10 were women (59.30±12.60 years). In total, there were 126 study visits. In multiple regression, higher tHcy was associated with more MES in both preoxygenation (OR 1.34 (95% CI 1.07 to 1.68, P=0.009)) and postoxygenation (OR 1.40 (95% CI 1.07 to 1.83, P=0.01)) phases. Current smoking and the length of time between the operation and monitoring also correlated with a higher number of MES before and after breathing oxygen, particularly in women.

Conclusions

Higher tHcy and smoking were associated with a higher MES count in both preoxygenation and postoxygenation phases. Because smoking can be stopped and hyperhomocysteinaemia is treatable, these are clinically important findings.

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

Atrial fibrillation (AF), the most common sustained arrhythmia, is associated with a series of adverse complications that cause so-called AF socioeconomic burden. Apart from the classical risk factors, it seems to be novel factors that increase the risk of AF and AF-related stroke. Recently, more and more evidence has well documented the close relationships between homocysteine (Hcy) and AF. As a well-known marker for pro-oxidation and pro-inflammation, Hcy plays an important role in a number of vascular diseases having strong association with AF. This review will discuss the expression of Hcy and its association with ischemic stroke in AF patients especially for elderly patients, and the role and clinical implications of Hcy in the thromboembolic events and rhythm outcome in AF patients. The possible mechanisms linking elevated Hcy and cardiovascular events in AF patients will also be addressed, including oxidative stress, inflammatory response, atrial remodeling, etc.

Regression of warfarin-resistant left atrial appendage thrombus after ablation of atrial fibrillation and permanent pacing

Atrial fibrillation is the most common rhythm disturbance and can also occur in absence of true cardiac disease. However, also in these cases, it can generate left atrial appendage thrombi with systemic embolic potential. A regular and well conducted anticoagulant therapy with dicoumarol derivatives, as indicated in these patients, is not always successful. We report the case of a patient with lone atrial fibrillation and a left atrial appendage thrombus resistant to anticoagulant therapy with warfarin, which disappeared after catheter ablation of atrial fibrillation by electrical disconnection of the pulmonary veins, restoration of sinus rhythm and dual-chamber pacemaker implantation.

Culprit Factors for the Failure of Well-Conducted Warfarin Therapy to Prevent Ischemic Events in Patients With Atrial Fibrillation

BACKGROUND AND PURPOSE

In patients with atrial fibrillation (AF), oral anticoagulant therapy (OAT) is effective in reducing stroke and embolism. However, despite OAT, ischemic events do occur in some patients. Studies specifically addressing the identification of risk factors for ischemic events during well-conducted OAT are not available. In this study, we prospectively investigated the role of classic risk factors and homocysteine levels in the occurrence of ischemic complications in 364 AF patients on OAT.

METHODS

The quality of anticoagulation levels and the occurrence of bleeding and thrombotic events were recorded.

RESULTS

During follow-up (859 patient years) 21 patients had ischemic complications (rate 2.4 x 100 patient-years). Homocysteine plasma levels were higher in these patients than in patients without ischemic complications during OAT (P<0.01), whereas no difference was observed in relation to the quality of OAT. The presence of a history of previous ischemic events, hypertension, and homocysteine plasma levels over the 90th percentile were all associated with an increased risk of ischemic events during OAT (odds ratio [OR]=7, 4.5, and 4.7, respectively). The coexistence of these risk factors markedly increased the risk (OR=13.1; 95% CI, 3.7 to 45.7; P=0.001).

CONCLUSIONS

In conclusion, our results indicate that AF patients with multiple risk factors may not be sufficiently protected by OAT, even when this is well conducted.

Hyperhomocysteinemia and vitamin B6 deficiency: new risk markers for nonvalvular atrial fibrillation?

BACKGROUND

A recent "ex-vivo" study showed that nonvalvular atrial fibrillation (NVAF) is associated with enhanced activity of metalloproteinases at the atrial level, and in animal models homocysteine (Hcy) is able to activate metalloproteinases. The aim of this case-control study was to investigate the association of total Hcy plasma levels, vitamin status (folate, vitamin B6, and vitamin B12), and methylenetetrahydrofolate reductase C677T and CBS 844ins68 polymorphisms with NVAF. Furthermore, the role of these variables in the occurrence of ischemic events was investigated.

METHODS

We studied 310 NVAF patients on oral anticoagulant treatment (168 patients with previous ischemic events and 142 without) and 310 controls.

RESULTS

Hyperhomocysteinemia (highest quartile) and vitamin B6 deficiency (lowest quartile) were independently associated with NVAF after multivariate analysis (Hcy: odds ratio [OR] 6.40, 95% CI 3.29-12.46; vitamin B6: OR 3.02, 95% CI 1.02-8.95). A significant correlation was found between Hcy levels and left atrial diameter (r = 0.46; P <.001). As shown by multivariate analysis, elevated Hcy levels were an independent risk factor for ischemic complications during NVAF (OR 2.66, 95% CI 1.15-6.20).

CONCLUSIONS

This study demonstrates a significant association of both elevated Hcy levels and low vitamin B6 levels with the presence of NVAF; in addition, it confirms the role of Hcy as a risk factor for ischemic events during NVAF.