Central sleep apnea in left ventricular dysfunction: prevalence and implications for arrhythmic risk

Transvenous phrenic nerve stimulation: setting up a clinical program

BACKGROUND

Central sleep apnea (CSA) is a form of sleep-disordered breathing caused by a lack of the drive to breathe during sleep. Phrenic nerve stimulation (PNS) was approved in 2017 for treatment of moderate to severe CSA. However, information on setting up a successful PNS program is lacking. We describe our institution's program to provide a framework to bridge the gap between clinical research and clinical application for PNS therapy.

METHODS

The PNS program was created as a joint program between cardiology and sleep medicine. The program team included cardiologists, sleep medicine specialists, advanced practice providers, clinic managers, and staff who worked together in the evaluation, implantation, and management of patients.

RESULTS

Thus far, 33 patients have been implanted at our institution. We have noted resolution of central apneas with PNS and improvement in patient sleep symptoms. The multidisciplinary clinic with cardiology and sleep medicine has led to high patient satisfaction and has facilitated a cohesive relationship between implant and management teams.

CONCLUSIONS

PNS therapy is an effective treatment option for CSA. While the therapy treats central apneas, it will not affect upper airway obstruction. Proper patient identification is important and cooperative management between cardiology and sleep medicine enhances patient care and experience. Challenges of establishing a multidisciplinary program include identification of providers, clinic space, and scheduling. Once established, the program provides an important service to a vulnerable patient population.

Obesity: the perfect storm for heart failure

Obesity condition causes morphological and functional alterations involving the cardiovascular system. These can represent the substrates for different cardiovascular diseases, such as atrial fibrillation, coronary artery disease, sudden cardiac death, and heart failure (HF) with both preserved ejection fraction (EF) and reduced EF. Different pathogenetic mechanisms may help to explain the association between obesity and HF including left ventricular remodelling and epicardial fat accumulation, endothelial dysfunction, and coronary microvascular dysfunction. Multi-imaging modalities are required for appropriate recognition of subclinical systolic dysfunction typically associated with obesity, with echocardiography being the most cost-effective technique. Therapeutic approach in patients with obesity and HF is challenging, particularly regarding patients with preserved EF in which few strategies with high level of evidence are available. Weight loss is of extreme importance in patients with obesity and HF, being a primary therapeutic intervention. Sodium-glucose co-transporter-2 inhibitors have been recently introduced as a novel tool in the management of HF patients. The present review aims at analysing the most recent studies supporting pathogenesis, diagnosis, and management in patients with obesity and HF.

Recommended assessment and management of sleep disordered breathing in patients with atrial fibrillation, hypertension and heart failure: Taiwan Society of Cardiology/Taiwan Society of sleep Medicine/Taiwan Society of pulmonary and Critical Care Medicine joint consensus statement

Sleep disordered breathing (SDB) is highly prevalent and may be linked to cardiovascular disease in a bidirectional manner. The Taiwan Society of Cardiology, Taiwan Society of Sleep Medicine and Taiwan Society of Pulmonary and Critical Care Medicine established a task force of experts to evaluate the evidence regarding the assessment and management of SDB in patients with atrial fibrillation (AF), hypertension and heart failure with reduced ejection fraction (HFrEF). The GRADE process was used to assess the evidence associated with 15 formulated questions. The task force developed recommendations and determined strength (Strong, Weak) and direction (For, Against) based on the quality of evidence, balance of benefits and harms, patient values and preferences, and resource use. The resulting 11 recommendations are intended to guide clinicians in determining which the specific patient-care strategy should be utilized by clinicians based on the needs of individual patients.

Interaction of positive airway pressure mask magnets with cardiac implantable electronic devices

STUDY OBJECTIVES

To evaluate for potential interactions between magnetic positive airway pressure (mPAP) masks and cardiac implantable electronic devices (CIEDs) for patients with sleep apnea.

METHODS

Adult patients with a CIED who used an mPAP mask were recruited from our sleep clinic to undergo a safety visit at our pacemaker clinic. We tested whether the mPAP interacted with the implanted device at home during normal use and in the clinic during simulated normal use and with direct contact. The magnetic field strength of 6 mPAP masks was tested with a gaussmeter.

RESULTS

Of 13 patients tested, 1 (8%), wearing a full face mask (ResMed AirFit F30 [ResMed, San Diego, California]), had a magnet response event (interaction) with direct contact, but no interactions were identified during normal or simulated normal use in any patient. The magnetic field strength of the mPAP masks increased the closer the mask got to the CIED, from 0.4 mT (4 G) at the mask manufacturer's recommended 5.1-cm (2-inch) distance from an implanted medical device up to 291 mT (2,910 G) at 0 cm (0 inches; direct contact).

CONCLUSIONS

An mPAP mask may interact with a CIED if placed directly on the skin overlying the CIED. The use of Philips Respironics (Philips, Cambridge, Massachusetts) mPAP masks is now contraindicated in patients with a CIED. Until additional studies are conducted to better document the risks and benefits of mPAP masks, we recommend discouraging patients with CIEDs from using any mPAP mask.

CITATION

Ruoff CM, Tashman YS, Cheema KPK, et al. Interaction of positive airway pressure mask magnets with cardiac implantable electronic devices. J Clin Sleep Med. 2023;19(5):941-946.

Central sleep apnea: pathophysiologic classification

Central sleep apnea is not a single disorder; it can present as an isolated disorder or as a part of other clinical syndromes. In some conditions, such as heart failure, central apneic events are due to transient inhibition of ventilatory motor output during sleep, owing to the overlapping influences of sleep and hypocapnia. Specifically, the sleep state is associated with removal of wakefulness drive to breathe; thus, rendering ventilatory motor output dependent on the metabolic ventilatory control system, principally PaCO2. Accordingly, central apnea occurs when PaCO2 is reduced below the "apneic threshold". Our understanding of the pathophysiology of central sleep apnea has evolved appreciably over the past decade; accordingly, in disorders such as heart failure, central apnea is viewed as a form of breathing instability, manifesting as recurrent cycles of apnea/hypopnea, alternating with hyperpnea. In other words, ventilatory control operates as a negative-feedback closed-loop system to maintain homeostasis of blood gas tensions within a relatively narrow physiologic range, principally PaCO2. Therefore, many authors have adopted the engineering concept of "loop gain" (LG) as a measure of ventilatory instability and susceptibility to central apnea. Increased LG promotes breathing instabilities in a number of medical disorders. In some other conditions, such as with use of opioids, central apnea occurs due to inhibition of rhythm generation within the brainstem. This review will address the pathogenesis, pathophysiologic classification, and the multitude of clinical conditions that are associated with central apnea, and highlight areas of uncertainty.

Augmented O-GlcNAcylation exacerbates right ventricular dysfunction and remodeling via enhancement of hypertrophy, mitophagy, and fibrosis in mice exposed to long-term intermittent hypoxia

Previously, we showed that augmented O-linked N-acetylglucosaminylation (O-GlcNAcylation) mitigates cardiac remodeling in O-GlcNAc transferase-transgenic (Ogt-Tg) mice exposed to acute (2-week) intermittent hypoxia (IH) by suppressing nuclear factor of activated T cells (NFAT) and nuclear factor kappa B (NF-κB) via the O-GlcNAcylation of glycogen synthase kinase 3 beta (GSK-3β) and NF-κB p65. Because this effect is time dependent, we exposed Ogt-Tg mice to IH for 4 weeks (IH4W) in the present study. O-GlcNAcylation was significantly enhanced in Ogt-Tg mice vs. wild-type (WT) mice exposed to normoxia and IH4W. Total O-GlcNAcylation levels were significantly increased in WT and Ogt-Tg mice after IH4W vs. normoxia. After IH4W, Ogt-Tg mice displayed significantly exacerbated signs of cardiac hypertrophy and fibrosis in the right ventricles (RVs) but not the left ventricles (LVs). Echocardiography revealed IH4W-induced right ventricular dysfunction. Phosphorylated GSK-3β levels were increased in Ogt-Tg mice vs. WT mice after IH4W, whereas phosphorylated NF-κB p65 levels were unaffected. Mitophagy, which is associated with cardiac dysfunction, was increased in the RVs of Ogt-Tg mice after IH4W. Furthermore, the levels of phosphorylated dynamin-related protein 1 (p-Drp1) were significantly increased, and the expression of mitofusin-2 (MFN2) was significantly decreased. In human embryonic kidney cells, mitochondrial uncoupler-induced mitochondrial dysfunction was accelerated in Ogt-overexpressing cells. In addition to increasing the levels of phosphorylated Smad2, IH4W promoted cardiac fibrosis in the RVs of Ogt-Tg mice. Thus, augmented O-GlcNAcylation may aggravate IH4W-induced right ventricular dysfunction and remodeling by promoting hypertrophy, mitophagy, and fibrosis via GSK-3β inactivation, an increased p-Drp-1/MFN2 ratio, and Smad2 activation, respectively.

Effects of ANP and BNP on the generation of respiratory rhythms in brainstem-spinal cord preparation isolated from newborn rats

Natriuretic peptides (NPs) are a family of peptide hormones produced in cardiac muscle cells and consist mainly of three types: atrial NP (ANP), B-type (or brain) NP (BNP), and C-type NP. We herein report the effects of ANP and BNP on central respiratory activity in brainstem-spinal cord preparation isolated from newborn rats. Bath application of these peptides (100 nM) induced a weak transient depression of the respiratory rhythm followed by recovery. Respiratory-related neurons in the rostral ventrolateral medulla showed a tendency for transient hyperpolarization followed by recovery during the application of ANP or BNP. The application of a membrane-permeable cGMP, 8-Br-cGMP (10 or 20 μM), did not induce significant effects on respiratory rhythm, suggesting no involvement of guanylyl cyclase in effects of ANP or BNP. We also examined effects of BNP on respiratory depression induced by the sedative dexmedetomidine, which exerts an inhibitory influence on respiratory rhythm. When pretreated with 50 nM BNP, the inhibitory effect of 100 nM dexmedetomidine was significantly reduced. Our findings suggest that ANP and BNP act as mild excitatory agents with sustained effects on respiratory rhythm after an initial transient depression.

Phrenic nerve stimulation for the treatment of central sleep apnea in patients with heart failure

Objective

Central sleep apnea (CSA) is associated with increased morbidity and mortality in patients with heart failure (HF). We aimed to explore the effectiveness of phrenic nerve stimulation (PNS) on CSA in patients with HF.

Methods

This was a prospective and non-randomized study. The stimulation lead was inserted into the right brachiocephalic vein and attached to a proprietary neurostimulator. Monitoring was conducted during the implantation process, and all individuals underwent two-night polysomnography.

Results

A total of nine subjects with HF and CSA were enrolled in our center. There was a significant decrease in the apnea–hypopnea index (41 ± 18 vs 29 ± 25, p = 0.02) and an increase in mean arterial oxygen saturation (SaO2) (93% ± 1% vs 95% ± 2%, p = 0.03) after PNS treatment. We did not observe any significant differences of oxygen desaturation index (ODI) and SaO2 < 90% (T90) following PNS. Unilateral phrenic nerve stimulation might also categorically improve the severity of sleep apnea.

Conclusion

In our non-randomized study, PNS may serve as a therapeutic approach for CSA in patients with HF.

Abnormal Sleep-Related Breathing Related to Heart Failure

Sleep-disordered breathing (SDB) is highly prevalent in patients with heart failure (HF). Untreated obstructive sleep apnea (OSA) and central sleep apnea (CSA) in patients with HF are associated with worse outcomes. Detailed sleep history along with polysomnography (PSG) should be conducted if SDB is suspected in patients with HF. First line of treatment is the optimization of medical therapy for HF and if symptoms persist despite optimization of the treatment, positive airway pressure (PAP) therapy will be started to treat SDB. At present, there is limited evidence to prescribe any drugs for treating CSA in patients with HF. There is limited evidence for the efficacy of continuous positive airway pressure (CPAP) or adaptive servo-ventilation (ASV) in improving mortality in patients with heart failure with reduced ejection fraction (HFrEF). There is a need to perform well-designed studies to identify different phenotypes of CSA/OSA in patients with HF and to determine which phenotype responds to which therapy. Results of ongoing trials, ADVENT-HF, and LOFT-HF are eagerly awaited to shed more light on the management of CSA in patients with HF. Until then the management of SDB in patients with HF is limited due to the lack of evidence and guidance for treating SDB in patients with HF.

Preventing heart failure: a position paper of the Heart Failure Association in collaboration with the European Association of Preventive Cardiology

The heart failure epidemic is growing and its prevention, in order to reduce associated hospital readmission rates and its clinical and economic burden, is a key issue in modern cardiovascular medicine. The present consensus document aims to provide practical evidence-based information to support the implementation of effective preventive measures. After reviewing the most common risk factors, an overview of the population attributable risks in different continents is presented, to identify potentially effective opportunities for prevention and to inform preventive strategies. Finally, potential interventions that have been proposed and have been shown to be effective in preventing HF are listed.

Preventing heart failure: a position paper of the Heart Failure Association in collaboration with the European Association of Preventive Cardiology

The heart failure epidemic is growing and its prevention, in order to reduce associated hospital readmission rates and its clinical and economic burden, is a key issue in modern cardiovascular medicine. The present position paper aims to provide practical evidence-based information to support the implementation of effective preventive measures. After reviewing the most common risk factors, an overview of the population attributable risks in different continents is presented, to identify potentially effective opportunities for prevention and to inform preventive strategies. Finally, potential interventions that have been proposed and have been shown to be effective in preventing heart failure are listed.

Central Sleep Apnea Is Associated with an Abnormal P-Wave Terminal Force in Lead V1 in Patients with Acute Myocardial Infarction Independent from Ventricular Function

Sleep-disordered breathing (SDB) is highly prevalent in patients with cardiovascular disease. We have recently shown that an elevation of the electrocardiographic (ECG) parameter P wave terminal force in lead V₁ (PTFV₁) is linked to atrial proarrhythmic activity by stimulation of reactive oxygen species (ROS)-dependent pathways. Since SDB leads to increased ROS generation, we aimed to investigate the relationship between SDB-related hypoxia and PTFV₁ in patients with first-time acute myocardial infarction (AMI). We examined 56 patients with first-time AMI. PTFV₁ was analyzed in 12-lead ECGs and defined as abnormal when ≥4000 µV*ms. Polysomnography (PSG) to assess SDB was performed within 3–5 days after AMI. SDB was defined by an apnea-hypopnea-index (AHI) >15/h. The multivariable regression analysis showed a significant association between SDB-related hypoxia and the magnitude of PTFV₁ independent from other relevant clinical co-factors. Interestingly, this association was mainly driven by central but not obstructive apnea events. Additionally, abnormal PTFV₁ was associated with SDB severity (as measured by AHI, B 21.495; CI [10.872 to 32.118]; p < 0.001), suggesting that ECG may help identify patients suitable for SDB screening. Hypoxia as a consequence of central sleep apnea may result in atrial electrical remodeling measured by abnormal PTFV₁ in patients with first-time AMI independent of ventricular function. The PTFV₁ may be used as a clinical marker for increased SDB risk in cardiovascular patients.

Ventrikuläre Arrhythmien bei obstruktiver und zentraler Schlafapnoe

Hintergrund

Ventrikuläre Arrhythmien treten mit einer hohen Prävalenz auf und sind mit einer hohen Morbidität und Mortalität assoziiert. Sowohl die obstruktive (OSA) als auch die zentrale (ZSA) Schlafapnoe können auf Grund ihrer Pathophysiologie zu vermehrten ventrikulären Arrhythmien beitragen.

Ziel

Dieser Artikel soll die komplexen Zusammenhänge und Erkenntnisse jüngster Forschungen bezüglich schlafbezogenen Atmungsstörungen (SBAS) und ventrikulärer Arrhythmien und deren Therapiemöglichkeiten beleuchten.

Material und Methoden

Es erfolgte eine Literaturrecherche basierend auf prospektiven, retrospektiven, klinischen und experimentellen Studien sowie Reviews, Metaanalysen und aktuellen Leitlinien, die seit 2014 in der Medline-Datenbank gelistet wurden.

Ergebnisse

Es besteht ein bidirektionaler Zusammenhang zwischen der SBAS und ventrikulären Arrhythmien. Intermittierende Hypoxie, oxidativer Stress, wiederkehrende Arousals, intrathorakale Druckschwankungen und kardiales Remodeling tragen im Rahmen der SBAS zu einer erhöhten ventrikulären Arrhythmieneigung bei. Der Schweregrad der OSA, gemessen mittels Apnoe-Hypopnoe-Index, ist mit der Prävalenz ventrikulärer Arrhythmien assoziiert. Ähnliche Ergebnisse liegen für Patienten mit ZSA und Herzinsuffizienz vor. Studien zu ventrikulären Arrhythmien bei ZSA-Patienten ohne Herzinsuffizienz fehlen. Eine Positivdrucktherapie (PAP) bei OSA- oder ZSA-Patienten führte in verschiedenen Studien zu einer reduzierten Anzahl an ventrikulären Arrhythmien. Dieser Zusammenhang konnte jedoch nicht in allen Studien bestätigt werden. Ventrikuläre Arrhythmien treten bei der OSA gehäuft nachts auf, bei der ZSA gleichmäßig über den Tag verteilt.

Diskussion

Bisherige Studien weisen einen Zusammenhang zwischen der OSA bzw. der ZSA und ventrikulären Arrhythmien trotz unterschiedlicher Pathophysiologie nach. Hinsichtlich des Effektes der PAP auf ventrikuläre Arrhythmien bei Patienten mit OSA und ZSA sind weitere Studien erforderlich.

PSG-Audio, a scored polysomnography dataset with simultaneous audio recordings for sleep apnea studies

The sleep apnea syndrome is a chronic condition that affects the quality of life and increases the risk of severe health conditions such as cardiovascular diseases. However, the prevalence of the syndrome in the general population is considered to be heavily underestimated due to the restricted number of people seeking diagnosis, with the leading cause for this being the inconvenience of the current reference standard for apnea diagnosis: Polysomnography. To enhance patients' awareness of the syndrome, a great endeavour is conducted in the literature. Various home-based apnea detection systems are being developed, profiting from information in a restricted set of polysomnography signals. In particular, breathing sound has been proven highly effective in detecting apneic events during sleep. The development of accurate systems requires multitudinous datasets of audio recordings and polysomnograms. In this work, we provide the first open access dataset, comprising 212 polysomnograms along with synchronized high-quality tracheal and ambient microphone recordings. We envision this dataset to be widely used for the development of home-based apnea detection techniques and frameworks.

Ventricular arrhythmia in heart failure patients with reduced ejection fraction and central sleep apnoea

Cheyne–Stokes respiration (CSR) may trigger ventricular arrhythmia in patients with heart failure with reduced ejection fraction (HFrEF) and central sleep apnoea (CSA). This study determined the prevalence and predictors of a high nocturnal ventricular arrhythmia burden in patients with HFrEF and CSA (with and without CSR) and to evaluate the temporal association between CSR and the ventricular arrhythmia burden.

 This cross-sectional ancillary analysis included 239 participants from the SERVE-HF major sub-study who had HFrEF and CSA, and nocturnal ECG from polysomnography. CSR was stratified in ≥20% and <20% of total recording time (TRT). High burden of ventricular arrhythmia was defined as >30 premature ventricular complexes (PVCs) per hour of TRT. A sub-analysis was performed to evaluate the temporal association between CSR and ventricular arrhythmias in sleep stage N2.

 High ventricular arrhythmia burden was observed in 44% of patients. In multivariate logistic regression analysis, male sex, lower systolic blood pressure, non-use of antiarrhythmic medication and CSR ≥20% were significantly associated with PVCs >30·h⁻¹ (OR 5.49, 95% CI 1.51–19.91, p=0.010; OR 0.98, 95% CI 0.97–1.00, p=0.017; OR 5.02, 95% CI 1.51–19.91, p=0.001; and OR 2.22, 95% CI 1.22–4.05, p=0.009; respectively). PVCs occurred more frequently during sleep phases with versus without CSR (median (interquartile range): 64.6 (24.8–145.7) versus 34.6 (4.8–75.2)·h⁻¹ N2 sleep; p=0.006).

 Further mechanistic studies and arrhythmia analysis of major randomised trials evaluating the effect of treating CSR on ventricular arrhythmia burden and arrhythmia-related outcomes are warranted to understand how these data match with the results of the parent SERVE-HF study.

High ventricular arrhythmia burden occurs in 44% of heart failure patients with reduced ejection fraction and central sleep apnoea. Arrhythmia burden is higher in sleep phases with versus without Cheyne–Stokes respiration.https://bit.ly/2QBDamC

Evolving Cardiac Electrical Therapies for Advanced Heart Failure Patients

Symptomatic heart failure (HF) patients despite optimal medical therapy and advances such as invasive hemodynamic monitoring remain challenging to manage. While cardiac resynchronization therapy remains a highly effective therapy for a subset of HF patients with wide QRS, a majority of symptomatic HF patients are poor candidates for such. Recently, cardiac contractility modulation, neuromodulation based on carotid baroreceptor stimulation, and phrenic nerve stimulation have been approved by the US Food and Drug Administration and are emerging as therapeutic options for symptomatic HF patients. This state-of-the-art review examines the role of these evolving electrical therapies in advanced HF.

Sleep disturbance in heart failure: A concept analysis

AIM

This concept analysis aims to analyze the concept of sleep disturbance (SD) in the context of heart failure (HF) to guide the development of a clearly defined definition.

BACKGROUND

The term "sleep disturbance" has been used in the literature to describe sleep problems and sleep disorders among individuals with HF. Environmental, physical, psychological, behavioral, and developmental factors complicate the phenomenon of SD in HF.

DESIGN

Walker and Avant's method was used for this concept analysis.

DATA SOURCE

Published literature from 2000 to 2020 was identified from electronic health profession-related databases. The current definition and usages of SD were abstracted from empirical work and electronic databases.

REVIEW METHODS

A focused review of abstracts and full text relating to SD in HF was performed. Studies featuring original data and peer-reviewed articles written in English were included to investigate the multifactorial contextual meaning of the concept.

RESULTS

SD in HF can be described as a condition in which individuals experience difficulty initiating and maintaining sleep, and difficulty continuing or resuming sleep due to frequent nocturnal arousals due to HF symptoms, sleep-disordered breathing, insomnia, and psychological burdens.

CONCLUSIONS

To evaluate SD in HF, clinicians must examine the underlying causes to provide the contextual meaning of the concept. A clearly defined and distinguishable concept of SD in HF provides a possibility for accurate measurements of sleep quality, exploring interventions, and evaluating outcomes.

Prognostic value of implantable defibrillator-computed respiratory disturbance index: The DASAP-HF study

BACKGROUND

Sleep apnea, as measured by polysomnography, is associated with adverse outcomes in heart failure. The DASAP-HF (Diagnosis and Treatment of Sleep Apnea in Patient With Heart Failure) study previously demonstrated that the respiratory disturbance index (RDI) computed by the ApneaScan algorithm (Boston Scientific) accurately identifies severe sleep apnea in implantable cardioverter-defibrillator (ICD) patients.

OBJECTIVE

The purpose of the long-term study phase was to assess the incidence of clinical events after 24 months and investigate the association with RDI values.

METHODS

Patients with left ventricular ejection fraction ≤35% implanted with an ICD were enrolled and followed-up for 24 months. The RDI calculated at 1 month after implantation was used to stratify patients (below or above 30 episodes/h). The endpoints were all-cause death and a combination of all-cause death or cardiovascular hospitalization.

RESULTS

Of the 265 enrolled patients, 224 had usable RDI values. Severe sleep apnea (RDI ≥30 episodes/h) was diagnosed in 115 patients (51%). These patients were more frequently male (84% vs 72%; P = .030) and had higher creatinine levels. During median follow-up of 25 months, 19 patients (8%) died. Cardiovascular hospitalizations were reported in 19 patients (8%). The risk of all-cause death was higher in patients with RDI ≥30 episodes/h (hazard ratio [HR] 3.33; 95% confidence interval [CI] 1.35-8.21; P = .023), as well as the risk of all-cause death or cardiovascular hospitalization (HR 1.94; 95% CI 1.01-3.76; P = .048). At multivariate analysis, independent predictors of death were RDI ≥30 episodes/h (HR 4.02; 95% CI 1.16-13.97; P = .029) and creatinine levels (HR 2.36; 95% CI 1.26-4.42; P = .008).

CONCLUSION

In heart failure patients implanted with an ICD, higher RDI values are associated with death and cardiovascular hospitalizations. Device-detected severe sleep apnea independently predicts death.

Narrative review of sleep and stroke

Sleep disorders, such as sleep-disordered breathing (SDB), insomnia or restless legs syndrome (RLS), are common in the general population and after stroke. In some cases, sleep disturbances are pre-existing, but can also appear de novo as a direct consequence of brain damage or due to stroke-related complications. Furthermore, some sleep conditions may act as a risk factor of stroke. This review explores the available evidence of the two-way relationship between sleep and stroke. Cardiovascular physiological changes during sleep are described, as well as the evidence on the relationship between stroke and sleep duration, SDB, RLS, insomnia, excessive daytime sleepiness (EDS), and circadian rhythm alterations. Potential changes on sleep architecture, and the links that may exist between sleep and functional outcomes after stroke are also discussed. Importantly, sleep-related disturbances may be associated with worse stroke recovery outcomes and increased cerebrovascular morbidity. It is therefore relevant that the bidirectional association between stroke and sleep is taken into consideration by clinicians taking care of these patients. Future research may focus on this mutual relationship for a better understanding of the impact of stroke on sleep, the importance of sleep in stroke incidence and recovery, and have further evidence on treatment strategies that may improve functional outcome after stroke.

Obstructive sleep apnea versus central sleep apnea: prognosis in systolic heart failure

Background

In chronic heart failure (CHF), obstructive sleep apnea (OSA) and Cheyne-Stokes respiration (CSR) are associated with increased mortality. The present study aimed to evaluate the prognostic effect of CSR compared to OSA, in otherwise similar groups of CHF patients.

Methods

Screening for sleep-disordered breathing (SDB) was conducted among patients with CHF of New York Heart Association (NYHA) class II-IV, and left ventricular ejection fraction (LVEF) of ≤45%. The study included 43 patients (4 women) with >25% CSR during sleeping time, and 19 patients (2 women) with OSA and an apnea-hypopnea index (AHI) of ≥6. Patients were followed for a median of 1,371 days. The primary endpoint was mortality, and the secondary endpoint was combined mortality and hospital admissions.

Results

Baseline parameters did not significantly differ between groups, but CSR patients were older and had higher AHI values than OSA patients. Five OSA patients (26%) died, and 14 (74%) met the combined end-point of death or hospitalization. CSR patients had significantly higher risk for both end-points, with 23 (53%) deaths [log-rank P=0.040; HR, 2.70 (1.01-7.22); P=0.047] and 40 (93%) deaths or readmissions [log-rank P=0.029; HR, 1.96 (1.06-3.63); P=0.032]. After adjustment for confounding risk factors, the association between CSR and death remained significant [HR, 4.73 (1.10-20.28); P=0.037], hospital admission rates were not significantly different.

Conclusions

Among patients with CHF, CSR was associated with higher mortality than OSA independently of age and cardiac systolic function. CSR was also an age-independent predictor of unfavorable outcome, but hospital admission rates were not significantly different between the two groups after adjustment.

Effects of central apneas on sympathovagal balance and hemodynamics at night: impact of underlying systolic heart failure

BACKGROUND

Increased sympathetic drive is the key determinant of systolic heart failure progression, being associated with worse functional status, arrhythmias, and increased mortality. Central sleep apnea is highly prevalent in systolic heart failure, and its effects on sympathovagal balance (SVB) and hemodynamics might depend on relative phase duration and background pathophysiology.

OBJECTIVE

This study compared the effects of central apneas in patients with and without systolic heart failure on SVB and hemodynamics during sleep.

METHODS

During polysomnography, measures of SVB (heart rate and diastolic blood pressure variability) were non-invasively recorded and analyzed along with baroreceptor reflex sensitivity and hemodynamic parameters (stroke volume index, cardiac index, total peripheral resistance index). Data analysis focused on stable non-rapid eye movement N2 sleep, comparing normal breathing with central sleep apnea in subjects with and without systolic heart failure.

RESULTS

Ten patients were enrolled per group. In heart failure patients, central apneas had neutral effects on SVB (all p > 0.05 for the high, low, and very low frequency components of heart rate and diastolic blood pressure variability). Patients without heart failure showed an increase in very low and low frequency components of diastolic blood pressure variability in response to central apneas (63 ± 18 vs. 39 ± 9%; p = 0.001, 43 ± 12 vs. 31 ± 15%; p = 0.002). In all patients, central apneas had neutral hemodynamic effects when analyzed over a period of 10 min, but had significant acute hemodynamic effects.

CONCLUSION

Effects of central apneas on SVB during sleep depend on underlying systolic heart failure, with neutral effects in heart failure and increased sympathetic drive in idiopathic central apneas.

A review on four different paths to respiratory arrest from brain injury in children; implications for child abuse

Child abuse was suspected in a case of out-of-hospital arrest with minor brain injuries. Confronted with continued disputes on pathophysiologic correlates even after autopsy, to assist the differentiation of potential causes of sudden cardiopulmonary arrest in children, we tried to identify the mechanism of cardiopulmonary arrest in brain injuries from different causes. Systematic review was carried out in two stages. First, major external causes of cardiopulmonary arrest among children and infants were identified from Pubmed and Google Scholar search, and then the exact sequence of cardiopulmonary arrest, and their pathophysiologic features were identified based on articles of animal models of brain injury. From the review, we have identified four major groups of external circumstances for rather sudden cardiopulmonary arrest from brain damage in children, after excluding congenital and other unrelated diseases; 1) impact brain apnea, 2) anoxic insults, 3) drug or other substance induced central nervous system depression, and 4) traumatic brain damage. Each group has different features in the course of cardiac and respiratory arrests. Based on this review of pathophysiologic features of cardio-respiratory responses from external causes, we have presented a suspected, but unlikely, child abuse case of respiratory arrest from brain injury. The social consequences of both unknowingly missing, and falsely incriminating the abuse can be grave, and the identification of the mechanisms of cardiopulmonary arrest from brain injury can be important for the differentiation of various potential causes.

In patients with heart failure the burden of central sleep apnea increases in the late sleep hours

Study Objectives

Periodic breathing with central sleep apnea (CSA) is common in patients with left ventricular systolic dysfunction. Based on the pathophysiological mechanisms underlying CSA, we hypothesized that the frequency of CSA episodes would increase in the late hours of non-rapid eye movement (NREM) of sleep.

Methods

Forty-one patients with left ventricular ejection fraction <40% underwent full-night-attended polysomnography scored by a central core lab. Because central apneas occur primarily in NREM sleep, total NREM sleep time for each patient was divided into 8 equal duration segments. Segment event counts were normalized to an events/hour index based on sleep segment duration.

Results

Central apnea index (CAI) varied among sleep segments (p = 0.001). As expected CAI was higher in segment 1 compared to segments 2 and 3, increasing during later segments. The minimum CAI occurred in segment 2 with mean ± SD of 21 ± 3 events/hour and maximum CAI was in segment 8 with 37 ± 4 events/hour. We also determined central apnea duration which varied among segments (p = 0.005), with longer durations later in the night (segment 1: 22 ± 1 seconds; segment 8: 26 ± 1 seconds, p < 0.001). Data were also analyzed including rapid eye movement (REM) sleep, with similar results. Further, comparison of CAI between the first and second half of the night showed a significant increase in the index. Circulation time did not change across the segments (p = 0.073).

Conclusions

In patients with left ventricular dysfunction and CSA, central apnea burden (number and duration) increases during later hours of sleep. These findings have pathophysiological and therapeutic implications.

Clinical Trial Registration

NCT01124370.

Phrenic Nerve Stimulation for the Treatment of Central Sleep Apnea: A Pooled Cohort Analysis

STUDY OBJECTIVES

Early evidence with transvenous phrenic nerve stimulation (PNS) demonstrates improved disease severity and quality of life (QOL) in patients with central sleep apnea (CSA). The goal of this analysis is to evaluate the complete prospective experience with PNS in order to better characterize its efficacy and safety, including in patients with concomitant heart failure (HF).

METHODS

Using pooled individual data from the pilot (n = 57) and pivotal (n = 151) studies of the remedē System in patients with predominant moderate to severe CSA, we evaluated 12-month safety and 6- and 12-month effectiveness based on polysomnography data, QOL, and cardiac function.

RESULTS

Among 208 combined patients (June 2010 to May 2015), a remedē device implant was successful in 197 patients (95%), 50/57 pilot study patients (88%) and 147/151 pivotal trial patients (97%). The pooled cohort included patients with CSA of various etiologies, and 141 (68%) had concomitant HF. PNS reduced apnea-hypopnea index (AHI) at 6 months by a median of -22.6 episodes/h (25th and 75th percentile; -38.6 and -8.4, respectively) (median 58% reduction from baseline, P < .001). Improvement in sleep variables was maintained through 12 months of follow-up. In patients with HF and ejection fraction ≤ 45%, PNS was associated with improvement in systolic function from 27.0% (23.3, 36.0) to 31.1% (24.0, 41.5) at 12 months (P = .003). In the entire cohort, improvement in QOL was concordant with amelioration of sleep measures.

CONCLUSIONS

Transvenous PNS significantly improves CSA severity, sleep quality, ventricular function, and QOL regardless of HF status. Improvements, which are independent of patient compliance, are sustained at 1 year and are associated with acceptable safety.

Exercise oscillatory ventilation and prognosis in heart failure patients with reduced and mid-range ejection fraction

AIMS

Exercise oscillatory ventilation (EOV) is a pivotal cardiopulmonary exercise test parameter for the prognostic evaluation of patients with chronic heart failure (HF). It has been described in patients with HF with reduced ejection fraction (<40%, HFrEF) and with HF with preserved ejection fraction (>50%, HFpEF), but no data are available for patients with HF with mid-range ejection fraction (40-49%, HFmrEF). The aim of the study was to evaluate the prognostic role of EOV in HFmrEF patients.

METHODS AND RESULTS

We analysed 1239 patients with HFmrEF and 4482 patients with HFrEF, enrolled in the MECKI score database, with a 2-year follow-up. The study endpoint was the composite of cardiovascular death, urgent heart transplant, and ventricular assist device implantation. We identified EOV in 968 cases (16% and 17% of cases in HFmrEF and HFrEF, respectively). HFrEF EOV+ patients were significantly older, and their parameters suggested a more severe HF than HFrEF EOV- patients. A similar behaviour was found in HFmrEF EOV+ vs. EOV- patients. Kaplan-Meier analysis, irrespective of ejection fraction, showed that EOV is associated with a worse survival, and that patients with HFrEF and HFmrEF EOV+ had a significantly worse outcome than the EOV- of the same ejection fraction groups. EOV-associated survival differences in HFmrEF patients started after 18 months of follow-up.

CONCLUSION

Exercise oscillatory ventilation has a similar prevalence and ominous prognostic value in both HFmrEF and HFrEF patients, indicating a group of patients in need of a more intensive follow-up and a more aggressive therapy. In HFmrEF, the survival curves between EOV+ and EOV- patients diverged only after 18 months.

Feasibility of automated detection of sleep apnea using implantable pacemakers and defibrillators: a comparison with simultaneous polysomnography recording

PURPOSE

Sleep-related breathing disorders (SRBD) have been associated with adverse cardiovascular events and prognosis. Some modern pacemakers (PMK) and implantable cardioverter defibrillators (ICD) are equipped with thoracic impedance monitoring systems which allow detecting fluctuations in tidal volume occurring in SRBD. This study aimed at assessing the accuracy of a novel transthoracic impedance-based PMK/ICD sensor for automatic detection of SRBD.

METHODS

We prospectively enrolled 31 consecutive patients scheduled for implantation of a PMK or an ICD with sleep respiratory disturbances monitoring capability. The results of unattended home nocturnal recordings expressed as apnea/hypopnea index (AHI) were compared with the respiratory disturbance index (RDI) stored in the cardiac device memory at the time polygraphy was performed.

RESULTS

Among the 31 enrolled patients (20 men, mean age 70 ± 8 years), a comparison between the data from polygraphy and cardiac device was feasible in 29 patients. According to the results of home nocturnal recording, a severe SRBD was observed in 7/29 (24.1%) patients. On the basis of receiver-operating characteristic curve analysis of RDI values, the optimal RDI cutoff value to identify severe SRBD was 47 episodes/h (sensitivity 100%, specificity 100%). Bland-Altman agreement analysis of AHI-RDI revealed a bias between measurements of - 11 episodes/h, with limits of agreement - 38 to 15 episodes/h.

CONCLUSIONS

In the present study, the novel transthoracic impedance-based monitoring system ApneaScan^TM appeared effective in screening PMK and ICD patients for SRBD.

Central and Obstructive Apneas in Heart Failure With Reduced, Mid-Range and Preserved Ejection Fraction

Background: Although central apneas (CA) and obstructive apneas (OA) are highly prevalent in heart failure (HF), a comparison of apnea prevalence, predictors and clinical correlates in the whole HF spectrum, including HF with reduced ejection fraction (HFrEF), mid-range EF (HFmrEF) and preserved EF (HFpEF) has never been carried out so far.

Materials and methods: 700 HF patients were prospectively enrolled and then divided according to left ventricular EF (408 HFrEF, 117 HFmrEF, 175 HFpEF). All patients underwent a thorough evaluation including: 2D echocardiography; 24-h Holter-ECG monitoring; cardiopulmonary exercise testing; neuro-hormonal assessment and 24-h cardiorespiratory monitoring.

Results: In the whole population, prevalence of normal breathing (NB), CA and OA at daytime was 40, 51, and 9%, respectively, while at nighttime 15, 55, and 30%, respectively. When stratified according to left ventricular EF, CA prevalence decreased (daytime: 57 vs. 43 vs. 42%, p = 0.001; nighttime: 66 vs. 48 vs. 34%, p < 0.0001) from HFrEF to HFmrEF and HFpEF, while OA prevalence increased (daytime: 5 vs. 8 vs. 18%, p < 0.0001; nighttime 20 vs. 29 vs. 53%, p < 0.0001).

In HFrEF, male gender and body mass index (BMI) were independent predictors of both CA and OA at nighttime, while age, New York Heart Association functional class and diastolic dysfunction of daytime CA. In HFmrEF and HFpEF male gender and systolic pulmonary artery pressure were independent predictors of CA at daytime, while hypertension predicted nighttime OA in HFpEF patients; no predictor of nighttime CA was identified. When compared to patients with NB, those with CA had higher neuro-hormonal activation in all HF subgroups. Moreover, in the HFrEF subgroup, patients with CA were older, more comorbid and with greater hemodynamic impairment while, in the HFmrEF and HFpEF subgroups, they had higher left atrial volumes and more severe diastolic dysfunction, respectively. When compared to patients with NB, those with OA were older and more comorbid independently from background EF.

Conclusions: Across the whole spectrum of HF, CA prevalence increases and OA decreases as left ventricular systolic dysfunction progresses. Different predictors and specific clinical characteristics might help to identify patients at risk of developing CA or OA in different HF phenotypes.

Augmented O-GlcNAcylation attenuates intermittent hypoxia-induced cardiac remodeling through the suppression of NFAT and NF-κB activities in mice

Type 2 diabetes mellitus (T₂DM) has been reported to be associated with cardiac remodeling. Although O-GlcNAcylation is known to be elevated in diabetic and ischemic hearts, the effects of O-GlcNAcylation on cardiac remodeling induced by intermittent hypoxia (IH), such as sleep apnea syndrome (SAS), remain unknown. To evaluate the effects, we induced IH in wild-type (WT) and transgenic O-GlcNAc transferase (Ogt-Tg) mice. Two weeks of IH increased O-GlcNAcylation in the heart tissues of both strains of mice, whereas O-GlcNAcylation in Ogt-Tg mice was significantly higher than that in WT mice under both normoxic and IH conditions. WT mice exhibited cardiac remodeling after IH, whereas cardiac remodeling was significantly attenuated in Ogt-Tg mice. Oxidative stress and apoptosis increased after IH in both strains of mice, whereas the rate of increase in these processes in Ogt-Tg mice was significantly lower than that in WT mice. To examine the mechanism of cardiac remodeling attenuation in Ogt-Tg mice after IH, the effects of O-GlcNAcylation on the activities of the master regulators nuclear factor of activated T cells (NFAT) and NF-κB were determined. The O-GlcNAcylation of GSK-3β, a negative regulator of NFAT, was significantly increased in Ogt-Tg mice, whereas the phosphorylation of GSK-3β was reciprocally reduced. The same result was observed for NF-κB p65. An in vitro reporter assay showed that the augmentation of O-GlcNAcylation by an O-GlcNAcase inhibitor suppressed NFAT and NF-κB promoter activity. These data suggest that augmented O-GlcNAcylation mitigates IH-induced cardiac remodeling by suppressing NFAT and NF-κB activities through the O-GlcNAcylation of GSK-3β and NF-κB p65.

Central Sleep Apnoea and Arrhythmogenesis After Myocardial Infarction-The CESAAR Study

The prevalence of sleep disordered breathing (SDB) after acute myocardial infarction (AMI) is high. However, little is known about predominant SDB type and the impact of SDB severity on arrhythmogenesis. We conducted a prospective single-center observational study and performed an unattended sleep study and Holter monitoring within 10 days after AMI, and an unattended sleep study 11.3 months after AMI. All patients were included from the Department of Cardiology at the University Hospital Schleswig-Holstein, Lübeck, Germany. A total of 202 subjects with AMI (73.8% with ST-elevation; 59.8 years; 73.8% male) were included. The mean BMI was 27.8 kg/m² and the mean neck/waist circumference was 41.7/103.3 cm. The mean left ventricular ejection fraction was 56.6%. The SDB prevalence defined as apnoea-hypopnea-index (AHI) ≥ 5/h was 66.7% with 44.9% having central (CSA), and 21.8% obstructive sleep apnoea (OSA). The mean AHI was 13.8 1/h. In 10.2% nsVT was detected in the Holter monitoring. AI >23/h was independently associated with higher risk of nsVT in the subacute AMI period. SDB is highly prevalent and CSA a predominant type of SDB in the subacute phase after uncomplicated AMI treated with modern revascularization procedures and evidence-based pharmacological therapy. Severe SDB is independently associated with higher risk for nsVT in the subacute AMI period and its course should be monitored as it can potentially have a negative impact on relevant outcomes of AMI patients. Further prospective studies are needed to assess long-term follow up of SDB after AMI and its impact on mortality and morbidity.

Diagnosis and management of central sleep apnea syndrome

Introduction: Central sleep apnea (CSA) syndrome has gained a considerable interest in the sleep field within the last 10 years. It is overrepresented in particular subpopulations such as patients with stroke or heart failure. Early detection and diagnosis, as well as appropriate treatment of central breathing disturbances during sleep remain challenging. Areas covered: Based on a systematic review of CSA in adults the clinical evidence and polysomnographic patterns useful for discerning central from obstructive events are discussed. Current therapeutic indications of CSA and perspectives are presented, according to the type of respiratory disturbances during sleep, alterations in blood gases and ventilatory control. Expert opinion: The precise identification of central events during polysomnographic recording is mandatory. Therapeutic choices for CSA depend on the typology of respiratory disturbances observed by polysomnography, changes in blood gases and ventilatory control. In CSA with normocapnia and ventilatory instability, adaptive servo-ventilation is recommended. In CSA with hypercapnia and/or rapid-eye movement sleep hypoventilation, non-invasive ventilation is required. Further studies are required as strong evidence is lacking regarding the long-term consequences of CSA and the long-term impact of current treatment strategies.

[Complex sleep apnea syndrome]

Complex sleep apnea syndrome (Comp-SAS) is the term used to describe a specific form of sleep disordered breathing characterized by the arise of central sleep apnea in patient with previous obstructive sleep apnea syndrome (OSAS) treated with continuous positive airway pressure devices (CPAP). The mechanisms of its occurrence are not well understood, but partly it seems to be a consequence of increased carbon dioxide elimination under positive airway pressure treatment and related improvement of pulmonary ventilation. The prevalence of Comp-SAS ranges from 5% to 20% of OSAS patient getting CPAP therapy with no significant predictors in comparison with simple obstructive sleep apnea, but more likely to happened in older males with more severe OSAS and accompanying cardiovascular pathology such as ischemic heart disease, atrial fibrillation and heart failure. In most cases of Comp-SAS, central apnea events are transient and disappear after continuous CPAP therapy use for 1 to 2 months. Novel treatment options like adaptive servo-ventilation or BiPAP-ST are available for such non-responders to CPAP but contra-indicated to patients with systolic heart failure. From the other hand, still not clear is it mandatory to treat all affected individuals with Comp-SAS if the disease is uncomplicated and patient is asymptomatic.

How to implant a phrenic nerve stimulator for treatment of central sleep apnea?

Background

Central sleep apnea (CSA) is a breathing disorder caused by the intermittent absence of central respiratory drive. Transvenous phrenic nerve stimulation is a new therapeutic option, recently approved by the FDA , for the treatment of CSA.

Objective

To describe the technique used to implant the transvenous phrenic nerve stimulation system (the remedē System, Respicardia, Inc).

Methods

The remedē System is placed in the pectoral region, typically on the right side. A single stimulation lead is placed in either the left pericardiophrenic vein (PPV) or the right brachiocephalic vein (RBC). A sensing lead is placed into the azygous vein to detect respiration.

Results

In the remedē System Pivotal trial, 147 of 151 (97%) patients were successfully implanted with the system. Sixty‐two percent of stimulation leads were placed in the PPV and 35% in the RBC. Mean procedure time was 2.7 ± 0.8 hours and 94% of patients were free from implant‐related serious adverse events through 6 months.

Conclusion

In patients with CSA, transvenous phrenic nerve stimulation is an effective and safe therapy with an implant procedure similar to that of cardiac implantable electronic devices.

Impact of Non-cardiac Comorbidities in Adults with Congenital Heart Disease: Management of Multisystem Complications

The prevalence and impact of non-cardiac comorbidities in adult patients with congenital heart disease increase over time, and these complications are often specifically a consequence of the long-term altered cardiovascular physiology or sequelae of previous therapies. For the ACHD patient admitted to the intensive care unit (ICU) for either surgical or medical treatment, an assessment of the burden of multisystem disease, as well as an understanding of the underlying cardiovascular pathophysiology, is essential for optimal management of these complex patients. This chapter takes an organ-system-based approach to reviewing common comorbidities in the ACHD patient, focusing on conditions that are directly related to ACHD status and may significantly impact ICU care.

A phenotype of increased sleepiness in a mouse model of pulmonary hypertension and right ventricular hypertrophy

The relationship between cardiovascular disease and abnormalities in sleep architecture is complex and bi-directional. Sleep disordered breathing (SDB) often confounds human studies examining sleep in the setting of heart failure, and the independent impact of isolated right or left heart failure on sleep is difficult to assess. We utilized an animal model of right heart failure using pulmonary artery banding (PAB) in mice to examine the causal effect of right heart failure on sleep architecture. Four weeks after PAB or sham (control) surgery, sleep was measured by polysomnography for 48 hours and right ventricular (RV) hypertrophy confirmed prior to sacrifice. PAB resulted in right ventricular hypertrophy based on a 30% increase in the Fulton Index (p < 0.01). After PAB, mice spent significantly more time in NREM sleep compared to the control group over a 24 hour period (53.5 ± 1.5% vs. 46.6 ± 1.4%; p < 0.01) and exhibited an inability to both cycle into REM sleep and decrease delta density across the light/sleep period. Our results support a phenotype of impaired sleep cycling and increased ‘sleepiness’ in a mouse model of RV dysfunction.

Daytime loop gain is elevated in obstructive sleep apnea but not reduced by CPAP treatment

Reduced ventilatory control stability (elevated loop gain) is a key nonanatomical, pathological trait contributing to obstructive sleep apnea (OSA), yet the mechanisms responsible remain unclear. We sought to identify the key factors contributing to elevated loop gain in OSA (controller vs. plant contributions) and to examine whether abnormalities in these factors persist after OSA treatment. In 15 males (8 OSA, 7 height, weight- and age -matched controls), we measured loop gain, controller gain, and plant gain using a pseudorandom binary CO₂ stimulation method during wakefulness. Factors potentially influencing plant gain were also assessed (supine lung volume via helium dilution and spirometry). Measures were repeated 2 and 6 wk after initiating continuous positive airway pressure treatment. Loop gain (LG) was higher in OSA versus controls (LG at 1 cycle/min 0.28 ± 0.04 vs. 0.16 ± 0.04, P = 0.046, respectively), and the controller exhibited a greater peak response to CO₂ and faster roll-off in OSA. OSA patients also exhibited reduced forced expiratory volume in the first second and forced vital capacity compared with controls (92.2 ± 1.7 vs. 102.9 ± 3.5% predicted, P = 0.021; 93.4 ± 3.1 vs. 106.6 ± 3.6% predicted, P = 0.015, respectively). There was no effect of treatment on any variable. These findings confirm loop gain is higher in untreated OSA patients than in matched controls; however, this was not affected by treatment. NEW & NOTEWORTHY Elevated loop gain contributes to obstructive sleep apnea (OSA) pathophysiology. However, whether loop gain is inherently elevated in OSA or induced by OSA itself, whether it is elevated due to increased chemoreflex sensitivity or obesity-dependent reduced lung volume, and whether it is treatment reversible, are all currently uncertain. This study found loop gain was elevated in OSA versus age-, sex-, height-, and weight-matched controls. However, this was not altered by 6-wk continuous positive airway pressure treatment.

Sleep-disordered breathing in patients with cardiovascular diseases cannot be detected by ESS, STOP-BANG, and Berlin questionnaires

Sleep-disordered breathing (SDB) is highly prevalent in patients with cardiovascular diseases (CVD) and associated with poor outcome. At least 50% of heart failure (HF) patients present with SDB, equally divided in obstructive sleep apnea (OSA) and central sleep apnea (CSA). CVD patients with SDB do not always present with typical SDB symptoms. Therefore, we asked whether established questionnaires allow for the reliable detection of SDB. In this prospective cohort study, 89 CVD patients (54 male, 59 ± 15 years, BMI 30 ± 6 kg/m²) in stable clinical state underwent an ambulatory polygraphy. SDB was defined as an apnea-hypopnea index (AHI) ≥ 15/h. We evaluated the Epworth Sleepiness Scale (ESS), STOP-BANG and Berlin questionnaires as well as anthropometric data and comorbidities regarding their ability to predict SDB. The ESS showed no correlation with SDB. The sensitivity of the Berlin Questionnaire to detect SDB was 73%, specificity was 42%. The STOP-BANG questionnaire showed a sensitivity of 97% while specificity was 13%. Coronary heart disease and/or history of myocardial infarction, hyperuricemia and age significantly contributed to a logistic regression model predicting presence of SDB. However, our regression model explains only 36% of the variance regarding the presence or absence of SDB. The approach to find variables, which would allow an early and reliable differentiation between patients with CVD and coexistence or absence of SDB, failed. Thus, as CVD patients show a high SDB prevalence and poor outcome, only a systematic screening based on measures of respiration-related parameters (i.e., respiratory flow, blood oxygen saturation, etc.) allows for a reliable SDB assessment.

Characteristics and circadian distribution of cardiac arrhythmias in patients with heart failure and sleep-disordered breathing

BACKGROUND

Cardiac arrhythmias and sleep-disordered breathing (SDB) are common comorbidities in heart failure with reduced ejection fraction (HFrEF). However, understanding of the association between arrhythmias and SDB is poor. This study assessed the occurrence and circadian distribution of ventricular arrhythmias in HFrEF patients with and without SDB.

METHODS

This retrospective analysis included HFrEF patients admitted for unattended overnight cardiorespiratory polygraphy and 24-h Holter-ECG recording. Holter-ECG data (events/h) were categorized by time of day: morning, 06:00-13:59; afternoon, 14:00-21:59; nighttime, 22:00-05:59. Respiratory events were expressed using the apnea-hypopnea index (AHI) and an AHI ≥ 15/h was categorized as moderate to severe SDB.

RESULTS

167 patients were included (82% male, age 65 ± 10.4 years, left ventricular ejection fraction 30.9 ± 7.9%); SDB was predominantly central sleep apnea (CSA) in 45.5%, obstructive sleep apnea (OSA) in 23.9% or none/mild (nmSDB) in 17.4%. Morning premature ventricular contractions (PVCs) were detected significantly more frequently in CSA versus nmSDB patients (44.4/h versus 1.8/h; p = 0.02). Non-sustained VT was more frequent in patients with CSA versus versus OSA or nmSDB (17.9 versus 3.2 or 3.2%/h; p = 0.003 and p = 0.005, respectively). There was no significant variation in VT occurrence by time of day in HFrEF patients with CSA (p = 0.3). CSA was an independent predictor of VT occurrence in HFrEF in multivariate logistic regression analysis (odds ratio 4.1, 95% confidence interval 1.5-11.4, p = 0.007).

CONCLUSION

CSA was associated with VT occurrence irrespective of sleep/wake status in HFrEF patients, and independently predicted the occurrence of VT. This association may contribute to chances by which CSA increases sudden death risk in HFrEF patients.

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.

Sleep Apnea: Types, Mechanisms, and Clinical Cardiovascular Consequences

Sleep apnea is highly prevalent in patients with cardiovascular disease. These disordered breathing events are associated with a profile of perturbations that include intermittent hypoxia, oxidative stress, sympathetic activation, and endothelial dysfunction, all of which are critical mediators of cardiovascular disease. Evidence supports a causal association of sleep apnea with the incidence and morbidity of hypertension, coronary heart disease, arrhythmia, heart failure, and stroke. Several discoveries in the pathogenesis, along with developments in the treatment of sleep apnea, have accumulated in recent years. In this review, we discuss the mechanisms of sleep apnea, the evidence that addresses the links between sleep apnea and cardiovascular disease, and research that has addressed the effect of sleep apnea treatment on cardiovascular disease and clinical endpoints. Finally, we review the recent development in sleep apnea treatment options, with special consideration of treating patients with heart disease. Future directions for selective areas are suggested.

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.