Cardiac resynchronization therapy for the treatment of sleep apnoea: a meta-analysis

Severe sleep apnea as a predictor of failure to respond to cardiac resynchronization therapy

BACKGROUND

The response to cardiac resynchronization therapy (CRT) is suboptimal in one-third of patients.

OBJECTIVES

The study aimed to evaluate the impact of sleep-disordered breathing (SDB) on the CRT-induced left ventricular (LV) reverse remodeling and response for CRT in patients with ischemic congestive heart failure (CHF).

METHODS

A total of 37 patients aged 65.43 years (SD 6.05), seven of whom were females, were treated with CRT according to class I European Society of Cardiology recommendations. Clinical evaluation, polysomnography, and contrast echocardiography were performed twice during the six-month follow-up (6M-FU) to assess the effect of CRT.

RESULTS

In 33 patients (89.1%), sleep-disordered breathing (SDB), predominantly central sleep apnea (70.3%) was observed. This include nine patients (24.3%) with an apnea-hypopnea index (AHI) of >30 events/hour. During the 6M-FU, 16 patients (47.1%) responded to CRT by reducing LV end-systolic volume index (LVESVi) by ≥15%. We stated a directly proportional linear relationship between AHI value and LV volume: LVESVi p = 0.004, and LV end-diastolic volume index p = 0.006.

CONCLUSIONS

Pre-existing severe SDB can impair the LV volumetric response to CRT even in an optimally selected group with class I indications for resynchronization, which may have an impact on long-term prognosis.

Evaluation and Treatment of Central Sleep Apnea in Patients with Heart Failure

Sleep-disordered breathing (SDB) is a common comorbidity in patients with heart failure (HF). Prevalence of the most common subtypes of SDB, central sleep apnea (CSA) and obstructive sleep apnea (OSA), is increasing, which is concerning due to the association of SDB with increased mortality in patients with heart failure. Despite an increasing burden of CSA in HF, it is difficult to detect using current diagnostic tools and the treatment modalities are limited by variable efficacy and patient adherence. Though positive airway pressure therapies remain the cornerstone of OSA treatment, the management of CSA in the setting of HF continues to evolve. The association of the presence of CSA with worse prognosis in HF patients warrants the need for routine screening for signs and symptoms of CSA in this population. In this review, we examine the connection between CSA and HF, highlighting advancements in timely diagnostics, treatment modalities, and strategies to promote facilitation of compliance in this high-risk cohort.

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 Apnoea and Heart Failure

Heart Failure (HF) and Sleep-Disordered-Breathing (SDB) are two common conditions that frequently overlap and have been studied extensively in the past three decades. Obstructive Sleep Apnea (OSA) may result in myocardial damage, due to intermittent hypoxia increased sympathetic activity and transmural pressures, low-grade vascular inflammation and oxidative stress. On the other hand, central sleep apnoea and Cheyne-Stokes respiration (CSA-CSR) occurs in HF, irrespective of ejection fraction either reduced (HFrEF), preserved (HFpEF) or mildly reduced (HFmrEF). The pathophysiology of CSA-CSR relies on several mechanisms leading to hyperventilation, breathing cessation and periodic breathing. Pharyngeal collapse may result at least in part from fluid accumulation in the neck, owing to daytime fluid retention and overnight rostral fluid shift from the legs. Although both OSA and CSA-CSR occur in HF, the symptoms are less suggestive than in typical (non-HF related) OSA. Overnight monitoring is mandatory for a proper diagnosis, with accurate measurement and scoring of central and obstructive events, since the management will be different depending on whether the sleep apnea in HF is predominantly OSA or CSA-CSR. SDB in HF are associated with worse prognosis, including higher mortality than in patients with HF but without SDB. However, there is currently no evidence that treating SDB improves clinically important outcomes in patients with HF, such as cardiovascular morbidity and mortality.

Implantable cardiac devices in sleep apnoea diagnosis: A systematic review and meta-analysis

BACKGROUND

A particularly high burden of sleep apnoea is reported in patients treated with cardiac implants such as pacemakers and defibrillators. Sleep apnoea diagnosis remains a complex procedure mainly based on sleep and respiratory indices captured by polysomnography (PSG) or respiratory polygraphy (PG).

AIM

We aimed to evaluate the performance of implantable cardiac devices for sleep apnoea diagnosis compared to reference methods.

METHOD

Systematic structured literature searches were performed in PubMed, Embase and. Cochrane Library was performed to identify relevant studies. Quantitative characteristics of the studies were summarized and a qualitative synthesis was performed by a randomized bivariate meta-analysis and completed by pre-specified sensitivity analyses for different implant types and brands.

RESULTS

16 studies involving 999 patients met inclusion criteria and were included in the meta-analysis. The majority of patients were men, of mean age of 64 ± 4.6 years. Sensitivity of cardiac implants for sleep apnoea diagnosis ranged from 60 to 100%, specificity from 50 to 100% with a prevalence of sleep apnoea varying from 22 to 91%. For an apnoea-hypopnoea index threshold ≥30 events/h during polysomnography (corresponding to severe sleep apnoea), the overall performance of the implants was relevant with a sensitivity of 78% and a specificity of 79%. Subgroup analyses on implant type and brand provided no additional information owing to the small number of studies.

CONCLUSION

The respiratory disturbance index provided by cardiac implants is clinically relevant and might improve access to sleep apnoea diagnosis in at-risk cardiovascular populations. PROSPERO Registration number: CRD42020181656.

Positionspapier „Schlafmedizin in der Kardiologie“, Update 2021

Es hat sich viel getan in der Welt der Schlafmedizin in der Kardiologie, weshalb eine vollwertige Überarbeitung des Positionspapiers „Schlafmedizin in der Kardiologie“ erforderlich wurde. In der aktuellen neuartigen Version finden sich nicht nur alle verfügbaren Studien, Literaturstellen und Updates zu Pathophysiologie, Diagnostik- und Therapieempfehlungen, sondern auch Ausblicke auf neue Entwicklungen und zukünftige Forschungserkenntnisse. Dieses überarbeitete Positionspapier gibt Empfehlungen für Diagnostik und Therapie von Patienten mit kardiovaskulären Erkrankungen mit schlafassoziierten Atmungsstörungen und erteilt darüber hinaus einen fundierten Überblick über verfügbare Therapien und Evidenzen, gibt aber ebenso Ratschläge wie mit Komorbiditäten umzugehen ist. Insbesondere enthält dieses überarbeitete Positionspapier aktualisierte Stellungnahmen zu schlafassoziierten Atmungsstörungen bei Patienten mit koronarer Herzerkrankung, Herzinsuffizienz, arterieller Hypertonie, aber auch für Patienten mit Vorhofflimmern. Darüber hinaus finden sich erstmals Empfehlungen zur Telemedizin als eigenes, neues Kapitel. Dieses Positionspapier bietet Kardiologen sowie Ärzten in der Behandlung von kardiovaskulären Patienten die Möglichkeit einer evidenzbasierten Behandlung der wachsend bedeutsamen und mit zunehmender Aufmerksamkeit behafteten Komorbidität schlafassoziierter Atmungsstörungen. Und nicht zuletzt besteht mit diesem neuen Positionspapier eine enge Verknüpfung mit dem neuen Curriculum Schlafmedizin der Deutschen Gesellschaft für Kardiologie, weshalb dieses Positionspapier eine Orientierung für die erworbenen Fähigkeiten des Curriculums im Umgang von kardiovaskulären Patienten mit schlafassoziierten Atmungsstörungen darstellt.

Benefit of Atrial Overdrive Pacing in Patients with Sleep Apnea: A Meta-Analysis

BACKGROUND

Sleep apnea is one of the most common conditions around the world. This disorder can significantly impact cardiovascular morbidity and mortality. Atrial overdrive pacing (AOP) is a treatment modality that can potentially decrease respiratory events. There is currently a lack of evidence to confirm the benefits of AOP. We aimed to assess the impact of AOP in patients with obstructive sleep apnea (OSA), central sleep apnea (CSA), and mixed type.

METHODS

A literature search for studies that reported the impact on apnea-hypopnea index (AHI) by cardiac implantable electronic devices with different pacing modes was conducted using MEDLINE, Embase, and Cochrane Database from inception through July 2020. Pooled standard mean difference with 95%CI was calculated using a random-effects model.

RESULTS

Fifteen studies, including thirteen randomized studies and two observational studies containing 440 patients, were identified. The standard mean difference in apnea-hypopnea index of atrial overdrive pacing demonstrated less duration of apnea/hypopnea in patients with atrial overdrive pacing (AOP) (SMD -0.29, 95%CI: -0.48, -0.10, I² = 57%). Additional analysis was performed to assess the effect of atrial overdrive pacing in patients with or without severe sleep apnea syndrome (mean AHI < 30 defined as non-severe). There was no statistically significant difference in standardized mean in AHI in both subgroups between AOP and control groups (SMD -0.25, severe sleep apnea syndrome SMD -0.03, I² = 0.00%).

CONCLUSIONS

AOP was associated with a statistically significant reduction in AHI, but the magnitude of reduction was small. AOP may potentially be used as an adjunctive treatment with other modalities in treating patients with sleep apnea.

Sleep Disordered Breathing and Cardiovascular Disease: JACC State-of-the-Art Review

Sleep disordered breathing causes repetitive episodes of nocturnal hypoxemia, sympathetic nervous activation, and cortical arousal, often associated with excessive daytime sleepiness. Sleep disordered breathing is common in people with, or at risk of, cardiovascular (CV) disease including those who are obese or have hypertension, coronary disease, heart failure, or atrial fibrillation. Current therapy of obstructive sleep apnea includes weight loss (if obese), exercise, and positive airway pressure (PAP) therapy. This improves daytime sleepiness. Obstructive sleep apnea is associated with increased CV risk, but treatment with PAP in randomized trials has not been shown to improve CV outcome. Central sleep apnea (CSA) is not usually associated with daytime sleepiness in heart failure or atrial fibrillation and is a marker of increased CV risk, but PAP has been shown to be harmful in 1 randomized trial. The benefits of better phenotyping, targeting of higher-risk patients, and a more personalized approach to therapy are being explored in ongoing trials.

Obstructive Sleep Apnea Syndrome as a Trigger of Cardiac Arrhythmias

PURPOSE OF REVIEW

Obstructive sleep apnea syndrome (OSAS) has a high prevalence in western countries. Many papers have been published with the purpose of demonstrating that OSAS acts as an arrhythmia trigger and is responsible for an increase in cardiovascular morbidity and mortality. The aim of this study was to review our knowledge on this topic.

RECENT FINDINGS

There is a lot of evidence demonstrating the relationship between OSAS and arrhythmias, but there remains a lack of an interventional randomized trial to demonstrate that by treating OSAS we can reduce arrhythmia burden. OSAS is a highly prevalent illness in western countries and is clearly related to an increase in cardiovascular mortality and morbidity. Cardiac arrhythmias are triggered by a repetitive hypoxemia, hypercapnia, acidosis, intrathoracic pressure fluctuations, reoxygenation, and arousals during apnea and hypopnea episodes. Early diagnosis and treatment of these patients can reduce further cardiovascular morbidity and mortality.

Central Sleep Apnea and Pacing-Induced Cardiomyopathy

The role of central sleep apnea (CSA) in pacing-induced cardiomyopathy (PICM) remains speculative. In a prospective trial entitled UPGRADE, the presence of CSA was assessed by single-night polysomnography (PSG) in 54 PICM patients within 1 month after left ventricular lead implantation (with biventricular stimulation still not activated). CSA was diagnosed in half of patients (n = 27). Patients with moderate or severe CSA were randomized to cardiac resynchronization therapy (CRT) versus right ventricular pacing (RVP) in a double-blinded cross-over design and re-scheduled for a follow-up PSG within 3 to 5 months. After crossing-over of stimulation mode another PSG was conducted 3 to 5 months later. CRT led to a significant increase in left ventricular ejection fraction and significant reduction in left ventricular end systolic volumes and N-terminal pro brain natriuretic peptide plasma levels, whereas no significant effects were observed with ongoing RVP. CSA was significantly improved after 3.9 (3.2 to 4.4) months of CRT: apnea-hypopnea index decreased from 39.1 (32.1 to 54.0) events per hour at baseline to 22.2/h (10.9 to 36.7) by CRT (p <0.001). Central apnea index decreased from 27.1/h (17.7 to 36.1) at baseline to 6.8/h (1.1 to 14.4) after CRT activation (p <0.001). Ongoing RVP yielded only a minor improvement in apnea-hypopnea index and central apnea index. Pre-existent CSA did not affect structural response rate and had no impact on mid-term follow-up (median 2.8 years). In conclusion, CSA is highly prevalent in patients with PICM. CRT upgrading significantly improves CSA leading to a similar outcome in PICM patients without pre-existent CSA.

Continuous monitoring of sleep-disordered breathing with pacemakers: Indexes for risk stratification of atrial fibrillation and risk of stroke

BACKGROUND

Sleep apnea (SA) is a risk factor for atrial fibrillation (AF). Advanced pacemakers are now able to calculate indexes of SA severity.

HYPOTHESIS

We investigated the changes in pacemaker-measured indexes of SA, we assessed their predictive value for AF occurrence and the associated risk of stroke and death at long-term.

METHODS

We enrolled 439 recipients of a pacemaker endowed with an algorithm for the calculation of a Respiratory Disturbance Index (RDI). The RDI variability was measured over the first 12 months after implantation, as well as its potential association with the occurrence of AF, defined as device-detected cumulative AF burden ≥6 hoursours in a day.

RESULTS

The individual RDI mean was 30 ± 18 episodes/h, and the RDI maximum was 59 ± 21 episodes/h. RDI ≥30 episodes/h was detected in 351 (80%) patients during at least one night. The proportion of nights with RDI ≥30 episodes/h was 14% (2%-36%). AF ≥6 hours was detected in 129 (29%) patients during the first 12 months. The risk of AF was higher in patients with RDI maximum ≥63 episodes/h (HR:1.74; 95%CI: 1.22-2.48; P = .001) and with RDI mean ≥ 46 episodes/h (HR:1.63; 95%CI: 1.03-2.57; P = .014). The risk of all-cause death or stroke was higher in patients with AF burden ≥6 hours (HR:1.75; 95%CI: 1.06-2.86; P = .016). Moreover, among patients with no previous history of AF the risk was higher in those with RDI maximum ≥63 episodes/h (HR:1.96; 95%CI: 1.06-3.63; P = .031).

CONCLUSIONS

Pacemaker-detected SA showed a considerable variability during follow-up. We confirmed the association between RDI and higher risk of AF, and we observed an association between higher RDI maximum and all-cause death or stroke among patients with no previous history of AF.

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.

[Sleep disordered breathing in patients with chronic heart failure: prognosis and management]

Sleep disordered breathing is a frequent comorbidity (50-75%) in patients with chronic heart failure, but it is usually underestimated. This review analyzes sleep disordered breathing in patients with chronic heart failure, demonstrates pathogenetic relationships and the prognostic role of sleep apnea. The authors present modern treatment options for sleep apnea in this cohort (from non-invasive ventilation to implantable devices), highlight the role of drug therapy and outline perspectives of different treatment approaches. This clinical problem is designated as multidisciplinary, which requires a dialogue between researchers and doctors of various specialties to organize comprehensive effective care for this cohort of patients.

Arrhythmogenic mechanisms of obstructive sleep apnea in heart failure patients

Heart failure (HF) affects 23 million people worldwide and results in 300000 annual deaths. It is associated with many comorbidities, such as obstructive sleep apnea (OSA), and risk factors for both conditions overlap. Eleven percent of HF patients have OSA and 7.7% of OSA patients have left ventricular ejection fraction <50% with arrhythmias being a significant comorbidity in HF and OSA patients. Forty percent of HF patients develop atrial fibrillation (AF) and 30%-50% of deaths from cardiac causes in HF patients are from sudden cardiac death. OSA is prevalent in 32%-49% of patients with AF and there is a dose-dependent relationship between OSA severity and resistance to anti-arrhythmic therapies. HF and OSA lead to various downstream arrhythmogenic mechanisms, including metabolic derangement, remodeling, inflammation, and autonomic imbalance. (1) Metabolic derangement and production of reactive oxidative species increase late Na+ currents, decrease outward K+ currents and downregulate connexin-43 and cell-cell coupling. (2) remodeling also features downregulated K+ currents in addition to decreased Na+/K+ ATPase currents, altered Ca2+ homeostasis, and increased density of If current. (3) Chronic inflammation leads to downregulation of both Nav1.5 channels and K+ channels, altered Ca2+ homeostasis and reduced cellular coupling from alterations of connexin expression. (4) Autonomic imbalance causes arrhythmias by evoking triggered activity through increased Ca2+ transients and reduction of excitation wavefront wavelength. Thus, consideration of these multiple pathophysiological pathways (1-4) will enable the development of novel therapeutic strategies that can be targeted against arrhythmias in the context of complex disease, such as the comorbidities of HF and OSA.

Managing comorbid cardiovascular disease and sleep apnea with pharmacotherapy

INTRODUCTION

Highly prevalent sleep disordered breathing (SDB) has been recognized as an independent cardiovascular disease (CVD) risk factor. Although these two entities often coexist, there is a shortage of sufficiently-powered studies testing the interplay between the course of sleep apnea and CVD pharmacotherapy. The mutual relationship between treated/untreated obstructive sleep apnea (OSA) with ongoing cardiovascular pharmacotherapies is an evident gap in clinical expertise.

AREAS COVERED

In this article, the authors review the available evidence and outline future research directions concerning the reciprocal relationship between the pharmacological treatment of CVD and SDB. Several attempts have been made to identify the most efficacious hypotensive agents for patients with both OSA and hypertension. Various cardiovascular drugs are also evaluated in terms of their influence on sleep apnea severity.

EXPERT OPINION

The question of whether OSA should be included in cardiovascular pharmacotherapy individualization algorithms is a matter of debate and more evidence is needed. Cautious intensification of diuretics with the use of aldosterone receptor antagonists deserves attention when both high blood pressure and sleep apnea coexist.

Management of Sleep Disordered Breathing in Patients with Heart Failure

PURPOSE OF REVIEW

This paper reviews treatment options for sleep disordered breathing (SDB) in patients with heart failure. We sought to identify therapies for SDB with the best evidence for long-term use in patients with heart failure and to minimize uncertainties in clinical practice by examining frequently discussed questions: what is the role of continuous positive airway pressure (CPAP) in patients with heart failure? Is adaptive servo-ventilation (ASV) safe in patients with heart failure? To what extent is SDB a modifiable risk factor?

RECENT FINDINGS

Consistent evidence has demonstrated that the development of SDB in patients with heart failure is a poor prognostic indicator and a risk factor for cardiovascular mortality. However, despite numerous available interventions for obstructive sleep apnea and central sleep apnea, it remains unclear what effect these therapies have on patients with heart failure. To date, all major randomized clinical trials have failed to demonstrate a survival benefit with SDB therapy and one major study investigating the use of adaptive servo-ventilation demonstrated harm. Significant questions persist regarding the management of SDB in patients with heart failure. Until appropriately powered trials identify a treatment modality that increases cardiovascular survival in patients with SDB and heart failure, a patient's heart failure management should remain the priority of medical care.

Sleep-Disordered Breathing-Do We Have to Change Gears in Heart Failure?

The majority of patients with heart failure have sleep-disordered breathing (SDB)—with central (rather than obstructive) sleep apnoea becoming the predominant form in those with more severe disease. Cyclical apnoeas and hypopnoeas are associated with sleep disturbance, hypoxaemia, haemodynamic changes, and sympathetic activation. Such patients have a worse prognosis than those without SDB. Mask-based therapies of positive airway pressure targeted at SDB can improve measures of sleep quality and partially normalise the sleep and respiratory physiology, but recent randomised trials of cardiovascular outcomes in central sleep apnoea have been neutral or suggested the possibility of harm, likely from increased sudden death. Further randomised outcome studies (with cardiovascular mortality and hospitalisation endpoints) are required to determine whether mask-based treatment for SDB is appropriate for patients with chronic systolic heart failure and obstructive sleep apnoea, for those with heart failure with preserved ejection fraction, and for those with decompensated heart failure. New therapies for sleep apnoea—such as implantable phrenic nerve stimulators—also require robust assessment. No longer can the surrogate endpoints of improvement in respiratory and sleep metrics be taken as adequate therapeutic outcome measures in patients with heart failure and sleep apnoea.

Sleep-disordered breathing in heart failure: The state of the art after the SERVE-HF trial

Heart failure (HF) is one of the most prevalent conditions worldwide and despite therapeutic advances, its prognosis remains poor. Among the multiple comorbidities in HF, sleep-disordered breathing (SDB) is frequent and worsens the prognosis. Preliminary observational studies suggested that treatment of SDB could modify the prognosis of HF, and the issue has gained importance in recent years. The diagnosis of SDB is expensive, slow and suboptimal, and there is thus a need for screening devices that are easier to use and validated in this population. The first-line treatment involves optimization of medical therapy for heart failure. Continuous positive airway pressure (CPAP) is used in patients who mainly suffer from obstructive sleep apnea. In patients with predominantly central sleep apnea, CPAP is not sufficient and adaptive servo-ventilation (ASV), despite promising results in observational studies, showed no benefit in patients with symptomatic HF and reduced ejection fraction in the SERVE-HF randomized trial; on the contrary, there was unexpectedly increased mortality in the ASV group compared to controls, and so ASV is contraindicated in these patients, calling into question the definition and pathogenesis of SDB and risk stratification in these patients. There are many gaps in the evidence, and so further research is needed to better understand this issue: definitions, simple screening methods, and whether and how to treat SDB in patients with HF.

Heart failure and sleep disordered breathing

Sleep-disordered breathing (SDB) is frequently observed in patients with heart failure (HF), and complex pathologic conditions exist between both conditions. In this review article, we describe the characteristics of SDB complicated with HF, the prognostic impact of SDB in HF patients, and the favorable effects of positive airway pressure in HF patients with SDB.

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.

Sleep-Disordered Breathing During Congestive Heart Failure: To Intervene or Not to Intervene?

Sleep-disordered breathing is common in heart failure patients and is associated with increased morbidity and mortality. Central sleep apnea occurs more commonly in heart failure-reduced ejection fraction, and obstructive sleep apnea occurs more frequently in heart failure with preserved ejection fraction. Although the two types of sleep-disordered breathing have distinct pathophysiologic mechanisms, both contribute to abnormal cardiovascular consequences. Treatment with continuous positive airway pressure for obstructive sleep apnea in heart failure has been well defined, whereas treatment strategies for central sleep apnea in heart failure continue to evolve. Unilateral transvenous neurostimulation has shown promise for the treatment of central sleep apnea. In this paper, we examine the current state of knowledge of treatment options for sleep-disordered breathing in heart failure.

Comorbidities in Heart Failure

Comorbidities frequently accompany chronic heart failure (HF), contributing to increased morbidity and mortality, and an impaired quality of life. We describe the prevalence of several high-impact comorbidities in chronic HF patients and their impact on morbidity and mortality. Furthermore, we try to explain the underlying pathophysiological processes and the complex interaction between chronic HF and specific comorbidities. Although common risk factors are likely to contribute, it is reasonable to believe that factors associated with HF might cause other comorbidities and vice versa. Potential factors are inflammation, neurohormonal activation, and hemodynamic changes.

Management of Sleep Apnea Syndromes in Heart Failure

Central sleep apnea (CSA) and obstructive sleep apnea (OSA) are prevalent in heart failure (HF) and associated with a worse prognosis. Nocturnal oxygen therapy may decrease CSA events, sympathetic tone, and improve left ventricular ejection fraction, although mortality benefit is unknown. Although treatment of OSA in patients with HF is recommended, therapy for CSA remains controversial. Continuous positive airway pressure use in HF-CSA may improve respiratory events, hemodynamics, and exercise capacity, but not mortality. Adaptive servo ventilation is contraindicated in patients with symptomatic HF with predominant central sleep-disordered events. The role of phrenic nerve stimulation in CSA therapy is promising.

Sleep-disordered breathing and echocardiographic measures of function and dyssynchrony: a complex approach to cardiac resynchronization therapy

INTRODUCTION

We investigated the relationship between sleep-disordered breathing (SDB), cardiac function, and cardiac resynchronization therapy (CRT).

METHODS

Fifty-five CRT patients with SDB diagnosed by Holter ECG (apnea/hypopnea index - AHI) were included in the study. We sought to determine right ventricle (RV) predictors of short-term SDB improvement and long-term outcome in patients with (AHI dippers) and without (AHI nondippers) 25% AHI improvement, markers of CRT response, and SDB influence on survival.

RESULTS

Baseline tricuspid E-wave (AUC - 0.925, cut-off value > 0.336 m/s; sensitivity - 90%, specificity - 100%) and RV E/E' - 0.864, ≤16.25; 73%, 100%, respectively) were found as predictors of 25% AHI reduction. Spiroergometric tests, mitral regurgitation, and LVEF results improved significantly in AHI dippers. Regression analysis identified the absence of 25% AHI reduction (OR-7.67, 95% CI 1.52-38.6 and OR-9.92, 95%CI 6.02-15.3) and septal-lateral atrial velocities delay (OR-1.09, 95% CI 0.99-1.2 and 1.07, 95% CI 0.99-1.16) as independent predictors of both clinical and echocardiographic nonresponse. During median follow-up of 6.8 years, mortality was significantly reduced in patients with both AHI 25% reduction and 10% absolute LVEF increase in the first 3 months of CRT, compared with the subjects with only one or none of those criteria.

CONCLUSION

The baseline RV diastolic indices were found as independent predictors of SDB improvement during CRT. Both clinical and echocardiographic long-term response can be independently predicted by SDB and intraatrial dyssynchrony. The best survival rate was observed in patients with SDB and LVEF improvement noted in the first 3 months of CRT.

Heart failure and sleep-disordered breathing

PURPOSE OF REVIEW

Sleep-disordered breathing, which includes both obstructive and central sleep apnoea (OSA and CSA, respectively), is highly prevalent in patients with heart failure. In this review, we outline our current understanding of the bidirectional relationship between these disorders and heart failure. We also explore the role of recent advances in therapeutics.

RECENT FINDINGS

Although early studies suggest promise of adaptive servoventilation in treating sleep-disordered breathing, particularly CSA with associated Cheyne-Stokes respiration, the recent clinical trial in the heart failure patient population has demonstrated worse cardiovascular outcome in symptomatic patients.

SUMMARY

Both OSA and CSA are highly prevalent in patients with heart failure. Effective treatment of OSA with continuous positive airway pressure can improve cardiovascular outcome in these patients. However, recent evidence suggests that adaptive servoventilation cannot be safely recommended as a therapy for CSA in the context of heart failure, as a result of increased risk of cardiovascular mortality.

Heart failure and sleep disorders

Awareness of the importance of sleep-related disorders in patients with cardiovascular diseases is growing. In particular, sleep-disordered breathing, short sleep time, and low sleep quality are frequently reported by patients with heart failure (HF). Sleep-disordered breathing, which includes obstructive sleep apnoea (OSA) and central sleep apnoea (CSA), is common in patients with HF and has been suggested to increase the morbidity and mortality in these patients. Both OSA and CSA are associated with increased sympathetic activation, vagal withdrawal, altered haemodynamic loading conditions, and hypoxaemia. Moreover, OSA is strongly associated with arterial hypertension, the most common risk factor for cardiac hypertrophy and failure. Intrathoracic pressure changes are also associated with OSA, contributing to haemodynamic alterations and potentially affecting overexpression of genes involved in ventricular remodelling. HF treatment can decrease the severity of both OSA and CSA. Indeed, furosemide and spironolactone administration, exercise training, cardiac resynchronization therapy, and eventually heart transplantation have shown a positive effect on OSA and CSA in patients with HF. At present, whether CSA should be treated and, if so, which is the optimal therapy is still debated. By contrast, more evidence is available on the beneficial effects of OSA treatment in patients with HF.

Sleep-disordered breathing in heart failure

Sleep-disordered breathing-comprising obstructive sleep apnoea (OSA), central sleep apnoea (CSA), or a combination of the two-is found in over half of heart failure (HF) patients and may have harmful effects on cardiac function, with swings in intrathoracic pressure (and therefore preload and afterload), blood pressure, sympathetic activity, and repetitive hypoxaemia. It is associated with reduced health-related quality of life, higher healthcare utilization, and a poor prognosis. Whilst continuous positive airway pressure (CPAP) is the treatment of choice for patients with daytime sleepiness due to OSA, the optimal management of CSA remains uncertain. There is much circumstantial evidence that the treatment of OSA in HF patients with CPAP can improve symptoms, cardiac function, biomarkers of cardiovascular disease, and quality of life, but the quality of evidence for an improvement in mortality is weak. For systolic HF patients with CSA, the CANPAP trial did not demonstrate an overall survival or hospitalization advantage for CPAP. A minute ventilation-targeted positive airway therapy, adaptive servoventilation (ASV), can control CSA and improves several surrogate markers of cardiovascular outcome, but in the recently published SERVE-HF randomized trial, ASV was associated with significantly increased mortality and no improvement in HF hospitalization or quality of life. Further research is needed to clarify the therapeutic rationale for the treatment of CSA in HF. Cardiologists should have a high index of suspicion for sleep-disordered breathing in those with HF, and work closely with sleep physicians to optimize patient management.

Altered breathing syndrome in heart failure: newer insights and treatment options

In patients with heart failure (HF), altered breathing patterns, including periodic breathing, Cheyne-Stokes breathing, and oscillatory ventilation, are seen in several situations. Since all forms of altered breathing cause similar detrimental effects on clinical outcomes, they may be considered collectively as an "altered breathing syndrome." Altered breathing syndrome should be recognized as a comorbid condition of HF and as a potential therapeutic target. In this review, we discuss mechanisms and therapeutic options of altered breathing while sleeping, while awake at rest, and during exercise.

Arrhythmia risk associated with sleep disordered breathing in chronic heart failure

The intersecting relationships of sleep disordered breathing (SDB), arrhythmogenic risk and chronic heart failure (HF) are complex and most likely multi-directional and synergistic. Autonomic dysfunction is a common pathophysiological feature of each of these entities. Intermittent hypoxia, hypercapnia, mechanical cardiac influences due to upper airway obstruction and rostral fluid shifts are SDB-specific mechanisms which may trigger, perpetuate and exacerbate HF and arrhythmogenesis. Specific pathophysiological mechanisms will vary according to the predominance of central as compared to obstructive sleep apnea. The risk of cardiac arrhythmias and HF attributable to SDB may be considerable given the high prevalence of SDB and its likely physiologic burden. The current review focuses on the data, which have accrued elucidating the specific contributory mechanisms of SDB in cardiac arrhythmias and HF, highlighting the clinical relevance and effects of standard SDB treatment on these outcomes, and describing the role of novel therapeutics.

Severe central sleep apnea is associated with atrial fibrillation in patients with left ventricular systolic dysfunction

BACKGROUND

The results of previous studies investigating the association between atrial fibrillation (AF) and central sleep apnea (CSA) in patients with left ventricular (LV) systolic dysfunction are contradictory.

METHODS

We prospectively enrolled 267 patients in this cross-sectional study with LV ejection fractions ≤50%, who were screened for sleep disordered breathing using cardiorespiratory polysomnography after patients with predominantly obstructive sleep apnea or insufficient sleep studies had been excluded.

RESULTS

AF at study entry was found in 70 of 267 patients (26%). CSA with an apnea/hypopnea index (AHI) ≥15/hour was present in 116 patients (43%) and 67 patients (25%) had severe CSA with an AHI > 30/hour. Univariate analysis revealed a significant association between AF and severe CSA, age, male gender, arterial hypertension, left atrial diameter, brain natriuretic peptide, chronic kidney disease, New York Heart Association class, digitalis, and the lack of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Multivariate analysis revealed a significant association between AF and severe CSA (odds ratio [OR]: 5.21; 95% confidence interval [CI]: 1.67-16.27, P = 0.01), age (OR: 1.22 per 5-year increase; 95% CI: 1.05-1.40, P = 0.01), left atrial diameter (OR 1.61 per 5-mm increase; 95% CI: 1.22-2.01, P < 0.01), and digitalis (OR: 2.7; 95% CI: 1.26-5.79, P = 0.01).

CONCLUSIONS

AF is associated with severe CSA but not with moderate CSA in addition to age, use of digitalis, and left atrial size in patients with LV systolic dysfunction. Future studies evaluating the potential benefit of adaptive servo-ventilation therapy to prevent AF or to decrease the AF burden in heart failure patients should therefore focus on patients with severe central sleep apnea.

Sleep and breathing in congestive heart failure

Heart failure (HF) is one of the most prevalent and costly diseases in the United States. Sleep apnea is now recognized as a common, yet underdiagnosed, comorbidity of HF. This article discusses the unique qualities that sleep apnea has when it occurs in HF and explains the underlying pathophysiology that illuminates why sleep apnea and HF frequently occur together. The authors provide an overview of the treatment options for sleep apnea in HF and discuss the relative efficacies of these treatments.

Sleep-disordered breathing in patients with heart failure: new trends in therapy

Heart failure (HF) is a growing health problem which paradoxically results from the advances in the treatment of etiologically related diseases (especially coronary artery disease). HF is commonly accompanied by sleep-disordered breathing (SDB), which may directly exacerbate the clinical manifestations of cardiovascular disease and confers a poorer prognosis. Obstructive sleep apnoea predominates in mild forms while central sleep apnoea in more severe forms of heart failure. Identification of SDB in patients with HF is important, as its effective treatment may result in notable clinical benefits to the patients. Continuous positive airway pressure (CPAP) is the gold standard in the management of SDB. The treatments for central breathing disorders include CPAP, bilevel positive airway pressure (BPAP), and adaptive servoventilation (ASV), with the latter being the most modern method of treatment for the Cheyne-Stokes respiration and involving ventilation support with a variable synchronisation dependent on changes in airflow through the respiratory tract and on the patient's respiratory rate. ASV exerts the most favourable effect on long-term prognosis. In this paper, we review the current state of knowledge on the diagnosis and treatment of SDB with a particular emphasis on the latest methods of treatment.

Therapy for sleep hypoventilation and central apnea syndromes

OPINION STATEMENT

• Primary Central Sleep Apnea (CSA): We would recommend a trial of Positive Airway Pressure (PAP), acetazolamide, or zolpidem based on thorough consideration of risks and benefits and incorporation of patient preferences.• Central Sleep Apnea Due to Cheyne-Stokes Breathing Pattern in Congestive Heart Failure (CSR-CHF): We would recommend PAP devices such as continuous positive airway pressure (CPAP) or adaptive servo-ventilation (ASV) to normalize sleep-disordered breathing after optimizing treatment of heart failure. Oxygen may also be an effective therapy. Acetazolamide and theophylline may be considered if PAP or oxygen is not effective.• Central Sleep Apnea due to High-Altitude Periodic Breathing: We would recommend descent from altitude or supplemental oxygen. Acetazolamide may be used when descent or oxygen are not feasible, or in preparation for ascent to high altitude. Slow ascent may be preventative.• Central Sleep Apnea due to Drug or Substance: If discontinuation or reduction of opiate dose is not feasible or effective, we would recommend a trial of CPAP, and if not successful, treatment with ASV. If ASV is ineffective or if nocturnal hypercapnia develops, bilevel positive airway pressure-spontaneous timed mode (BPAP-ST) is recommended.• Obesity hypoventilation syndrome: We would recommend an initial CPAP trial. If hypoxia or hypercapnia persists on CPAP, BPAP, BPAP-ST or average volume assured pressure support (AVAPS™) is recommended. Tracheostomy with nocturnal ventilation should be considered when the above measures are not effective. Weight loss may be curative.• Neuromuscular or chest wall disease: We would recommend early implementation of BPAP-ST based on thorough consideration of risks and benefits and patient preferences. AVAPS™ may also be considered. We recommend close follow up due to disease progression.

Sleep apnea and heart failure

Sleep apnea is frequently observed in patients with heart failure (HF). In general, sleep apnea consists of two types: obstructive and central sleep apnea (OSA and CSA, respectively). OSA results from upper airway collapse, whereas CSA arises from reductions in central respiratory drive. In patients with OSA, blood pressure is frequently elevated as a result of sympathetic nervous system overactivation. The generation of exaggerated negative intrathoracic pressure during obstructive apneas further increases left ventricular (LV) afterload, reduces cardiac output, and may promote the progression of HF. Intermittent hypoxia and post-apneic reoxygenation cause vascular endothelial damage and possibly atherosclerosis and consequently coronary artery disease and ischemic cardiomyopathy. CSA is also characterized by apnea, hypoxia, and increased sympathetic nervous activity and, when present in HF, is associated with increased risk of death. In patients with HF, abolition of coexisting OSA by continuous positive airway pressure (CPAP) improves LV function and may contribute to the improvement of long-term outcomes. Although treatment options of CSA vary compared with OSA treatment, CPAP and other types of positive airway ventilation improve LV function and may be a promising adjunctive therapy for HF patients with CSA. Since HF remains one of the major causes of mortality in the industrialized countries, the significance of identifying and managing sleep apnea should be more emphasized to prevent the development or progression of HF.

Sleep apnea, cardiac arrhythmias, and conduction disorders

Sleep apnea (SA) is a common breathing disorder. It is associated with a myriad of medical conditions including increased cardiovascular morbidity and mortality. Recent studies have shown that cardiac arrhythmias and conduction disorders are common in patients with SA. Sleep apnea has also been also linked to heart failure, hypertension, coronary artery disease, and stroke. The purpose of this brief review is to analyze the available information that links SA with different cardiac arrhythmias and conduction disorders and the role of intracardiac devices for the diagnosis and management of this condition.

[Sleep-disordered breathing and cardiac resynchronization therapy]

Patients with progressive heart failure often suffer from sleep-disordered breathing (SDB). Upon receiving cardiac resynchronization therapy (CRT), there is an improvement of cardiac function and central sleep apnea syndrome (CSA) with Cheyne-Stokes respiration; however, effects of CRT on obstructive sleep apnea syndrome seemed to be without clinical relevance. Likewise, additional atrial overdrive pacing did not improve CRT effects relevantly in CSA patients. During CRT, there is an improvement in sleep parameters, sleep quality by reduction of depressive syndromes, and in long-term survival. Therefore, all patients with chronic heart failure and indication for CRT should be monitored regarding SDB before and after CRT device implantation.