Endothelial function in patients with atrial fibrillation

Hypertension and Atrial Fibrillation: Bridging the Gap Between Mechanisms, Risk, and Therapy

Background and objectives: Atrial fibrillation (AF), the most prevalent sustained arrhythmia, poses a significant public health challenge due to its links with stroke, heart failure, and mortality. Hypertension, a primary modifiable cardiovascular risk factor, is a well-established risk factor for AF that facilitates structural and electrical changes in the atria, including dilation, fibrosis, and pressure overload. Material and Methods: we conducted a literature search regarding the shared mechanisms, risks and treatments of hypertension and atrial fibrillation. Results: The renin-angiotensin-aldosterone system plays a pivotal role in this remodelling and inflammation, increasing AF susceptibility. Uncontrolled hypertension complicates AF management, diminishing the effectiveness of mainstay treatments, including antiarrhythmic drugs, catheter ablation, and cardioversion. Effective blood pressure management, particularly with therapies targeting the renin-angiotensin-aldosterone system (RAAS), can lower the risk of new-onset AF and reduce the incidence of recurrent AF, enhancing the success of rhythm control strategies. These antihypertensive therapies mitigate myocardial hypertrophy and fibrosis and attenuate both atrial pressure strain and the inflammatory response, mitigating the substrates for AF. Conclusion: This review highlights the urgent need for integrated strategies that combine BP control, AF screening, and lifestyle modifications to minimise the burden of AF and its complications. Future research should investigate the specific mechanisms of cellular-level interactions associated with a hypertensive predisposition to AF, including systematic inflammation and the role of genetics, the impact of blood pressure variations on AF risk, and individualised treatment strategies specifically targeting the shared mechanisms, simultaneously propagating hypertension and AF.

Epigenetic regulation on left atrial function and disease recurrence after catheter ablation in atrial fibrillation

BACKGROUND

Genetic variation and modifiable risk factors play a significant role in the pathogenesis of atrial fibrillation (AF). The influence of epigenetic modification on AF remains to be elucidated. We investigated the role of DNA methylation in the etiology of AF. Epigenetic evaluation was performed in 115 AF patients who underwent radiofrequency catheter ablation in a single institution. We measured methylation at approximately 850,000 bp cytosine-phosphate-guanine (CpG) sites in the 115 samples. The degree of methylation was compared across seven classification criteria: type of AF, late recurrence, impaired left atrium (LA) function, late gadolinium enhancement, LA diameter, LA volume, and flow velocity of the LA appendage.

RESULTS

The four most significantly methylated genes were DEFB104B, C3, TANC1, and TMEM9B. The DEFB104B gene (cg20223677 in the transcription start site), which encodes β-defensin 104B, was hypomethylated in three groups: AF patients with late recurrence, impaired LA function, and impaired LAA flow velocity. Enriched functional annotation of the differentially methylated datasets revealed that five out of the seven AF groups in this cohort were associated with genes involved in the cell movement of endothelial cell lines, sprouting angiogenesis by endothelial cell lines, or migration of endothelial cell lines.

CONCLUSIONS

Epigenetic profiling revealed that epigenetic modification might affect important characteristics of AF. Our results suggest that the pathogenesis of AF might be affected by not only genetic variation or modifiable factors but also by epigenetic modulation.

Pathophysiology, Diagnosis, and Management of Coronary Artery Disease in the Setting of Atrial Fibrillation

Atrial fibrillation (AF) and coronary artery disease are frequently associated and, when so, lead to a grim prognosis. Recent studies suggest the presence of interconnected pathophysiological pathways between the 2 conditions that can promote and aggravate each other, igniting a vicious cycle. Notwithstanding, in contrast with the attention dedicated to the management of antithrombotic treatment, research on other aspects of coronary artery disease in AF is only recently gaining traction. The clinical impact of correct assessment of coronary artery stenosis in AF is especially high, due to the antithrombotic therapy imposed by both AF and coronary stenting. Until recently, an in-depth characterization of coronary microcirculation in AF was lacking. However, contemporary studies indicate that coronary microvascular dysfunction is a frequent encounter in AF, possibly explaining the ischemic symptoms even in the absence of obstructive coronary artery disease and interfering with the use of pressure-based indices to evaluate the hemodynamic significance of coronary artery stenosis. This comprehensive review addresses our current knowledge on coronary physiology in AF and its repercussion on the invasive management of coronary artery disease in this setting.

Mitochondrial Dysfunction in Atrial Fibrillation: The Need for a Strong Pharmacological Approach

Despite great progress in treating atrial fibrillation (AF), especially with the development of increasingly effective invasive techniques for AF ablation, many unanswered questions remain regarding the pathogenic mechanism of the arrhythmia and its prevention methods. The development of AF is based on anatomical and functional alterations in the cardiomyocyte resulting from altered ionic fluxes and cardiomyocyte electrophysiology. Electric instability and electrical remodeling underlying the arrhythmia may result from oxidative stress, also caused by possible mitochondrial dysfunction. The role of mitochondrial dysfunction in the pathogenesis of AF is not yet fully elucidated; however, the reduction in AF burden after therapeutic interventions that improve mitochondrial fitness tends to support this concept. This selected review aims to summarize the mechanisms of mitochondrial dysfunction related to AF and the current pharmacological treatment options that target mitochondria to prevent or improve the outcome of AF.

Association of induced atrial fibrillation in the electrophysiology laboratory with endothelial dysfunction and documented atrial fibrillation

OBJECTIVE

Atrial fibrillation (AF) is a common arrhythmia that increases morbidity and mortality, as well as healthcare costs. The induction of AF (IAF) during programmed atrial pacing in an electrophysiological study (EPS) is a prevalent phenomenon that has been underappreciated by electrophysiologists. Despite extensive research on AF, only a few studies have focused on this phenomenon. The aim of our study was to investigate the association between history of AF and IAF and the underlying pathophysiological factors such as arterial stiffness, subclinical atherosclerosis, and impaired endothelial function.

METHODS

This cross-sectional and observational study included 87 patients who had palpitations and were scheduled for EPS. Patients underwent biochemical investigations, transthoracic echocardiography, carotid ultrasound, carotid-femoral artery pulse wave velocity (PWV), and flow-mediated dilatation (FMD) measurements before EPS. Patients were divided into two groups, AF-induced and non-induced in EPS, for further statistical analysis.

RESULTS

AF was induced in 16 of 87 patients (18.3%) included in the analysis. The FMD (%) was significantly lower (16.01 ± 10.1 vs. 8.7 ± 5.7, P = 0.022) and, remarkably, the proportion of patients with a history of AF was significantly higher (2.8% vs. 37.5%, P < 0.001) in the IAF group. ROC analysis showed that a documented AF and FMD predicted IAF, with AUC of 0.741 (p = 0.012) and 0.740 (p = 0.001), respectively. Logistic regression analysis revealed that FMD and history of AF were strong predictors of IAF (odds ratio [OR], 0.853; 95% confidence interval [CI] 0.737-0.988; P = 0.034, OR: 10.1, 95% CI 4.9-20.5; P = 0.003, respectively).

CONCLUSION

Endothelial dysfunction and documented AF were associated with IAF during EPS.

Spectrum of Non-Obstructive Coronary Artery Disease and Its Relationship with Atrial Fibrillation

This article aims to analyze the relationship between non-obstructive coronary artery disease (NOCAD) and atrial fibrillation (AF), exploring the underlying pathophysiological mechanisms and implications for clinical management. NOCAD and AF are prevalent cardiovascular conditions that often coexist, yet their interrelation is not well understood. NOCAD can lead to ischemic necrosis of cardiomyocytes and their replacement with fibrous tissue, sustaining focal ectopic activity in atrial myocardium. Atrial fibrillation, on the other hand, the most common sustained cardiac arrhythmia, is able to accelerate atherosclerosis and increase oxygen consumption in the myocardium, creating a mismatch between supply and demand, and thus promoting the development or worsening of coronary ischemia. Therefore, NOCAD and AF seem to be a complex interplay with one begets another.

Factors influencing early recurrence of atrial fibrillation among elderly patients following radiofrequency catheter ablation and the impact of different antiarrhythmic regimens

Background

Patients with atrial fibrillation (AF) who undergo radiofrequency catheter ablation (RFCA) necessitate the administration of antiarrhythmic drugs to prevent early recurrence. The clinical outcomes among these patients may be influenced by varying antiarrhythmic regimens.

Objectives

To identify the risk factors associated with early recurrence and compare the clinical outcomes among different antiarrhythmic regimens in elderly patients with AF following radiofrequency catheter ablation (RFCA) during a 3-month period.

Methods

A retrospective observational study encompassed 420 elderly patients with AF following RFCA. Baseline data were collected during the initial postoperative visit and clinical outcomes were carefully monitored over a 3-month follow-up period. Logistic regression and Cox-proportional hazard regression analyses were performed to investigate the relationship between various antiarrhythmic regimens and the clinical outcomes.

Results

Multivariate logistic regression analysis revealed that age (p = 0.001), left atrial diameter (p < 0.001), left ventricular diameter (p = 0.015), reactive hyperemia index (RHI) (p < 0.001), antiarrhythmic drug (p < 0.001) and hs-cTnI (p = 0.017) were independent risk factors of early recurrence. Furthermore, in cox survival regression analysis model, survival rate of early recurrence in the amiodarone group was higher than in the propafenone group (HR 2.30, 95%CI 1.17-4.53, p = 0.016) and in the sotalol group (HR 3.60, 95%CI 2.17-5.95, p < 0.001). Compared to the amiodarone group, the incidence of liver dysfunction was lower in the dronedarone group (p = 0.046) and the propafenone group (p = 0.021). The incidence of bradyarrhythmia (p = 0.003), QT interval prolongation (p = 0.035) and atrioventricular transmission block (p = 0.021) were higher in the sotalol group than in the amiodarone group.

Conclusion

RHI was identified as an independent risk factor for early recurrence among elderly AF patients after RFCA. Compared to amiodarone, propafenone and sotalol exhibited an elevated risk of early recurrence. Although there was no significant difference in early recurrence between amiodarone and dronedarone, dronedarone emerged as the preferred option due to its lower frequency of adverse drug reactions than amiodarone.

Repurposing Metformin for the Treatment of Atrial Fibrillation: Current Insights

Metformin is an orally effective anti-hyperglycemic drug that despite being introduced over 60 years ago is still utilized by an estimated 120 to 150 million people worldwide for the treatment of type 2 diabetes (T2D). Metformin is used off-label for the treatment of polycystic ovary syndrome (PCOS) and for pre-diabetes and weight loss. Metformin is a safe, inexpensive drug with side effects mostly limited to gastrointestinal issues. Prospective clinical data from the United Kingdom Prospective Diabetes Study (UKPDS), completed in 1998, demonstrated that metformin not only has excellent therapeutic efficacy as an anti-diabetes drug but also that good glycemic control reduced the risk of micro- and macro-vascular complications, especially in obese patients and thereby reduced the risk of diabetes-associated cardiovascular disease (CVD). Based on a long history of clinical use and an excellent safety record metformin has been investigated to be repurposed for numerous other diseases including as an anti-aging agent, Alzheimer's disease and other dementias, cancer, COVID-19 and also atrial fibrillation (AF). AF is the most frequently diagnosed cardiac arrythmia and its prevalence is increasing globally as the population ages. The argument for repurposing metformin for AF is based on a combination of retrospective clinical data and in vivo and in vitro pre-clinical laboratory studies. In this review, we critically evaluate the evidence that metformin has cardioprotective actions and assess whether the clinical and pre-clinical evidence support the use of metformin to reduce the risk and treat AF.

Synergistic Effects of Weight Loss and Catheter Ablation: Can microRNAs Serve as Predictive Biomarkers for the Prevention of Atrial Fibrillation Recurrence?

In atrial fibrillation (AF), multifactorial pathologic atrial alterations are manifested by structural and electrophysiological changes known as atrial remodeling. AF frequently develops in the context of underlying cardiac abnormalities. A critical mechanistic role played by atrial stretch is played by abnormal substrates in a number of conditions that predispose to AF, including obesity, heart failure, hypertension, and sleep apnea. The significant role of overweight and obesity in the development of AF is known; however, the differential effect of overweight, obesity, cardiovascular comorbidities, lifestyle, and other modifiable risk factors on the occurrence and recurrence of AF remains to be determined. Reverse remodeling of the atrial substrate and subsequent reduction in the AF burden by conversion into a typical sinus rhythm has been associated with weight loss through lifestyle changes or surgery. This makes it an essential pillar in the management of AF in obese patients. According to recently published research, microRNAs (miRs) may function as post-transcriptional regulators of genes involved in atrial remodeling, potentially contributing to the pathophysiology of AF. The focus of this review is on their modulation by both weight loss and catheter ablation interventions to counteract atrial remodeling in AF. Our analysis outlines the experimental and clinical evidence supporting the synergistic effects of weight loss and catheter ablation (CA) in reversing atrial electrical and structural remodeling in AF onset and in recurrent post-ablation AF by attenuating pro-thrombotic, pro-inflammatory, pro-fibrotic, arrhythmogenic, and male-sex-associated hypertrophic remodeling pathways. Furthermore, we discuss the promising role of miRs with prognostic potential as predictive biomarkers in guiding approaches to AF recurrence prevention.

Oxidized high-density lipoprotein associates with atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common heart arrhythmia and considered to be a progressive chronic disease associated with increased morbidity and mortality. Recent data suggest a link between inflammation, oxidative stress, and AF, although the underlying mechanisms are not fully understood. Because oxidized lipoproteins cause structural damage and electrophysiologic changes in cardiomyocytes, it is feasible that the transformation of atheroprotective high-density lipoprotein (HDL) into dysfunctional HDL contributes to the development of AF.

OBJECTIVE

The purpose of this study was to determine whether a reduced antioxidant function of HDL is associated with the presence of AF.

METHODS

In this multicenter cross-sectional cohort study, we assessed HDL function in sera of 1206 participants. Patients were divided into groups according to the presence of AF (n = 233) or no AF (n = 973). A validated cell-free biochemical assay was used to determine reduced HDL antioxidant function as assessed by increased normalized HDL lipid peroxide content (nHDLox).

RESULTS

Participants with AF had a 9% higher mean relative nHDLox compared to persons without AF (P = .025). nHDLox was strongly associated with AF in all models of logistic regression, including the analysis adjusted for age, sex, and risk factors for AF (all P ≤.01).

CONCLUSION

Reduced antioxidant HDL function is associated with the presence of AF, which supports growing evidence that impaired lipoprotein function is linked to electrophysiological changes in cardiomyocytes. nHDLox is one of several contributors to the initiation and perpetuation of AF.

Atrial Fibrillation and Early Vascular Aging: Clinical Implications, Methodology Issues and Open Questions-A Review from the VascAgeNet COST Action

Atrial fibrillation (AF), the most common cardiac arrhythmia, is associated with adverse CV outcomes. Vascular aging (VA), which is defined as the progressive deterioration of arterial function and structure over a lifetime, is an independent predictor of both AF development and CV events. A timing identification and treatment of early VA has therefore the potential to reduce the risk of AF incidence and related CV events. A network of scientists and clinicians from the COST Action VascAgeNet identified five clinically and methodologically relevant questions regarding the relationship between AF and VA and conducted a narrative review of the literature to find potential answers. These are: (1) Are VA biomarkers associated with AF? (2) Does early VA predict AF occurrence better than chronological aging? (3) Is early VA a risk enhancer for the occurrence of CV events in AF patients? (4) Are devices measuring VA suitable to perform subclinical AF detection? (5) Does atrial-fibrillation-related rhythm irregularity have a negative impact on the measurement of vascular age? Results showed that VA is a powerful and independent predictor of AF incidence, however, its role as risk modifier for the occurrence of CV events in patients with AF is debatable. Limited and inconclusive data exist regarding the reliability of VA measurement in the presence of rhythm irregularities associated with AF. To date, no device is equipped with tools capable of detecting AF during VA measurements. This represents a missed opportunity to effectively perform CV prevention in people at high risk. Further advances are needed to fill knowledge gaps in this field.

Anticoagulation Intensity during Appendage Occlusion: Lessons from Silent Cerebral Embolism

INTRODUCTION

Endovascular left atrial appendage occlusion (LAAO) is associated with a high incidence of peri-procedure silent cerebral embolism (SCE), while the recommended activated clotting time (ACT) level by the expert consensus is lower than that in atrial fibrillation (AF) ablation. The aim of our study was to investigate whether raising the targeted ACT level during LAAO to the same level as AF ablation could decrease the incidence of SCE.

METHODS

It was a prospective observational cohort study. Consecutive AF patients receiving LAAO between January 2021 and December 2022 were included and categorized into two groups based on the time of enrollment. Patients enrolled in 2021 (group 250) maintained a target ACT level of ≥250 s during LAAO procedure, while patients enrolled in 2022 (group 300) maintained the peri-procedure ACT ≥300 s. All patients underwent cerebral magnetic resonance imaging before and after the procedure.

RESULTS

A total of 81 patients were included (38 in the group 250 and 43 in the group 300). After inverse probability of treatment weighting (IPTW), patients in the group 250 showed a significantly lower incidence of SCE than group 300 (IPTW p = 0.038). Only a stable high ACT pattern could decrease the risk of SCE. No significant differences were found between other ACT change patterns on the SCE incidence.

CONCLUSION

Raising the peri-procedure ACT level to a stable 300 s could decrease the risk of the SCE without increasing the major bleeding events.

Blood pressure variability, nocturnal heart rate variability and endothelial function predict recurrent cerebro-cardiovascular events following ischemic stroke

Introduction

Cardiovascular parameters characterizing blood pressure (BP), heart rate (HR), endothelial function and arterial stiffness predict cerebro-cardiovascular events (CCVE) in the general population. Considering the paucity of data in stroke patients, we assessed these parameters as potential predictors of recurrent CCVE at acute stroke stroke.

Patients and methods

This is a secondary outcome analysis of a prospective observational longitudinal Sleep Deficiency & Stroke Outcome Study (ClinicalTrials.gov Identifier: NCT02559739). The study consecutively recruited acute ischemic stroke patients. Cardiovascular parameters (blood pressure variability [BPV], heart rate variability [HRV], endothelial function, and arterial stiffness) were assessed within the first week post-stroke. Future CCVE were recorded over a 3-year follow-up. Multivariate Cox regression analysis was used to investigate the prognostic value of 48 cardiovascular parameters regarding CCVE risk.

Results

Out of 447 recruited patients, 359 were included in this analysis. 20% of patients developed a future CCVE. A high variability of systolic BP (n = 333) and nocturnal HR (non-linear parameters; n = 187) at acute stroke predicted CCVE risk after adjustment for demographic parameters, cardiovascular risk factors and mean BP or HR, respectively. Endothelial dysfunction (n = 105) at acute stroke predicted CCVE risk after adjustment for age and sex, but not after adjustment for cardiovascular risk factors. Diurnal HR and arterial stiffness at acute stroke were not associated with CCVE risk.

Conclusion

High blood pressure variability, high nocturnal HRV and endothelial function contribute to the risk for future CCVE after stroke.

Modulating activity of PVN neurons prevents atrial fibrillation induced circulation dysfunction by electroacupuncture at BL15

BACKGROUND

Circulation dysfunction is a major contributing factor to thrombosis in patients with atrial fibrillation (AF) for which effective interventions are lacking. Growing evidence indicates that regulating the paraventricular nucleus (PVN), an autonomic control center, could offer a novel strategy for treating cardiovascular and circulatory diseases. Concurrently, electroacupuncture (EA) at Xinshu (BL15), a form of peripheral nerve stimulation, has shown efficacy in treating several cardiovascular conditions, although its specific mechanism remains unclear. This study aimed to assess the impact of EA at BL15 on circulatory dysfunction in a rat AF model and investigate the pivotal role of PVN neuronal activity.

METHODS

To mimic the onset of AF, male SD rats received tail intravenous injection of ACh-CaCl2 and were then subjected to EA at BL15, sham EA, or EA at Shenshu (BL23). Macro- and micro-circulation function were evaluated using in vivo ultrasound imaging and laser doppler testing, respectively. Vasomotricity was assessed by measuring dimension changes during vascular relaxation and contraction. Vascular endothelial function was measured using myograph, and the activation of the autonomic nerve system was evaluated through nerve activity signals. Additionally, chemogenetic manipulation was used to block PVN neuronal activation to further elucidate the role of PVN activation in the prevention of AF-induced blood circulation dysfunction through EA treatment.

RESULTS

Our data demonstrate that EA at BL15, but not BL23 or sham EA, effectively prevented AF-induced macro- and micro-circulation dysfunction. Furthermore, EA at BL15 restored AF-induced vasomotricity impairment. Additionally, EA treatment prevented abnormal activation of the autonomic nerve system induced by AF, although it did not address vascular endothelial dysfunction. Importantly, excessive activation of PVN neurons negated the protective effects of EA treatment on AF-induced circulation dysfunction in rats.

CONCLUSION

These results indicate that EA treatment at BL15 modulates PVN neuronal activity and provides protection against AF-induced circulatory dysfunction.

Association Between Pulmonary Vascular Volume and Cardiac Structure and Function in Patients With Atrial Fibrillation

Pulmonary vascular abnormalities, quantified from computed tomography scans, have frequently been observed in patients with pulmonary diseases. However, little is known about pulmonary vascular changes in patients with cardiac disease. Thus, we aimed to examine the cardiopulmonary relation in patients with atrial fibrillation (AF) by comparing pulmonary vascular volume (PVV) to echocardiographic measures and AF severity. A total of 742 patients (median age 63 years, 70% men) who underwent ablation for AF were included. Preprocedural cardiac computed tomography was used to measure the total and small-vessel PVV, along with the pulmonary artery to aorta ratio and the degree of emphysema. The association between PVV and echocardiographic parameters was evaluated using a multivariable linear regression analysis. Lower total and small-vessel PVV were associated with more impaired measures of cardiac structure and function, including but not limited to left ventricular ejection fraction and peak atrial longitudinal strain. Patients with reduced total and small-vessel PVV had higher odds of having persistent AF than paroxysmal AF in the unadjusted logistic regression analyses. However, after clinical and echocardiographic adjustments, only reduced small-vessel PVV remained independently associated with persistent AF (odds ratio 1.90, 95% confidence interval 1.26 to 2.87, p = 0.002). In conclusion, pulmonary vascular remodeling is associated with persistent AF and with more impaired measures of cardiac structure and function, providing further insights into heart-lung interactions in this patient group.

Atrial fibrillation and coronary artery disease: An integrative review focusing on therapeutic implications of this relationship

The incidence of both atrial fibrillation (AF) and coronary artery disease (CAD) increases with advancing age. They share common risk factors and very often coexist. Evidence points to an intricate relationship between atrial tissue excitability and neuronal remodeling with ischemia at the microcirculatory level. In this review, we delineated this complex relationship, identified a common theme between the two, and discussed how the knowledge of this relationship translates into a positive and meaningful impact in patient management. Recent research indicates a high prevalence of CAD among AF patients undergoing coronary angiography. Further, the incidence of AF is much higher in those suffering from CAD compared to age-matched adults without CAD underlying this reciprocal relationship. CAD adversely affects AF by promoting progression via re-entry and increasing excitability of atrial tissue as a result of ischemia and electrical inhomogeneity. AF in turn accelerates atherosclerosis via endothelial dysfunctional and inflammation and together with enhanced thrombogenicity and hypercoagulability contribute to micro and macrothrombi throughout cardiovascular system. In a nutshell, the two form a vicious cycle wherein one disease promotes the other. Most AF recommendations focuses on rate/rhythm control and prevention of thromboembolism. Very few studies have discussed the importance of unmasking coexistent CAD and how the treatment of underlying ischemia will impact the burden of AF in these patients. Inflammation and endothelial dysfunction remain central to both disease processes and form a handsome therapeutic target in the management of the two diseases. The relationship between AF and CAD is complex and much more than mere coincidence. The two diseases share common risk factor and pathophysiology. Hence, it is impractical to treat them in isolation. Accordingly, we share the implications of managing underlying ischemia and inflammation to positively impact and improve quality of life among AF patients.

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.

Endogenous Glycosaminoglycans in Various Pathologic Plasma Samples as Measured by a Fluorescent Quenching Method

Endogenous glycosaminoglycans (GAGs) with a similar structure to heparin are widely distributed in various tissues. A fluorescence probe, namely Heparin Red, can detect polyanionic GAGs in plasma samples. The purpose of this study is to measure endogenous GAGs in various plasma samples obtained from different pathologic states in comparison to healthy controls utilizing this method. Plasma samples were obtained from patient groups including atrial fibrillation (AF), end-stage-renal-disease (ESRD), diabetes mellitus (DM), sepsis, cancer, liver disease (LD), and pulmonary embolism (PE). Normal human plasma (NHP) was used as healthy controls. The Heparin Red kit from Red Probes (Münster, Germany) was used for the quantification of endogenous GAGs in each sample before and after heparinase I degradation. All results were compiled as group means  ±  SD for comparison. NHP was found to have relatively low levels of endogenous GAGs with a mean concentration of 0.06 μg/mL. The AF, ESRD, DM, and sepsis patient samples had a mean endogenous GAG concentration of 0.55, 0.72, 0.92, and 0.94 μg/mL, respectively. The levels of endogenous GAGs were highest in cancer, LD, and PE patient plasma samples with a mean concentration of 1.95, 2.78, and 2.83 μg/mL, respectively. Heparinase I degradation resulted in a decline in GAG levels in plasma samples. These results clearly show that detectable Heparin Red sensitive endogenous GAGs are present in circulating plasma at varying levels in various patient groups. Additional studies are necessary to understand this complex pathophysiology.

In-hospital Outcomes of Patients with Septic Shock and Underlying Chronic Atrial Fibrillation: A Propensity Matched Analysis from A National Dataset

INTRODUCTION

Atrial fibrillation (AF) is one of the most common arrhythmias among hospitalized patients. Among patients admitted with septic shock (SS), the new occurrence of atrial fibrillation has been associated with an increase in intensive care unit (ICU) length of stay and in-hospital mortality. This is partially related to further reduction in cardiac output and thus worsening organ perfusion due to atrial fibrillation. However, there is a paucity of research on the outcomes of patients who have underlying chronic AF (UCAF) and then develop SS. This study aimed to identify the clinical characteristics and outcomes of patients with UCAF admitted with SS compared to patients with SS without UCAF.

METHODS

This study was a retrospective analysis of the 2016 and 2017 Nationwide Readmission Database. ICD-10 codes were used to identify patients with SS, and these patients were stratified into those with and without UCAF. Propensity matching analyses were performed to compare clinical outcomes and in-hospital mortality between the two groups.

RESULTS

A total of 353,422 patients with hospitalization for SS were identified, 5.8% (n = 20,772) of whom had UCAF. After 2:1 propensity matching, 20,719 patients were identified as having SS with UCAF, and 41,438 patients were identified as having SS without UCAF. Patients with SS and UCAF had a higher incidence of ischemic stroke [2.5% versus 2.2%, p = 0.012], length of stay [11.5 days versus 10.9 days, p < 0.001], mean total charges [$154,094 versus $144,037, p < 0.001] compared to those with SS without UCAF. In-hospital mortality was high in both groups, but was slightly higher among those with SS and UCAF than those with SS and no UCAF [34.4% versus 34.1%, p = 0.049].

CONCLUSIONS

This study identified UCAF as an adverse prognosticator for clinical outcomes. Patients with SS and UCAF need to be identified as a higher risk category of SS who will require more intensive management.

The effects of apixaban on clot characteristics in atrial fibrillation: A novel pharmacodynamic biomarker

Atrial fibrillation (AF) is a major risk factor for stroke. We aim to characterize AF patients and the effects of apixaban therapy in terms of clot microstructure using gel point analysis, a novel biomarker. Seventy-eight patients were included in the study, 50 Stroke with AF (AF-S), and 28 AF without stroke (AF). Pre- and post-anticoagulation samples were collected: gel point (GP) analysis was performed to obtain (i) TGP (the time taken to reach the GP or the clot formation time) and (ii) d_{f ,} the fractal dimension of the clot, a quantification of clot fibrin microstructure at the GP. At baseline, the AF-S group had a d_f  = 1.70 (±0.05) and TGP = 306 (±73 s). The AF group had a df = 1.70 ± 0.05 and TGP = 346 ± 78 s, showing a significantly shortened TGP in the stroke group (p = .008). For both groups, apixaban significantly prolonged TGP, p = .005, but resulted in no change in df. Apixaban prolonged clotting time while having no significant impact on the blood's ability to form stable clots (no change in d_f ). This indicates that apixaban provides protection from the formation of thrombi by reducing clotting kinetics.

Poor Nutritional Status Is Associated with Arrhythmic Events on 24-Hour Holter Recording

BACKGROUND

Malnutrition is associated with cardiovascular disease morbidity and mortality. Arrhythmias may be the cardiac consequences of malnutrition.

OBJECTIVES

The objective of the study was to evaluate the association between prognostic nutritional index (PNI), Controlling Nutritional Status (CONUT) score, and arrhythmic events on 24-h electrocardiography (ECG) Holter recording in patients without manifested arrhythmia.

METHODS

In this retrospective analysis of 477 patients who underwent 24-h ECG Holter monitoring, PNI and CONUT score were calculated and patients were divided into tertiles according to PNI and into three groups according to CONUT score; 0: normal, 1-2: mild risk of malnutrition, ≥3: moderate-severe risk of malnutrition. Arrhythmic events were compared between PNI tertiles and CONUT score groups.

RESULTS

Total number of premature atrial contractions, premature ventricular contractions (PVCs), PVC burden, and incidence of paroxysmal atrial fibrillation (PAF) were significantly higher in patients within the lowest PNI tertile. Total number of PVCs, PVC burden, and incidence of PAF were significantly higher in patients with CONUT score ≥3. The cut-off value for PNI to predict the presence of PVC was defined as 39.41 using ROC curve analysis. The area under the curve was 0.650 (p < 0.001). Multivariate analysis showed that PNI was independent predictor of the presence of PVC and PAF. Also, CONUT score was independent predictor of the presence of PVC and PAF. Incidence of nonsustained ventricular tachycardia did not differ between PNI tertiles or CONUT score groups.

CONCLUSION

Poor nutritional status, assessed by PNI and CONUT score, is associated with arrhythmic events on 24-h ECG Holter recording in patients without manifested arrhythmia.

Abnormal sialylation and fucosylation of saliva glycoproteins: Characteristics of lung cancer-specific biomarkers

Dysregulated surface glycoproteins play an important role in tumor cell proliferation and progression. Abnormal glycosylation of these glycoproteins may activate tumor signal transduction and lead to tumor development. The tumor microenvironment alters its molecular composition, some of which regulate protein glycosylation biosynthesis. The glycosylation of saliva proteins in lung cancer patients is different from healthy controls, in which the glycans of cancer patients are highly sialylated and hyperfucosylated. Most studies have shown that O-glycans from cancer are truncated O-glycans, while N-glycans contain fucoses and sialic acids. Because glycosylation analysis is challenging, there are few reports on how glycosylation of saliva proteins is related to the occurrence or progression of lung cancer. In this review, we discussed glycoenzymes involved in protein glycosylation, their changes in tumor microenvironment, potential tumor biomarkers present in body fluids, and abnormal glycosylation of saliva or lung glycoproteins. We further explored the effect of glycosylation changes on tumor signal transduction, and emphasized the role of receptor tyrosine kinases in tumorigenesis and metastasis.

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.

Endothelial dysfunction and vascular maladaptation in atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmia and is associated with worsened morbidity and mortality. The prevalence of AF is estimated to increase with an ageing population resulting in an ever-increasing burden on the healthcare system. Despite improvements in AF treatment, several questions remain unanswered in relation to the development and progression of AF. In this review, we discuss the evidence supporting the presence of vascular dysfunction in the development of AF, but also as a final common pathway explaining why AF constitutes a markedly increased risk of cardiovascular morbidity and mortality. Specifically, we summarise the work performed in humans related to the impact of AF on vascular structure and function, and whether measures of vascular function predict AF progression and the development of cardiovascular events. Subsequently, we discuss the potential mechanisms linking AF to the development of vascular dysfunction. Finally, we propose future perspectives of vascular health and AF, advocating a strong focus on regular exercise training as a safe and effective strategy to improve vascular function and, hence, reduce the risk for development and progression of AF and its associated risk for cardiovascular events.

Decreased bioavailability of hydrogen sulfide links vascular endothelium and atrial remodeling in atrial fibrillation

Oxidative stress drives the pathogenesis of atrial fibrillation (AF), the most common arrhythmia. In the cardiovascular system, cystathionine γ-lyase (CSE) serves as the primary enzyme producing hydrogen sulfide (H₂S), a mammalian gasotransmitter that reduces oxidative stress. Using a case control study design in patients with and without AF and a mouse model of CSE knockout (CSE-KO), we evaluated the role of H₂S in the etiology of AF. Patients with AF (n = 51) had significantly reduced plasma acid labile sulfide levels compared to patients without AF (n = 65). In addition, patients with persistent AF (n = 25) showed lower plasma free sulfide levels compared to patients with paroxysmal AF (n = 26). Consistent with an important role for H₂S in AF, CSE-KO mice had decreased atrial sulfide levels, increased atrial superoxide levels, and enhanced propensity for induced persistent AF compared to wild type (WT) mice. Rescuing H₂S signaling in CSE-KO mice by Diallyl trisulfide (DATS) supplementation or reconstitution with endothelial cell specific CSE over-expression significantly reduced atrial superoxide, increased sulfide levels, and lowered AF inducibility. Lastly, low H₂S levels in CSE KO mice was associated with atrial electrical remodeling including longer effective refractory periods, slower conduction velocity, increased myocyte calcium sparks, and increased myocyte action potential duration that were reversed by DATS supplementation or endothelial CSE overexpression. Our findings demonstrate an important role of CSE and H₂S bioavailability in regulating electrical remodeling and susceptibility to AF.

Impaired left atrial mechanical functions as indicators for increased aortic root diameter in hypertensive and diabetic patients

OBJECTIVES

Previous studies have demonstrated that increased aortic root diameter (ARD) is frequently associated with increased cardiovascular (CV) events and is a predictor of stroke. Two-dimensional speckle tracking echocardiography (2D-STE) provides a better evaluation of left atrial (LA) functions. Left atrial mechanical dispersion is a useful predictor of new-onset atrial fibrillation (AF) independent of LA enlargement and dysfunction. We aimed to investigate the relationship between ARD and LA mechanical functions.

METHODS

The present study included 93 consecutive patients with hypertension and diabetes. The relationships between ARD and LA functions was evaluated.

RESULTS

Study population was divided into two groups according to the mean ARD values: group 1 (ARD ≤30.03 mm, n = 53) and group 2 (ARD >30.03 mm, n = 40). In group 2, age, LA max volume (vol), LA pre A vol, LA min vol, LA emptying fraction, LA active ejection fraction (EF), and LA expansion index were significantly higher compared to group 1. S‑LAs and SR-LAs (peak LA strain and strain rate, respectively, during ventricular systole) and S‑LAe and SR-LAe (peak early diastolic LA strain and strain rate, respectively) were significantly lower in group 2 compared to group 1. Age, LA max vol, LA pre A vol, LA min vol, LA emptying fraction, LA active EF, LA expansion index, S‑LAs, S‑LAe, SR-LAs, and SR-LAe were significantly associated with increased ARD. In multivariate logistic regression analysis, age, LA expansion index, and SR-LAe were independent predictors for ARD.

CONCLUSION

Impaired LA mechanical functions determined by speckle tracking methods are related with increased ARD independent of LV diastolic dysfunction.