Epidemiology of Sleep-Disordered Breathing and Heart Failure: What Drives What

Translating physiology of the arterial chemoreflex into novel therapeutic interventions targeting carotid bodies in cardiometabolic disorders

This review resulted from a conference on the pathological role of arterial chemoreflex and carotid bodies in cardiometabolic diseases held at the 27th Congress of the Polish Cardiac Society in September 2023 in Poznan, Poland. It reflects the contribution of Polish researchers and their international collaborations, which have been fundamental in the development of the field. Aberrant activity of the carotid bodies leads to both high tonicity and increased sensitivity of the arterial chemoreflex with resultant sympathoexcitation in chronic heart failure, resistant hypertension and obstructive sleep apnoea. This observation has led to several successful attempts of removing or denervating the carotid bodies as a therapeutic option in humans. Regrettably, such interventions are accompanied by serious respiratory and acid-base balance side-effects. Rather than a single stereotyped reaction, arterial chemoreflex comprises an integrative multi-system response to a variety of stimulants and its specific reflex components may be individually conveyed at varying intensities. Recent research has revealed that carotid bodies express diverse receptors, synthesize a cocktail of mediators, and respond to a plethora of metabolic, hormonal and autonomic nervous stimuli. This state-of-the-art summary discusses exciting new discoveries regarding GLP-1 receptors, purinergic receptors, the glutamate-GABA system, efferent innervation and regulation of blood flow in the carotid body and how they open new avenues for novel pharmacological treatments selectively targeting specific receptors, mediators and neural pathways to correct distinct responses of the carotid body-evoked arterial chemoreflex in cardiometabolic diseases. The carotid body offers novel and advantageous therapeutic opportunities for future consideration by trialists.

CPAP Therapy for OSA and Its Impact on Various Cardiovascular Disorders

Obstructive sleep apnea (OSA), a highly prevalent and serious disorder with significant complications, causes considerable daytime and nighttime symptoms as well as long-term consequences and is yet an underdiagnosed and inadequately treated condition. Patients with OSA undergo frequent awakenings during the sleep cycle and find it impossible to get restorative sleep. Individuals are extremely fatigued, sleepy, and irritable throughout the day. Reduced exercise performance and physical activity contribute to a decrease in energy metabolism and weight gain. Those in this population may experience decreased motivation, which could result in depressive symptoms. The abrupt drops in oxygen levels during the sleep cycle result in profound spikes in blood pressure and strain the cardiovascular system. Given its close tie with major cardiovascular risk factors, OSA is linked with various cardiovascular diseases, including coronary artery disease, cardiac arrhythmia, poorly controlled blood pressure, heart failure, and stroke. Continuous positive airway pressure is an effective and tried-trusted approach for symptom relief and improving quality of life. Despite its benefits, patients struggle with compliance and often go untreated because of physical discomfort and perceived inconvenience of using these machines. One other explanation for this could be the lack of awareness, comprehensive data, and extensive research on its effects on long-term cardiovascular and metabolic complications caused by OSA. The current standard treatment for OSA, using adequate positive airway pressure, greatly reduces cardiovascular morbidity. Nevertheless, patients with cardiovascular disorders continue to be highly susceptible to OSA and its detrimental clinical consequences, even with effective therapy available. In summary, continuous positive airway pressure has an indirect potential to affect cardiovascular outcomes, but further studies should be done to address issues with patient compliance and adherence.

Up-to-date advance in the relationship between obstructive sleep apnea and heart failure: a narrative review

PURPOSE

Obstructive sleep apnea (OSA) is recognized as an independent and significant risk factor for various cardiovascular and cerebrovascular conditions, including heart failure (HF). In this review, we explore the impact of OSA on HF, examine shared contributing factors and underlying pathophysiological mechanisms, and assess the treatment options for OSA and their potential therapeutic value in HF patients.

METHODS

Pubmed/MEDLINE were searched through September 2024 to explore the relationship between OSA and HF. The relevant papers included OSA and HF, risk factors of OSA and HF, and the prognosis and treatment of HF patients with OSA.

RESULTS

The results showed that OSA increased the risk of HF. OSA can exacerbate or contribute to the onset of HF in several ways. The application of continuous positive airway pressure (CPAP) and other treatments may benefit HF patients with OSA. Drug therapy has shown promise for treating OSA, extensive multi-center studies remain essential, particularly in patients with both OSA and HF.

CONCLUSION

OSA can exacerbate or contribute to the onset and recurrence of HF in several ways. Further studies should be carried out to explore effective treatments in patients with HF and OSA.

Sleep Apnea and Heart Failure-Current State-of-The-Art

Sleep-disordered breathing (SDB), including obstructive and central sleep apnea, significantly exacerbates heart failure (HF) through adverse cardiovascular mechanisms. This review aims to synthesize existing literature to clarify the relationship between SDB and HF, focusing on the pathophysiological mechanisms, diagnostic challenges, and the effectiveness of treatment modalities like continuous positive airway pressure (CPAP) and adaptive servo-ventilation ASV. We analyzed peer-reviewed articles from 2003 to 2024 sourced from PubMed, EMBASE, Scopus, and Web of Science databases. The prevalence of SDB in HF patients is high, often underdiagnosed, and underappreciated. Management strategies, including CPAP and ASV, have been shown to mitigate symptoms and improve cardiac function. However, despite the availability of effective treatments, significant challenges in screening and diagnosis persist, affecting patient management and outcomes. DB significantly impacts HF prognosis. Enhanced screening strategies and broader utilization of therapeutic interventions like CPAP and ASV are essential to improve the management and outcomes of HF patients with concomitant SDB. Future research should focus on refining diagnostic and treatment protocols to optimize care for HF patients with SDB.

Effects of daily sleep on physical activity after cardiac surgery

BACKGROUND

Maintaining physical activity is challenging after cardiac surgery. Postsurgical cardiac patients often experience sleep problems showing a reciprocal interaction with physical activity. As sleep and physical activity show day-to-day variations, their daily relationships need to be assessed. However, no studies have examined daily sleep-physical activity relationships in postsurgical cardiac patients.

OBJECTIVES

This study aimed to examine the effects of daily sleep factors on daily physical activity after cardiac surgery.

METHODS

Among 33 patients who underwent cardiac surgery at least 10 weeks earlier, 5 sleep and 4 physical activity variables were measured using a wrist-worn ActiGraph for 7 days. Mixed-effects models were applied for data analyses.

RESULTS

Most participants were male (57.6 %), non-Hispanic whites (63.6 %) who had coronary artery bypass graft surgery (54.6 %). Participants averaged 60.8 ± 10.1 years of age and 85.7 ± 91.2 months since surgery. They slept for an average of 385.6 ± 74.6 min (6.4 ± 1.2 h). Among sleep factors, greater number of awakenings (NOA) predicted lower next-day sedentary time. Higher sleep efficiency (SE) was associated with lower next-day sedentary time when not controlling for covariates. Among the psychosocial, demographic, and clinical covariates, higher comorbidity index was associated with fewer kcals expended, less daily moderate-to-vigorous physical activity, and more daily sedentary time.

CONCLUSIONS

Daily SE and NOA and individual health status, including comorbidity, should be assessed over time to support improvement of daily physical activity after cardiac surgery. Researchers should examine the relationship between NOA and next-day sedentary time with larger samples. Such research should address multiple psychosocial, demographic, and clinical factors and the potential mediating role of sleep.

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.

Tablet-Based Assessment of Cognitive Function Among Heart Failure Patients

BACKGROUND

Cognitive impairment accompanying heart failure (HF) is an additional HF comorbidity, which may potentially affect the patient's self-care and compliance. We aimed to assess cognitive function (CF) using an application with games created as a cognitive training tool for children and adults, applied using a tablet, and to compare the results obtained by HF patients with the results obtained by healthy age-matched controls.

METHODS

A total of 69 individuals (49 HF patients and 10 healthy controls) were assessed using 4 games dedicated to measuring cognitive skills as well as questionnaires regarding their socioeconomic status. Additionally, HF patients were asked about their quality of life and anxiety and depression.

RESULTS

HF patients demonstrated worse results in each game assessing their cognitive functions as compared to the healthy age-matched controls, which is consistent with the previous studies on CF in HF. We have also noticed interesting patterns of relations between CF and sleep and education.

CONCLUSIONS

We have demonstrated that information and communication technology devices can be successfully applied as feasible tools for cognitive assessment in the HF population. This is important as tablet-based CF assessment can be done on a large population without the involvement of trained personnel.

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.

The role of sleep disorders in cardiovascular diseases: Culprit or accomplice?

Sleep disorders frequently comorbid with several cardiovascular diseases (CVDs), attracting increasing scientific attention and interest. Sleep disorders include insomnia, sleep-disordered breathing, restless legs syndrome, etc. It is well known that inflammation, sympathetic activation, and endothelial dysfunction play critical roles in sleep disorders, all of which are predisposing factors for CVDs. The comorbidity of sleep disorders and CVDs may have a bidirectional relationship. Patients with CVDs may have a high incidence of sleep disorders and vice versa. This review focused on the comorbidity of sleep disorders and CVDs and discussed the potential pathophysiological mechanisms and therapeutic strategies. In addition to the existing mechanisms, this review summarized novel potential mechanisms underlying comorbidities, such as gut microbiota, orexin, and extracellular vesicles, which may provide a theoretical basis for further basic research and clinical investigations on improving therapeutic outcomes.

Sleep in Neurologic Disorders

Sleep is a complex brain state with fundamental relevance for cognitive functions, synaptic plasticity, brain resilience, and autonomic balance. Sleep pathologies may interfere with cerebral circuit organization, leading to negative consequences and favoring the development of neurologic disorders. Conversely, the latter can interfere with sleep functions. Accordingly, assessment of sleep quality is always recommended in the diagnosis of patients with neurologic disorders and during neurorehabilitation programs. This review investigates the complex interplay between sleep and brain pathologies, focusing on diseases in which the association with sleep disturbances is commonly overlooked and whereby major benefits may derive from their proper management.

Nailfold capillaroscopic changes of sleep apnea patients

BACKGROUND

Obstructive Sleep Apnea Syndrome (OSAS) have frequent association with comorbidities and this makes it an independent risk factor for cardiovascular disease. Not only endothelial dysfunction, but also arterial stiffening, increased inflammatory mediators, oxidative stress after hypoxemia that develops due to OSAS, cause vascular pathologies in all diameters of vessels. Nail bed capillaroscopy is a simple, noninvasive, useful method to examine microcirculation and evaluate nail bed capillary abnormalities in diseases that cause vascular damage. The aim of this study is to examine microvascular changes in the nail bed of OSAS patients by capillaroscopy.

METHODS

59 OSAS patients and 60 healthy cases (totally 119) were included. One single attended polysomnography was applied with Embla N7000 series (RemLogic Eastmed, Natus); and apnea-hypopnea index (AHI), oxygen de-saturation index >4% (ODI4%), minimum oxygen saturation (SaO2 Min.), total duration of oxygen desaturation, comorbidities, body mass index (BMI), smoking habit, sleep questionnaire applications were analyzed. Nailfold capillaroscopy was performed using a digital dermoscope (Molemax II, X30) and all images were evaluated for capillary density, capillary loop enlargement, capillary tortuosity, branching vessels, micro hemorrhages, avascular areas and splinter hemorrhages.

RESULTS

The prevalence rates of all capillaroscopy findings were significantly higher in the patient group (p < 0.05). There was an inverse and moderate relationship between AHI and mean saturation (p < 0.05). A statistically significant correlation was detected between the presence of hypertension (HT) and the severity of capillary tortuosity (CT) (p = 0.002), avascular area (AA) (p = 0.004), and periungual cyanosis (PUC) (p = 0.042); also between smoking habit and intensity of capillary dilatation, enlargement dilatation-enlarged giant capillaries (CELON) (p = 0.004), CT (p = 0.018) findings. Capillary distribution (CD), CELON, CT and AA findings were significantly higher in the group with low mean saturation (p < 0.05). DM was found to be significantly higher in individuals with high Epworth Sleep Scale (ESS) (p = 0.035).

CONCLUSION

In this study; 1) the nail bed capillaroscopy was used to examine vascular damage in OSAS, and 2) irregularities detected in the distal nail bed specific to a disease have been mentioned for the first time. It has been shown that endothelial damage is particularly related to the severity of hypoxia. HT and smoking history causes endothelial damage independent of the severity of the disease and hypoxia. Also, ESS may be more determinant in the screening of sleep disorders in diabetic patients.

Sleep apnea prediction in acute ischemic stroke (SLAPS score): a derivation study

BACKGROUND

Despite its high prevalence and negative impact, sleep-disordered breathing (SDB) remain commonly underdiagnosed and undertreated in stroke subjects. Multiple stroke comorbidities and risk factors, including obesity, hypertension, diabetes mellitus, ischemic heart disease, atrial fibrillation, and heart failure (H.F.) have been associated with SDB. This study aimed to examine associations of clinical and demographic characteristics with moderate-to-severe SDB (msSDB) in stroke patients and to develop a predictive score.

METHODS

Consecutive patients with ischemic stroke were enrolled in an open, prospective study. SDB was assessed using standard polysomnography. Clinical and demographic characteristics, as well as findings from echocardiography, entered the analysis. Multivariate logistic regression models were used to examine the associations with msSDB. Based on the results, an original score to predict msSDB was proposed and tested.

RESULTS

120 patients with acute ischemic stroke (mean age: 64.0 ± 12.2 years, median NIHSS: 4) were included. Body-mass index (BMI), wake-up stroke onset (WUS), and diastolic dysfunction were independently associated with msSDB. A score allocating 1 point for BMI≥25 kg/m² and <30 kg/m², 2 points for BMI≥30 kg/m², 1 point for WUS and 1 point for diastolic dysfunction resulted in an area under the curve of 0.81 (95% CI 0.71-0.90, p<0.001), sensitivity 82.9%, specificity 71.9% to identify stroke patients with msSDB.

CONCLUSIONS

BMI, WUS, and diastolic dysfunction were associated with msSDB. A simple score might help to identify acute stroke patients with msSDB, who are usual candidates for positive airway pressure therapy.

Cardiometabolic comorbidities in obstructive sleep apnea patients are related to disease severity, nocturnal hypoxemia, and decreased sleep quality

BACKGROUND

Obstructive sleep apnea syndrome (OSA) is currently recognized as an independent risk factor for hypertension, arrhythmia, coronary heart disease, stroke, and metabolic disorders (e.g. diabetes, dyslipidemia). In clinical practice, apnea-hypopnea index (AHI) is the marker used to classify disease severity and guide treatment. However, AHI alone does not sufficiently identify OSA patients at risk for cardiometabolic comorbidities. With this in mind, the aim of this retrospective study was to determine whether some polysomnographic parameters (e.g. apnea-hypopnea duration, sleep structure, nocturnal hypoxemia) are specifically associated with cardiometabolic comorbidities in OSA.

METHODS

In this retrospective study, 1717 patients suffering from moderate/severe OSA were included between 2013 and 2017. Data on demographics, comorbidities, and polysomnographic characteristics were collected and analyzed to identify factors associated with cardiometabolic complications.

RESULTS

The medical files of 1717 patients (68% male) were reviewed. The mean AHI was 43.1 +/- 27.7 with 57.3% of patients suffering from severe OSA, and 52% from at least one cardiovascular comorbidity (CVCo). Diabetes affected 22% of the patients and 27% exhibited dyslipidemia. Patients affected by CVCos were older, and more often women and non-smokers. These patients also had worse sleep quality, and a more marked intermittent/global nocturnal hypoxemia. With regard to diabetes, diabetics were older, more often non-smoker, non-drinker women, and were more obese. These patients also exhibited more severe OSA, especially in non-REM (NREM) sleep, worse sleep quality, and a more marked intermittent/global nocturnal hypoxemia. Dyslipidemia was more frequent in the absence of alcohol consumption, and was associated with OSA severity, decreased sleep quality, and longer AH in REM sleep.

CONCLUSIONS

This study identifies demographic and polysomnographic factors associated with cardiometabolic comorbidities. Patients (especially women) suffering from more severe OSA, longer sleep apneas and hypopneas, worse sleep quality, and marked intermittent/global nocturnal hypoxemia are more likely to develop cardiometabolic comorbidities. This should stimulate clinicians to obtain adequate treatment in this population.

Sleep Apnea and Heart Failure With a Reduced Ejection Fraction Among Persons Living With Human Immunodeficiency Virus

Background

Sleep apnea (SA) is common and has prognostic significance among broad groups of patients with heart failure (HF). There are no data characterizing the presence, associations, and prognostic significance of SA among persons living with human immunodeficiency virus (PLHIV) with HF.

Methods

We conducted a single-center study of PLHIV with HF with reduced ejection fraction (HFrEF; left ventricular ejection fraction [LVEF] <50%) and analyzed the relationship of SA with 30-day HF hospital readmission rate.

Results

Our cohort included 1124 individuals admitted with HFrEF; 15% were PLHIV, and 92% were on antiretroviral therapy. SA was noted in 28% of PLHIV and 26% of uninfected controls. Compared to uninfected controls with HFrEF and SA, PLHIV with HFrEF and SA had a lower body mass index, lower LVEF, a higher pulmonary artery systolic pressure (PASP), were more likely to have obstructive rather than central SA (P < .05 for all). In a multivariable model, PASP, low CD4 count, high viral load (VL), and SA parameters (apnea-hypopnea index, CPAP use and duration) were predictors of 30-day HF readmission rate. Each 1-hour increase in CPAP use was associated with a 14% decreased risk of 30-day HF readmission among PLHIV.

Conclusions

Compared to uninfected controls, PLHIV were more likely to have obstructive SA than central SA. Apnea severity, low CD4 count, high VL, and cocaine use were positively associated with 30-day HF hospital readmission rate, whereas CPAP use and increased duration of CPAP use conferred protection.

Acetazolamide Therapy in Patients with Heart Failure: A Meta-Analysis

Background and objectives: Fluid overload and central sleep apnea are highly prevalent in patients with heart failure (HF). We performed this meta-analysis to assess the effects of acetazolamide therapy on acid/base balance and apnea indexes. Methods: A literature search was conducted using EMBASE, MEDLINE, and Cochrane Database from inception through 18 November 2017 to identify studies evaluating the use of acetazolamide in HF. Study results were analyzed using a random effects model. The protocol for this systematic review is registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42017065401). Results: Nine studies (three randomized controlled trials and six cohort studies) with a total of 229 HF patients were enrolled. After acetazolamide treatment, there were significant decreases in serum pH (mean difference (MD) of −0.04 (95% CI, −0.06 to −0.02)), pCO₂ (MD of −2.06 mmHg (95% CI, −3.60 to −0.53 mmHg)), and serum bicarbonate levels (MD of −6.42 mmol/L (95% CI, −10.05 to −2.79 mmol/L)). When compared to a placebo, acetazolamide significantly increased natriuresis (standardized mean difference (SMD) of 0.67 (95% CI, 0.08 to 1.27)), and decreased the apnea-hypopnea index (AHI) (SMD of −1.06 (95% CI, −1.75 to −0.36)) and central apnea index (CAI) (SMD of −1.10 (95% CI, −1.80 to −0.40)). Egger’s regression asymmetry tests revealed no publication bias with p = 0.20, 0.75 and 0.59 for analysis of the changes in pH, pCO₂, and serum bicarbonate levels with use of acetazolamide in HF patients. Conclusion: Our study demonstrates significant reduction in serum pH, increase in natriuresis, and improvements in apnea indexes with use of acetazolamide among HF patients.

Severe sleep apnea, Cheyne-Stokes respiration and desaturation in patients with decompensated heart failure at high altitude

Objectives:

To determine the sleep-disordered breathing in patients with decompensated HF (DHF) at an altitude of 2640m.

Methods:

Polysomnogram during the first 48 hours of admission in patients hospitalized for DHF. Sleep apnea (SA) was defined as an apnea hypopnea index (AHI) > 5/hour and central sleep apnea (CSA) as central apnea index (CAI) ≥ 50% of the AHI.

Results:

Sixteen participants, LVEF 24.2±9.9%. All patients had SA, severe in 12 (75%), CSA in 8 (50%) and 7 (43.8%) presented Cheyne-Stokes respiration (CSR). Out of the eight patients with obstructive SA, five had a central component (CAI ≥ 5/h). The SpO2 decreased during sleep to 80.6±5.5% and in patients with CSR to 77.6±6.9%.

Conclusions:

At an altitude of 2640m all patients with DHF presented sleep apnea, most were severe, with CSA and a significant percentage of CSR that was associated with higher oxygen desaturation.