The impact of rapid atrial pacing on ADMA and endothelial NOS

Novel method to avoid serious injurious effects on the atrioventricular nodal (AVN) conduction during catheter ablation of the AVN slow pathway utilizing cryofreezing energy

BACKGROUND

Slow pathway elimination of the atrioventricular node (AVN) is essential to treat AVN reentrant tachycardia (AVNRT). However, injury to the AVN conduction (IAVN) is one of the serious complications. Cryofreezing energy is expected to reduce the incidence of IAVN. This study aimed to investigate the usefulness of a novel method to avoid IAVN during cryoablation of AVNRT.

METHODS

A total of 157 patients (average age, 65.8 years; male, 71) suffering from AVNRT were included. Once the AVNRT terminated during cryo-ablation, then rapid atrial constant pacing (RACP) was performed during freezing at a rate lower 10 bpm than that inducing Wenchebach AV block in 74 (47.1 %) patients (Group A). The RACP rate was decreasingly reduced by 10 bpm in case of the occurrence of IAVN. When the RACP reached 100 bpm, the cryoablation was prematurely terminated. Group B patients (83 = 52.9 %) underwent cryoablation during sinus rhythm. All patients were allocated in a randomized fashion. We compared the severity of the IAVN between Groups A and B.

RESULTS

There were no significant differences at 12 months regarding the freedom from the AVNRT between Groups A and B. However, the duration of the IAVN was significantly longer in Group B than A (p = 0.02). There were no significant differences regarding the distance between the His recording sites and successful ablation sites between Groups A and B. No permanent IAVN requiring pacemaker implantation was provoked in either group.

CONCLUSION

RACP was useful to avoid sustained and serious IAVN during cryoablation of AVNRT.

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.

Pathophysiology and clinical relevance of atrial myopathy

Atrial myopathy is a condition that consists of electrical, structural, contractile, and autonomic remodeling of the atria and is the substrate for development of atrial fibrillation, the most common arrhythmia. Pathophysiologic mechanisms driving atrial myopathy are inflammation, oxidative stress, atrial stretch, and neurohormonal signals, e.g., angiotensin-II and aldosterone. These mechanisms initiate the structural and functional remodeling of the atrial myocardium. Novel therapeutic strategies are being developed that target the pathophysiologic mechanisms of atrial myopathy. In this review, we will discuss the pathophysiology of atrial myopathy, as well as diagnostic and therapeutic strategies.

Impaired retinal micro-vascular function in patients with atrial fibrillation

BACKGROUND

Cardiovascular (CV) risk factors and CV diseases, in particular heart failure, are strongly associated with impaired microvascular retinal endothelial function. Whether atrial fibrillation (AF) contributes to vascular dysfunction is not clear. Therefore, the aim of this study was to investigate the impact of AF on retinal microvascular function.

METHODS

In this study, vascular function was measured non-invasively with flicker-light induced vasodilatation of retinal arterioles (FIDart%). Patients with a history of AF and risk factors for heart failure (HF) or heart failure (n = 69; age 67.9 ± 9.2 years, 71% male, 35% HFrEF, 56% paroxysmal, 25% persistent, 19% permanent AF), as well as age, sex and ejection fraction matched patients with absent history of AF (n = 66; age 63.4 ± 10.6 years, 67% male, 47% HFrEF) were included. Patients with AF were further divided into those with paroxysmal AF (in sinus rhythm - AFSR: n = 38, age 71.4 ± 9.2, 73% male), and those with AF at the time of the study visit.

RESULTS

Retinal microvascular function was impaired in patients with AF compared to patients without AF (FIDart% 1.1% [0.3-2.8] vs. 2.7% [1.3-5.1], p < 0.001). Patients currently in AF have poorer retinal microvascular function (FIDart% 0.8% [0.1-1.9) compared to patients with a history of AF but currently in SR at the time of retinal function measurement (1.5% [0.6-4.9] p = 0.017). In patients with AF, impaired retinal vascular function was independently associated with larger left atrial volume (mean 49.8 ± 18.4), even after correction for confounding factors in different models (SCR = -0. 251 to -0.256, p = 0.035-0.01).

CONCLUSIONS

AF in patients with heart failure is associated with impaired vascular function, even if currently in sinus rhythm. The association of retinal microvascular dysfunction with left atrial volume, a surrogate for elevated cardiac filling pressures, may further highlight the important interplay between the vasculature and elevated filling pressures in the development of AF.

Contributing Factors to Endothelial Dysfunction in Individuals with Spinal Cord Injuries

Background

Patients with spinal cord injuries (SCIs) are at a greater risk for the development of cardiovascular diseases (CVDs) than able-bodied individuals due to the high risk of endothelial dysfunction.

Summary

For instance, patients with SCIs lose autonomic control of the heart and vasculature, which results in severe fluctuations in blood pressure. These oscillations between hypotension and hypertension have been shown to damage blood vessel endothelial cells and may contribute to the development of atherosclerosis. Furthermore, the loss of skeletal muscle control results in skeletal muscle atrophy and inward remodeling of the conduit arteries. It has been shown that blood vessels in the legs are chronically exposed to high shear, while the aorta experiences chronically low shear. These alterations to shear forces may adversely impact endothelial vasodilatory capacity and promote inflammatory signaling and leukocyte adherence. Additionally, microvascular endothelial vasodilatory capacity is impaired in patients with an SCI, and this may precede changes in conduit artery endothelial function. Finally, due to immobility and a loss of skeletal muscle mass, patients with SCIs have a higher risk of metabolic disorders, inflammation, and oxidative stress.

Key Messages

Collectively, these factors may impair endothelium-dependent vasodilatory capacity, promote leukocyte adhesion and infiltration, promote the peroxidation of lipids, and ultimately support the development of atherosclerosis. Therefore, future interventions to prevent CVDs in patients with SCIs should focus on the management of endothelial health to prevent endothelial dysfunction and atherosclerosis.

Atrial fibrillation and stroke prevention: 25 years of research at EP Europace journal

Stroke prevention in patients with atrial fibrillation (AF) is one pillar of the management of this common arrhythmia. Substantial advances in the epidemiology and associated pathophysiology underlying AF-related stroke and thrombo-embolism are evident. Furthermore, the introduction of the non-vitamin K antagonist oral anticoagulants (also called direct oral anticoagulants) has clearly changed our approach to stroke prevention in AF, such that the default should be to offer oral anticoagulation for stroke prevention, unless the patient is at low risk. A strategy of early rhythm control is also beneficial in reducing strokes in selected patients with recent onset AF, when compared to rate control. Cardiovascular risk factor management, with optimization of comorbidities and attention to lifestyle factors, and the patient's psychological morbidity are also essential. Finally, in selected patients with absolute contraindications to long-term oral anticoagulation, left atrial appendage occlusion or exclusion may be considered. The aim of this state-of-the-art review article is to provide an overview of the current status of AF-related stroke and prevention strategies. A holistic or integrated care approach to AF management is recommended to minimize the risk of stroke in patients with AF, based on the evidence-based Atrial fibrillation Better Care (ABC) pathway, as follows: A: Avoid stroke with Anticoagulation; B: Better patient-centred, symptom-directed decisions on rate or rhythm control; C: Cardiovascular risk factor and comorbidity optimization, including lifestyle changes.

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

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

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

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

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.

Atrial Cardiomyopathy: Pathophysiology and Clinical Consequences

Around the world there are 33.5 million patients suffering from atrial fibrillation (AF) with an annual increase of 5 million cases. Most AF patients have an established form of an atrial cardiomyopathy. The concept of atrial cardiomyopathy was introduced in 2016. Thus, therapy of underlying diseases and atrial tissue changes appear as a cornerstone of AF therapy. Furthermore, therapy or prevention of atrial endocardial changes has the potential to reduce atrial thrombogenesis and thereby cerebral stroke. The present manuscript will summarize the underlying pathophysiology and remodeling processes observed in the development of an atrial cardiomyopathy, thrombogenesis, and atrial fibrillation. In particular, the impact of oxidative stress, inflammation, diabetes, and obesity will be addressed.

Renal function and outcome of patients with non-valvular atrial fibrillation

AIMS

Atrial fibrillation and renal dysfunction are associated with increased cardiovascular risk. We examined the association between renal function and incident ischaemic stroke or myocardial infarction in patients with atrial fibrillation treated with direct oral anticoagulants (DOACs).

METHODS AND RESULTS

This study was conducted using a large health record database. Included were 19 713 patients with first time diagnosis of non-valvular atrial fibrillation treated with DOACs between 2010 and 2018. Patients were categorized into four groups according to the estimated glomerular filtration rate (eGFR) (<30, 30-59, 60-89, and ≥90 mL/min/1.73 m2). Ischaemic stroke and acute myocardial infarction rates were compared between the groups. During 55 086 person-years of follow-up, there were 2295 (11.6%) cases of ischaemic stroke and 1158 (5.9%) cases of acute myocardial infarction. There was a significant inverse association between eGFR and the risk of myocardial infarction. A multivariate analysis using the group with eGFR ≥90 mL/min/1.73 m2 as a reference demonstrated an increased risk of myocardial infarction with lower eGFR [hazard ratio (HR) = 1.2 95% confidence interval (CI) 0.9-1.4, HR = 1.4, 95% CI 1.2-1.7, and HR = 2.5, 95% CI 1.8-3.4 for patients with eGFR 60-89, 30-59, and <30 mL/min/1.73 m2, respectively, P < 0.001]. Each 10 mL decrease in eGFR was associated with an 8% increase in the risk of myocardial infarction. There was no association between eGFR and the risk of ischaemic stroke (HR = 0.9 95% CI 0.8-1.1, HR = 0.93, 95% CI 0.8-1.1, and HR = 1.1, 95% CI 0.8-1.4 for patients with eGFR 60-89, 30-59, and <30 mL/min/1.73 m2, respectively, P = 0.325).

CONCLUSIONS

Renal dysfunction is associated with an increased risk of myocardial infarction but not of ischaemic stroke among patients with atrial fibrillation treated with DOACs.

Vorhofflimmern – was wir nicht wissen („gaps in evidence“)

Auch nach Jahrzehnten intensiver grundlagenwissenschaftlicher und klinischer Forschungsbemühungen können nicht alle Fragestellungen, die sich bei der Diagnosestellung und Behandlung von Vorhofflimmern stellen, abschließend beantwortet werden. Das Konzept der atrialen Kardiomyopathie unterstreicht, dass es sich bei Vorhofflimmern um keine einheitliche Krankheitsentität handelt, sondern um einen Prozess, dem eine Vielzahl unterschiedlicher Ursachen und Mechanismen zugrunde liegt. Noch nicht abschließend geklärt bleibt die hieraus resultierende klinische Konsequenz. Neue Studienergebnisse weisen auf einen ausgeprägten klinischen Benefit von rhythmuskontrollierenden Therapiestrategien, sowohl bei neu diagnostiziertem paroxysmalem Vorhofflimmern als auch bei Herzinsuffizienzpatienten mit Vorhofflimmern, hin und stellen damit erneut die Frage, ob Rhythmuskontrolle Frequenzkontrolle vorzuziehen ist.

Effects of Atrial Fibrillation and Chronic Kidney Disease on Major Adverse Cardiovascular Events

Atrial fibrillation (AF) is strongly linked to chronic kidney disease (CKD) and both of these conditions contribute to poor cardiovascular outcomes. We evaluated the impact of renal failure on major adverse cardiovascular events (MACE) in AF, and predictive value of the 2MACE score in this post-hoc analysis of the AMADEUS trial. The primary endpoint was MACE (composite of myocardial infarction, cardiac revascularisation and cardiovascular mortality). Secondary endpoints included the composite of stroke, major bleeding and non-cardiovascular mortality, and each of the specific outcomes separately. Of the 4,554 patients, 1,526 (33.5%) were females and the median age was 71 (IQR 64 to 77) years. There were 3,838 (84.3%) non-CKD and 716 (15.7%) CKD patients. The incidence of cardiovascular and non-cardiovascular mortality were 1.41% and 2.44% per 100 patient-years, respectively. There was no significant difference in crude study endpoints between the groups. Multivariable regression analysis found no association between CKD and MACE (HR 1.03 [95% CI, 0.45 to 2.34]). The c-index of the 2MACE score for MACE was 0.65 (95% CI, 0.59 to 0.71, p <0.001). In the presence of CKD, each additional point of the 2MACE score contributed to a greater risk of MACE (HR 3.17 [95% CI, 1.28 to 7.85] vs 1.48 [95% CI, 1.17 to 1.87] in the non-CKD group). In conclusion, the 2MACE score may be a useful tool for clinical risk stratification of high-risk AF patients with CKD and those at high MACE risk could be targeted for more intensive cardiovascular prevention strategies. The presence of CKD was not found to be independently associated with MACE in AF patients.

Atrial Myopathy Underlying Atrial Fibrillation

While AF most often occurs in the setting of atrial disease, current assessment and treatment of patients with AF does not focus on the extent of the atrial myopathy that serves as the substrate for this arrhythmia. Atrial myopathy, in particular atrial fibrosis, may initiate a vicious cycle in which atrial myopathy leads to AF, which in turn leads to a worsening myopathy. Various techniques, including ECG, plasma biomarkers, electroanatomical voltage mapping, echocardiography, and cardiac MRI, can help to identify and quantify aspects of the atrial myopathy. Current therapies, such as catheter ablation, do not directly address the underlying atrial myopathy. There is emerging research showing that by targeting this myopathy we can help decrease the occurrence and burden of AF.

Atrial fibrillation and the prothrombotic state: revisiting Virchow’s triad in 2020

Atrial fibrillation (AF) is characterised by an increased risk of pathological thrombus formation due to a disruption of physiological haemostatic mechanisms that are better understood by reference to Virchow’s triad of ‘abnormal blood constituents’, ‘vessel wall abnormalities’ and ‘abnormal blood flow’. First, there is increased activation of the coagulation cascade, platelet reactivity and impaired fibrinolysis as a result of AF per se, and these processes are amplified with pre-existing comorbidities. Several prothrombotic biomarkers including platelet factor 4, von Willebrand factor, fibrinogen, β-thromboglobulin and D-dimer have been implicated in this process. Second, structural changes such as atrial fibrosis and endothelial dysfunction are linked to the development of AF which promote further atrial remodelling, thereby providing a suitable platform for clot formation and subsequent embolisation. Third, these factors are compounded by the presence of reduced blood flow secondary to dilatation of cardiac chambers and loss of atrial systole which have been confirmed using various imaging techniques. Overall, an improved understanding of the various factors involved in thrombus formation will allow better clinical risk stratification and targeted therapies in AF.

Curcumin attenuates endothelial cell fibrosis through inhibiting endothelial-interstitial transformation

Curcumin (Cur) has various pharmacological activities, including anti-inflammatory, antiapoptotic and anticancer effects. However, there is no report on the effect of Cur on endothelial cell fibrosis. This study was designed to investigate the effect and mechanism of Cur on endothelial cell fibrosis. An endothelial cell fibrosis model was established by using transforming growth factor (TGF) induction. Proliferation assays, qRT-PCR, western blotting and immunostaining were performed to investigate the effects and mechanism of Cur on endothelial cell fibrosis. We found that in human umbilical vein endothelial cells (HUVECs), TGF-β1 treatment significantly decreased the expression of nuclear factor erythroid-2-related factor 2 (NRF-2), dimethylarginine dimethylaminohydrolase-1 (DDAH1), and VE-cadherin, the secretion of cellular nitric oxide (NO) and the activity of nitrous oxide synthase (NOS), while asymmetric dimethylarginine (ADMA) and the release of inflammatory factors were elevated. Immunofluorescence showed decreased CD31 and increased α-smooth muscle actin (α-SMA). Overexpression of NRF-2 significantly attenuated the effects of TGF-β1, while downregulation of DDAH1 potently counteracted the effect of NRF-2. In addition, ADMA treatment resulted in similar results to those of TGF-β1, and Cur significantly attenuated the effect of TGF-β1, accompanied by increased VE-cadherin, DDAH1 and NRF-2 and decreased matrix metalloproteinase-9 (MMP-9) and extracellular regulated protein kinases 1/2 (ERK1/2) phosphorylation. The NRF-2 inhibitor ML385 had the opposite effect as that of Cur. These results demonstrated that Cur inhibits TGF-β1-induced endothelial-to-mesenchymal transition (EndMT) by stimulating DDAH1 expression via the NRF-2 pathway, thus attenuating endothelial cell fibrosis.

Arginine derivatives in atrial fibrillation progression phenotypes

Arginine, homoarginine (hArg), asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) affect nitric oxide metabolism and altered concentrations are associated with cardiovascular morbidity and mortality. We analyzed these metabolites using liquid chromatography-tandem mass spectrometry in patients with atrial fibrillation (AF) (n = 241) with a focus on heart rhythm at blood withdrawal, AF progression phenotypes, and successful sinus rhythm (SR) restoration (n = 22). AF progression phenotypes were defined as paroxysmal AF with/without low voltage areas (LVA) and persistent AF with/without LVA. While arginine, ADMA, and hArg were within reference limits for healthy controls, SDMA was higher in the AF cohort (0.57 ± 0.12 vs. 0.53 μmol/L (97.5th percentile in reference cohort)). SR restoration in AF patients resulted in normalization of SDMA concentrations (0.465 ± 0.082 vs. 0.570 ± 0.134 μmol/L at baseline, p < 0.001). Patients with AF at the time of blood sampling had significantly lower hArg (1.65 ± 0.51 vs. 1.85 ± 0.60 μmol/L, p = 0.006) and higher ADMA concentrations (0.526 ± 0.08 vs. 0.477 ± 0.08 μmol/L, p < 0.001) compared with AF patients in SR. hArg concentrations were lower in patients with advanced AF progression phenotypes (persistent AF with LVA (p = 0.046)) independent of heart rhythm at blood sampling. Summarizing, arginine metabolism imbalance is associated with AF in general and AF progression and may contribute to associated risk. KEY MESSAGES: • Heart rhythm at blood withdrawal affects ADMA and hArg level in AF patients. • SDMA is higher in AF patients. • SDMA levels normalize after sinus rhythm restoration. • hArg levels decrease in advanced AF progression phenotypes.

The CHA2DS2-VASc score predicts chronic kidney disease among patients with atrial fibrillation

BACKGROUND

It is unclear how the CHA2DS2-VASc score can predict subsequent chronic kidney disease (CKD) and end-stage renal disease (ESRD) among atrial fibrillation (AF) patients.

METHODS

We identified incident AF patients without CKD between 2000 and 2013 from the National Health Insurance Research Database (NHIRD) of Taiwan and calculated the CHA₂DS₂-VASc score for each patient. Adjusted hazard ratio (HR) with 95% confidence interval (CI) was estimated from multivariate cause-specific Cox models to assess the risk of CKD and ESRD associated with the CHA₂DS₂-VASc score.

RESULTS

A total of 8764 participants with AF who did not have CKD were included in the analysis. The mean age was 69.63 ± 13.48 years and 4800 (54.8%) were males. The adjusted HR of CKD displayed a stepwise increase with the increase in the CHA₂DS₂-VASc score. When compared with those with a CHA₂DS₂-VASc score of 0, the adjusted HRs of CKD were 1.57 (95% CI 1.09-2.26), 2.04 (95% CI 1.42-2.94), 2.48 (95% CI 1.70-3.62), 2.88 (95% CI 1.95-4.26), 3.29 (95% CI 2.18-4.95) and 4.00 (95% CI 2.61-6.13) for the AF patients with a CHA₂DS₂-VASc score of 1, 2, 3, 4, 5 and ≥ 6, respectively. Similarly, as the CHA₂DS₂-VASc score increased, the adjusted HR of ESRD showed a gradual increase.

CONCLUSIONS

Patients with a higher CHA₂DS₂-VASc score were linked to a higher risk of CKD and ESRD in a dose-dependent effect, i.e. the incidence of CKD/ESRD increased with the increasing CHA₂DS₂-VASc score.

Effect of concomitant antiplatelet agents on clinical outcomes in the edoxaban vs warfarin in subjects undergoing cardioversion of atrial fibrillation (ENSURE-AF) randomized trial

AIMS

In ENSURE-AF (NCT02072434), the oral Factor Xa inhibitor edoxaban showed similar efficacy and safety vs enoxaparin-warfarin in patients undergoing electrical cardioversion of nonvalvular atrial fibrillation (AF). This ancillary analysis compares primary efficacy and safety end points for patients receiving vs not receiving concomitant antiplatelet therapy (APT) in ENSURE-AF.

METHODS

The primary efficacy end point was a composite of stroke, systemic embolic events, myocardial infarction, and cardiovascular death during 28 days on study drug after cardioversion plus 30 days of follow-up. The primary safety end point was the composite of major and clinically relevant non-major bleeding occurring between the first and the last dose of study drug.

RESULTS

Of 2199 patients enrolled, 1095 were randomized to edoxaban and 1104 to enoxaparin-warfarin. Patients receiving concomitant APT were older; more naïve to vitamin K antagonist; had lower creatinine clearance; and more likely to have history of coronary artery disease, hypertension, diabetes, or ischemic stroke/transient ischemic attack. In patients receiving vs not receiving concomitant APT, primary efficacy event rate was numerically higher (0.92% vs 0.60%, p = 0.64) and primary safety event rate was significantly higher (3.21% vs 0.92%, p = 0.0096). Stepwise logistic regression analysis identified age and APT as covariates correlated with bleeding. There was a trend toward increased bleeding risk in elderly patients receiving vs not receiving concomitant APT.

CONCLUSION

In ENSURE-AF, thromboembolic events were rare and absolute bleeding event rates were higher with concomitant APT. These findings may be relevant for AF-patients considered for dual therapy; even for a short treatment duration of 1 month.

Endothelial function in patients with atrial fibrillation

Atrial fibrillation (AF) is the most common heart arrhythmia and is associated with poor outcomes. The adverse effects of AF are mediated through multiple pathways, including endothelial dysfunction, as measured by flow-mediated dilatation. Flow-mediated dilatation has demonstrated endothelial dysfunction in several conditions and is associated with poor outcomes including mortality, yet can be improved with medical therapy. It is thus a useful tool in assessing endothelial function in patients. Endothelial dysfunction is present in patients with AF and is associated with poor outcomes. These patients are generally older and have other co-morbidities such as hypertension, hypercholesterolaemia and diabetes. The precise process by which AF is affiliated with endothelial damage/dysfunction remains elusive. This review explores the endothelial structure, its physiology and how it is affected in patients with AF. It also assesses the utility of flow mediated dilatation as a technique to assess endothelial function in patients with AF. Key MessagesEndothelial function is affected in patients with atrial fibrillation as with other cardiovascular conditions.Endothelial dysfunction is associated with poor outcomes such as stroke, myocardial infarction and death, yet is a reversible condition.Flow-mediated dilatation is a reliable tool to assess endothelial function in patients with atrial fibrillation.Patients with atrial fibrillation should be considered for endothelial function assessment and attempts made to reverse this condition.

Novel Models for the Prediction of Left Atrial Appendage Thrombus in Patients with Chronic Nonvalvular Atrial Fibrillation

Predicting left atrial appendage thrombus (LAAT) in chronic nonvalvular atrial fibrillation remains challenging despite the fact that several predictive models have been proposed to date. In this study, we sought to develop new and simpler models for LAAT prediction in chronic nonvalvular atrial fibrillation. The study enrolled 144 patients with chronic nonvalvular atrial fibrillation who underwent transesophageal echocardiography for LAAT detection. We examined the association of LAAT incidence with the CHA₂DS₂-VASc score and echocardiographic parameters pertaining to the left atrium (LA), including diameter, volume index, strain, and strain rate measured on speckle tracking echocardiography. LAAT was found in 24.3% of patients (39/144). The following parameters had good diagnostic performance for LAAT: LA volume index >57 mL (area under the curve (AUC), 0.72; sensitivity, 77.1%; specificity, 64.2%), LA positive strain ≤6.7% in the four-chamber view (AUC, 0.84; sensitivity, 77.1%; specificity, 77.1%), and LA negative strain rate >−0.73 s⁻¹ in the four-chamber view (AUC, 0.83; sensitivity, 85.7%; specificity, 70.6%). The CHA₂DS₂-VASc score alone had a low predictive value for LAAT in this population (χ² = 3.53), whereas the combination of CHA₂DS₂-VASc score with LA volume index had significant association and better predictive value (χ² = 12.03), and the combination of CHA₂DS₂-VASc score with LA volume index and LA positive strain or negative strain rate in the four-chamber view had the best predictive ability for LAAT (χ²: 33.47 and 33.48, respectively). We propose two novel and simple models for noninvasive LAAT prediction in patients with chronic nonvalvular atrial fibrillation. These models combine the CHA₂DS₂-VASc score with LA volume index and LA longitudinal strain parameters measured on speckle tracking echocardiography in the four-chamber view. We hope these simple models can help with decision-making in managing the antithrombotic treatment of such patients, whose risk of stroke cannot be determined solely based on the CHA₂DS₂-VASc score.

Biomarkers of Atrial Fibrillation: Which One Is a True Marker?

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmias and associated with the risk of stroke and death. Continuous development of the diagnostic tool and prognostic stratification may lead to optimal management of AF. The use of biomarkers in the management of AF has been grown as an interesting topic. However, the AF biomarkers are not yet well established in the major guidelines. Among these biomarkers, a lot of data show troponin and brain natriuretic peptides are promising for the prediction of future events. The troponin elevation in AF patients may not necessarily be diagnosed as myocardial infarction or significant coronary artery stenosis, and brain natriuretic peptide elevation may not necessarily confirm heart failure. Troponin T and troponin I may predict postoperative AF. Furthermore, troponin and brain natriuretic peptide gave better prognostic performance when compared with the risk score available today.

EHRA White Paper: knowledge gaps in arrhythmia management—status 2019

Clinicians accept that there are many unknowns when we make diagnostic and therapeutic decisions. Acceptance of uncertainty is essential for the pursuit of the profession: bedside decisions must often be made on the basis of incomplete evidence. Over the years, physicians sometimes even do not realize anymore which the fundamental gaps in our knowledge are. As clinical scientists, however, we have to halt and consider what we do not know yet, and how we can move forward addressing those unknowns. The European Heart Rhythm Association (EHRA) believes that scanning the field of arrhythmia / cardiac electrophysiology to identify knowledge gaps which are not yet the subject of organized research, should be undertaken on a regular basis. Such a review (White Paper) should concentrate on research which is feasible, realistic, and clinically relevant, and should not deal with futuristic aspirations. It fits with the EHRA mission that these White Papers should be shared on a global basis in order to foster collaborative and needed research which will ultimately lead to better care for our patients. The present EHRA White Paper summarizes knowledge gaps in the management of atrial fibrillation, ventricular tachycardia/sudden death and heart failure.

Effect of increasing heart rate on finger photoplethysmography fitness index (PPGF) in subjects with implanted cardiac pacemakers

Finger photoplethysmography (PPG) is a noninvasive method that measures blood volume changes in the finger. The PPG fitness index (PPGF) has been proposed as an index of vascular risk and vascular aging. The objectives of the study were to determine the effects of heart rate (HR) on the PPGF and to determine whether PPGF is influenced by blood pressure (BP) changes. Twenty subjects (78±8 years, 3 female) with permanent cardiac pacemakers or cardioverter defibrillators were prospectively recruited. HR was changed by pacing, in a random order from 60 to 100 bpm and in 10 bpm increments. At each paced HR, the PPGF was derived from a finger photoplethysmogram. Cardiac output (CO), stroke volume (SV) and total peripheral resistance (TPR) were derived from the finger arterial pressure waveform. Brachial blood pressure (BP) was measured by the oscillometric method. This study found that as HR was increased from 60 to 100 bpm, brachial diastolic BP, brachial mean BP and CO were significantly increased (p<0.01), whilst the PPGF and SV were significantly decreased (p<0.001). The effects of HR on the PPGF were influenced by BP, with a decreasing HR effect on the PPGF that resulted from a higher BP. In conclusion, HR was a significant confounder for PPGF and it must be taken into account in analyses of PPGF, when there are large changes or differences in the HR. The magnitude of this effect was BP dependent.

The CHA2DS2-VASc score strongly correlates with glomerular filtration rate and predicts renal function decline over time in elderly patients with atrial fibrillation and chronic kidney disease

BACKGROUND

The decline of renal function affects stroke risk in patients with atrial fibrillation (AF). Here, we aim to study the predictive value of the CHA₂DS₂-VASc score, a stroke-risk stratification model in AF, for renal function and renal decline in patients with AF and chronic kidney disease (CKD).

METHODS

Two electronic health record cohorts with AF and CKD stage III/IV were evaluated (Cohort #1 (IMS-DA, Germany): 18,539 patients with 125,149 estimated glomerular filtration rate (eGFR) measurements; Cohort #2 (IMS-THIN, United Kingdom): 18,240 patients with 133,676 eGFR measurements). The eGFR trajectories were analysed with multi-level mixed-effects regression and joint models for longitudinal and survival data.

RESULTS

In IMS-DA, the mean baseline eGFR was 52.0ml/min/1.73m², and declined by 1.03ml/min/1.73m²/year (95%CI: 0.86-1.19, p<0.0001). In IMS-THIN, the mean baseline eGFR was 48.0ml/min/1.73m², and declined by 0.44ml/min/1.73m²/year (95%CI: 0.37-0.51, p<0.0001). In both datasets, higher CHA₂DS₂-VASc scores (median: 4 points) were strongly associated with both lower baseline eGFR (p<0.0001) and faster progression of CKD (p=0.002). Mean baseline eGFR values were higher in patients with a CHA₂DS₂-VASc score of 0 compared to patients with a score of 8 points. Conversely, the annual declines in eGFR were lower in patients with a score of 0 compared to patients with a score of 8 points in both databases.

CONCLUSION

The CHA₂DS₂-VASc score can identify AF patient subgroups with lower baseline eGFR and a higher risk of CKD progression, which has important implications for the management of anticoagulation in these patients.

CREM-transgene mice: An animal model of atrial fibrillation and thrombogenesis

BACKGROUND

The molecular pathomechanisms underlying atrial thrombogenesis are multifactorial and still require detailed investigations. Transgenic mice with cardiomyocyte-directed expression of the transcriptional repressor CREM-IbΔC-X (CREM-TG) represent an experimental model of atrial fibrillation (AF) that shows a gradual, age-dependent progression from atrial ectopy to persistent AF. Importantly, this model develops biatrial thrombi. The molecular characteristics related to the thrombogenesis in CREM-TG mice have not been studied, yet.

METHODS

The inflammatory and prothrombotic state was evaluated at the transcriptional (qRT-PCR) and protein level in the left (LA) and right atria (RA) from CREM-TG mice at the age of 20weeks and compared to wild-type controls. Moreover, histological analyses of atrial thrombi were performed.

RESULTS

The endocardial dysfunction was mirrored by diminished levels of eNOS-mRNA in both atria (RA: 0.79±0.04, LA: 0.72±0.06; each P<0.05). Moreover, the PAI-1/t-PA mRNA ratio was significantly increased in both atria (RA: 3.6±0.6; P<0.01, LA: 4.0±1.0; P<0.05) indicating a high risk of thrombus formation. However, the inflammatory phenotype was more pronounced in the RA and was reflected by a significant increase in the mRNA levels encoding adhesion molecules ICAM-1 (2.1±0.2; P<0.01), VCAM-1 (2.3±0.5; P<0.05), and selectin P (3.6±0.5: P<0.05).

CONCLUSIONS

CREM-TG mice represent a valuable model for studying atrial thrombogenesis and assessing therapeutic approaches preventing embolic events in the systemic and pulmonary circulation.

Asymmetric dimethylarginine, related arginine derivatives, and incident atrial fibrillation

BACKGROUND

Oxidative stress plays an important role in the development of atrial fibrillation (AF). Arginine derivatives including asymmetric dimethylarginine (ADMA) are central to nitric oxide metabolism and nitrosative stress. Whether blood concentrations of arginine derivatives are related to incidence of AF is uncertain.

METHODS AND RESULTS

In 3,310 individuals (mean age 58 ± 10 years, 54% women) from the community-based Framingham Study, we prospectively examined the relations of circulating levels of ADMA, l-arginine, symmetric dimethylarginine (SDMA), and the ratio of l-arginine/ADMA to incidence of AF using proportional hazards regression models. Over a median follow-up time of 10 years, 247 AF cases occurred. Using age- and sex-adjusted regression models, ADMA was associated with a hazard ratio of 1.15 per 1-SD increase in loge-biomarker concentration (95% CI 1.02-1.29, P = .02) for AF, which was no longer significant after further risk factor adjustment (hazard ratio 1.09, 95% CI 0.97-1.23, P = .15). Neither l-arginine nor SDMA was related to new-onset AF. A clinical model comprising clinical risk factors for AF (for age, sex, height, weight, systolic blood pressure, diastolic blood pressure, current smoking, diabetes, hypertension treatment, myocardial infarction, and heart failure; c statistic = 0.781; 95% CI 0.753-0.808) was not improved by the addition of ADMA (0.782; 95% CI 0.755-0.809).

CONCLUSIONS

Asymmetric dimethylarginine and related arginine derivatives were not associated with incident AF in the community after accounting for other clinical risk factors and confounders. Its role in the pathogenesis of AF needs further refinement.

Associations of functional alanine-glyoxylate aminotransferase 2 gene variants with atrial fibrillation and ischemic stroke

Asymmetric and symmetric dimethylarginines (ADMA and SDMA) impair nitric oxide bioavailability and have been implicated in the pathogenesis of atrial fibrillation (AF). Alanine–glyoxylate aminotransferase 2 (AGXT2) is the only enzyme capable of metabolizing both of the dimethylarginines. We hypothesized that two functional AGXT2 missense variants (rs37369, V140I; rs16899974, V498L) are associated with AF and its cardioembolic complications. Association analyses were conducted using 1,834 individulas with AF and 7,159 unaffected individuals from two coronary angiography cohorts and a cohort comprising patients undergoing clinical exercise testing. In coronary angiography patients without structural heart disease, the minor A allele of rs16899974 was associated with any AF (OR = 2.07, 95% CI 1.59-2.68), and with paroxysmal AF (OR = 1.98, 95% CI 1.44–2.74) and chronic AF (OR = 2.03, 95% CI 1.35–3.06) separately. We could not replicate the association with AF in the other two cohorts. However, the A allele of rs16899974 was nominally associated with ischemic stroke risk in the meta-analysis of WTCCC2 ischemic stroke cohorts (3,548 cases, 5,972 controls) and with earlier onset of first-ever ischemic stroke (360 cases) in the cohort of clinical exercise test patients. In conclusion, AGXT2 variations may be involved in the pathogenesis of AF and its age-related thromboembolic complications.

New insights into symptomatic or silent atrial fibrillation complicating acute myocardial infarction

Atrial fibrillation (AF) is the most frequent heart rhythm disorder in the general population and contributes not only to a major deterioration in quality of life but also to an increase in cardiovascular morbimortality. The onset of AF in the acute phase of myocardial infarction (MI) is a major event that can jeopardize the prognosis of patients in the short-, medium- and long-term, and is a powerful predictor of a poor prognosis after MI. The suspected mechanism underlying the excess mortality is the drop in coronary flow linked to the acceleration and arrhythmic nature of the left ventricular contractions, which reduce the left ventricular ejection fraction. The principal causes of AF-associated death after MI are linked to heart failure. Moreover, the excess risk of death in these heart failure patients has also been associated with the onset of sudden death. Whatever its form, AF has a major negative effect on patient prognosis. In recent studies, symptomatic AF was associated with inhospital mortality of 17.8%, to which can be added mortality at 1year of 18.8%. Surprisingly, silent AF also has a negative effect on the prognosis, as it is associated with an inhospital mortality rate of 10.4%, which remains high at 5.7% at 1year. Moreover, both forms of AF are independent predictors of mortality beyond traditional risk factors. The frequency and seriousness of silent AF in the short- and long-term, which were until recently rarely studied, raises the question of systematically screening for it in the acute phase of MI. Consequently, the use of continuous ECG monitoring could be a simple, effective and inexpensive solution to improve screening for AF, even though studies are still necessary to validate this strategy. Finally, complementary studies also effect of oxidative stress and endothelial dysfunction, which seem to play a major role in triggering this rhythm disorder.

Atrial Fibrillation Is Associated with a Marker of Endothelial Function and Oxidative Stress in Patients with Acute Myocardial Infarction

Background

Atrial fibrillation (AF), whether silent or symptomatic, is a frequent and severe complication of acute myocardial infarction (AMI). Asymmetric dimethylarginine (ADMA), an endogenous eNOS inhibitor, is a risk factor for endothelial dysfunction. We addressed the relationship between ADMA plasma levels and AF occurrence in AMI.

Methods

273 patients hospitalized for AMI were included. Continuous electrocardiographic monitoring (CEM) ≥48 hours was recorded and ADMA was measured by High Performance Liquid Chromatography on admission blood sample.

Results

The incidence of silent and symptomatic AF was 39(14%) and 29 (11%), respectively. AF patients were markedly older than patients without AF (≈ 20 y). There was a trend towards higher ADMA levels in patients with symptomatic AF than in patients with silent AF or no AF (0.53 vs 0.49 and 0.49 μmol/L, respectively, p = 0.18,). After matching on age, we found that patients with symptomatic AF had a higher heart rate on admission and a higher rate of patients with LV dysfunction (28% vs. 3%, p = 0.025). Patients who developed symptomatic AF had a higher ADMA level than patients without AF (0.53 vs. 0.43 μmol/L; p = 0.001). Multivariate logistic regression analysis to estimate symptomatic AF occurrence showed that ADMA was independently associated with symptomatic AF (OR: 2.46 [1.21–5.00], p = 0.013) beyond history of AF, LVEF<40% and elevated HR.

Conclusion

We show that high ADMA level is associated with the occurrence of AF. Although no causative role can be concluded from our observational study, our work further supports the hypothesis that endothelial dysfunction is involved in the pathogenesis of AF in AMI.

Platelet hyperaggregability in patients with atrial fibrillation. Evidence of a background proinflammatory milieu

OBJECTIVE

Atrial fibrillation (AF) is a condition where platelet hyperaggregability is commonly present. We examined potential physiological bases for platelet hyperaggregability in a cohort of patients with acute and chronic AF. In particular, we sought to identify the impact of inflammation [myeloperoxidase (MPO) and C-reactive protein (CRP)] and impaired nitric oxide (NO) signaling.

METHODS

Clinical and biochemical determinants of adenosine diphosphate (ADP)-induced platelet aggregation were sought in patients (n = 106) hospitalized with AF via univariate and multivariate analysis.

RESULTS

Hyper-responsiveness of platelets to ADP was directly (r = 0.254, p < 0.01) correlated with plasma concentrations of thrombospondin-1 (TSP-1), a matricellular protein that impairs NO responses and contributes to development of oxidative stress. In turn, plasma TSP-1 concentrations were directly correlated with MPO concentrations (r = 0.221, p < 0.05), while MPO concentrations correlated with those of asymmetric dimethylarginine (ADMA, r = 0.220, p < 0.05), and its structural isomer symmetric dimethylarginine (SDMA, r = 0.192, p = 0.05). Multivariate analysis identified TSP-1 (β = 0.276, p < 0.05) concentrations, as well as female sex (β = 0.199, p < 0.05), as direct correlates of platelet aggregability, and SDMA concentrations (β = - 0.292, p < 0.05) as an inverse correlate.

CONCLUSION

We conclude that platelet hyperaggregability, where present in the context of AF, may be engendered by impaired availability of NO, as well as via MPO-related inflammatory activation.

MicroRNA profiling of atrial fibrillation in canines: miR-206 modulates intrinsic cardiac autonomic nerve remodeling by regulating SOD1

Background

A critical mechanism in atrial fibrillation (AF) is cardiac autonomic nerve remodeling (ANR). MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at the post-transcriptional level. Numerous miRNAs are involved in diseases of the nervous and cardiovascular systems.

Objective

We aimed to assess the underlying role of miRNAs in regulating cardiac ANR in AF by right atrial tachypacing (A-TP) in canines.

Methods and Results

Following 4-week A-TP, the superior left ganglionated plexuses (SLGPs), which are embedded in the fat pads of the left atrium, were subjected to miRNA expression profiling to screen preferentially expressed miRNAs. Sixteen miRNAs showed significantly differential expression between the control and A-TP groups, including miR-206, miR-203, miR-224 and miR-137. In particular, we focused on miR-206, which was elevated ~10-fold in A-TP dogs. Forced expression of miR-206 through lentiviral infection based on A-TP in vivo significantly shortened the atrial effective refractory period (AERP) (81 ± 7 vs. 98 ± 7 ms, P < 0.05). Immunohistochemical analysis showed that the regeneration of nerves increased more than 2-fold by miR-206 overexpression (P < 0.01). The expression of superoxide dismutase 1 (SOD1) was repressed by miR-206 overexpression by Western blot and luciferase assay, indicative of SOD1 as a direct target of miR-206. Overexpression of miR-206 increased reactive oxygen species (ROS) levels in vitro and in vivo, whereas miR-206 silencing attenuated irradiation- or A-TP-induced ROS. Knockdown of SOD1 effectively abolished ROS reduction caused by miR-206 silencing.

Conclusions

Our results found the differential expression of miRNAs in response to ANR in AF and elucidated the important role of miR-206 by targeting SOD1. The study illustrated the novel molecular mechanism of ANR and indicated a potential therapeutic target for AF.

Impact of atrial fibrillation ablation on left ventricular filling pressure and left atrial remodeling

BACKGROUND

Left ventricular (LV) diastolic dysfunction is associated with new-onset atrial fibrillation (AF), and the estimation of elevated LV filling pressures by E/e' ratio is related to worse outcomes in patients with AF. However, it is unknown if restoring sinus rhythm reverses this process.

OBJECTIVE

To evaluate the impact of AF ablation on estimated LV filling pressure.

METHODS

A total of 141 patients underwent radiofrequency (RF) ablation to treat drug-refractory AF. Transthoracic echocardiography was performed 30 days before and 12 months after ablation. LV functional parameters, left atrial volume index (LAVind), and transmitral pulsed and mitral annulus tissue Doppler (e' and E/e') were assessed. Paroxysmal AF was present in 18 patients, persistent AF was present in 102 patients, and long-standing persistent AF in 21 patients. Follow-up included electrocardiographic examination and 24-h Holter monitoring at 3, 6, and 12 months after ablation.

RESULTS

One hundred seventeen patients (82.9%) were free of AF during the follow-up (average, 18 ± 5 months). LAVind reduced in the successful group (30.2 mL/m(2) ± 10.6 mL/m(2) to 22.6 mL/m(2) ± 1.1 mL/m(2), p < 0.001) compared to the non-successful group (37.7 mL/m(2) ± 14.3 mL/m(2) to 37.5 mL/m(2) ± 14.5 mL/m(2), p = ns). Improvement of LV filling pressure assessed by a reduction in the E/e' ratio was observed only after successful ablation (11.5 ± 4.5 vs. 7.1 ± 3.7, p < 0.001) but not in patients with recurrent AF (12.7 ± 4.4 vs. 12 ± 3.3, p = ns). The success rate was lower in the long-standing persistent AF patient group (57% vs. 87%, p = 0.001).

CONCLUSION

Successful AF ablation is associated with LA reverse remodeling and an improvement in LV filling pressure.

Redox control of cardiac remodeling in atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and is a potential cause of thromboembolic events. AF induces significant changes in the electrophysiological properties of atrial myocytes and causes alterations in the structure, metabolism, and function of the atrial tissue. The molecular basis for the development of structural atrial remodeling of fibrillating human atria is still not fully understood. However, increased production of reactive oxygen or nitrogen species (ROS/RNS) and the activation of specific redox-sensitive signaling pathways observed both in patients with and animal models of AF are supposed to contribute to development, progression and self-perpetuation of AF.

SCOPE OF REVIEW

The present review summarizes the sources and targets of ROS/RNS in the setting of AF and focuses on key redox-sensitive signaling pathways that are implicated in the pathogenesis of AF and function either to aggravate or protect from disease.

MAJOR CONCLUSIONS

NADPH oxidases and various mitochondrial monooxygenases are major sources of ROS during AF. Besides direct oxidative modification of e.g. ion channels and ion handling proteins that are crucially involved in action potential generation and duration, AF leads to the reversible activation of redox-sensitive signaling pathways mediated by activation of redox-regulated proteins including Nrf2, NF-κB, and CaMKII. Both processes are recognized to contribute to the formation of a substrate for AF and, thus, to increase AF inducibility and duration.

GENERAL SIGNIFICANCE

AF is a prevalent disease and due to the current demographic developments its socio-economic relevance will further increase. Improving our understanding of the role that ROS and redox-related (patho)-mechanisms play in the development and progression of AF may allow the development of a targeted therapy for AF that surpasses the efficacy of previous general anti-oxidative strategies. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.

Successful catheter ablation decreases platelet activation and improves endothelial function in patients with atrial fibrillation

BACKGROUND

Nonvalvular atrial fibrillation (AF) confers a five-fold increased risk of stroke. Whether catheter ablation (CA) subsequently decreases prothrombotic risk is unknown.

OBJECTIVE

The purpose of this study was to assess the long-term effects of CA for AF on prothrombotic risk.

METHODS

Fifty-seven patients undergoing CA for AF were prospectively studied. Platelet activation (CD62P [platelet P-selectin] and PAC-1 [glycoprotein IIb/IIIa] expression) and endothelial function (asymmetric dimethylarginine [ADMA] levels) were measured at baseline and 6-months postablation.

RESULTS

Thirty-seven (65%) patients remained in sinus rhythm (SR group) and 20 (35%) sustained AF recurrence (AF recurrence group) at 6-months. Patients with AF-recurrence were older, had a higher proportion of hypertension and long-standing persistent AF. There were no significant differences in CD62P (P = .3), PAC-1 (P = .1) and ADMA (P = .7) levels at baseline between the two groups. In the SR group, markers of platelet activation decreased significantly at 6-month follow-up compared to baseline; log CD62P % 0.79 ± 0.28 vs 1.03 ± 0.27 (P <.05) and log PAC-1 % 0.22 ± 0.58 vs 0.89 ± 0.31 (P <.01). This was not significant in the AF-recurrence group (P = .8, log CD62P; P = .1, log PAC-1). For endothelial function, ADMA levels decreased significantly at 6-months compared to baseline in the SR group (log ADMA μM/L 0.15 ± 0.02 vs 0.17 ± 0.04; P <.05), but did not alter significantly in the AF-recurrence group (P = .4, log ADMA).

CONCLUSION

Catheter ablation and successful maintenance of SR leads to a decrease in platelet activation and improvement in endothelial function in patients with AF. These findings suggest that AF is an important determinant of the prothrombotic state and that this may be reduced by successful catheter ablation.