Obstructive sleep apnea and the recurrence of atrial fibrillation

The Interplay between Obstructive Sleep Apnea and Atrial Fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Obstructive sleep apnea (OSA) is also an increasingly common condition. Both entities are risk factors for ischemic stroke and both conditions are linked with increased mortality. Mechanical effects of obesity and sleep apnea can lead to increased afterload, left ventricular hypertrophy, and left atrial fibrosis and remodeling. These changes can result in an increased risk of AF development. The current paper summarizes the evidence for the bidirectional relationship between AF and OSA. The merits of selective screening for these two conditions are also discussed.

Atrial Substrate and Triggers of Paroxysmal Atrial Fibrillation in Patients With Obstructive Sleep Apnea

BACKGROUND

Obstructive sleep apnea (OSA) is associated with atrial remodeling, atrial fibrillation (AF), and increased incidence of arrhythmia recurrence after pulmonary vein (PV) isolation. We aimed to characterize the atrial substrate, including AF triggers in patients with paroxysmal AF and OSA.

METHODS AND RESULTS

In 86 patients with paroxysmal AF (43 with ≥moderate OSA [apnea-hypopnea index ≥15] and 43 without OSA [apnea-hypopnea index <5]), right atrial and left atrial voltage distribution, conduction velocities, and electrogram characteristics were analyzed during atrial pacing. AF triggers were examined before and after PV isolation and targeted for ablation. Patients with OSA had lower atrial voltage amplitude (right atrial, P=0.0005; left atrial, P=0.0001), slower conduction velocities (right atrial, P=0.02; left atrial, P=0.0002), and higher prevalence of electrogram fractionation (P=0.0001). The areas of atrial abnormality were consistent among patients, most commonly involving the left atrial septum (32/43; 74.4%). At baseline, the PVs were the most frequent triggers for AF in both groups; however, after PV isolation patients with OSA had increased incidence of additional extra-PV triggers (41.8% versus 11.6%; P=0.003). The 1-year arrhythmia-free survival was similar between patients with and without OSA (83.7% and 81.4%, respectively; P=0.59). In comparison, control patients with paroxysmal AF and OSA who underwent PV isolation alone without ablation on extra-PV triggers had increased risk of arrhythmia recurrence (83.7% versus 64.0%; P=0.003).

CONCLUSIONS

OSA is associated with structural and functional atrial remodeling and increased incidence of extra-PV triggers. Elimination of these triggers resulted in improved arrhythmia-free survival.

Mask Refills as a Measure of PAP Adherence

STUDY OBJECTIVES

Positive airway pressure (PAP) adherence data are a routine aspect of clinical care for obstructive sleep apnea (OSA), but not uniformly available. We hypothesized that mask refills are a measure of PAP adherence.

METHODS

We measured PAP use over the first 90 days of treatment in 123 patients with OSA. The number and timing of mask refills was assessed over 18 months. Demographic and medical information was obtained from the electronic medical record.

RESULTS

Average PAP use in the first week of more than 4 h/d was a predictor of adherence over the first 90 days (P < .0001). PAP use over 90 days was greater in datacard-derived data dependent on patients presenting a datacard to the clinic compared to modem-derived data (P = .0006). A mask refill within the first 30 days of treatment was associated with a 1.3 h/d lower PAP usage in the first 90 days (P = .0044). Conversely, the number of mask refills between 30 days and 18 months was associated with higher PAP adherence during the first 90 days, with an additional 0.61 h/d of use for each additional refill (P = .0015).

CONCLUSIONS

In a retrospective cohort of veterans with OSA, first week PAP use was a strong predictor of 90-day use. Use of autonomously transmitted modem data avoided potential selection bias in adherence estimates. Mask refills in the first month were associated with less 90-day PAP use, whereas more mask refills after 30 days were associated with greater PAP use.

Prevalence of Cardiac Arrhythmias in Asian Patients With Obstructive Sleep Apnea: A Singapore Sleep Center Experience

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity and mortality. Cardiac arrhythmias are common in patients with OSA. However, the prevalence and significance of cardiac arrhythmias in Asian patients with OSA are not well studied. The aim of this study is to determine the prevalence of cardiac arrhythmias in patients with OSA in Singapore and to evaluate possible factors that may predispose patients with OSA to arrhythmias.

METHODS

A retrospective study of 2,019 patients was carried out from January 2011 to December 2012 at a sleep center in a tertiary medical center. Of the population, 1,457 patients were found to have OSA and 144 patients were found to have cardiac arrhythmias. Data collected included patient demographics, comorbidities, and polysomnogram parameters.

RESULTS

The prevalence of cardiac arrhythmias in our OSA population is 8.0%, compared to that of primary snorers at 4.8% (P = .015). The univariate analysis revealed that older age, higher body mass index, comorbidities, and severity of OSA, including apnea-hypopnea index (AHI), lowest oxygen saturation (LSAT) and hypoxic time were correlated with a higher prevalence of cardiac arrhythmias (P < .05). However, the multivariate analysis showed that only age and body mass index were significantly correlated with arrhythmias. AHI, LSAT, and hypoxic time were no longer statistically significant.

CONCLUSIONS

Our study demonstrated that cardiac arrhythmias are common in patients with OSA in Singapore. It also suggests that given the different demographics of our population, ethnicity may play a significant role in the development of cardiovascular disease among patients with OSA.

COMMENTARY

A commentary on this article appears in this issue on page 1229.

Intermittent hypoxia-induced cardiomyopathy and its prevention by Nrf2 and metallothionein

The mechanism for intermittent hypoxia (IH)-induced cardiomyopathy remains obscure. We reported the prevention of acute and chronic IH-induced cardiac damage by selective cardiac overexpression of metallothionein (MT). Herein we defined that MT-mediated protection from IH-cardiomyopathy is via activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a critical redox-balance controller in the body. For this, mice were exposed to IH for 3 days (acute) or 4 or 8 weeks (chronic). Cardiac Nrf2 and MT expression in response to IH were significantly increased acutely yet decreased chronically. Interestingly, cardiac overexpression (Nrf2-TG) or global deletion of the Nrf2 gene (Nrf2-KO) made mice highly resistant or highly susceptible, respectively, to IH-induced cardiomyopathy and MT expression. Mechanistically, 4-week IH exposure significantly decreased cardiac Nrf2 binding to the MT gene promoter, and thus, depressed both MT transcription and translation in WT mice but not Nrf2-TG mice. Likewise, cardiac MT overexpression prevented chronic IH-induced cardiomyopathy and down-regulation of Nrf2 likely via activation of a PI3K/Akt/GSK-3β/Fyn-dependent signaling pathway. These results reveal an integrated relationship between cardiac Nrf2 and MT expression in response to IH -- acute compensatory up-regulation followed by chronic down-regulation and cardiomyopathy. Cardiac overexpression of either Nrf2 or MT offered cardioprotection from IH via complicated PI3K/Akt/GSK3B/Fyn signaling. Potential therapeutics may target either Nrf2 or MT to prevent chronic IH-induced cardiomyopathy.

Implantable cardioverter-defibrillator-computed respiratory disturbance index accurately identifies severe sleep apnea: The DASAP-HF study

BACKGROUND

Sleep apnea (SA) is a relevant issue in the management of patients with heart failure for risk stratification and for implementing treatment strategies.

OBJECTIVE

The purpose of this study was to evaluate in patients with implantable cardioverter-defibrillators (ICDs) the performance of the respiratory disturbance index (RDI) computed by the ApneaScan algorithm (Boston Scientific Inc., Natick, MA) as a discriminator of severe SA.

METHODS

ICD-indicated patients with left ventricular ejection fraction ≤35% were enrolled. One month after implantation, patients underwent a polysomnographic study. We evaluated the accuracy of the RDI for the prediction of severe SA (apnea-hypopnea index [AHI] ≥30 episodes/h) and the agreement between RDI and AHI during the sleep study night.

RESULTS

Two hundred sixty-five patients were enrolled to obtain the required sample of 173 patients with AHI and RDI data for analysis. The mean AHI was 21 ± 15 episodes/h and severe SA was diagnosed in 38 patients (22%), while the mean RDI was 33 ± 13 episodes/h. On the basis of the receiver operating characteristic curve analysis of RDI values, the area under the curve was 0.77 (95% confidence interval [CI] 0.70-0.83; P < .001). At an RDI value of 31 episodes/h, severe SA was detected with 87% (95% CI 72%-96%) sensitivity and 56% (95% CI 48%-66%) specificity. RDI closely correlated with AHI recorded during the same night (r = 0.74; 95% CI 0.57-0.84; P < .001), and the Bland-Altman agreement analysis revealed a bias of 11 episodes/h, with limits of agreement being -10 to 32 episodes/h.

CONCLUSION

The RDI accurately identified severe SA and demonstrated good agreement with AHI. Therefore, it may serve as an efficient tool for screening patients at risk of SA.

Predominant obstructive or central sleep apnea in patients with atrial fibrillation: influence of characterizing apneas versus apneas and hypopneas

OBJECTIVE/BACKGROUND

Sleep-disordered breathing (SDB) is common in patients with atrial fibrillation (Afib). Although a high proportion of respiratory events are hypopneas, previous studies have only used apneas to differentiate obstructive (OSA) from central (CSA) sleep apnea. This study investigated the impact of using apneas and hypopneas versus apneas only to define the predominant type of SDB in Afib patients with preserved ejection fraction.

PATIENTS/METHODS

This retrospective analysis was based on high-quality cardiorespiratory polygraphy (PG) recordings (07/2007-03/2016) that were re-analyzed using 2012 American Academy of Sleep Medicine criteria, with differentiation of apneas and hypopneas as obstructive or central. Classification of predominant (>50% of events) OSA and CSA was defined based on apneas only (OSA_AI and CSA_AI) or apneas and hypopneas (OSA_AHI and CSA_AHI). SDB was defined as an apnea-hypopnea index ≥5/h.

RESULTS

A total of 211 patients were included (146 male, age 68.7 ± 8.5 y). Hypopneas accounted for >50% of all respiratory events. Based on apneas only, 46% of patients had predominant OSA and 44% had predominant CSA. Based on apneas and hypopneas, the proportion of patients with OSA was higher (56%) and that with CSA was lower (36%). In the subgroup of patients with moderate to severe SDB (AHI ≥ 15/h), the proportion with predominant CSA was 55.2% based on apneas only versus 42.1% with apneas and hypopneas.

CONCLUSIONS

In hospitalized patients with Afib and SDB, use of apneas and hypopneas versus apneas alone had an important influence on the proportion of patients classified as having predominant OSA or CSA.

Treatment of Obstructive Sleep Apnea: Choosing the Best Positive Airway Pressure Device

Positive airway pressure (PAP) remains primary therapy for most patients with obstructive sleep apnea (OSA). CPAP, APAP, and BPAP are all reasonable therapies that can be used for patients with uncomplicated OSA across the spectrum of disease severity. BPAP should be considered for patients who are nonadherent to CPAP or APAP therapy because of pressure intolerance. Several additional factors should be considered when choosing the type of PAP device for a given patient, including associated symptoms and comorbid medical problems, cost, access to online data management and patient portals, and the portability for the device for patients who travel frequently.

Sleep, sleep apnea and atrial fibrillation: Questions and answers

Sleep apnea (SA) is a common sleep disorder increasingly recognized as a risk for cardiovascular disease. Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with significant morbidity and mortality. An increasing number of investigations in recent years have linked SA to AF. In this review, we aim to provide a critical overview of the existing evidence in a question and answer format by addressing the following: What is the prevalent association between the two conditions (separating nocturnally detected AF episodes from AF as a prevalent condition)? Is SA a risk factor for incident AF? Is SA a risk factor for recurrence of AF following cardioversion/catheter-based ablation? What is the association between SA and AF in patients with heart failure? Are there signature electrocardiographic markers of AF found in patients with SA? Are there electrophysiology-based studies supporting the link between SA and AF? What other sleep characteristics (beyond SA) are found in patients with AF? What is the impact of SA treatment on AF? What is the effect of AF treatment on sleep? Finally, we address unsolved questions and suggest future directions to enhance our understanding of the AF-SA relationship.

Stratification of cardiovascular risk in patients with atrial fibrillation and obstructive sleep apnea-validity of the 2MACE score

BACKGROUND

Risk stratification in patients with atrial fibrillation (AF) is critically important because this group is at high risk of mortality and morbidity. One of the comorbidities potentially affecting thromboembolic and total cardiovascular risk is obstructive sleep apnea (OSA). The aim of this study was to determine whether or not patients with atrial fibrillation and concomitant obstructive sleep apnea have a higher predicted cardiovascular risk than those without sleep-disordered breathing.

METHODS

The study was designed to be a cross-sectional observational study. Consecutive patients with primary diagnosis of AF who qualified for first-ever catheter ablation between 2011 and 2013 were enrolled. All patients had an overnight polysomnography performed for the diagnosis of OSA and calculation of a 2MACE score-a cardiovascular risk assessment score for AF.

RESULTS

We studied 211 AF patients (mean age 57.1 ± 10.2 years, 62.6% males). OSA with apnea-hypopnea index (AHI) ≥15/h was found in 48 patients (22.7%). Cardiovascular disease and risk factors were as follows: 8 (3.8%) patients had congestive heart failure, 27 (12.8%) diabetes, 16 (7.6%) history of stroke or thromboembolic disease, 194 (91.9%) arterial hypertension, 24 (11.4%) vascular disease, and 31 (14.7%) were current smokers. A significantly higher percentage of patients with OSA was at high risk of cardiovascular disease (29.2 vs. 8.1%; p < 0.0001). The trend remained significant in different categories of obstructive sleep apnea when categorized by AHI into non-OSA, and mild, moderate, and severe OSA. Similarly, the mean 2MACE score was statistically significantly higher in OSA than non-OSA patients (2.1 ± 1.1 vs. 1.4 ± 1.0; p < 0.0001).

CONCLUSION

OSA prevalence is increased in AF patients and is associated with an increase 2MACE score-an indicator of major cardiovascular events. There is a linear relationship between severity of OSA and increasing 2MACE scores, indicating increasing cardiovascular risk related to OSA severity.

Pathway for the Management of Sleep Apnea in the Cardiac Patient

Sleep-disordered breathing is a highly prevalent medical condition, which if undiagnosed leads to increased morbidity and mortality, particularly related to increased incidence of cardiovascular events. It is therefore imperative that we identify patient population at high risk for sleep apnea and refer them to the appropriate therapy as early as possible. Up-to-date there is no management guideline specifically geared towards cardiac patients. Thus, we propose a (SAP) Sleep Apnea Pathway to correctly identify and triage these patients to the appropriate therapy.

Atrial Fibrillation Ablation

The prevalence of atrial fibrillation (AF) has risen significantly over the past two decades. Catheter ablation is an increasingly utilized treatment strategy and has evolved significantly over the same time period. Successful ablation improves patient symptoms, reduces stroke risk, and can preserve or improve cardiac function. Recurrences following ablation can occur, particularly in patients with persistent AF. Procedural efficacy can best be improved through continued advancements in ablation technology and strategy, better understanding of the mechanisms of AF initiation and perpetuation, and rigorous integration of ablation into a multidisciplinary AF management approach.

Atrial fibrillation and psychological factors: a systematic review

BACKGROUND

Psychological factors have been suggested to have an influence in Atrial Fibrillation (AF) onset, progression, severity and outcomes, but their role is unclear and mainly focused on anxiety and depression.

METHODS

A systematic electronic search had been conducted to identify studies exploring different psychological factors in AF. The search retrieved 832 articles that were reviewed according to inclusion criteria: observational study with a control/comparison group; use of standardized and validated instruments for psychological assessment. Results were summarized qualitatively and quantitatively by effect size measure (Cohen's d and its 95% confidence interval). Cochrane Collaboration guidelines and the PRISMA Statement were adopted.

RESULTS

Eight studies were included in the systematic review. Depression was the most studied construct/ but only one study showed a clear link with AF. The remaining studies showed small and non-significant (95% CI [-0.25-1.00]) differences between AF and controls, no differences in frequency of depression history (95% CI [-0.14-0.22]) or in case frequency (95% CI [-0.50-0.04]). Miscellaneous results were found as far as anxiety: AF patients showed higher levels when compared to healthy subjects (95% CI [2.05-2.95]), but findings were inconsistent when compared to other heart diseases. Considering personality and life-events preceding AF, we respectively found a large (95% CI [1.87-2.49]) and a moderate to large effect (95% CI [0.48-0.98]).

DISCUSSION

The small number of studies does not allow to draw clear-cut conclusions on the involvement of psychological factors in AF. Promising lines of research are related to personality and adverse life-events, and to the increase of longitudinal design studies. Some methodological problems could be overcome by including clinical psychologists in the implementation of research protocols.

Variants in angiopoietin-2 (ANGPT2) contribute to variation in nocturnal oxyhaemoglobin saturation level

Genetic determinants of sleep-disordered breathing (SDB), a common set of disorders that contribute to significant cardiovascular and neuropsychiatric morbidity, are not clear. Overnight nocturnal oxygen saturation (SaO2) is a clinically relevant and easily measured indicator of SDB severity but its genetic contribution has never been studied. Our recent study suggests nocturnal SaO2 is heritable. We performed linkage analysis, association analysis and haplotype analysis of average nocturnal oxyhaemoglobin saturation in participants in the Cleveland Family Study (CFS), followed by gene-based association and additional tests in four independent samples. Linkage analysis identified a peak (LOD = 4.29) on chromosome 8p23. Follow-up association analysis identified two haplotypes in angiopoietin-2 (ANGPT2) that significantly contributed to the variation of SaO2 (P = 8 × 10-5) and accounted for a portion of the linkage evidence. Gene-based association analysis replicated the association of ANGPT2 and nocturnal SaO2. A rare missense SNP rs200291021 in ANGPT2 was associated with serum angiopoietin-2 level (P = 1.29 × 10-4), which was associated with SaO2 (P = 0.002). Our study provides the first evidence for the association of ANGPT2, a gene previously implicated in acute lung injury syndromes, with nocturnal SaO2, suggesting that this gene has a broad range of effects on gas exchange, including influencing oxygenation during sleep.

Progression and reversibility of stretch induced atrial remodeling: Characterization and clinical implications

Atrial fibrillation (AF) is the most common sustained arrhythmia and across the developed nations, it contributes to increasing hospitalizations and healthcare burden. Several comorbidities and risk factors including hypertension, heart failure, obstructive sleep apnoea and obesity are known to play an important role in the initiation and perpetuation of AF and atrial stretch or dilatation may play a central mechanistic role. The impact of atrial stretch in the development of AF can vary dependent on the underlying disease. This review focuses on understanding the substrate for AF in conditions of acute and chronic stretch and in the presence of common co-morbidities or risk factors through the review of findings in both animal and human studies. Additionally, the reversibility of atrial remodeling following stretch release will also be discussed. Identification of clinical conditions associated with increased atrial stretch as well as the treatment or prevention of these conditions may help to prevent AF progression and improve sinus rhythm maintenance.

Considerations and treatment options for patients with comorbid atrial fibrillation and diabetes mellitus

INTRODUCTION

Atrial fibrillation (AF) and diabetes mellitus (DM) are common worldwide and their incidence is increasing, representing a significant public health and economic burden as well as an increase in individual increased morbidity and mortality risk profiles. Both conditions are closely related, as patients with DM are at increased risk of incident AF, and AF patients with DM are at higher risk of cardiovascular events compared to non-AF patients. Areas covered: This review article aims to provide an overview of the current evidence linking DM and AF, as well as the impact of obesity, weight loss and stroke on these coexisting conditions. Second, the effects of new oral anti hyperglycaemic medications on cardiovascular risk will be considered. Expert opinion: In conclusion, coexisting AF and DM represent a high risk population of patients requiring aggressive risk factor identification and treatment optimisation. The multifactorial interplay between these conditions requires individual assessment of patient risk profiles with the aim of minimising the impact of each modifiable risk factor.

Obstructive and Central Sleep Apnea and the Risk of Incident Atrial Fibrillation in a Community Cohort of Men and Women

BACKGROUND

Previous studies have documented a high prevalence of atrial fibrillation (AF) in individuals with obstructive sleep apnea (OSA). Central sleep apnea (CSA) has been associated with AF in patients with heart failure. However, data from prospective cohorts are sparse and few studies have distinguished the associations of obstructive sleep apnea from CSA with AF in population studies.

METHODS AND RESULTS

We assessed the association of obstructive sleep apnea and CSA with incident AF among 2912 individuals without a history of AF in the SHHS (Sleep Heart Health Study), a prospective, community-based study of existing ("parent") cohort studies designed to evaluate the cardiovascular consequences of sleep disordered breathing. Incident AF was documented by 12-lead ECG or assessed by the parent cohort. obstructive sleep apnea was defined by the obstructive apnea-hypopnea index (OAHI). CSA was defined by a central apnea index ≥5 or the presence of Cheyne Stokes Respiration. Logistic regression was used to assess the association between sleep disordered breathing and incident AF. Over a mean of 5.3 years of follow-up, 338 cases of incident AF were observed. CSA was a predictor of incident AF in all adjusted models and was associated with 2- to 3-fold increased odds of developing AF (central apnea index ≥5 odds ratio [OR], 3.00, 1.40-6.44; Cheyne-Stokes respiration OR, 1.83, 0.95-3.54; CSA or Cheyne-Stokes respiration OR, 2.00, 1.16-3.44). In contrast, OAHI was not associated with incident AF (OAHI per 5 unit increase OR, 0.97, 0.91-1.03; OAHI 5 to <15 OR, 0.84, 0.59-1.17; OAHI 15 to <30 OR, 0.93, 0.60-1.45; OAHI ≥30 OR, 0.76, 0.42-1.36).

CONCLUSIONS

In a prospective, community-based cohort, CSA was associated with incident AF, even after adjustment for cardiovascular risk factors.

Recognition and treatment of sleep-disordered breathing: an important component of chronic disease management

Sleep-disordered breathing (SDB) is a highly prevalent condition, and is associated with many debilitating chronic diseases. The role of untreated obstructive sleep apnea (OSA) in arterial hypertension has been recognized in international guidelines. Treatment with continuous positive airway pressure (CPAP) is associated with clinically-relevant reductions in blood pressure. In heart failure (HF), SDB is associated with worse prognosis and increased mortality. Major HF guidelines recommend that patients should be treated for sleep apnea to improve their HF status. Severe OSA increases the risk of arrhythmias, including atrial fibrillation, influences risk management in stroke, and is highly prevalent in patients with type 2 diabetes. Effective treatment with CPAP improves the success of antiarrhythmic interventions, improves outcomes in stroke and reduces hyperglycemia in diabetes. Patients with coronary artery disease also have a high prevalence of SDB, which is independently associated with worse outcomes. The role of CPAP for secondary cardiovascular prevention remains to be determined. Data from large, well-conducted clinical trials have shown that noninvasive ventilation, targeted to markedly reduce hypercapnia, significantly improves survival and reduces readmission in stable hypercapnic chronic obstructive pulmonary disease. The association of SDB with chronic diseases contributes to the high healthcare costs incurred by SDB patients. SDB also has an important negative impact on quality of life, which is reversed by CPAP treatment. The high prevalence of SDB, and its association with diseases that cause significant morbidity and mortality, suggest that the diagnosis and management of SDB is an important therapeutic goal. First, adherent CPAP treatment significantly improves the quality of life of all patients with SDB; second, it eliminates the negative impact of untreated SDB on any associated chronic diseases; and third, it significantly reduces the increased costs of all hospital and medical services directly associated with untreated SDB. In short, the recognition and treatment of SDB is vital for the continued health and wellbeing of individual patients with SDB.

Nocturnal Desaturation is Associated With Atrial Fibrillation in Patients With Ischemic Stroke and Obstructive Sleep Apnea

STUDY OBJECTIVES

Both atrial fibrillation (AF) and obstructive sleep apnea (OSA) are risk factors for ischemic stroke. Previous studies suggested that OSA is associated with AF in individuals who have not had a stroke. For better secondary prevention of stroke, this study determined the association between OSA and AF among patients with ischemic stroke.

METHODS

This cross-sectional study recruited consecutive patients with subacute ischemic stroke admitted for neurorehabilitation. The baseline and clinical data were collected, and standard polysomnography was performed in a sleep center.

RESULTS

The 47 women and 111 men enrolled in this study were divided into two groups according to the presence of AF. The AF group (n = 26) had a significantly older age (72.2 versus 60.1 years, P = .016), significantly more disability (Barthel index: 35 versus 45, P = .045), and marginally higher mean oxygen desaturation (6.7% versus 5.6%, P = .079) compared to the non-AF group. The two groups did not significantly differ in sex, body mass index, prevalence of hyperthyroidism, and other parameters of OSA. The multivariate logistic regression analysis revealed that mean desaturation was significantly associated with AF after adjusting for age, neck circumference, Barthel index and high-density lipoprotein level (odds ratio = 1.19 (95% confidence interval 1.05-1.35), P = .008).

CONCLUSIONS

Nocturnal hypoxia due to OSA is an independent predictor of AF in patients with subacute ischemic stroke. The use of overnight pulse oximeter to assess nocturnal hypoxia and predict paroxysmal AF in patients with cryptogenic stroke needs further evaluation.

COMMENTARY

A commentary on this article appears in this issue on page 667.

Management of Obstructive Sleep Apnea in Commercial Motor Vehicle Operators: Recommendations of the AASM Sleep and Transportation Safety Awareness Task Force

ABSTRACT

The American Academy of Sleep Medicine Sleep and Transportation Safety Awareness Task Force responded to the Federal Motor Carrier Safety Administration and Federal Railroad Administration Advance Notice of Proposed Rulemaking and request for public comments regarding the evaluation of safety-sensitive personnel for moderate-to-severe obstructive sleep apnea (OSA). The following document represents this response. The most salient points provided in our comments are that (1) moderate-to-severe OSA is common among commercial motor vehicle operators (CMVOs) and contributes to an increased risk of crashes; (2) objective screening methods are available and preferred for identifying at-risk drivers, with the most commonly used indicator being body mass index; (3) treatment in the form of continuous positive airway pressure (CPAP) is effective and reduces crashes; (4) CPAP is economically viable; (5) guidelines are available to assist medical examiners in determining whether CMVOs with moderate-to-severe OSA should continue to work without restrictions, with conditional certification, or be disqualified from operating commercial motor vehicles.

Relations of Liver Fat With Prevalent and Incident Atrial Fibrillation in the Framingham Heart Study

Background

Obesity is an important risk factor for nonalcoholic fatty liver disease and atrial fibrillation (AF). Less is known about the relations between nonalcoholic fatty liver disease and AF. We sought to evaluate the association between fatty liver and prevalent and incident AF in the community.

Methods and Results

We examined Framingham Heart Study participants who underwent a study‐directed computed tomography scan, had hepatic steatosis (HS) evaluated, and did not report heavy alcohol use between 2002 and 2005. We evaluated cross‐sectional associations between liver fat and prevalent AF with logistic regression models. We assessed the relations between liver fat and incident AF during 12‐year follow‐up with Cox proportional hazards models. Of 2122 participants (53% women; mean age, 59.0±9.6 years), 20% had HS. AF prevalence (n=62) among individuals with HS was 4% compared to 3% among those without HS. There was no significant association between HS (measured as continuous or dichotomous variables) and prevalent AF in age‐ and sex‐adjusted or multivariable‐adjusted models. Incidence of AF (n=153) among participants with and without HS was 8.7 cases and 7.8 cases per 1000 person‐years, respectively. In age‐ and sex‐adjusted and multivariable‐adjusted models, there were no significant associations between continuous or dichotomous measures of HS and incident AF.

Conclusions

In our community‐based, longitudinal cohort study, liver fat by computed tomography scan was not significantly associated with increased prevalence or incidence of AF over 12 years of follow‐up.

Relation of Obstructive Sleep Apnea and a Common Variant at Chromosome 4q25 to Atrial Fibrillation

Obstructive sleep apnea (OSA) and single nucleotide polymorphisms (SNPs) at the 4q25 locus are associated with increased risk of atrial fibrillation (AF). Whether these associations are independent of traditional risk factors for AF remains unknown. Using billing code queries and manual chart review, we assembled a cohort of adults that underwent overnight polysomnography and at least 1 12-lead electrocardiogram. Case status was defined by electrocardiographic data in support of AF or documentation of AF by a staff cardiologist. Controls were defined by a lack of primary evidence of AF and absence of a diagnosis of AF in the medical record. OSA severity was categorized based on Apnea-Hypopnea Index. Genotyping for a key 4q25 SNP (rs2200733) was performed using the Sequenom platform. Logistic regression was used to test for associations of AF with OSA category and 4q25 SNP genotype while adjusting for age, gender, body mass index, ancestry, hypertension status, and heart failure status. The cohort consisted of 674 subjects (62 ± 13 years; 44% women), including 132 patients with AF. After adjustment for established risk factors, the association between AF and OSA severity was borderline significant (odds ratio 1.2, 95% CI 1.0 to 1.5). The association between AF and 4q25 SNP status remained significant in a fully adjusted model that included OSA severity (odds ratio 1.5, 95% CI 1.3 to 5.7). In conclusion, OSA severity and the chromosome 4q25 SNP genotype were associated with AF status independent of clinical risk factors. Knowledge of AF-related SNPs may enhance AF risk stratification for those undergoing polysomnography.

Atrial Fibrillation: Epidemiology, Pathophysiology, and Clinical Outcomes

The past 3 decades have been characterized by an exponential growth in knowledge and advances in the clinical treatment of atrial fibrillation (AF). It is now known that AF genesis requires a vulnerable atrial substrate and that the formation and composition of this substrate may vary depending on comorbid conditions, genetics, sex, and other factors. Population-based studies have identified numerous factors that modify the atrial substrate and increase AF susceptibility. To date, genetic studies have reported 17 independent signals for AF at 14 genomic regions. Studies have established that advanced age, male sex, and European ancestry are prominent AF risk factors. Other modifiable risk factors include sedentary lifestyle, smoking, obesity, diabetes mellitus, obstructive sleep apnea, and elevated blood pressure predispose to AF, and each factor has been shown to induce structural and electric remodeling of the atria. Both heart failure and myocardial infarction increase risk of AF and vice versa creating a feed-forward loop that increases mortality. Other cardiovascular outcomes attributed to AF, including stroke and thromboembolism, are well established, and epidemiology studies have championed therapeutics that mitigate these adverse outcomes. However, the role of anticoagulation for preventing dementia attributed to AF is less established. Our review is a comprehensive examination of the epidemiological data associating unmodifiable and modifiable risk factors for AF and of the pathophysiological evidence supporting the mechanistic link between each risk factor and AF genesis. Our review also critically examines the epidemiological data on clinical outcomes attributed to AF and summarizes current evidence linking each outcome with AF.

[Continuous positive airway pressure in obstructive sleep apnea]

Continuous positive airway pressure (CPAP) is currently the most used and efficient therapy in OSAS. Efficiency of CPAP on sleep respiratory disorders is the same whether in fixed or automatic mode. Larger studies are required to evaluate their respective beneficial impact on cardiovascular or metabolic complications of OSAS. Close medical monitoring is necessary during the first weeks of CPAP therapy. Compliance to CPAP therapy is crucial for efficacy in preventing cardiovascular or metabolic complications of OSAS. As beneficial effects of CPAP in obese patients are modest, on blood pressure levels and metabolic disorders, its use has to be part of a comprehensive care of OSAS and related comorbidities.

Development, Validation, and Assessment of an Ischemic Stroke or Transient Ischemic Attack-Specific Prediction Tool for Obstructive Sleep Apnea

BACKGROUND

Screening instruments for obstructive sleep apnea (OSA), as used routinely to guide clinicians regarding patient referral for polysomnography (PSG), rely heavily on symptomatology. We sought to develop and validate a cerebrovascular disease-specific OSA prediction model less reliant on symptomatology, and to compare its performance with commonly used screening instruments within a population with ischemic stroke or transient ischemic attack (TIA).

METHODS

Using data on demographic factors, anthropometric measurements, medical history, stroke severity, sleep questionnaires, and PSG from 2 independently derived, multisite, randomized trials that enrolled patients with stroke or TIA, we developed and validated a model to predict the presence of OSA (i.e., Apnea-Hypopnea Index ≥5 events per hour). Model performance was compared with that of the Berlin Questionnaire, Epworth Sleepiness Scale (ESS), the Snoring, Tiredness, Observed apnea, high blood Pressure, Body mass index, Age, Neck circumference, and Gender instrument, and the Sleep Apnea Clinical Score.

RESULTS

The new SLEEP Inventory (Sex, Left heart failure, ESS, Enlarged neck, weight [in Pounds], Insulin resistance/diabetes, and National Institutes of Health Stroke Scale) performed modestly better than other instruments in identifying patients with OSA, showing reasonable discrimination in the development (c-statistic .732) and validation (c-statistic .731) study populations, and having the highest negative predictive value of all in struments.

CONCLUSIONS

Clinicians should be aware of these limitations in OSA screening instruments when making decisions about referral for PSG. The high negative predictive value of the SLEEP INventory may be useful in determining and prioritizing patients with stroke or TIA least in need of overnight PSG.

Blood Pressure and Metabolic Changes After 3-Month CPAP Therapy in a Very Elderly Obese with Severe Obstructive Sleep Apnea: A Case Report and Review of the Literature

Age is one of the main risk factor for the presence of obstructive sleep apnea (OSA). This syndrome is associated with hypertension, cardiovascular disease, cognitive impairment and metabolic abnormalities, such as type 2 diabetes. Continuous positive airway pressure (CPAP) represents the gold standard therapy, but its benefit is still to be determined in very elderly. We report the blood pressure and metabolic changes in a very elderly obese with severe OSA after 3-month CPAP therapy. We have evaluated a very elderly obese male affected by severe symptomatic OSA, poor controlled nocturnal hypertension and insulin resistance. After 3-month CPAP therapy, without any changes in drug therapy, we observed a normalization of circadian blood pressure (BP) pattern, an improved insulin sensitivity, together with a reduced resting energy expenditure, despite no significant change in weight. This case report shows the benefits of OSA treatment with CPAP, not only on BP profile, but also on metabolic parameters in a very elderly, a particular type of patient in which scientific evidence is still scant. Further studies are needed to better investigate the relationship between OSA, CPAP therapy and energy expenditure not only in adults but also in elderly patients.

A Practical Approach to the Identification and Management of Sleep-Disordered Breathing in Heart Failure Patients

Sleep-disordered breathing (SDB) is a major health problem affecting much of the general population. Although SDB is responsible for rapid progression of heart failure (HF) and the worsening morbidity and mortality, advanced HF state is associated with accelerated development of SDB. In the face of recent developments in SDB treatment and availability of effective therapeutic options known to improve quality of life, exercise tolerance, and heart function, most HF patients with SDB are left unrecognized and untreated. This article provides an overview of SDB in HF with focus on practical approaches intended to facilitate screening and treatment.

Sleep-Disordered Breathing and Arrhythmia in Heart Failure Patients

Heart failure (HF) treatment remains complex and challenging, with current recommendations aiming at consideration and treatment of comorbidities in patients with HF. Sleep-disordered breathing (SDB) and arrhythmia come into play, as both are associated with quality of life deterioration, and morbidity and mortality increase in patients with HF. Interactions of these diseases are versatile and may appear intransparent in daily practice. Nevertheless, because of their importance for patients' condition and prognosis, SDB and arrhythmia individually, but also through interaction on one another, necessitate attention, following the fact that treatment is requested and desired considering latest research findings and outcomes.

Atrial fibrillation among patients under investigation for suspected obstructive sleep apnea

Study objectives

Obstructive sleep apnea is common among patients with atrial fibrillation, but the prevalence and risk factors for atrial fibrillation among patients who are being investigated on suspicion of sleep apnea are not well known. The aim of the study was to estimate the prevalence of atrial fibrillation among patients investigated for suspected obstructive sleep apnea and to identify risk factors for atrial fibrillation among them.

Methods

The prevalence of atrial fibrillation was investigated among 201 patients referred for suspected obstructive sleep apnea. Patients without known atrial fibrillation were investigated with a standard 12-lead ECG at hospital and short intermittent handheld ECG recordings at home, during 14 days.

Results

Atrial fibrillation occurred in 13 of 201 subjects (6.5%), and in 12 of 61 men aged 60 years and older (20%). The prevalence of atrial fibrillation increased with sleep apnea severity (p = 0.038). All patients with atrial fibrillation were men and all had sleep apnea. Age 60 or older, the occurrence of central sleep apnea and diabetes mellitus were independent risk factors for atrial fibrillation after adjustments for body mass index, gender, sleep apnea and cardiovascular disease.

Conclusions

Atrial fibrillation is common among subjects referred for sleep apnea investigation and the prevalence of atrial fibrillation increases with sleep apnea severity. Independent risk factors for atrial fibrillation among patients investigated for suspected obstructive sleep apnea include the occurrence of coexisting central sleep apnea, age 60 years or older and diabetes mellitus.

A Comparison of Different Success Definitions in Non-Continuous Positive Airway Pressure Treatment for Obstructive Sleep Apnea Using Cardiopulmonary Coupling

STUDY OBJECTIVES

The definition and the criteria for the successful treatment of obstructive sleep apnea vary, depending on the study. This study aimed to compare different success criteria of non-continuous positive airway pressure (non-CPAP) treatment for obstructive sleep apnea in terms of sleep quality by using cardiopulmonary coupling.

METHODS

We included 98 patients who had been treated with sleep surgery or with a mandibular advancement device at our sleep clinic from January 2011 to March 2013. The success and failure groups were divided by 6 criteria that have been used in the literature. The validity of each of the 6 criteria was evaluated by cardiopulmonary coupling-based sleep quality.

RESULTS

The parameters of cardiopulmonary coupling indicated that sleep quality improved with non-CPAP treatment: low-frequency coupling decreased from 57.4% ± 17.7% to 46.9% ± 16.5%, whereas high-frequency coupling increased from 30.2% ± 17.1% to 37.4% ± 16.7%. In multiple regression analysis, only the criterion of a reduction in the apnea-hypopnea index greater than 50% was significantly associated with sleep quality improvement (p = 0.016; 95% confidence interval, 1.008-1.076 in the high-frequency coupling increment; p = 0.001; 95% confidence interval, 1.025-1.099 in the low-frequency coupling decrement).

CONCLUSIONS

Cardiopulmonary coupling analysis showed that a reduction in the apnea-hypopnea index of more than 50% might be the optimal criterion to determine the success or failure of non-CPAP treatment in terms of sleep quality.

[Obstructive sleep apnea syndrome. Diagnostic strategies in various clinical settings]

Obstructive Sleep Apnea Syndrome (OSAS) is a common disease, whose prevalence and expression may vary depending on the associated pathology, age or gender. Thus, the prevalence of OSAS is up to 80% in case of refractory hypertension. This led up to individualize clinical presentation of clusters, although currently, the individualization of these different phenotypes did not conduct to a specific care or predict different evolution. Offering the best strategy for the right patient remains an important objective. However, the frequent association of OSAS and various metabolic diseases, and thus induced cardiovascular risk factors, is to be considered in the therapeutic care and judgment of the response to established treatments. By acting on all components in pathological cause in these patients with OSAS, a combined support will thus permit optimal beneficial effect.