Obstructive Sleep Apnea and its Relationship to Cardiac Arrhythmias

Assessment of Nocturnal Autonomic Cardiac Imbalance in Positional Obstructive Sleep Apnea. A Multiscale Nonlinear Approach

Positional obstructive sleep apnea (POSA) is a major phenotype of sleep apnea. Supine-predominant positional patients are frequently characterized by milder symptoms and less comorbidity due to a lower age, body mass index, and overall apnea-hypopnea index. However, the bradycardia-tachycardia pattern during apneic events is known to be more severe in the supine position, which could affect the cardiac regulation of positional patients. This study aims at characterizing nocturnal heart rate modulation in the presence of POSA in order to assess potential differences between positional and non-positional patients. Patients showing clinical symptoms of suffering from a sleep-related breathing disorder performed unsupervised portable polysomnography (PSG) and simultaneous nocturnal pulse oximetry (NPO) at home. Positional patients were identified according to the Amsterdam POSA classification (APOC) criteria. Pulse rate variability (PRV) recordings from the NPO readings were used to assess overnight cardiac modulation. Conventional cardiac indexes in the time and frequency domains were computed. Additionally, multiscale entropy (MSE) was used to investigate the nonlinear dynamics of the PRV recordings in POSA and non-POSA patients. A total of 129 patients (median age 56.0, interquartile range (IQR) 44.8-63.0 years, median body mass index (BMI) 27.7, IQR 26.0-31.3 kg/m2) were classified as POSA (37 APOC I, 77 APOC II, and 15 APOC III), while 104 subjects (median age 57.5, IQR 49.0-67.0 years, median BMI 29.8, IQR 26.6-34.7 kg/m2) comprised the non-POSA group. Overnight PRV recordings from positional patients showed significantly higher disorderliness than non-positional subjects in the smallest biological scales of the MSE profile (τ = 1: 0.25, IQR 0.20-0.31 vs. 0.22, IQR 0.18-0.27, p < 0.01) (τ = 2: 0.41, IQR 0.34-0.48 vs. 0.37, IQR 0.29-0.42, p < 0.01). According to our findings, nocturnal heart rate regulation is severely affected in POSA patients, suggesting increased cardiac imbalance due to predominant positional apneas.

Contribution of Neurochemical Inputs to the Decrease of Motoneuron Excitability During Non-REM and REM Sleep: A Systematic Review

The sleep-related depression of excitability of upper airway motoneurons is a major neurological cause of obstructive sleep apnea whereas a disruption in the inhibition of spinal motoneurons during rapid eye movement (REM) sleep causes the REM sleep behavioral disorder. The large amount of experimental data has been obtained that deal with neurochemical mechanisms that are responsible for sleep-related depression of various motoneuron groups. However, there is a disagreement regarding the outcome of these studies primarily due to the use of different animal models and approaches, as well as due to differences in quantification and interpretation of obtained results. In this study, we sought to apply the same calculation methodology in order to uniformly quantify and compare the relative contribution of excitatory or inhibitory inputs to the decrease of excitability of different motoneuronal pools during REM and/or non-REM sleep. We analyzed only published quantitative data that were obtained by using receptor antagonists or chemogenetic approach to block receptors or silence neuronal populations. The outcomes of this analysis highlight the differences in the neurotransmitter mechanisms of sleep-related motoneuron depression between different motoneuronal pools and demonstrate the consistency of these mechanisms for hypoglossal motoneurons among various animal models.

Obstructive sleep apnoea-hypopnoea and arrhythmias: new updates

AIMS

Obstructive sleep apnoea-hypopnoea (OSAH) is a prevalent condition characterized by repetitive pharyngeal collapse during sleep, leading to hypoxemia, hypercapnia, and persistent inspiratory efforts against an occluded airway until arousal. Several studies demonstrated that OSAH exerts acute and chronic effects on the cardiovascular system. Thus, although being a respiratory problem, the most important consequences of OSAH are cardiovascular, among which there are arrhythmias. The purpose of this review is to systematically analyse what has been recently published about the relationship between OSAH and every cardiac arrhythmia separately.

METHODS

We searched Pubmed, Scopus, Web of Science and Cochrane Collaboration databases for 'OSAHS arrhythmias', 'OSAH arrhythmias' and 'OSA arrhythmias'. We analyse 1298 articles and meta-analyses, excluding already edited reviews.

RESULTS

Arrhythmias, especially of ventricular origin, are frequent in OSAH. Ventricular premature beats, couplets and ventricular tachycardia runs are even more frequent in patients suffering from heart failure. They may be due to left heart remodelling, overwork and ischaemia and can explain at least some sudden deaths occurring between midnight and 6 a.m. Sinus pauses and atrioventricular blocks are increased according to the severity of the disturbance and may be reduced by continuous positive airway pressure therapy, preventing pace-maker implantation. Finally, atrial fibrillation, resistance against antiarrhythmic drugs and recurrences after surgical procedures are strongly related to OSAH.

CONCLUSION

Arrhythmias are frequent in OSAH. Treatment of OSAH may reduce some of them. An implantable cardioverter-defibrillator and continuous positive airway pressure should be considered in some patients.

Ambulatory positional obstructive sleep apnea syndrome

Objective

To establish the prevalence of positional (PP) OSA patients using self-administered home-based respiratory polygraphy (RP).

Materials and Methods

52 month retrospective study based on RP records.

Results

200 PR records: 70.5% men 29.5% women. 76% were diagnosed with OSA and 54.6% with PP OSA. There were no significant differences in Epworth Sleepiness Scale, apnea hypopnea index and oxygen desaturation index. PP OSA patients were younger, had a lower BMI (30.3±0.9 vs. 35.3±1.2) (p<0.0001), and the time they spent with oxygen saturation <90% (T<90) was lower (8.8 vs. 28.7±6.7, p=0.0038). The PP OSA group spent 43% of total recording time in the supine position.

Conclusions

The prevalence of PP OSA patients studied with RP is similar to the one described by sleep laboratories. They have lower BMI, present mostly mild OSA with less desaturation, and are less likely to receive CPAP therapy.

Atrial fibrillation and sleep-disordered breathing

Atrial fibrillation (AF) is a common supraventricular arrhythmia that increases in prevalence with increasing age and in the presence of comorbidities such as heart failure (HF). AF increases the risk of a number of serious complications, including stroke and HF. As a result, the rate of hospitalization is high, making AF a costly disease. Treatment strategies for AF are broadly based around rate and rhythm control, either pharmacological or mechanical. There appear to be a number of links between sleep-disordered breathing (SDB) and AF, although further studies are needed to fully understand the physiological mechanisms that link these conditions. Patients with AF and SDB share a number of risk factors and comorbidities, including age, male sex, hypertension, congestive HF and coronary artery disease (CAD), and the prevalence of SDB in AF is higher than in the general population. Prevalence rates of obstructive sleep apnea (OSA) in patients with AF have been reported to range from 21% to just over 80%. The prevalence of central sleep apnea (CSA) in patients with AF is less well defined, but appears to be particularly high in patients who also have HF and a reduced left ventricular ejection fraction (LVEF). The frequency of apneas can be reduced by effective treatment of AF, while co-existing OSA reduces the effectiveness of treatments for AF and there is an increased risk of arrhythmia recurrence in the presence of SDB. Treating OSA with continuous positive airway pressure (CPAP) therapy has shown the potential to decrease the incidence of AF, improve the effectiveness of AF interventions, and decrease the risk of arrhythmia recurrence, although data from large randomized, controlled clinical trials are lacking. Based on available data, inclusion of SDB recognition and management strategies as part of AF management appears to have the potential to reduce the impact of this arrhythmia at both the individual and societal levels, and has been recognized as important in recent guidelines.

Revisiting Antagonist Effects in Hypoglossal Nucleus: Brainstem Circuit for the State-Dependent Control of Hypoglossal Motoneurons: A Hypothesis

We reassessed and provided new insights into the findings that were obtained in our previous experiments that employed the injections of combined adrenergic, serotonergic, GABAergic, and glycinergic antagonists into the hypoglossal nucleus in order to pharmacologically abolish the depression of hypoglossal nerve activity that occurred during carbachol-induced rapid-eye-movement (REM) sleep-like state in anesthetized rats. We concluded that noradrenergic disfacilitation is the major mechanism that is responsible for approximately 90% of the depression of hypoglossal motoneurons, whereas the remaining 10% can be explained by serotonergic mechanisms that have net inhibitory effect on hypoglossal nerve activity during REM sleep-like state. We hypothesized that both noradrenergic and serotonergic state-dependent mechanisms indirectly control hypoglossal motoneuron excitability during REM sleep; their activities are integrated and mediated to hypoglossal motoneurons by reticular formation neurons. In addition, we proposed a brainstem neural circuit that can explain the new findings.

Clinical effectiveness and cost-effectiveness results from the randomised controlled Trial of Oral Mandibular Advancement Devices for Obstructive sleep apnoea-hypopnoea (TOMADO) and long-term economic analysis of oral devices and continuous positive airway pressure

BACKGROUND

Obstructive sleep apnoea-hypopnoea (OSAH) causes excessive daytime sleepiness (EDS), impairs quality of life (QoL) and increases cardiovascular disease and road traffic accident risks. Continuous positive airway pressure (CPAP) treatment is clinically effective but undermined by intolerance, and its cost-effectiveness is borderline in milder cases. Mandibular advancement devices (MADs) are another option, but evidence is lacking regarding their clinical effectiveness and cost-effectiveness in milder disease.

OBJECTIVES

(1) Conduct a randomised controlled trial (RCT) examining the clinical effectiveness and cost-effectiveness of MADs against no treatment in mild to moderate OSAH. (2) Update systematic reviews and an existing health economic decision model with data from the Trial of Oral Mandibular Advancement Devices for Obstructive sleep apnoea-hypopnoea (TOMADO) and newly published results to better inform long-term clinical effectiveness and cost-effectiveness of MADs and CPAP in mild to moderate OSAH.

TOMADO

A crossover RCT comparing clinical effectiveness and cost-effectiveness of three MADs: self-moulded [SleepPro 1™ (SP1); Meditas Ltd, Winchester, UK]; semibespoke [SleepPro 2™ (SP2); Meditas Ltd, Winchester, UK]; and fully bespoke [bespoke MAD (bMAD); NHS Oral-Maxillofacial Laboratory, Addenbrooke's Hospital, Cambridge, UK] against no treatment, in 90 adults with mild to moderate OSAH. All devices improved primary outcome [apnoea-hypopnoea index (AHI)] compared with no treatment: relative risk 0.74 [95% confidence interval (CI) 0.62 to 0.89] for SP1; relative risk 0.67 (95% CI 0.59 to 0.76) for SP2; and relative risk 0.64 (95% CI 0.55 to 0.76) for bMAD (p < 0.001). Differences between MADs were not significant. Sleepiness [as measured by the Epworth Sleepiness Scale (ESS)] was scored 1.51 [95% CI 0.73 to 2.29 (SP1)] to 2.37 [95% CI 1.53 to 3.22 (bMAD)] lower than no treatment (p < 0.001), with SP2 and bMAD significantly better than SP1. All MADs improved disease-specific QoL. Compliance was lower for SP1, which was unpopular at trial exit. At 4 weeks, all devices were cost-effective at £20,000/quality-adjusted life-year (QALY), with SP2 the best value below £39,800/QALY.

META-ANALYSIS

A MEDLINE, EMBASE and Science Citation Index search updating two existing systematic reviews (one from November 2006 and the other from June 2008) to August 2013 identified 77 RCTs in adult OSAH patients comparing MAD with conservative management (CM), MADs with CPAP or CPAP with CM. MADs and CPAP significantly improved AHI [MAD -9.3/hour (p < 0.001); CPAP -25.4/hour (p < 0.001)]. Effect difference between CPAP and MADs was 7.0/hour (p < 0.001), favouring CPAP. No trials compared CPAP with MADs in mild OSAH. MAD and CPAP reduced the ESS score similarly [MAD 1.6 (p < 0.001); CPAP 1.6 (p < 0.001)].

LONG-TERM COST-EFFECTIVENESS

An existing model assessed lifetime cost-utility of MAD and CPAP in mild to moderate OSAH, using the revised meta-analysis to update input values. The TOMADO provided utility estimates, mapping ESS score to European Quality of Life-5 Dimensions three-level version for device cost-utility. Using SP2 as the standard device, MADs produced higher mean costs and mean QALYs than CM [incremental cost-effectiveness ratio (ICER) £6687/QALY]. From a willingness to pay (WTP) of £15,367/QALY, CPAP is cost-effective, although the likelihood of MADs (p = 0.48) and CPAP (p = 0.49) being cost-effective is very similar. Both were better than CM, but there was much uncertainty in the choice between CPAP and MAD (at a WTP £20,000/QALY, the probability of being the most cost-effective was 47% for MAD and 52% for CPAP). When SP2 lifespan increased to 18 months, the ICER for CPAP compared with MAD became £44,066. The ICER for SP1 compared with CM was £1552, and for bMAD compared with CM the ICER was £13,836. The ICER for CPAP compared with SP1 was £89,182, but CPAP produced lower mean costs and higher mean QALYs than bMAD. Differential compliance rates for CPAP reduces cost-effectiveness so MADs become less costly and more clinically effective with CPAP compliance 90% of SP2.

CONCLUSIONS

Mandibular advancement devices are clinically effective and cost-effective in mild to moderate OSAH. A semi-bespoke MAD is the appropriate first choice in most patients in the short term. Future work should explore whether or not adjustable MADs give additional clinical and cost benefits. Further data on longer-term cardiovascular risk and its risk factors would reduce uncertainty in the health economic model and improve precision of effectiveness estimates.

TRIAL REGISTRATION

This trial is registered as ISRCTN02309506.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 18, No. 67. See the NIHR Journals Library website for further project information.

Rhythm disturbances in childhood obstructive sleep apnea during apnea-hypopnea episodes

BACKGROUND

Obstructive sleep apnoea (OSA) can result in cardiovascular complications. Nocturnal arrhythmias are reported up to 50% of adult OSA patients. Arrhythmias and heart rate variability in children with OSA have not been well studied.

AIMS

We sought to study rhythm disturbances in childhood OSA and also to analyze the relationship of heart rate variability to the severity of OSA in children.

METHODS

In a retrospective cross sectional study, records of children aged < 15 years with history of snoring and suspected OSA, who had undergone polysomnography (PSG) for first time were analyzed. The cardiac rhythm and heart rate variability were studied during PSG.

RESULTS

A total of 124 patients diagnosed with OSA were grouped into mild (n = 52), moderate (n = 30), and severe (n = 42) OSA. During PSG, all had sinus arrhythmias and only three patients had premature atrial contractions (PACs). The standard deviation of heart rate (SD-HR) during rapid eye movement (REM) sleep in severe OSA (9.1 ± 2.4) was significantly higher than SD-HR in mild OSA (7.5 ± 1.3, P < 0.0001). The maximum heart rate (max-HR) during REM-sleep in severe OSA (132.1 ± 22.1) was significantly higher than the max-HR in mild OSA (121.3 ± 12.6 bpm, P = 0.016).

CONCLUSIONS

There was no significant arrhythmia in children with OSA during their sleep. Heart rate variability correlated with the severity of OSA.

[Sleep disordered breathing and nonsustained ventricular tachycardia in patients with chronic heart failure]

BACKGROUND

Patients with chronic heart failure (CHF) have a high incidence of sleep disordered breathing (SDB). It is assumed that patients with the combination of CHF and SDB have more ventricular couplets and nonsustained ventricular tachycardia (NSVT) than patients without SDB.

METHODS

In 63 patients, 49 men and 14 women with chronic heart failure (EF < 45%), all-night polysomnography and long-term-ECG were performed. Mean age was 59 ± 15 years, mean BMI 27 ± 5 kg/m(2). 56% had an ischemic, 44% a nonischemic heart disease. 51% had heart insufficiency classification NYHA III.

RESULTS

42 of the 63 patients (67%) had sleep disordered breathing (SDB) with an AHI ≥5/h. In 24 patients (38%) SDB was central, in 18 (29%) obstructive. More patients with SDB than patients without SDB had NSVT (50% vs. 19%). Nocturnal frequency of NSVT in patients with SDB was about twice as high as the rate observed during daytime (0.48/h vs. 0.21/h). In patients without SDB there was no relevant difference between day and night (0.23/h vs. 0.21/h). AHI correlated with NSVT (r = 0.329, p < 0.01). Day/night comparison of couplets was 2.3/h vs. 1.9/h in SDB patients and 2.0/h vs. 1.6/h in patients without SDB.

CONCLUSIONS

Patients with chronic heart failure have a high prevalence of SDB. The combination of CHF and SDB predisposes for nocturnal malignant ventricular arrhythmias.

Obstructive sleep apnea and cardiac arrhythmias

Sleep-disordered breathing (SDB), which includes obstructive sleep apnea (OSA) as its most extreme variant, is characterized by intermittent episodes of partial or complete obstruction of the upper airway, leading to cessation of breathing while asleep. Cardiac arrhythmias are common problems in OSA patients, although the true prevalence and clinical relevance of cardiac arrhythmias remains to be determined. The presence and complexity of tachyarrhythmias and bradyarrhythmias may influence morbidity, mortality and quality of life for patients with OSA. Although the exact mechanisms underlying the link between OSA and cardiac arrhythmias are not well established, they could be some of the same proposed mechanisms relating OSA to different cardiovascular diseases, such as repetitive pharyngeal collapse during sleep, which leads to markedly reduced or absent airflow, followed by oxyhemoglobin desaturation, persistent inspiratory efforts against an occluded airway and termination by arousal from sleep. These mechanisms elicit a variety of autonomic, hemodynamic, humoral and neuroendocrine responses that evoke acute and chronic changes in cardiovascular function. However, despite substantial research effort, the goals of determining in advance which patients will respond most favorably to certain treatment options (such as continuous positive airway pressure, tracheostomy or cardioversion) and the developing alternative treatments remain largely elusive. Therefore, this literature review aims to summarize a broad array of the pathophysiological mechanisms underlying the relationship between OSA and cardiac arrhythmias and the extent of this association from an epidemiological perspective, thereby attempting to assess the effects of OSA treatment on the presence of cardiac arrhythmias.

Light-dark dependence of electrocardiographic changes during asphyxia and reoxygenation in a rat model

The aim of this study was to evaluate the effect of ventilation on electrocardiographic time intervals as a function of the light-dark (LD) cycle in an in vivo rat model. RR, PQ, QT and QTc intervals were measured in female Wistar rats anaesthetized with both ketamine and xylazine (100 mg/15 mg/kg, i.m., open chest experiments) after adaptation to the LD cycle (12:12h) for 4 weeks. Electrocardiograms (ECG) were recorded before surgical interventions; after tracheotomy, and thoracotomy, and 5 minutes of stabilization with artificial ventilation; 30, 60, 90 and 120 seconds after the onset of apnoea; and after 5, 10, 15, and 20 minutes of artificial reoxygenation. Time intervals in intact animals showed significant LD differences, except in the QT interval. The initial significant (p<0,001) LD differences in PQ interval and loss of dependence on LD cycle in the QT interval were preserved during short-term apnoea-induced asphyxia (30–60 sec) In contrast, long-term asphyxia (90–120 sec) eliminated LD dependence in the PQ interval, but significant LD differences were shown in the QT interval. Apnoea completely abolished LD differences in the RR interval. Reoxygenation restored the PQ and QT intervals to the pre-asphyxic LD differences, but with the RR intervals, the LD differences were eliminated. We have concluded that myocardial vulnerability is dependent on the LD cycle and on changes of pulmonary ventilation.

Treatment outcomes of mandibular advancement devices in positional and nonpositional OSA patients

OBJECTIVE

The aim of the study was to investigate treatment outcome of mandibular advancement devices (MADs) for positional and nonpositional obstructive sleep apnea (OSA).

STUDY DESIGN

Forty-two positional (supine apnea-hypopnea index [AHI] > or = 2 times lateral AHI) and 30 nonpositional (supine AHI < 2 times lateral AHI) OSA patients performed 2-nights of sleep study before and after insertion of MADs.

RESULTS

The decreases in apnea severity based on a reduction in the overall and supine AHI values after MADs therapy were significantly greater for the positional OSA than nonpositional OSA group. A multiple linear regression analysis showed that decrease in overall AHI was significantly associated with being in the positional group (standardized coefficient = 0.505). Age, body mass index, gender, and time in supine position during sleep did not show significant associations with decrease in overall AHI after MAD therapy.

CONCLUSION

Our data suggest that MADs are more effective in positional OSA than nonpositional OSA patients.

Cardiorespiratory response to spontaneous cortical arousals during stage 2 and rapid eye movement sleep in healthy children

Arousal from sleep is associated with transient and abrupt cardiorespiratory changes, and elevated arousals associated with sleep disorders may trigger adverse cardiovascular sequela. In this paper, we provide the first data in children on cardiorespiratory responses to cortical arousal. Heart rate and ventilatory responses to arousal from stage 2 and rapid eye movement (REM) sleep were investigated in 40 normal, healthy Caucasian children (age: 7.7 +/- 2.6 years; body mass index z-score: 0.30 +/- 0.8). All children underwent overnight polysomnography studies. Cortical arousals were scored according to standard criteria. Heart rate changes were assessed over 30 s, starting 15 s prior to cortical arousal onset. Breathing rates were quantified three breaths before and after arousal onset. Arousals from stage 2 as well as REM sleep resulted in an R-R interval shortening of about 15%, independent of age and gender. The R-R interval shortening initiated at least 3 s before the cortical arousal onset. The breathing interval immediately after cortical arousal onset was significantly shortened (P < 0.001). In conclusion, cortical arousals in children are associated with an increase in breathing rate and significant heart rate accelerations, which typically precede the cortical arousal onset.

Triggering of nocturnal arrhythmias by sleep-disordered breathing events

OBJECTIVES

This study sought to evaluate respiratory disturbances as potential triggers for arrhythmia in patients with sleep-disordered breathing (SDB).

BACKGROUND

SDB is associated with an increased risk of atrial fibrillation and nonsustained ventricular tachycardia (NSVT) as well as a predilection for sudden cardiac death during nocturnal sleeping hours. However, prior research has not established whether respiratory disturbances operate as triggers for nocturnal arrhythmias.

METHODS

Overnight polysomnograms from the Sleep Heart Health Study (n = 2,816) were screened for paroxysmal atrial fibrillation and NSVT. We used the case-crossover design to determine whether apneas and/or hypopneas are temporally associated with episodes of paroxysmal atrial fibrillation or NSVT. For each arrhythmia, 3 periods of sinus rhythm were identified as control intervals. Polysomnograms were examined for the presence of respiratory disturbances, oxygen desaturations, and cortical arousals within a 90-s hazard period preceding each arrhythmia or control period.

RESULTS

Fifty-seven participants with a wide range of SDB contributed 62 arrhythmias (76% NSVT). The odds of an arrhythmia after a respiratory disturbance were nearly 18 times (odds ratio: 17.5; 95% confidence interval: 5.3 to 58.4) the odds of an arrhythmia occurring after normal breathing. The absolute rate of arrhythmia associated with respiratory disturbances was low (1 excess arrhythmia per 40,000 respiratory disturbances). Neither hypoxia nor electroencephalogram-defined arousals alone increased arrhythmia risk.

CONCLUSIONS

Although the absolute arrhythmia rate is low, the relative risk of paroxysmal atrial fibrillation and NSVT during sleep is markedly increased shortly after a respiratory disturbance. These results support a direct temporal link between SDB events and the development of these arrhythmias.

Nocturnal Arrhythmias across a spectrum of obstructive and central sleep-disordered breathing in older men: outcomes of sleep disorders in older men (MrOS sleep) study

BACKGROUND

Rates of cardiac arrhythmias increase with age and may be associated with clinically significant morbidity. We studied the association between sleep-disordered breathing (SDB) with nocturnal atrial fibrillation or flutter (AF) and complex ventricular ectopy (CVE) in older men.

METHODS

A total of 2911 participants in the Outcomes of Sleep Disorders in Older Men Study underwent unattended polysomnography. Nocturnal AF and CVE were ascertained by electrocardiogram-specific analysis of the polysomnographic data. Exposures were (1) SDB defined by respiratory disturbance index (RDI) quartile (a major index including all apneas and hypopneas), and ancillary definitions incorporating (2) obstructive events, obstructive sleep apnea (OSA; Obstructive Apnea Hypopnea Index quartile), or (3) central events, central sleep apnea (CSA; Central Apnea Index category), and (4) hypoxia (percentage of sleep time with <90% arterial oxygen percent saturation). Multivariable logistic regression analyses were performed.

RESULTS

An increasing RDI quartile was associated with increased odds of AF and CVE (P values for trend, .01 and <.001, respectively). The highest RDI quartile was associated with increased odds of AF (odds ratio [OR], 2.15; 95% confidence interval [CI], 1.19-3.89) and CVE (OR, 1.43; 95% CI, 1.12-1.82) compared with the lowest quartile. An increasing OSA quartile was significantly associated with increasing CVE (P value for trend, .01) but not AF. Central sleep apnea was more strongly associated with AF (OR, 2.69; 95% CI, 1.61-4.47) than CVE (OR, 1.27; 95% CI, 0.97-1.66). Hypoxia level was associated with CVE (P value for trend, <.001); those in the highest hypoxia category had an increased odds of CVE (OR, 1.62; 95% CI, 1.23-2.14) compared with the lowest quartile.

CONCLUSIONS

In this large cohort of older men, increasing severity of SDB was associated with a progressive increase in odds of AF and CVE. When SDB was characterized according to central or obstructive subtypes, CVE was associated most strongly with OSA and hypoxia, whereas AF was most strongly associated with CSA, suggesting that different sleep-related stresses may contribute to atrial and ventricular arrhythmogenesis in older men.

Reimbursed drugs in patients with sleep-disordered breathing: A static-charge-sensitive bed study

BACKGROUND

Co-morbidities in men and women with sleep-disordered breathing (SDB) were compared retrospectively to an age-standardized, general Finnish population. The prevalence of diseases was based on the reimbursement refunds of medications.

METHODS

Two hundred thirty-three age- and BMI-matched male-female pairs and 368 consecutive women identified from our sleep recording database were included. Data on medication were gathered from the National Agency for Medicines and Social Insurance Institution database.

RESULTS

Men with SDB had three-fold prevalence of reimbursed medication for diabetes and two-fold prevalence of reimbursed medication for chronic arrhythmia. Women with SDB had three-fold prevalence of reimbursed medication for thyroid insufficiency, and postmenopausal women had two-fold prevalence of reimbursed medication for psychosis. BMI and age did not explain prevalence of reimbursed medications for chronic arrhythmia or psychosis. In both genders with SDB, prevalence of reimbursed medications compared to the general population was two-fold for hypertension and seven-fold for asthma and/or chronic obstructive pulmonary disease (COPD). Partial upper airway obstruction was associated with three-fold prevalence of reimbursed medication for asthma and/or COPD in both genders and 60% reduced prevalence of reimbursed medication for hypertension in females matched for age and BMI.

CONCLUSIONS

Co-morbidity profile differed between genders. Our results emphasize the importance of diagnosis and treatment of co-morbidities and partial upper airway obstruction.

[Update on arrhythmias and cardiac electrophysiology]

This article contains a review of the most important developments in clinical arrhythmology and interventional cardiac electrophysiology that have been reported during the past year. Special emphasis has been placed on clinical conditions that are most prevalent in the general population as well as on progress that has been achieved using the main therapeutic approaches, whether pharmacologic or interventional.

Obstructive sleep apnoea risk profile and the risk of recurrence of atrial fibrillation after catheter ablation

AIMS

The aim of this study was to identify the impact of obstructive sleep apnoea (OSA) on recurrence after catheter ablation of paroxysmal atrial fibrillation (AF).

METHODS AND RESULTS

One hundred and seventy-eight consecutive patients with paroxysmal AF who underwent index circumferential pulmonary vein (PV) isolation were prospectively enrolled. The patients were divided into high risk (HR group) and low risk (LR group) for OSA group with Berlin questionnaire. Of the 178 patients, 104 (58.4%) were in the HR group and 74 (41.6%) were in the LR group. After a mean follow-up of 344 +/- 137 (91-572) days, 44 patients (24.7%) experienced recurrence, and the recurrence rate did not differ between the HR (25.0%) and LR groups (24.3%, P = 0.855). Cox analysis revealed that PV isolation was the only independent predictor of recurrence (hazard ratio 5.11, 95% confidence interval 1.42-18.47, P = 0.013). There was no significant difference in the incidence of complications between the HR and LR groups (2.9 vs. 1.9%, P = 0.729).

CONCLUSION

The recurrence rate and incidence of complications did not differ in patients with different risk profiles for OSA. The presence of OSA should not lower the decision threshold to choose an ablative procedure in paroxysmal AF.

The overlap syndrome: chronic obstructive pulmonary disease and obstructive sleep apnea

The overlap syndrome defines the relationship between obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD), and is a commonly noted but poorly studied disorder. Individuals who have the overlap syndrome have been recognized to have greater risk for pulmonary hypertension, right heart failure, and hypercapnia than patients who have either disorder alone. In patients who have advanced-stage COPD, concomitant OSA likely has significant adverse consequences. The interaction between these two diseases is unclear, however. Further clinical trials of the overlap syndrome are urgently needed.

Obstructive sleep apnea presenting as recurrent cardiopulmonary arrest

A non-obese patient who was admitted initially with hypoglycemia had multiple episodes of cardiopulmonary arrests requiring resuscitations and a short period of mechanical ventilation. A subsequent sleep study confirmed the diagnosis of severe obstructive sleep apnea (OSA) and documented an episode of near-arrest with cerebral hypoxia during rapid eye movement sleep. We suggest that OSA coupled with impairment of arousal response and other apnea termination mechanisms had resulted in prolonged apnea, life-threatening hypoxemia, and cardiopulmonary arrest in this patient. We review the current understanding of the mechanisms of apnea termination in OSA and suggest that further studies are needed to investigate these mechanisms and their roles in sudden death during sleeping hours in patients with OSA.