Assessment of endothelial (dys)function in atrial fibrillation

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.

Association of Erectile Dysfunction with Incident Atrial Fibrillation: The Multi-Ethnic Study of Atherosclerosis (MESA)

PURPOSE

Erectile dysfunction has been associated with atrial fibrillation in cross-sectional studies, but the association of erectile dysfunction with incident atrial fibrillation is less well established. This study aimed to determine whether erectile dysfunction is independently associated with incident atrial fibrillation after adjusting for conventional risk factors.

METHODS

We studied 1760 male participants (mean age 68 ± 9 years) from the Multi-Ethnic Study of Atherosclerosis (MESA), who completed self-reported erectile dysfunction assessment at MESA exam 5 (2010-2012). Cumulative incidence of atrial fibrillation was estimated by Kaplan-Meier analysis. Cox proportional hazards regression was used to calculate the unadjusted and adjusted hazard ratios (HR) using 3 models in which variables were added in a stepwise manner. In model 3, HR was adjusted for age, race and ethnicity, education, smoking status, alcohol use, systolic blood pressure, body mass index, diabetes, anti-hypertensive medication use, lipid-lowering medication use, total cholesterol, and estimated glomerular filtration rate.

RESULTS

During the median follow-up of 3.8 (interquartile range, 3.5-4.2) years, 94 cases of incident atrial fibrillation were observed. There was a significant difference between males with and without erectile dysfunction for cumulative incident atrial fibrillation rates at 4 years (9.6 vs 2.9%, P < .01). In the fully adjusted model, erectile dysfunction remained associated with incident atrial fibrillation (model 3; HR, 1.66; 95% confidence interval 1.01-2.72, P = .044).

CONCLUSIONS

Among older male participants in this prospective study, we found that self-reported erectile dysfunction was associated with incident atrial fibrillation.

P wave dispersion in patients with erectile dysfunction

Background and aims

P wave dispersion (PWD) has been reported to be a non-invasive electrocardiographic predictor for atrial fibrillation. The aim of this study is to evaluate PWD between men with erectile dysfunction (ED) and healthy controls in order to investigate whether PWD was prolonged in patients with ED and related to severity of the disease.

Methods

This study included a total of 72 men (42 patients with ED and 30 healthy controls). Demographic data and clinical features were recorded on admission. An electrocardiographic evaluation was obtained to measure PWD values for both patients and controls.

Results

Maximum P wave duration was 108.5 ± 4.7 and 108.3 ± 4.3 in ED group and control group, respectively (p = 0.748). Minumum P wave duration was significantly higher in the control group than in the ED group. PWD was 48.1 ± 5.9 in the ED group. As a result, PWD was prolonged in patients with ED (48.1 ± 5.9 vs. 38.0 ± 3.9, p < 0.05). A significant negative correlation was observed between IIEF score and PWD values (p < 0.05, r = −0.662).

Conclusions

Patients with ED exhibited prolonged PWD values compared with normal controls. In addition, PWD was found to be associated with severity of the disease.

Permanent atrial fibrillation impairs the function of circulating endothelial progenitor cells

OBJECTIVE

to determine whether functions of endothelial progenitor cells (EPCs) were impaired in patients with permanent atrial fibrillation (AF).

METHODS

35 patients with permanent AF (AF group) and 35 age and sex matched controls (control group) were collected. The numbers of circulating CD34⁺/KDR⁺ cells were determined with flow cytometry in the two groups. Cell proliferation, tube formation, nitric oxygen (NO) and vascular endothelial growth factor (VEGF) were assayed.

RESULTS

the numbers of CD34⁺/KDR⁺ cells were lower in the AF group than the control group (20.01 ± 12.66 /10⁵ vs 77.93 ± 58.93 /10⁵，p = 0.022). Colony formation unit (CFU) of EPCs were decreased in AF group compared to the control group（1.76 ± 0.59 CFU vs 3.45 ± 0.82 CFU, p = 0.0000). The AF group had lower cell proliferation ability than control group（0.401 ± 0.113 A vs 0.558 ± 0.130 A, p = 0.004). Tube formation ability was decreased in AF patients compared to controls（434.30 ± 96.22μm/mm² vs 568.09 ± 196.17μm/mm²，p = 0.041). AF patients had lower VEGF secretion than controls (27.35 ± 9.93 ng/L vs 41.86 ± 7.31 ng/L，p = 0.001），they also had lower NO secretion than controls（16.55 ± 6.92μmol/l vs 23.65 ± 5.48，p = 0.012).

CONCLUSIONS

proliferation, tube formation and paracrine of EPCs were reduced in patients with permanent AF.

Cardiovascular Effects of Exposure to Cigarette Smoke and Electronic Cigarettes: Clinical Perspectives From the Prevention of Cardiovascular Disease Section Leadership Council and Early Career Councils of the American College of Cardiology

Cardiovascular morbidity and mortality as a result of inhaled tobacco products continues to be a global healthcare crisis, particularly in low- and middle-income nations lacking the infrastructure to develop and implement effective public health policies limiting tobacco use. Following initiation of public awareness campaigns 50 years ago in the United States, considerable success has been achieved in reducing the prevalence of cigarette smoking and exposure to secondhand smoke. However, there has been a slowing of cessation rates in the United States during recent years, possibly caused by high residual addiction or fatigue from cessation messaging. Furthermore, tobacco products have continued to evolve faster than the scientific understanding of their biological effects. This review considers selected updates on the genetics and epigenetics of smoking behavior and associated cardiovascular risk, mechanisms of atherogenesis and thrombosis, clinical effects of smoking and benefits of cessation, and potential impact of electronic cigarettes on cardiovascular health.

Left atrial endocardial dysfunction and platelet activation in patients with atrial fibrillation and mitral stenosis

OBJECTIVE

This study demonstrated left atrial endocardial dysfunction and platelet activation in patients with atrial fibrillation and mitral stenosis.

METHODS

Study included 80 patients with mitral stenosis and atrial fibrillation (40 each with and without left atrial thrombosis), 15 healthy volunteers, and 10 left atrial appendage (LAA) specimens from donor hearts. Blood samples were collected through peripheral vein and left atrium, with peripheral blood samples of volunteers as controls. LAA specimens were collected during operations. LAA expressions of von Willebrand factor (vWF) and P-selectin were determined immunohistochemically; plasma concentrations were measured by enzyme-linked immunosorbent assay. LAA expressions of vWF and P-selectin genes in were quantitated with real-time fluorescent quantitative polymerase chain reaction.

RESULTS

The difference in vWF and P-selectin plasma levels between left atrial and peripheral venous blood was not significant; however, peripheral plasma levels of vWF and P-selectin were significantly higher in those with thrombosis than without thrombosis, which in turn were higher than in healthy subjects. Both vWF and P-selectin proteins were stained in both left atrial endocardium and cardiomyocytes. The normalized vWF gene expression relative to control was 3.04 in patients with thrombosis and 2.16 in those without thrombosis (P<.01). The difference in P-selectin gene expressions among the groups was not significant.

CONCLUSIONS

No differences were observed in plasma levels of vWF and P-selectin between left atrial and peripheral venous blood. Over expression of vWF gene in LAA may contribute to increased plasma vWF levels. P-selectin and vWF together may play a role in thrombosis.

Antioxidant therapies for the management of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice, representing a major public health problem. Recent evidence suggests oxidative stress may play an important role in the pathogenesis and perpetuation of AF. In the past few years, experimental data and clinical evidence have tested the concept of antioxidant therapies to prevent AF. Besides statins, ACE-inhibitors (ACEIs) and/or angiotensin-receptor blockers (ARBs), and omega-3 polyunsaturated fatty acids, several other interventions with antioxidant properties, such as Vitamin C and E, thiazolidinediones, N-acetylcysteine, probucol, nitric oxide donors or precursors, NADPH oxidase inhibitors, Xanthine oxidase inhibitors have emerged as novel strategies for the management of AF. We aim to review recent evidence regarding antioxidant therapies in the prevention and treatment of atrial fibrillation.

Asymmetric Dimethylarginine Levels are Highly Associated With Atrial Fibrillation in an Elderly Population

BACKGROUND

The importance of endothelial dysfunction in atrial fibrillation (AF) is not clarified. The aim of this study was to evaluate endothelial dysfunction assessed by selected inflammatory and haemostatic endothelial markers and nitric oxide (NO) associated variables as related to the presence of AF in an elderly population. NO is known to express anti-thrombotic as well as vasoactive properties.

METHODS

This is a cross sectional study of 75-year old subjects with AF (n = 62) and control subjects in sinus rhythm (n = 124), matched for gender. Fasting blood samples were collected for analyses of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO-synthase, L-arginine, E-selectin, vascular cell adhesion molecule-1 (VCAM-1) and von Willebrand factor (vWF).

RESULTS

Levels of vWF and ADMA were significantly higher in AF patients vs controls (P = 0.023 and P < 0.001, respectively) and the L-arginine/ADMA ratios were lower (P = 0.015), the latters still significant after adjustment for relevant covariates (P = 0.007 and P = 0.037, respectively). No significant differences in the levels of VCAM-1 and E-selectin were observed between the groups. When dividing the ADMA levels into quartiles there was a significant trend for having AF with increasing levels of ADMA (P < 0.001) with a cut-off at the 25th percentile (< 0.54 µmol/L), giving an adjusted OR for having AF of 12.46 (95% CI 3.11 - 49.86) (P < 0.001) with higher levels. A similar inverse trend was seen for the L-arginine/ADMA ratio.

CONCLUSION

Our population of 75-year-old AF patients had significantly impaired endothelial function assessed by increased levels of vWF, and more pronounced by high levels of ADMA. The results indicate AF in the elderly to be closely associated with the regulatory pathway of NO.