Atrial remodeling in obstructive sleep apnea: implications for atrial fibrillation

Long-term outcome of catheter ablation in atrial fibrillation patients with coexistent metabolic syndrome and obstructive sleep apnea: impact of repeat procedures versus lifestyle changes

INTRODUCTION

Metabolic syndrome (MS) and obstructive sleep apnea (OSA) are well-known independent risk factors for atrial fibrillation (AF) recurrence. This study evaluated ablation outcome in AF patients with coexistent MS and OSA and influence of lifestyle modifications (LSM) on arrhythmia recurrence.

METHODS AND RESULTS

We included 1,257 AF patients undergoing first catheter ablation (30% paroxysmal AF). Patients having MS + OSA were classified into Group 1 (n = 126; 64 ± 8 years; 76% male). Group 2 (n = 1,131; 62 ± 11 years; 72% male) included those with either MS (n = 431) or OSA (n = 112; no CPAP users) or neither of these comorbidities (n = 588). Patients experiencing recurrence after first procedure were divided into 2 subgroups; those having sporadic events (frequency < 2 months) remained on previously ineffective antiarrhythmic drugs (AAD) and aggressive LSM, while those with persistent arrhythmia (incessant or ≥2 months) underwent repeat ablation. After 34 ± 8 months of first procedure, 66 (52%) in Group 1 and 386 (34%) in Group 2 had recurrence (P < 0.001). Recurrence rate in only-MS, only-OSA, and without MS/OSA groups were 40%, 38%, and 29%, respectively. Patients with MS + OSA experienced substantially higher recurrence compared to those with lone MS or OSA (52% vs. 40% vs. 38%; P = 0.036). Of the 452 patients having recurrence, 250 underwent redo-ablation and 194 remained on AAD and LSM. At 20 ± 6 months, 76% of the redo group remained arrhythmia-free off AAD whereas 74% of the LSM group were free from recurrence (P = 0.71), 33% of which were off AAD.

CONCLUSIONS

MS and OSA have additive negative effect on arrhythmia recurrence following single procedure. Repeat ablation or compliant LSM increase freedom from recurrent AF.

Severity of obstructive sleep apnea influences the effect of genotype on response to anti-arrhythmic drug therapy for atrial fibrillation

STUDY OBJECTIVES

To examine the impact of genotype on the relationship between obstructive sleep apnea (OSA) and anti-arrhythmic drug (AAD) efficacy in atrial fibrillation (AF).

DESIGN

Registry based.

SETTING

Clinic-based.

PARTICIPANTS

Eighty-four individuals from Vanderbilt AF registry who had polysomnography, genotyping, and serial comprehensive evaluations of AF status.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Response to AADs was defined as a decrease in AF burden score by ≥ 75% or the combination of sinus rhythm on follow-up EKGs, stable AAD therapy for at least 6 months, objective AF burden below an established threshold, and the absence of non-pharmacologic therapies. Participants were genotyped for common AF susceptibility alleles at chromosomes 4q25 (near PITX2), 16q22 (in ZFHX3), and 1q21 (in KCNN3), and common SNPs in the β1-adrenergic receptor (ARDB1). Wild-type status for rs10033464 at 4q25 was associated with increased success of AAD therapy in patients with no or mild OSA (odds ratio: 10.0, 95% confidence interval: 1.03 to 97.5; p < 0.05), but did not influence response to AAD therapy in those with moderate-severe OSA. A similar trend was observed for rs1801252 on ARDB1.

CONCLUSION

In this hypothesis-generating pilot study of predominantly Caucasian men, the effect on AF response to AAD therapy of rs10033464 at 4q25 varied based on OSA status. The impact of genotype on AAD efficacy may be greatest in mild OSA and attenuated in more severe disease.

Renal denervation: effects on atrial electrophysiology and arrhythmias

Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with significant morbidity and mortality. Currently, atrial endocardial catheter ablation, mainly targeting focal discharges in the pulmonary veins, is the most widely used interventional treatment of drug-refractory AF. Despite technical improvements, results are not yet optimal. There is ongoing search for alternative and/or complementary interventional targets. Conditions associated with increased sympathetic activation such as hypertension, heart failure and sleep apnea lead to structural, neural and electrophysiological changes in the atrium thereby contributing to the progression from paroxysmal to persistent AF and increasing recurrence rate of AF after PVI. Until now, interventional modulation of autonomic nervous system was limited by highly invasive techniques. Catheter-based renal denervation (RDN) was introduced as a minimally invasive approach to reduce renal and whole body sympathetic activation with accompanying blood pressure control and left-ventricular morphological and functional changes in resistant hypertension. This review focuses on the potential atrial antiarrhythmic and antiremodeling effects of RDN in AF patients with hypertension, heart failure, and sleep apnea and discusses the possible role of RDN in the treatment of AF.

Epicardial adipose tissue and atrial fibrillation

Atrial fibrillation (AF) is the most frequent cardiac arrhythmia in clinical practice. AF is often associated with profound functional and structural alterations of the atrial myocardium that compose its substrate. Recently, a relationship between the thickness of epicardial adipose tissue (EAT) and the incidence and severity of AF has been reported. Adipose tissue is a biologically active organ regulating the metabolism of neighbouring organs. It is also a major source of cytokines. In the heart, EAT is contiguous with the myocardium without fascia boundaries resulting in paracrine effects through the release of adipokines. Indeed, Activin A, which is produced in abundance by EAT during heart failure or diabetes, shows a marked fibrotic effect on the atrial myocardium. The infiltration of adipocytes into the atrial myocardium could also disorganize the depolarization wave front favouring micro re-entry circuits and local conduction block. Finally, EAT contains progenitor cells in abundance and therefore could be a source of myofibroblasts producing extracellular matrix. The study on the role played by adipose tissue in the pathogenesis of AF is just starting and is highly likely to uncover new biomarkers and therapeutic targets for AF.

Structural and Functional Remodeling of the Left Atrium: Clinical and Therapeutic Implications for Atrial Fibrillation

Atrial fibrillation (AF) is the most commonly encountered arrhythmia in clinical practice. Despite advances in our understanding of the pathophysiology of this complex arrhythmia, current therapeutic options remain suboptimal. This review aimed to delineate the atrial structural and functional remodeling leading to the perpetuation of AF. We explored the complex changes seen in the atria in various substrates for AF and the therapeutic options available to prevent these changes or for reverse remodeling. Here we also highlighted the emerging role of aggressive risk factor management aimed at the arrhythmogenic atrial substrate to prevent or retard AF progression.

Uric acid levels in obstructive sleep apnea patients with atrial fibrillation

BACKGROUND AND AIMS

The objective of this observational study was to determine whether there is an association between atrial fibrillation (AF) and uric acid and to identify the risk markers for AF in obstructive sleep apnea (OSA).

METHODS

Consecutive patients with newly diagnosed OSA were screened at baseline. The final study population consisted of 516 patients. One hundred and eight patients had AF. Demographic, clinical, laboratory, and echocardiographic characteristics were carefully recorded. Logistic regression was used for the multivariate analysis of independent risk factors.

RESULTS

Uric acid, triglyceride, high-density lipoprotein, C-reactive protein (CRP), left atrial diameter, interventricular septum thickness, apnea hypopnea index, and Epworth sleepiness scale were significantly higher in OSA patients with AF than in those without AF (p <0.05). Among these patients, multiple logistic analyses indicated the independent risk factors for AF occurrence in the OSA subjects included serum uric acid level, left atrial diameter, percentage of time with SaO2 <90%, CRP. The diagnosis analysis showed that higher uric acid, CRP, left atrial diameter and percentage of time with SaO2 <90% had a significant ability to reflect the presence of AF occurrence.

CONCLUSIONS

The novel finding of this study is that the occurrence of AF in OSA patients is strongly related to serum uric acid level, left atrial diameter, percentage of time with SaO2 <90% and CRP level. These results may be helpful for monitoring AF occurrence in OSA patients.

P wave duration and dispersion in Holter electrocardiography of patients with obstructive sleep apnea

PURPOSE

The underlying mechanisms of the association between obstructive sleep apnea (OSA) and atrial fibrillation (AF) remained unclear. We investigated P wave parameters as indicators of atrial conduction status among OSA patients.

METHODS

We studied 42 untreated OSA patients, categorized into mild (6), moderate (18), and severe (18) OSA based on the apnea/hypopnea index (AHI) and 18 healthy controls. Twenty-four-hour Holter electrocardiography was applied to measure P wave parameters including P wave duration and P wave dispersion; difference between the maximum (P-max) and minimum (P-min) measured P wave duration.

RESULTS

Mean P wave duration ranged from 110.2 ± 9.3 ms in mild OSA patients to 121.1 ± 15.4 ms in severe OSA patients and was 113.4 ± 10.0 ms in controls with no significant difference among the groups, P = 0.281. P wave dispersion and P-max were significantly longer in those with moderate OSA (68.0 ± 9.3 and 154.2 ± 9.3 ms) and those with severe OSA (71.6 ± 13.7 and 157.2 ± 13.3 ms) than controls (52.6 ± 15.3 and 142.1 ± 15.4 ms), P < 0.05. AHI was significantly correlated with P-max (r = 0.407, P = 0.012) and P wave dispersion (r = 0.431, P = 0.008). With linear regression analysis controlling for age, gender, and BMI, the AHI was independently associated with P wave dispersion (β = 0.482, P = 0.002).

CONCLUSIONS

Using Holter monitoring for measurement of P wave parameters, this study showed an association of OSA with prolonged P-max and P wave dispersion. These results indicate that patients with OSA have disturbances in atrial conduction associated with OSA severity. Repeating this study in a larger sample of patients is warranted.

Effect of Renal Denervation on Neurohumoral Activation Triggering Atrial Fibrillation in Obstructive Sleep Apnea

Obstructive sleep apnea is characterized by repetitive collapses of the upper airway, negative thoracic pressure periods, and intermittent hypoxia, stimulating the autonomic nervous system. The increased sympathetic drive during obstructive sleep apnea results in postapneic blood pressure rises and neurohumoral activation potentially involved in the initiation and progression to permanent atrial fibrillation (AF). In a pig model mimicking obstructive sleep apnea, we studied the effects of repetitive obstructive respiratory events for 4 hours on the occurrence of spontaneous AF episodes, postapneic blood pressure rises, and neurohumoral activation. In addition, renal sympathetic denervation was performed to investigate the impact of the sympathetic nervous system. Repetitive obstructive respiratory events caused pronounced postapneic blood pressure rises, prolonged duration of spontaneous AF episodes triggered by spontaneous atrial beats, and increased plasma renin activity and aldosterone concentrations. This was associated with increased nicotinamide adenine dinucleotide phosphate-oxidase activity, reduced antioxidative capacity, and elevated expression of connective tissue growth factor, a redox-sensitive mediator of fibrosis. Renal sympathetic denervation inhibited postapneic blood pressure rises and decreased plasma renin activity and aldosterone concentrations. The occurrence and duration of spontaneous AF were reduced comparable with a combined pharmacological blockade of angiotensin receptor and β-adrenoceptor. Increased atrial oxidative stress, together with the activation of profibrotic pathways and intermittent hypoxia, was not attenuated after renal sympathetic denervation. Repetitive obstructive respiratory events triggered spontaneous AF, increased atrial oxidative stress, and activated profibrotic pathways in the atrium. Renal sympathetic denervation reduced spontaneous AF and postapneic blood pressure rises by combined reduction of sympathetic drive and components of the circulating renin–angiotensin system. However, the generation of atrial oxidative stress was not modulated.

Atrial arrhythmia in ageing spontaneously hypertensive rats: unraveling the substrate in hypertension and ageing

Background

Both ageing and hypertension are known risk factors for atrial fibrillation (AF) although the pathophysiological contribution or interaction of the individual factors remains poorly understood. Here we aim to delineate the arrhythmogenic atrial substrate in mature spontaneously hypertensive rats (SHR).

Methods

SHR were studied at 12 and 15 months of age (n = 8 per group) together with equal numbers of age-matched normotensive Wistar-Kyoto control rats (WKY). Electrophysiologic study was performed on superfused isolated right and left atrial preparations using a custom built high-density multiple-electrode array to determine effective refractory periods (ERP), atrial conduction and atrial arrhythmia inducibility. Tissue specimens were harvested for structural analysis.

Results

Compared to WKY controls, the SHR demonstrated: Higher systolic blood pressure (p<0.0001), bi-atrial enlargement (p<0.05), bi-ventricular hypertrophy (p<0.05), lower atrial ERP (p = 0.008), increased atrial conduction heterogeneity (p = 0.001) and increased atrial interstitial fibrosis (p = 0.006) & CD68-positive macrophages infiltration (p<0.0001). These changes resulted in higher atrial arrhythmia inducibility (p = 0.01) and longer induced AF episodes (p = 0.02) in 15-month old SHR. Ageing contributed to incremental bi-atrial hypertrophy (p<0.01) and atrial conduction heterogeneity (p<0.01) without affecting atrial ERP, fibrosis and arrhythmia inducibility. The limited effect of ageing on the atrial substrate may be secondary to the reduction in CD68-positive macrophages.

Conclusions

Significant atrial electrical and structural remodeling is evident in the ageing spontaneously hypertensive rat atria. Concomitant hypertension appears to play a greater pathophysiological role than ageing despite their compounding effect on the atrial substrate. Inflammation is pathophysiologically linked to the pro-fibrotic changes in the hypertensive atria.

Obstructive sleep apnea: a cardiometabolic risk in obesity and the metabolic syndrome

Obstructive sleep apnea (OSA) is an underdiagnosed condition characterized by recurrent episodes of obstruction of the upper airway leading to sleep fragmentation and intermittent hypoxia during sleep. Obesity predisposes to OSA, and the prevalence of OSA is increasing worldwide because of the ongoing epidemic of obesity. Recent evidence has shown that surrogate markers of cardiovascular risk, including sympathetic activation, systemic inflammation, and endothelial dysfunction, are significantly increased in obese patients with OSA versus those without OSA, suggesting that OSA is not simply an epiphenomenon of obesity. Moreover, findings from animal models and patients with OSA show that intermittent hypoxia exacerbates the metabolic dysfunction of obesity, augmenting insulin resistance and nonalcoholic fatty liver disease. In patients with the metabolic syndrome, the prevalence of moderate to severe OSA is very high (∼60%). In this population, OSA is independently associated with increased glucose and triglyceride levels as well as markers of inflammation, arterial stiffness, and atherosclerosis. A recent randomized, controlled, crossover study showed that effective treatment of OSA with continuous positive airway pressure for 3 months significantly reduced several components of the metabolic syndrome, including blood pressure, triglyceride levels, and visceral fat. Finally, several cohort studies have consistently shown that OSA is associated with increased cardiovascular mortality, independent of obesity. Taken together, these results support the concept that OSA exacerbates the cardiometabolic risk attributed to obesity and the metabolic syndrome. Recognition and treatment of OSA may decrease the cardiovascular risk in obese patients.

Obesity, diabetes and atrial fibrillation; epidemiology, mechanisms and interventions

The last few decades have witnessed a global rise in adult obesity of epidemic proportions. The potential impact of this is emphasized when one considers that body mass index (BMI) is a powerful predictor of death, type 2 diabetes (T2DM) and cardiovascular (CV) morbidity and mortality [1, 2]. Similarly we have witnessed a parallel rise in the incidence of atrial fibrillation (AF), the commonest sustained cardiac arrhythmia, which is also a significant cause of cardiovascular morbidity and mortality. Part of this increase is attributable to advances in the treatment of coronary heart disease (CHD) and heart failure (HF) improving life expectancy and consequently the prevalence of AF. However, epidemiological studies have demonstrated an independent association between obesity and AF, possibly reflecting common pathophysiology and risk factors for both conditions. Indeed, weight gain and obesity are associated with structural and functional changes of the cardiovascular system including left atrial and ventricular remodeling, haemodynamic alterations, autonomic dysfunction, and diastolic dysfunction. Moreover, diabetic cardiomyopathy is characterized by an adverse structural and functional cardiac phenotype which may predispose to the development of AF [3]. In this review, we discuss the pathophysiological and mechanistic relationships between obesity, diabetes and AF, and the challenges posed in the management of this high-risk group of individuals.

Treatment of obstructive sleep apnea reduces the risk of atrial fibrillation recurrence after catheter ablation

OBJECTIVES

The aim of this study was to examine the effect of continuous positive airway pressure (CPAP) therapy on atrial fibrillation (AF) recurrence in patients with obstructive sleep apnea (OSA) undergoing pulmonary vein isolation (PVI).

BACKGROUND

OSA is a predictor of AF recurrence following PVI. However, the impact of CPAP therapy on PVI outcome in patients with OSA is poorly known.

METHODS

Among 426 patients who underwent PVI between 2007 and 2010, 62 patients had a polysomnography-confirmed diagnosis of OSA. While 32 patients were "CPAP users" the remaining 30 patients were "CPAP nonusers." The recurrence of any atrial tachyarrhythmia, use of antiarrhythmic drugs, and need for repeat ablations were compared between the groups during a follow-up period of 12 months. Additionally, the outcome of patients with OSA was compared to a group of patients from the same PVI cohort without OSA.

RESULTS

CPAP therapy resulted in higher AF-free survival rate (71.9% vs. 36.7%; p = 0.01) and AF-free survival off antiarrhythmic drugs or repeat ablation following PVI (65.6% vs. 33.3%; p = 0.02). AF recurrence rate of CPAP-treated patients was similar to a group of patients without OSA (HR: 0.7, p = 0.46). AF recurrence following PVI in CPAP nonuser patients was significantly higher (HR: 2.4, p < 0.02) and similar to that of OSA patients managed medically without ablation (HR: 2.1, p = 0.68).

CONCLUSIONS

CPAP is an important therapy in OSA patients undergoing PVI that improves arrhythmia free survival. PVI offers limited value to OSA patients not treated with CPAP.

Atrial arrhythmias in obstructive sleep apnea: underlying mechanisms and implications in the clinical setting

Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive interruption of ventilation during sleep caused by recurrent upper airway collapse, which leads to intermittent hypoxia. The disorder is commonly undiagnosed despite its relationship with substantial cardiovascular morbidity and mortality. Moreover, the effects of the disorder appear to be particularly dangerous in young subjects. In the last decade, substantial clinical evidence has identified OSA as independent risk factor for both bradyarrhythmias and tachyarrhythmias. To date the mechanisms leading to such arrhythmias have not been completely understood. However, recent data from animal models and new molecular analyses have increased our knowledge of the field, which might lead to future improvement in current therapeutic strategies mainly based on continuous positive airway pressure. This paper aims at providing readers a brief and specific revision of current knowledge about the mechanisms underlying atrial arrhythmias in OSA and their clinical and therapeutic implications.

Atrial fibrillation in the 21st century: a current understanding of risk factors and primary prevention strategies

Atrial fibrillation (AF) is the most common arrhythmia worldwide, and it has a significant effect on morbidity and mortality. It is a significant risk factor for stroke and peripheral embolization, and it has an effect on cardiac function. Despite widespread interest and extensive research on this topic, our understanding of the etiology and pathogenesis of this disease process is still incomplete. As a result, there are no set primary preventive strategies in place apart from general cardiology risk factor prevention goals. It seems intuitive that a better understanding of the risk factors for AF would better prepare medical professionals to initially prevent or subsequently treat these patients. In this article, we discuss widely established risk factors for AF and explore newer risk factors currently being investigated that may have implications in the primary prevention of AF. For this review, we conducted a search of PubMed and used the following search terms (or a combination of terms): atrial fibrillation, metabolic syndrome, obesity, dyslipidemia, hypertension, type 2 diabetes mellitus, omega-3 fatty acids, vitamin D, exercise toxicity, alcohol abuse, and treatment. We also used additional articles that were identified from the bibliographies of the retrieved articles to examine the published evidence for the risk factors of AF.

Long-term outcomes of catheter ablation of atrial fibrillation: a systematic review and meta-analysis

BACKGROUND

In the past decade, catheter ablation has become an established therapy for symptomatic atrial fibrillation (AF). Until very recently, few data have been available to guide the clinical community on the outcomes of AF ablation at ≥3 years of follow-up. We aimed to systematically review the medical literature to evaluate the long-term outcomes of AF ablation.

METHODS AND RESULTS

A structured electronic database search (PubMed, Embase, Web of Science, Cochrane) of the scientific literature was performed for studies describing outcomes at ≥3 years after AF ablation, with a mean follow-up of ≥24 months after the index procedure. The following data were extracted: (1) single-procedure success, (2) multiple-procedure success, and (3) requirement for repeat procedures. Data were extracted from 19 studies, including 6167 patients undergoing AF ablation. Single-procedure freedom from atrial arrhythmia at long-term follow-up was 53.1% (95% CI 46.2% to 60.0%) overall, 54.1% (95% CI 44.4% to 63.4%) in paroxysmal AF, and 41.8% (95% CI 25.2% to 60.5%) in nonparoxysmal AF. Substantial heterogeneity (I(2)>50%) was noted for single-procedure outcomes. With multiple procedures, the long-term success rate was 79.8% (95% CI 75.0% to 83.8%) overall, with significant heterogeneity (I(2)>50%).The average number of procedures per patient was 1.51 (95% CI 1.36 to 1.67).

CONCLUSIONS

Catheter ablation is an effective and durable long-term therapeutic strategy for some AF patients. Although significant heterogeneity is seen with single procedures, long-term freedom from atrial arrhythmia can be achieved in some patients, but multiple procedures may be required.

The Relationship between Obstructive Sleep Apnea and Atrial Fibrillation: A Complex Interplay

In recent years, growing evidence suggests an association between obstructive sleep apnea (OSA), a common sleep breathing disorder which is increasing in prevalence as the obesity epidemic surges, and atrial fibrillation (AF), the most common cardiac arrhythmia. AF is a costly public health problem increasing a patient's risk of stroke, heart failure, and all-cause mortality. It remains unclear whether the association is based on mutual risk factors, such as obesity and hypertension, or whether OSA is an independent risk factor and causative in nature. This paper explores the pathophysiology of OSA which may predispose to AF, clinical implications of stroke risk in this cohort who display overlapping disease processes, and targeted treatment strategies such as continuous positive airway pressure and AF ablation.

Impact of Obstructive Sleep Apnea on Outcomes of Catheter Ablation of Atrial Fibrillation

Obstructive sleep apnea (OSA) is a growing epidemic in the United States and significantly contributes to the increasing prevalence of atrial fibrillation (AF) in the U.S.

POPULATION

Although a strong correlation between OSA and AF has been demonstrated, a causal relationship between these two conditions has not been definitively established. Evidence of OSA is an important consideration of AF management and impacts the success rate of catheter ablation. The presence of OSA tends to predict a lower success rate and higher complication rate for catheter ablation of AF. However, recent studies evaluating OSA as an independent risk predictor of AF recurrence following an ablation procedure have yielded conflicting results. A greater understanding of these conditions would allow for a more specific therapy targeting the type of AF associated with OSA. The following review provides a brief summary of obstructive sleep apnea etiology, focuses on the relationship between OSA and AF, and discusses the impact of OSA on the outcomes of catheter ablation of AF.

Sleep apnea and atrial fibrillation; 2012 update

Atrial fibrillation (AF) and obstructive sleep apnea (OSA) are very prevalent diseases in modern society. Recent years have seen the emergence of a wide body of literature suggesting an important association between these two diseases. This review will provide a summary of this evidence as it currently exists. First, it will review the literature suggesting an association between AF and OSA by highlighting the prevalence of AF in OSA, the correlation of AF prevalence with OSA severity and the trend towards increased AF recurrence in patients with OSA after treatment for AF. Second, it will identify the possible pathophysiologic mechanisms for this association. In doing so, it will discuss the investigated effects of intrathoracic pressure changes, autonomic instability and atrial remodeling. Finally, it will review the evidence of the effect of treatment of OSA on AF, highlighting the role of continuous positive airway pressure (CPAP) in the treatment of OSA and its impact on AF prevalence and recurrence.

Computational modeling of the human atrial anatomy and electrophysiology

This review article gives a comprehensive survey of the progress made in computational modeling of the human atria during the last 10 years. Modeling the anatomy has emerged from simple "peanut"-like structures to very detailed models including atrial wall and fiber direction. Electrophysiological models started with just two cellular models in 1998. Today, five models exist considering e.g. details of intracellular compartments and atrial heterogeneity. On the pathological side, modeling atrial remodeling and fibrotic tissue are the other important aspects. The bridge to data that are measured in the catheter laboratory and on the body surface (ECG) is under construction. Every measurement can be used either for model personalization or for validation. Potential clinical applications are briefly outlined and future research perspectives are suggested.

Renal sympathetic denervation suppresses postapneic blood pressure rises and atrial fibrillation in a model for sleep apnea

The aim of this study was to identify the relative impact of adrenergic and cholinergic activity on atrial fibrillation (AF) inducibility and blood pressure (BP) in a model for obstructive sleep apnea. Obstructive sleep apnea is associated with sympathovagal disbalance, AF, and postapneic BP rises. Renal denervation (RDN) reduces renal efferent and possibly also afferent sympathetic activity and BP in resistant hypertension. The effects of RDN compared with β-blockade by atenolol on atrial electrophysiological changes, AF inducibility, and BP during obstructive events and on shortening of atrial effective refractory period (AERP) induced by high-frequency stimulation of ganglionated plexi were investigated in 20 anesthetized pigs. Tracheal occlusion with applied negative tracheal pressure (NTP; at -80 mbar) induced pronounced AERP shortening and increased AF inducibility in all of the pigs. RDN but not atenolol reduced NTP-induced AF-inducibility (20% versus 100% at baseline; P=0.0001) and attenuated NTP-induced AERP shortening more than atenolol (27±5 versus 43±3 ms after atenolol; P=0.0272). Administration of atropine after RDN or atenolol completely inhibited NTP-induced AERP shortening. AERP shortening induced by high-frequency stimulation of ganglionated plexi was not influenced by RDN, suggesting that changes in sensitivity of ganglionated plexi do not play a role in the antiarrhythmic effect of RDN. Postapneic BP rise was inhibited by RDN and not modified by atenolol. We showed that vagally mediated NTP-induced AERP shortening is modulated by RDN or atenolol, which emphasizes the importance of autonomic disbalance in obstructive sleep apnea-associated AF. Renal denervation displays antiarrhythmic effects by reducing NTP-induced AERP shortening and inhibits postapneic BP rises associated with obstructive events.