Sleep apnoea in heart failure: To treat or not to treat?

Effect of SGLT2-Inhibitors on Polygraphic Parameters in Elderly Patients Affected by Heart Failure, Type 2 Diabetes Mellitus, and Sleep Apnea

Obstructive sleep apneas (OSAs) and central sleep apneas (CSAs) are the most common comorbidities in Heart Failure (HF) that are strongly associated with all-cause mortality. Several therapeutic approaches have been used to treat CSA and OSA, but none have been shown to significantly improve HF prognosis. Our study evaluated the effects of a 3-months treatment with sodium-glucose cotransporter type 2 inhibitor (SGLT2i) on polygraphic parameters in patients with sleep apnea (SA) and HF, across the spectrum of ejection fraction, not treated with continuous positive air pressure (CPAP). A group of 514 consecutive elderly outpatients with HF, type 2 diabetes mellitus (T2DM) and SA, eligible for treatment with SGLT2i, were included in the investigation before starting any CPAP therapy. The two groups were compared with the t-test and Mann-Whitney test for unpaired data when appropriate. Then, a simple logistic regression model was built using 50% reduction in AHI as the dependent variable and other variables as covariates. A multivariate stepwise logistic regression model was constructed using the variables that linked with the dependent variable to calculate the odds ratio (OR) for the independent predictors associated with the reduction of 50% in AHI. The treated group experienced significant improvements in polygraphic parameters between baseline values and follow-up with reduction in AHI (28.4 ± 12.9 e/h vs. 15.2 ± 6.5 e/h; p < 0.0001), ODI (15.4 ± 3.3 e/h vs. 11.1 ± 2.6 e/h; p < 0.0001), and TC90 (14.1 ± 4.2% vs. 8.2 ± 2.0%; p < 0.0001), while mean SpO2 improved (91. 3 ± 2.3 vs. 93.8 ± 2.5); p < 0.0001. These benefits were not seen in the untreated population. The use of SGLT2i in patients suffering from HF and mixed-type SA not on CPAP therapy significantly contributes to improving polygraphic parameters.

The Autonomic Coumel Triangle: A New Way to Define the Fascinating Relationship between Atrial Fibrillation and the Autonomic Nervous System

Arrhythmogenic substrate, modulating factors, and triggering factors (the so-called Coumel's triangle concept) play a primary role in atrial fibrillation (AF) pathophysiology. Several years have elapsed since Coumel and co-workers advanced the concept of the relevance of autonomic nervous system (ANS) influences on atrial cells' electrophysiological characteristics. The ANS is not only associated with cardiac rhythm regulation but also exerts an important role in the triggering and maintenance of atrial fibrillation. This review aims to describe in detail the autonomic mechanisms involved in the pathophysiology of atrial fibrillation (AF), starting from the hypothesis of an "Autonomic Coumel Triangle" that stems from the condition of the fundamental role played by the ANS in all phases of the pathophysiology of AF. In this article, we provide updated information on the biomolecular mechanisms of the ANS role in Coumel's triangle, with the molecular pathways of cardiac autonomic neurotransmission, both adrenergic and cholinergic, and the interplay between the ANS and cardiomyocytes' action potential. The heterogeneity of the clinical spectrum of the ANS and AF, with the ANS playing a relevant role in situations that may promote the initiation and maintenance of AF, is highlighted. We also report on drug, biological, and gene therapy as well as interventional therapy. On the basis of the evidence reviewed, we propose that one should speak of an "Autonomic Coumel's Triangle" instead of simply "Coumel's Triangle".

Vagal milieu or electrophysiologic substrate? The link between atrial fibrillation and obstructive sleep apnea

Atrial fibrillation is the most common cardiac arrhythmia with its prevalence expected to increase to 12.1 million people in the United States by 2030. Chronic underlying conditions that affect the heart and lungs predispose patients to develop atrial fibrillation. Obstructive sleep apnea is strongly associated with atrial fibrillation. Several pathophysiological mechanisms have been proposed to elucidate this relationship which includes electrophysiological substrate modification and the contribution of the autonomic nervous system. In this comprehensive review, we highlight important relationships and plausible causality between obstructive sleep apnea and atrial fibrillation which will improve our understanding in the evaluation, management, and prevention of atrial fibrillation. This is the most updated comprehensive review of the relationship between obstructive sleep apnea and atrial fibrillation.

Practice recommendations for the role of physiotherapy in the management of sleep disorders: the 2022 Brazilian Sleep Association Guidelines

This clinical guideline supported by the Brazilian Sleep Association comprises a brief history of the development of Brazilian sleep physiotherapy, outlines the role of the physiotherapist as part of a sleep health team, and describes the clinical guidelines in respect of the management of some sleep disorders by the physiotherapist (including sleep breathing disorders, i.e., obstructive sleep apnea, central sleep apnea, upper airway resistance syndrome, hypoventilation syndromes and overlap syndrome, and pediatric sleep breathing disorders; sleep bruxism; circadian rhythms disturbances; insomnia; and Willis-Ekbom disease/periodic limb movement disorder. This clinical practice guideline reflects the state of the art at the time of publication and will be reviewed and updated as new information becomes available.

Cheyne-stokes respiration in children with heart failure

Cheyne-Stokes respiration (CSA-CSR) is a form of central sleep apnea characterized by alternating periods of hyperventilation and central apneas or hypopneas. CSA-CSR develops following a cardiac insult resulting in a compensatory increase in sympathetic activity, which in susceptible patients causes hyperventilation and destabilizes respiratory control. The physiological changes that occur in CSA-CSR include hyperventilation, a reduced blood gas buffering capacity, and circulatory delay. In adults, 25% to 50% of patients with heart failure are reported to have CSA-CSR. The development of CSA-CSR in this group of patients is considered a poor prognostic sign. The prevalence, progression, and treatment outcomes of CSA-CSR in children remain unclear with only 11 children being described in the literature. The lack of data is possibly not due to the paucity of children with severe heart failure and CSA-CSR but because they may be under-recognized, compounded by the absence of routine polysomnographic assessment of children with moderate to severe heart failure. Building on much broader experience in the diagnosis and management of CSA-CSR in adult sleep medicine and our limited experience in a pediatric quaternary center, this paper will discuss the prevalence of CSA-CSR, its' treatment options, outcomes in children, and the potential future direction for research in this understudied area of pediatric sleep medicine.

Effects of Sacubitril-Valsartan on Clinical, Echocardiographic, and Polygraphic Parameters in Patients Affected by Heart Failure With Reduced Ejection Fraction and Sleep Apnea

Background

Heart failure with reduced ejection fraction (HFrEF) is a clinical condition frequently diagnosed in clinical practice. In patients affected by HFrEF, sleep apnea (SA) can be detected among the most frequent comorbidities. Sacubitril–valsartan (sac/val) association has been proven to be effective in reducing disease progression and all-cause mortality in HFrEF patients. Sac/val treatment can potentially attenuate SA development via several pathophysiologic mechanisms, including improvement of global hemodynamics, reduction of extracellular fluid overload, and decrease of sympathetic neural activity.

Methods

We recruited 132 patients affected by HFrEF and SA, already under treatment with continuous positive airway pressure (CPAP), which was discontinued 24 h before the scheduled study timepoints. Physical examination, echocardiography, nocturnal cardio-respiratory monitoring, and laboratory tests were performed in each patient at baseline and after a 6-month treatment with sac/val.

Results

After 6 months, sac/val induced statistically significant changes in clinical, hemodynamic, biohumoral (NT-proBNP, serum electrolytes, creatinine, and uric acid), and echocardiographic parameters. In particular, cardiac index (CI), both atrial and ventricular volumes and global longitudinal strain (GLS) improved. Moreover, polysomnography, carried out during a temporary CPAP interruption, revealed a significant reduction in global apnea-hypopnea index (AHI) value (p < 0.0001), central AHI (p < 0.0001), obstructive AHI (p < 0.0001), oxygen desaturation index (ODI) (p < 0.0001), and percentage time of saturation below 90% (TC90) (p < 0.0001). The changes of CI, estimated glomerular filtration rate (eGFR), NT-proBNP, and tricuspid annular plane excursion (TAPSE) contributed to 23.6, 7.6, 7.3, and 4.8% of AHI variability, respectively, and the whole model accounted for a 43.3% of AHI variation.

Conclusions

Our results suggest that treatment with sac/val is able to significantly improve the cardiorespiratory performance of patients with HFrEF and SA, integrating the positive impact of CPAP. Thus, both CPAP and sac/val therapy may synergistically contribute to lower the risks of both cardiac and pulmonary complications in HFrEF patients with SA.

Management of Obstructive Sleep Apnea in Patients With Heart Failure

Sleep apnea is traditionally classified as obstructive sleep apnea (OSA), which occurs when the upper airway collapses due to the relaxation of oropharyngeal musculature, and central sleep apnea occurs when the brainstem cannot stimulate breathing. Most sleep apnea in patients with heart failure (HF) results from coexisting OSA and central sleep apnea (CSA), or complex sleep apnea syndrome. OSA and CSA are common in HF and can be involved in its progression by exposure to the heart to intermittent hypoxia, increased preload and afterload, activating sympathetic, and decreased vascular endothelial function. A majority of treatments have been investigated in patients with CSA and HF; however, less or short-term randomized trials demonstrated whether treating OSA in patients with HF could improve morbidity and mortality. OSA could directly influence the patient's recovery. This review will focus on past and present studies on the various therapies for OSA in patients with HF and summarize CSA treatment options for reasons of reference and completeness. More specifically, the treatment covered include surgical and non-surgical treatments and reported the positive and negative consequences for these treatment options, highlighting possible implications for clinical practice and future research directions.

Sleep Apnea Syndrome (SAS) Clinical Practice Guidelines 2020

The prevalence of sleep disordered breathing (SDB) is reportedly very high. Among SDBs, the incidence of obstructive sleep apnea (OSA) is higher than previously believed, with patients having moderate-to-severe OSA accounting for approximately 20% of adult males and 10% of postmenopausal women not only in Western countries but also in Eastern countries, including Japan. Since 1998, when health insurance coverage became available, the number of patients using continuous positive airway pressure (CPAP) therapy for sleep apnea has increased sharply, with the number of patients about to exceed 500,000 in Japan. Although the "Guidelines for Diagnosis and Treatment of Sleep Apnea Syndrome (SAS) in Adults" was published in 2005, a new guideline was prepared in order to indicate the standard medical care based on the latest trends, as supervised by and in cooperation with the Japanese Respiratory Society and the "Survey and Research on Refractory Respiratory Diseases and Pulmonary Hypertension" Group, of Ministry of Health, Labor and Welfare and other related academic societies, including the Japanese Society of Sleep Research, in addition to referring to the previous guidelines. Because sleep apnea is an interdisciplinary field covering many areas, this guideline was prepared including 36 clinical questions (CQs). In the English version, therapies and managements for SAS, which were written from CQ16 to 36, were shown. The Japanese version was published in July 2020 and permitted as well as published as one of the Medical Information Network Distribution Service (Minds) clinical practice guidelines in Japan in July 2021.

Sleep Apnea Syndrome (SAS) Clinical Practice Guidelines 2020

The prevalence of sleep-disordered breathing (SDB) is reportedly very high. Among SDBs, the incidence of obstructive sleep apnea (OSA) is higher than previously believed, with patients having moderate-to-severe OSA accounting for approximately 20% of adult males and 10% of postmenopausal women not only in Western countries but also in Eastern countries, including Japan. Since 1998, when health insurance coverage became available, the number of patients using continuous positive airway pressure (CPAP) therapy for sleep apnea has increased sharply, with the number of patients about to exceed 500,000 in Japan. Although the "Guidelines for Diagnosis and Treatment of Sleep Apnea Syndrome (SAS) in Adults" was published in 2005, a new guideline was prepared to indicate the standard medical care based on the latest trends, as supervised by and in cooperation with the Japanese Respiratory Society and the "Survey and Research on Refractory Respiratory Diseases and Pulmonary Hypertension" Group, of Ministry of Health, Labor and Welfare and other related academic societies, including the Japanese Society of Sleep Research, in addition to referring to the previous guidelines. Since sleep apnea is an interdisciplinary field covering many areas, this guideline was prepared including 36 clinical questions (CQs). In the English version, therapies and managements for SAS, which were written from CQ16 to 36, were shown. The Japanese version was published in July 2020 and permitted as well as published as one of the Medical Information Network Distribution Service (Minds) clinical practice guidelines in Japan in July 2021.

Characterizing respiratory parameters, settings, and adherence in real-world patients using adaptive servo ventilation therapy: big data analysis

STUDY OBJECTIVES

There is minimal guidance around how to optimize inspiratory positive airway pressure (IPAP) levels during use of adaptive servo ventilation (ASV) in clinical practice. This real-world data analysis investigated the effects of IPAP and minimum pressure support settings on respiratory parameters and adherence in ASV-treated patients.

METHODS

A United States-based telemonitoring database was queried for patients starting ASV between August 1, 2014 and November 30, 2019. Patients meeting the following criteria were included: United States-based patients aged ≥ 18 years; AirCurve 10 device (ResMed); and ≥ 1 session with usage of ≥ 1 hour in the first 90 days. Key outcomes were mask leak and residual apnea-hypopnea index at different IPAP settings, adherence and therapy termination rates, and respiratory parameters at different minimum pressure support settings.

RESULTS

There were 63,996 patients included. Higher IPAP was associated with increased residual apnea-hypopnea index and mask leak but did not impact device usage per session (average > 6 h/day at all IPAP settings; 6.7 h/day at 95th percentile IPAP 25 cm H2O). There were no clinically relevant differences in respiratory rate, minute ventilation, leak, and residual apnea-hypopnea index across all possible minimum pressure support settings. Patients with a higher 95th percentile IPAP or with minimum pressure support of 3 cm H2O were most likely to remain on ASV therapy at 1 year.

CONCLUSIONS

Our findings showed robust levels of longer-term adherence to ASV therapy in a large group of real-world patients. There were no clinically important differences in respiratory parameters across a range of pressure and pressure support settings. Future work should focus on the different phenotypes of patients using ASV therapy.

CITATION

Malhotra A, Benjafield AV, Cistulli PA, et al. Characterizing respiratory parameters, settings, and adherence in real-world patients using adaptive servo ventilation therapy: big data analysis. J Clin Sleep Med. 2021;17(12):2355-2362.

Sleep-Disordered Breathing and Nocturnal Hypoxemia in Precapillary Pulmonary Hypertension: Prevalence, Pathophysiological Determinants, and Clinical Consequences

BACKGROUND AND OBJECTIVE

The clinical relevance and interrelation of sleep-disordered breathing and nocturnal hypoxemia in patients with precapillary pulmonary hypertension (PH) is not fully understood.

METHODS

Seventy-one patients with PH (age 63 ± 15 years, 41% male) and 35 matched controls were enrolled. Patients with PH underwent clinical examination with assessment of sleep quality, daytime sleepiness, 6-minute walk distance (6MWD), overnight cardiorespiratory polygraphy, lung function, hypercapnic ventilatory response (HCVR; by rebreathing technique), amino-terminal pro-brain natriuretic peptide (NT-proBNP) levels, and cardiac MRI (n = 34).

RESULTS

Prevalence of obstructive sleep apnea (OSA) was 68% in patients with PH (34% mild, apnea-hypopnea index [AHI] ≥5 to <15/h; 34% moderate to severe, AHI ≥15/h) versus 5% in controls (p < 0.01). Only 1 patient with PH showed predominant central sleep apnea (CSA). Nocturnal hypoxemia (mean oxygen saturation [SpO2] <90%) was present in 48% of patients with PH, independent of the presence of OSA. There were no significant differences in mean nocturnal SpO2, self-reported sleep quality, 6MWD, HCVR, and lung and cardiac function between patients with moderate to severe OSA and those with mild or no OSA (all p > 0.05). Right ventricular (RV) end-diastolic (r = -0.39; p = 0.03) and end-systolic (r = -0.36; p = 0.04) volumes were inversely correlated with mean nocturnal SpO2 but not with measures of OSA severity or daytime clinical variables.

CONCLUSION

OSA, but not CSA, is highly prevalent in patients with PH, and OSA severity is not associated with nighttime SpO2, clinical and functional status. Nocturnal hypoxemia is a frequent finding and (in contrast to OSA) relates to structural RV remodeling in PH.

Validating respiratory index of auto-titrating positive airway pressure device with polysomnography

PURPOSE

Positive airway pressure (PAP) devices have been widely used as the first line of treatment in obstructive sleep apnea (OSA). Most advanced PAP devices support the estimation of respiratory index (RI) using the patient's mask airflow. In addition to the compliance factor for PAP device use, which is important for monitoring patient sleep health, RI is also becoming important for monitoring. However, there are few reports that validate RI of a PAP device with polysomnography.

METHODS

Between January 2015 and December 2017, 50 participants were enrolled who were diagnosed with OSA and prescribed auto-titration PAP (APAP) devices. The RIs of participants were measured at night using APAP devices, concurrently with electroencephalography, respiratory inductance plethysmography sensors, and other polysomnographic sensors in a sleep laboratory. The respiratory-related data of APAP were prospectively analyzed with the manually scored polysomnographic data.

RESULTS

The apnea-hypopnea index and apnea index showed a statistically close relationship between the auto-scored respiratory data from the APAP device and the manually scored respiratory data from polysomnographic sensors. Obstructive apnea and central apnea indices showed relatively low correlations. The differences between the auto-scored RI and manually scored RI were influenced by BMI, waist circumference, weight, oxygen saturation, and respiratory distress indices of diagnostic polysomnographic factors.

CONCLUSIONS

The RIs of APAP devices have a tendency to be underestimated or mismatched when compared with polysomnography. Sleep specialists are advised to consider additional anthropometric and diagnostic factors to account for these differences during PAP treatment.

Positive airway pressure therapy for the treatment of central sleep apnoea associated with heart failure

BACKGROUND

Ischaemic heart disease including heart failure is the most common cause of death in the world, and the incidence of the condition is rapidly increasing. Heart failure is characterised by symptoms such as fatigue and breathlessness during light activity, as well as disordered breathing during sleep. In particular, sleep disordered breathing (SDB), including central sleep apnoea (CSA) and obstructive sleep apnoea (OSA), is highly prevalent in people with chronic heart failure. A previous meta-analysis demonstrated that positive airway pressure (PAP) therapy dramatically increased the survival rate of people with heart failure who had CSA, and thus could contribute to improving the prognosis of these individuals. However, recent trials found that adaptive servo-ventilation (ASV) including PAP therapy had a higher risk of all-cause mortality and cardiovascular mortality. A meta-analysis that included recent trials was therefore needed.

OBJECTIVES

To assess the effects of positive airway pressure therapy for people with heart failure who experience central sleep apnoea.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE, Embase, and Web of Science Core Collection on 7 February 2019 with no limitations on date, language, or publication status. We also searched two clinical trials registers in July 2019 and checked the reference lists of primary studies.

SELECTION CRITERIA

We excluded cross-over trials and included individually randomised controlled trials, reported as full-texts, those published as abstract only, and unpublished data.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted outcome data from the included studies. We double-checked that data had been entered correctly by comparing the data presented in the systematic review with study reports. We analysed dichotomous data as risk ratios (RRs) with 95% confidence intervals (CIs) and continuous data as mean difference (MD) or standardised mean difference (SMD) with 95% CIs. Furthermore, we performed subgroup analysis in the ASV group or continuous PAP group separately. We used GRADEpro GDT software to assess the quality of evidence as it relates to those studies that contribute data to the meta-analyses for the prespecified outcomes.

MAIN RESULTS

We included 16 randomised controlled trials involving a total of 2125 participants. The trials evaluated PAP therapy consisting of ASV or continuous PAP therapy for 1 to 31 months. Many trials included participants with heart failure with reduced ejection fraction. Only one trial included participants with heart failure with preserved ejection fraction. We are uncertain about the effects of PAP therapy on all-cause mortality (RR 0.81, 95% CI 0.54 to 1.21; participants = 1804; studies = 6; I² = 47%; very low-quality evidence). We found moderate-quality evidence of no difference between PAP therapy and usual care on cardiac-related mortality (RR 0.97, 95% CI 0.77 to 1.24; participants = 1775; studies = 5; I² = 11%). We found low-quality evidence of no difference between PAP therapy and usual care on all-cause rehospitalisation (RR 0.95, 95% CI 0.70 to 1.30; participants = 1533; studies = 5; I² = 40%) and cardiac-related rehospitalisation (RR 0.97, 95% CI 0.70 to 1.35; participants = 1533; studies = 5; I² = 40%). In contrast, PAP therapy showed some indication of an improvement in quality of life scores assessed by all measurements (SMD -0.32, 95% CI -0.67 to 0.04; participants = 1617; studies = 6; I² = 76%; low-quality evidence) and by the Minnesota Living with Heart Failure Questionnaire (MD -0.51, 95% CI -0.78 to -0.24; participants = 1458; studies = 4; I² = 0%; low-quality evidence) compared with usual care. Death due to pneumonia (N = 1, 3% of PAP group); cardiac arrest (N = 18, 3% of PAP group); heart transplantation (N = 8, 1% of PAP group); cardiac worsening (N = 3, 9% of PAP group); deep vein thrombosis/pulmonary embolism (N = 1, 3% of PAP group); and foot ulcer (N = 1, 3% of PAP group) occurred in the PAP therapy group, whereas cardiac arrest (N = 16, 2% of usual care group); heart transplantation (N = 12, 2% of usual care group); cardiac worsening (N = 5, 14% of usual care group); and duodenal ulcer (N = 1, 3% of usual care group) occurred in the usual care group across three trials.

AUTHORS' CONCLUSIONS

The effect of PAP therapy on all-cause mortality was uncertain. In addition, although we found evidence that PAP therapy did not reduce the risk of cardiac-related mortality and rehospitalisation, there was some indication of an improvement in quality of life for heart failure patients with CSA. Furthermore, the evidence was insufficient to determine whether adverse events were more common with PAP than with usual care. These findings were limited by low- or very low-quality evidence. PAP therapy may be worth considering for individuals with heart failure to improve quality of life.

Sleep Disturbances in the Elderly Patient with Inflammatory Bowel Disease

PURPOSE OF REVIEW

Studies have suggested that sleep and inflammatory bowel disease (IBD) appear to have an important bi-directional relationship, where active disease promotes sleep disruption and poor sleep promotes ongoing and worsening inflammation. In the geriatric population, poor sleep has been linked to increasing morbidity and mortality. The etiologies of poor sleep in the elderly are multifactorial and are understood to be a part of the geriatric syndromes, conditions in the elderly associated with poorer mortality and morbidity. We review the current literature regarding the common sources of sleep disturbances in the geriatric population and, by extension, the growing population of elderly patients with IBD.

RECENT FINDINGS

There is a high prevalence of sleep dysfunction in patients with inflammatory bowel disease, not only in patients in disease remission but also in patients with active disease. Poor sleep has been suggested a potential marker of ongoing subclinical inflammation, and sleep disturbances are linked to poorer outcomes in patients with IBD. Management of inflammation appears to improve fatigue symptoms but is not linked with the elimination of symptoms. Thus, alternative etiologies of poor sleep, especially in the geriatric population, include chronic medical conditions with polypharmacy, co-morbid mood disorders, and primary disorders of sleep. Sleep disturbances in the elderly patient with IBD are related to multiple etiologies. Poor sleep is linked to both worse disease-specific outcomes and higher morbidity and mortality. Coordination of care with geriatricians, mental health professionals, and sleep specialists is often required to target the appropriate cause. We provide an etiological framework in the assessment of poor sleep in the elderly patient with IBD.

Sleep Apnea and Cardiovascular Disease: An Enigmatic Risk Factor

Synchronization of molecular, metabolic, and cardiovascular circadian oscillations is fundamental to human health. Sleep-disordered breathing, which disrupts such temporal congruence, elicits hemodynamic, autonomic, chemical, and inflammatory disturbances with acute and long-term consequences for heart, brain, and circulatory and metabolic function. Sleep apnea afflicts a substantial proportion of adult men and women but is more prevalent in those with established cardiovascular diseases and especially fluid-retaining states. Despite the experimental, epidemiological, observational, and interventional evidence assembled in support of these concepts, this substantial body of work has had relatively modest pragmatic impact, thus far, on the discipline of cardiology. Contemporary estimates of cardiovascular risk still are derived typically from data acquired during wakefulness. The impact of sleep-related breathing disorders rarely is entered into such calculations or integrated into diagnostic disease-specific algorithms or therapeutic recommendations. Reasons for this include absence of apnea-related symptoms in most with cardiovascular disease, impediments to efficient diagnosis at the population level, debate as to target, suboptimal therapies, difficulties mounting large randomized trials of sleep-specific interventions, and the challenging results of those few prospective cardiovascular outcome trials that have been completed and reported. The objectives of this review are to delineate the bidirectional interrelationship between sleep-disordered breathing and cardiovascular disease, consider the findings and implications of observational and randomized trials of treatment, frame the current state of clinical equipoise, identify principal current controversies and potential paths to their resolution, and anticipate future directions.

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.

Factors Associated with Cheyne-Stokes Respiration in Acute Ischemic Stroke

Background and Purpose

Cheyne-Stokes respiration (CSR) is frequently observed in patients with acute stroke. There have been conflicting opinions about the associations of CSR with the location and size of the lesion. We aimed to better define the clinical relevance and pathogenesis of CSR in acute stroke.

Methods

We investigated patients who had been admitted with acute ischemic stroke and received an overnight sleep apnea test. We collected data on demographics, risk factors, etiologic subtypes, initial vital signs, clinical course of the stroke, and parameters associated with respiratory events during the sleep apnea test. We performed a multivariate logistic regression analysis to determine the factors associated with CSR.

Results

Among 182 patients, 35 patients showed CSR in sleep apnea testing. Large-artery atherosclerosis or cardioembolism, bilateral hemispheric involvement, atrial fibrillation, low left-ventricle ejection fraction (LVEF), and left atrium (LA) enlargement were all associated with the presence of CSR. Multivariate analysis revealed that the previous modified Rankin Scale (mRS) score, bilateral hemispheric involvement, low LVEF, and LA enlargement were significantly associated with CSR. Subgroup analysis with large-artery atherosclerosis without cardiac disease revealed that the previous mRS score is the only independent factor associated with CSR.

Conclusions

CSR frequently occurs in strokes involving large arteries or due to cardioembolism, regardless of the location and severity of the stroke. Predisposing conditions such as preexisting neurologic disability, low LVEF, and LA enlargement are associated with CSR in acute stroke.

Sleep Apnea and Cardiovascular Disease: Lessons From Recent Trials and Need for Team Science

Emerging research highlights the complex interrelationships between sleep-disordered breathing and cardiovascular disease, presenting clinical and research opportunities as well as challenges. Patients presenting to cardiology clinics have a high prevalence of obstructive and central sleep apnea associated with Cheyne-Stokes respiration. Multiple mechanisms have been identified by which sleep disturbances adversely affect cardiovascular structure and function. Epidemiological research indicates that obstructive sleep apnea is associated with increases in the incidence and progression of coronary heart disease, heart failure, stroke, and atrial fibrillation. Central sleep apnea associated with Cheyne-Stokes respiration predicts incident heart failure and atrial fibrillation; among patients with heart failure, it strongly predicts mortality. Thus, a strong literature provides the mechanistic and empirical bases for considering obstructive sleep apnea and central sleep apnea associated with Cheyne-Stokes respiration as potentially modifiable risk factors for cardiovascular disease. Data from small trials provide evidence that treatment of obstructive sleep apnea with continuous positive airway pressure improves not only patient-reported outcomes such as sleepiness, quality of life, and mood but also intermediate cardiovascular end points such as blood pressure, cardiac ejection fraction, vascular parameters, and arrhythmias. However, data from large-scale randomized controlled trials do not currently support a role for positive pressure therapies for reducing cardiovascular mortality. The results of 2 recent large randomized controlled trials, published in 2015 and 2016, raise questions about the effectiveness of pressure therapies in reducing clinical end points, although 1 trial supported the beneficial effect of continuous positive airway pressure on quality of life, mood, and work absenteeism. This review provides a contextual framework for interpreting the results of recent studies, key clinical messages, and suggestions for future sleep and cardiovascular research, which include further consideration of individual risk factors, use of existing and new multimodality therapies that also address adherence, and implementation of trials that are sufficiently powered to target end points and to support subgroup analyses. These goals may best be addressed through strengthening collaboration among the cardiology, sleep medicine, and clinical trial communities.

Heart-Rate Variability-More than Heart Beats?

Heart-rate variability (HRV) is frequently introduced as mirroring imbalances within the autonomous nerve system. Many investigations are based on the paradigm that increased sympathetic tone is associated with decreased parasympathetic tone and vice versa. But HRV is probably more than an indicator for probable disturbances in the autonomous system. Some perturbations trigger not reciprocal, but parallel changes of vagal and sympathetic nerve activity. HRV has also been considered as a surrogate parameter of the complex interaction between brain and cardiovascular system. Systems biology is an inter-disciplinary field of study focusing on complex interactions within biological systems like the cardiovascular system, with the help of computational models and time series analysis, beyond others. Time series are considered surrogates of the particular system, reflecting robustness or fragility. Increased variability is usually seen as associated with a good health condition, whereas lowered variability might signify pathological changes. This might explain why lower HRV parameters were related to decreased life expectancy in several studies. Newer integrating theories have been proposed. According to them, HRV reflects as much the state of the heart as the state of the brain. The polyvagal theory suggests that the physiological state dictates the range of behavior and psychological experience. Stressful events perpetuate the rhythms of autonomic states, and subsequently, behaviors. Reduced variability will according to this theory not only be a surrogate but represent a fundamental homeostasis mechanism in a pathological state. The neurovisceral integration model proposes that cardiac vagal tone, described in HRV beyond others as HF-index, can mirror the functional balance of the neural networks implicated in emotion-cognition interactions. Both recent models represent a more holistic approach to understanding the significance of HRV.

Monitoring mandibular movements to detect Cheyne-Stokes Breathing

Background

The patterns of mandibular movements (MM) during sleep can be used to identify increased respiratory effort periodic large-amplitude MM (LPM), and cortical arousals associated with “sharp” large-amplitude MM (SPM). We hypothesized that Cheyne Stokes breathing (CSB) may be identified by periodic abnormal MM patterns. The present study aims to evaluate prospectively the concordance between CSB detected by periodic MM and polysomnography (PSG) as gold-standard.

The present study aims to evaluate prospectively the concordance between CSB detected by periodic MM and polysomnography (PSG) as gold-standard.

Methods

In 573 consecutive patients attending an in-laboratory PSG for suspected sleep disordered breathing (SDB), MM signals were acquired using magnetometry and scored manually while blinded from the PSG signal. Data analysis aimed to verify the concordance between the CSB identified by PSG and the presence of LPM or SPM. The data were randomly divided into training and validation sets (985 5-min segments/set) and concordance was evaluated using 2 classification models.

Results

In PSG, 22 patients (mean age ± SD: 65.9 ± 15.0 with a sex ratio M/F of 17/5) had CSB (mean central apnea hourly indice ± SD: 17.5 ± 6.2) from a total of 573 patients with suspected SDB. When tested on independent subset, the classification of CSB based on LPM and SPM is highly accurate (Balanced-accuracy = 0.922, sensitivity = 0.922, specificity = 0.921 and error-rate = 0.078). Logistic models based odds-ratios for CSB in presence of SPM or LPM were 172.43 (95% CI: 88.23–365.04; p < 0.001) and 186.79 (95% CI: 100.48–379.93; p < 0.001), respectively.

Conclusion

CSB in patients with sleep disordered breathing could be accurately identified by a simple magnetometer device recording mandibular movements.

Ginsenoside Rb1 improves cardiac function and remodeling in heart failure

We investigated the effect of ginsenoside Rb1 on cardiac function and remodeling in heart failure (HF). Four weeks after HF induction, the rats were administrated with ginsenoside Rb1 (35 and 70 mg/kg) and losartan (4.5 mg/kg) for 8 weeks. Losartan was used as a positive control. Cardiac function was assessed by measuring hemodynamic parameters. Histological changes were analyzed by HE and Masson’s trichrome staining. Cardiac hypertrophy, fibrosis, mitochondrial membrane potential and glucose transporter type 4 (GLUT4) levels were evaluated. In the present study, high dose of (H−) ginsenoside Rb1 decreased heart rate, improved cardiac function and alleviated histological changes induced by HF. H-ginsenoside Rb1 attenuated cardiac hypertrophy and myocardial fibrosis by decreasing left ventricular (LV) weight/heart weight ratio and cardiomyocyte cross-sectional area and reducing the levels of atrial natriuretic factor (ANF), β-myosin heavy chain (β-MHC), periostin, collagen I, Angiotensin II (Ang II), Angiotensin converting enzyme (ACE) and Ang II type 1 (AT1) receptor. Moreover, H-ginsenoside Rb1 decreased mitochondrial membrane potential and enhanced the translocation of GLUT4 to plasma membrane. The TGF-β1/Smad and ERK signaling pathways were inhibited and the Akt pathway was activated. These findings suggest that ginsenoside Rb1 might restore cardiac/mitochondrial function, increase glucose uptake and protect against cardiac remodeling via the TGF-β1/Smad, ERK and Akt signaling pathways.