Increased arterial stiffness in obstructive sleep apnea: a systematic review

Biophysical modeling and diffusion kurtosis imaging reveal microstructural alterations in normal-appearing white-matter regions of the brain in obstructive sleep apnea

Study Objectives

Studies have indicated that sleep abnormalities are a strong risk factor for developing cognitive impairment, cardiomyopathies, and neurodegenerative disorders. However, neuroimaging modalities are unable to show any consistent markers in obstructive sleep apnea (OSA) patients. We hypothesized that, compared with those of the control cohort, advanced diffusion MRI metrics could show subtle microstructural alterations in the brains of patients with OSA.

Methods

Sixteen newly diagnosed patients with moderate to severe OSA and 15 healthy volunteers of the same age and sex were considered healthy controls. Multishell diffusion MRI data of the brain, along with anatomical data (T1 and T2 images), were obtained on a 3T MRI system (Siemens, Germany) after a polysomnography (PSG) test for sleep abnormalities and a behavioral test battery to evaluate cognitive and executive brain functions. Diffusion MRI data were used to compute diffusion tensor imaging and diffusion kurtosis imaging (DKI) parameters along with white-matter tract integrity (WMTI) metrics for only parallel white-matter fibers.

Results

OSA was diagnosed when the patient's apnea-hypopnea index was ≥ 15. No significant changes in cognitive or executive functions were observed in the OSA cohort. DKI parameters can show significant microstructural alterations in the white-matter region, while the WMTI metric, the axonal-water-fraction (fp), reveals a significant decrease in OSA patients concerning the control cohort.

Conclusions

Advanced diffusion MRI-based microstructural alterations in the white-matter region of the brain suggest that white-matter tracts are more sensitive to OSA-induced intermittent hypoxia.

Time delays between physiological signals in interpreting the body's responses to intermittent hypoxia in obstructive sleep apnea

Objective.Intermittent hypoxia, the primary pathology of obstructive sleep apnea (OSA), causes cardiovascular responses resulting in changes in hemodynamic parameters such as stroke volume (SV), blood pressure (BP), and heart rate (HR). However, previous studies have produced very different conclusions, such as suggesting that SV increases or decreases during apnea. A key reason for drawing contrary conclusions from similar measurements may be due to ignoring the time delay in acquiring response signals. By analyzing the signals collected during hypoxia, we aim to establish criteria for determining the delay time between the onset of apnea and the onset of physiological parameter response.Approach.We monitored oxygen saturation (SpO2), transcutaneous oxygen pressure (TcPO2), and hemodynamic parameters SV, HR, and BP, during sleep in 66 patients with different OSA severity to observe body's response to hypoxia and determine the delay time of above parameters. Data were analyzed using the Kruskal-Wallis test, Quade test, and Spearman test.Main results.We found that simultaneous acquisition of various parameters inevitably involved varying degrees of response delay (7.12-25.60 s). The delay time of hemodynamic parameters was significantly shorter than that of SpO2and TcPO2(p< 0.01). OSA severity affected the response delay of SpO2, TcPO2, SV, mean BP, and HR (p< 0.05). SV delay time was negatively correlated with the apnea-hypopnea index (r= -0.4831,p< 0.0001).Significance.The real body response should be determined after removing the effect of delay time, which is the key to solve the problem of drawing contradictory conclusions from similar studies. The methods and important findings presented in this study provide key information for revealing the true response of the cardiovascular system during hypoxia, indicating the importance of proper signal analysis for correctly interpreting the cardiovascular hemodynamic response phenomena and exploring their physiological and pathophysiological mechanisms.

Novel echocardiographic parameters in pulmonary hypertension assessment and the relationship between echocardiography and 6-minute walking test

Pulmonary artery stiffness (PAS) has been shown to be related to pulmonary artery pressure in patients with pulmonary artery hypertension (PAH). The aim of this study was to determine the correlation between functional capacity and echocardiographic indices of PAS in patients with PAH. This cross-sectional study was performed on patients with PAH who were confirmed by right heart catheterization and referred to Imam Reza PAH clinic for routine follow-up between November 2019 and January 2020. All patients underwent echocardiography and the maximum Doppler frequency shift, pulmonary acceleration time, peak velocity of the pulmonary flow, and velocity time integral, as well as PAS, were measured. All patients performed a 6-minute walk test. Fifty patients with a mean age of 41.90 ± 14.73 years old participated in this study. The majority of the patients were female (74%). The most common cause of PAH was idiopathic (74%). There was a significant correlation between PAS and pulmonary artery systolic pressure (r = 0.302, P = .041), second pulmonary valve pulse Doppler velocity (V2) (r = -0.461, P = .003), time from onset of pulmonary flow ejection to V2/first pulmonary valve pulse Doppler velocity (r = -0.311, P = .037) and Z3 ratio (r = -0.346, P = .023). There was no significant correlation between PAS and 6-minute walk test, pulmonary vascular resistance, and tricuspid annular plane systolic excursion (P > .05). There was a significant correlation between V2 and pulmonary vascular resistance (r = 0.359, P = .049). PAS and first pulmonary valve pulse Doppler velocity are simple, noninvasive, available tools for the evaluation of pulmonary vascular beds and diagnosis of presymptomatic clinical status in patients with PAH.

Cardiovascular remodeling in active and controlled acromegaly: association with sleep-disordered breathing

PURPOSE

We hypothesized that an unfavorable cardiovascular profile in acromegaly is associated with sleep-disordered breathing (SDB), while acromegaly control improves both respiratory sleep characteristics and the cardiovascular profile.

METHODS

The patients underwent the assessment of breathing during sleep and cardiovascular profile assessment at the start of the study including arterial stiffness, blood pressure, echocardiography, nocturnal heart rate variability (HRV). The assessment was repeated in patients with acromegaly at 1 year after transsphenoidal adenectomy (TSA).

RESULTS

A total of 47 patients with acromegaly and 55 control subjects were enrolled. At one year after TSA, 22 patients with acromegaly were reassessed. Multiple linear regression analysis with adjustment for age, sex and body mass index (BMI) showed the associations of insulin growth-like factor 1 (IGF-1) with obstructive apnea index (OAI: β=0.035/h, p<0.001), but not with cardiovascular parameters, in patients with acromegaly. The analysis of combined acromegaly and control dataset with adjustment for age, sex and BMI showed the association the presence of acromegaly with diastolic blood pressure (DBP; β=17.99 mmHg, p<0.001), ejection fraction (EF; β=6.23%, p=0.009), left heart remodeling (left ventricle posterior wall: β=0.81 mm, p=0.045) and the association of the presence of SDB (apnea-hypopnea index≥15/h) with left ventricular function (EF: -4.12%, p=0.040; end systolic volume: 10.12 ml, p=0.004). Control of acromegaly was accompanied by the decrease in OAI (5.9 [0.8, 14.5]/h and 1.7 [0.2, 5.1]/h, p=0.004) and nocturnal heart rate (66.1 [59.2, 69.8] bpm and 61.7 [54.0, 67.2] bpm, p=0.025) and by the increase in blood pressure (DBP: 78.0 [70.3, 86.0] mm Hg and 80.0 [80.0, 90.0] mm Hg, p=0.012).

CONCLUSION

The comorbidities of acromegaly, including sleep-disordered breathing, appear to have a long-term effect on cardiovascular remodeling in active acromegaly. Future studies should investigate the applicability of the treatment of SDB for the reduction of cardiovascular risk in acromegaly.

Association Between Arterial Stiffness and Measures of Autonomic Dysfunction in People With Chronic Kidney Disease

Background

Autonomic nervous system (ANS) dysfunction and vascular stiffness increase cardiovascular risk in people with chronic kidney disease (CKD). Chronic elevations in sympathetic activity can lead to increased arterial stiffness; however, the relationship between these variables is unknown in CKD.

Objective

To explore the association between measures of autonomic function and arterial stiffness in patients with moderate-to-severe CKD.

Methods

This study was a prespecified secondary analysis of a randomized controlled trial. This included the following measures: 24-hour ambulatory blood pressure (BP), carotid-femoral and carotid-radial pulse wave velocity (PWV), and postexercise heart rate recovery (HRR). We used mixed effect linear regression models with Bayesian information criteria (BIC) to assess the contribution of ANS measurements.

Results

Forty-four patients were included in the analysis. Mean carotid-femoral and carotid-radial PWV were 7.12 m/s (95% CI 6.13, 8.12) and 8.51 m/s (7.90, 9.11), respectively. Mean systolic dipping, calculated as percentage change in mean systolic readings from day to night, was 10.0% (95% CI 7.79, 12.18). Systolic dipping was independently associated with carotid-radial PWV, MD -0.09 m/s (95% CI -0.15, -0.02) and had the lowest BIC.

Conclusions

Systolic dipping was associated with carotid-radial PWV in people with moderate-to-severe CKD; however, there was no association with carotid-femoral PWV. Systolic dipping may be a feasible surrogate of ANS function, as the association with carotid-radial PWV was consistent with the minimal clinically important difference (MCID). Future studies are needed to define the relationship between ANS function, arterial stiffness, and CV events over time in people with CKD.

Vascular function in hypertension: does gender dimension matter?

Blood pressure and vascular ageing trajectories differ between men and women. These differences develop due to sex-related factors, attributable to sex chromosomes or sex hormones, and due to gender-related factors, mainly related to different sociocultural behaviors. The present review summarizes the relevant facts regarding gender-related differences in vascular function in hypertension. Among sex-related factors, endogenous 17ß-estradiol plays a key role in protecting pre-menopausal women from vascular ageing. However, as vascular ageing (preceding and inducing hypertension) has a steeper increase in women than in men starting already from the third decade, it is likely that gender-related factors play a prominent role, especially in the young. Among gender-related factors, psychological stress (including that one related to gender-based violence and discrimination), depression, some psychological traits, but also low socioeconomic status, are more common in women than men, and their impact on vascular ageing is likely to be greater in women. Men, on the contrary, are more exposed to the vascular adverse consequences of alcohol consumption, as well as of social deprivation, while "toxic masculinity" traits may result in lower adherence to lifestyle and preventive strategies. Unhealthy diet habits are more prevalent in men and smoking is equally prevalent in the two sexes, but have a disproportional negative effect on women's vascular health. In conclusion, given the major and complex role of gender-related factors in driving vascular alterations and blood pressure patterns, gender dimension should be systematically integrated into future research on vascular function and hypertension and to tailor cardiovascular prevention strategies.

Obstructive sleep apnea and hypertension-mediated organ damage in nonresistant and resistant hypertension

The potential role of obstructive sleep apnea (OSA) in hypertension-mediated organ damage (HMOD) may be influenced by the presence of resistant hypertension (RH). Herein, we enrolled patients with hypertension from a tertiary center for clinical evaluation and performed a sleep study to identify OSA (apnea-hypopnea index ≥15 events/h) and a blinded analysis of four standard HMOD parameters (left ventricular hypertrophy [LVH], increased arterial stiffness [≥10 m/s], presence of retinopathy, and nephropathy). RH was diagnosed based on uncontrolled blood pressure (BP) (≥140/90 mmHg) despite concurrent use of at least three antihypertensive drug classes or controlled BP with concurrent use of ≥4 antihypertensive drug classes at optimal doses. To avoid the white-coat effect, ambulatory BP monitoring was performed to confirm RH diagnosis. One-hundred patients were included in the analysis (mean age: 54 ± 8 years, 65% females, body mass index: 30.4 ± 4.5 kg/m²). OSA was detected in 52% of patients. Among patients with non-RH (n = 53), the presence of OSA (52.8%) was not associated with an increased frequency of HMOD. Conversely, among patients with RH, OSA (51.1%) was associated with a higher incidence of LVH (RH-OSA,61%; RH + OSA,87%; p = 0.049). Logistic regression analysis using the total sample revealed that RH (OR:7.89; 95% CI:2.18-28.52; p = 0.002), systolic BP (OR:1.04; 95% CI:1.00-1.07; p = 0.042) and OSA (OR:4.31; 95% CI:1.14-16.34; p = 0.032) were independently associated with LVH. No significant association was observed between OSA and arterial stiffness, retinopathy, or nephropathy. In conclusion, OSA is independently associated with LVH in RH, suggesting a potential role of OSA in RH prognosis.

The effect of CPAP therapy on heart rate variability in patients with obstructive sleep apnea

The aim of this study was to analyze the relationship between the initiation of CPAP therapy and HRV in patients with OSA. The study group consisted of 37 patients, aged 34-79 (mean 54.95 years) with OSA treated with CPAP. Two subgroups of patients were distinguished: less than severe (AHI < 30, n = 16) and severe OSA (AHI ≥ 30, n = 21). The second study was carried out around a month after the initiation of therapy. CPAP therapy caused the improvement in polysomnographic parameters, however, in most parameters in time and frequency analysis, there were no significant positive changes in parasympathetic tone. Moreover, in HRV time analysis, the reduced rMSSD and pNN50 parameters in the hours of night rest and rMSSD and SDSD during the 15-min N3 sleep period were noted. Especially, in the group with AHI ≥ 30, we observed significant decreases in rMSSD and pNN50 for the entire time. The changes were mainly for the night periods including the N3 sleep period, which is especially connected with sleep apnea (parameters: rMSSD, SDSD, and pNN50). In spectral analysis, the decrease in HF from the 15-min daily activity period and the N3 sleep period was observed. Inverse correlations were seen between the maximum, median, and mean positive airway pressure (PAP) and the change in rMSSD, SDNN, and SDSD, mainly during night hours and the N3 sleep period. Only in patients with AHI < 30 the increase in SDNN was observed in 15-min N3 sleep period. The beneficial increase in SDNN parameter from time analysis was observed only in one sleep period in less ill patients with OSA. The lack of significant changes was observed in the majority of the parameters of heart rate variability after initiation of CPAP therapy in a short observational time; however, the shift towards reduced HRV was observed in patients with AHI > 30, so the response to CPAP therapy may depends on the severity of the apnea. The results may suggest that a longer observational period is needed in such studies, and the problem is still not fully elucidated.

Exercise Intolerance in Untreated OSA: Role of Pulmonary Gas Exchange and Systemic Vascular Abnormalities

BACKGROUND

Reduced exercise capacity has been reported previously in patients with OSA hypopnea syndrome (OSAHS), although the underlying mechanisms are unclear.

RESEARCH QUESTION

What are the underlying mechanisms of reduced exercise capacity in untreated patients with OSAHS? Is there a role for systemic or pulmonary vascular abnormalities?

STUDY DESIGN AND METHODS

This was a cross-sectional observational study in which 14 patients with moderate to severe OSAHS and 10 control participants (matched for age, BMI, smoking history, and FEV1) underwent spirometry, incremental cycle cardiopulmonary exercise test (CPET) with arterial line, resting echocardiography, and assessment of arterial stiffness (pulse wave velocity [PWV] and augmentation index [AIx]).

RESULTS

Patients (age, 50 ± 11 years; BMI, 30.5 ± 2.7 kg/m2; smoking history, 2.4 ± 4.0 pack-years; FEV1 to FVC ratio, 0.78 ± 0.04; FEV1, 85 ± 14% predicted, mean ± SD for all) had mean ± SD apnea hypopnea index of 43 ± 19/h. At rest, PWV, AIx, and mean pulmonary artery pressure (PAP) were higher in patients vs control participants (P < .05). During CPET, patients showed lower peak work rate (WR) and oxygen uptake and greater dyspnea ratings compared with control participants (P < .05 for all). Minute ventilation (V·E), ventilatory equivalent for CO2 output (V·E/V·CO2), and dead space volume (VD) to tidal volume (VT) ratio were greater in patients vs control participants during exercise (P < .05 for all). Reduction in VD to VT ratio from rest to peak exercise was greater in control participants compared with patients (0.24 ± 0.08 vs 0.04 ± 0.14, respectively; P = .001). Dyspnea intensity at the highest equivalent WR correlated with corresponding values of V·E/V·CO2 (r = 0.65; P = .002), and dead space ventilation (r = 0.70; P = .001). Age, PWV, and mean PAP explained approximately 70% of the variance in peak WR, whereas predictors of dyspnea during CPET were rest-to-peak change in VD to VT ratio and PWV (R2 = 0.50; P < .001).

INTERPRETATION

Patients with OSAHS showed evidence of pulmonary gas exchange abnormalities during exercise (in the form of increased dead space) and resting systemic vascular dysfunction that may explain reduced exercise capacity and increased exertional dyspnea intensity.

Association between arterial stiffness and sleep apnoea in patients with resistant hypertension

Resistant Hypertension (RHT) is associated with a higher risk of Obstructive Sleep Apnoea (OSA). OSA and aortic stiffness (AS) measured by Pulse Wave Velocity (PWV) are independent risk factors for cardiovascular events. We assessed, in a cross-sectional study, the association between AS measured by PWV and OSA severity in patients with RHT. All patients were submitted to polysomnography, PWV measure and 24 h ABPM. Bivariate analysis compared patients with and without moderate/severe OSA. Multivariate analysis was performed to assess the independent correlates of moderate/severe OSA. A total of 376 patients were included, 31% were men with a mean age of 63 ± 10 years. Moderate/severe OSA was diagnosed in 214 patients (57%), 63 patients (17%) presented AS. Uncontrolled ABPM (true RHT) was found in 215 patients (57.2%) and among them 113 were diagnosed with moderate/severe OSA. Evaluating AS in patients with mild, moderate and severe apnoea, we observed a progressive increase in PWV (8.19 ± 1.55, 8.51 ± 1.84, 8.67 ± 1.68, respectively). Classifying them in 2 groups: (1) without apnoea/mild apnoea and (2) moderate/severe apnoea, we found higher values in group 2 (8.21 ± 1.52 m/s vs. 8.60 ± 1.75 m/s, p = 0.02), especially among true RHT patients (8.28 ± 1.62 vs. 8.81 ± 1.86, p = 0.029), women (8.13 ± 1.49 vs. 8.55 ± 1.73, p = 0.036), and uncontrolled nocturnal systolic BP (8.49 ± 1.63 vs. 8.58 ± 1.78, p = 0.04). In conclusion, in this RHT cohort, although with borderline results, the more severe the apnoea, the greater the arterial stiffness, mainly among women, true RHT and patients with an adverse nocturnal BP profile.

Association between sleep duration and sleep quality with arterial stiffness: A systematic review and meta-analysis

BACKGROUND

Altered sleep parameters, such as duration and quality, play an important role in the pathogenesis and progression of cardiovascular diseases, as well as in all-cause morbidity and mortality. It has been suggested that the specific mechanisms underlying this association could be through the influence of sleep parameters on vascular markers, such as arterial stiffness (AS), although this remains unclear. Thus, in this meta-analysis, we aimed to assess the association between sleep duration and sleep quality with AS in adults.

METHODS

PubMed, Scopus, Web of Science and Cochrane Library databases were searched from inception to July 30, 2021. The DerSimonian and Laird method was used to compute pooled effect size estimates and their respective 95% confidence intervals (95% CIs) of the association of sleep duration and sleep quality with AS. The Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies from the United States National Institute of Health National Heart, Lung, and Blood Institute was used to assess the risk of bias.

RESULTS

Finally, 14 studies (8 cross-sectional studies and baseline data from 6 prospective longitudinal studies) involving 97,837 individuals between 18 and 92 years of age were included. Our results showed that increased sleep duration, as continuous values, does not influence AS (effect size [ES]: 0.00; 95% CIs: -0.15, 0.15) in the general population. However, when sleep duration was longer than 8 hours (ES: 0.21; 95% CIs: 0.06, 0.36), according to sleep categories, a significant increase in pulse wave velocity was shown. Poor sleep quality was associated with increased AS (ES: 0.13; 95% CIs: 0.04, 0.21) in the general population. The overall risk of bias for studies examining sleep duration was fair in 77.8% of the included studies and the overall risk of bias for studies examining sleep quality was fair in 55.6%.

CONCLUSIONS

Our findings showed that both long sleep duration and poor sleep quality were associated with AS in adults. These findings underscore the influence of sleep on vascular health markers, specifically AS, as a possible pathway to explain the increased cardiovascular morbidity and mortality associated with sleep disorders.

The multisystemic effects of oral appliance therapy for obstructive sleep apnea: A narrative review

Obstructive sleep apnea (OSA) is a chronic condition accompanied by repeated obstruction of the upper airway during sleep despite respiratory efforts, resulting in intermittent hypoxemia, altered sleep structure, and sympathetic activation. Previous studies have shown a significant association between OSA and general health issues such as cardiovascular diseases, endocrine disorders, neurocognitive function decline, and poor quality of life. Continuous positive airway pressure (CPAP) has been considered as the first line treatment for OSA. However, accumulating evidence supports the role of oral appliance (OA) therapy, including mandibular advancement devices, as an alternative option for snoring and OSA patients who do not comply with or refuse CPAP usage. Despite a generally favorable outcome of OA therapy for OSA related respiratory indices, studies focusing on the impact of systemic effects of OA therapy in OSA patients are relatively scarce compared with the extensive literature focusing on the systemic effects of CPAP. Therefore, this article aimed to provide an overview of the current evidence regarding the multisystemic effects of OA therapy for OSA.

Economic evaluation of CPAP therapy for obstructive sleep apnea: a scoping review and evidence map

PURPOSE

To synthesize findings of economic evaluations investigating cost-effectiveness of continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA) and of strategies of organization of care related to CPAP therapy.

METHODS

Scoping review with searches conducted in MEDLINE, CRD, LILACS, and Embase in August 2020. Eligible studies were economic evaluations comparing CPAP to other alternative or assessing strategies of care for CPAP therapy. Results were presented narratively, and incremental cost-effectiveness ratios (ICER) were presented in evidence maps.

RESULTS

Of 34 studies, 3 concluded that CPAP is less costly and more effective when compared to usual care. Most studies indicated that CPAP is associated with better health outcomes, but at higher prices. ICER ranged from USD 316 to 98,793 per quality-adjusted life years (QALY) gained (median 16,499; IQR 8267 to 33,119). One study concluded that CPAP is more costly and less effective, when treatment is applied to all patients, regardless of disease severity. Variability of ICER was mainly due to definition of population and applied time horizons. When CPAP was compared to mandibular advancement device, ICER ranged from USD 21,153 to 361,028 (median 89,671; IQR 26,829 to 295,983), which represents the investment in CPAP therapy required to obtain one extra QALY. Three studies assessed the effects of organizing CPAP therapy in primary care, which was cost-effective or cost-saving.

CONCLUSIONS

Compared to usual care, CPAP is cost-effective after the second year of treatment, when indicated for moderate-to-severe OSA. CPAP therapy may be even more cost-effective by using different strategies of organization of care. These findings may inform decision making related to CPAP reimbursement in health systems.

CLINICAL TRIAL REGISTRATION NUMBER

Not applicable.

Six Months of Inspiratory Muscle Training to Lower Blood Pressure and Improve Endothelial Function in Middle-Aged and Older Adults With Above-Normal Blood Pressure and Obstructive Sleep Apnea: Protocol for the CHART Clinical Trial

Background: Cardiovascular disease is a major global health concern and prevalence is high in adults with obstructive sleep apnea (OSA). Lowering blood pressure (BP) can greatly reduce cardiovascular disease risk and physical activity is routinely prescribed to achieve this goal. Unfortunately, many adults with OSA suffer from fatigue, daytime sleepiness, and exercise intolerance—due to poor sleep quality and nocturnal hypoxemia—and have difficulty initiating and maintaining an exercise program. High-resistance inspiratory muscle strength training (IMST) is a simple, time-efficient breathing exercise consistently reported to reduce BP in small, selective groups of both healthy and at-risk adults. Herein we present the study protocol for a randomized clinical trial to determine the long-term efficacy of IMST performed regularly for 24 weeks in middle-aged and older adults with OSA. The primary outcome is casual systolic BP. Secondary outcomes are 24-h systolic BP and circulating plasma norepinephrine concentration. Other outcomes include vascular endothelial function (endothelial-dependent and -independent dilation), aortic stiffness, casual and 24-h diastolic BP, and the influence of circulating factors on endothelial cell nitric oxide and reactive oxygen species production. Overall, this trial will establish efficacy of high-resistance IMST for lowering BP and improving cardiovascular health in middle-aged and older adults with OSA.

Methods: This is a single-site, double-blind, randomized clinical trial. A minimum of 92 and maximum of 122 male and female adults aged 50–80 years with OSA and above-normal BP will be enrolled. After completion of baseline assessments, subjects will be randomized in a 1:1 ratio to participate in either high-resistance or sham (low-resistance) control IMST, performed at home, 5 min/day, 5 days/week, for 24 weeks. Repeat assessments will be taken after the 24-week intervention, and after 4 and 12 weeks of free living.

Discussion: This study is designed to assess the effects of 24 weeks of IMST on BP and vascular function. The results will characterize the extent to which IMST can reduce BP when performed over longer periods (i.e., 6 months) than have been assessed previously. Additionally, this study will help to determine underlying mechanisms driving IMST-induced BP reductions that have been reported previously.

Clinical Trial Registration: This trial is registered with ClinicalTrials.gov (Registration Number: NCT04932447; Date of registration June 21, 2021).

Effect of Maternal Obstructive Sleep Apnea-Hypopnea on 24-Hour Blood Pressure, Nocturnal Blood Pressure Dipping and Arterial Stiffness in Hypertensive Disorders of Pregnancy

Rationale: Maternal obstructive sleep apnea-hypopnea (OSAH) is associated with hypertensive disorders of pregnancy (HDP). Attenuation of the normal nocturnal blood pressure (BP) decline (non-dipping) is associated with adverse pregnancy outcomes. OSAH is associated with nocturnal non-dipping in the general population, but this has not been studied in pregnancy. We therefore analyzed baseline data from an ongoing RCT (NCT03309826) assessing the impact of OSAH treatment on HDP outcomes, to evaluate the relationship of OSAH to 24-h BP profile, in particular nocturnal BP dipping, and measures of arterial stiffness.

Methods: Women with a singleton pregnancy and HDP underwent level II polysomnography. Patients with OSAH (apnea-hypopnea index (AHI) ≥ 5 events/h) then underwent 24-h ambulatory BP monitoring and arterial stiffness measurements (applanation tonometry, SphygmoCor). Positive dipping was defined as nocturnal systolic blood pressure (SBP) dip ≥ 10%. The relationships between measures of OSAH severity, measures of BP and arterial stiffness were evaluated using linear regression analyses.

Results: We studied 51 HDP participants (36.5 ± 4.9 years, BMI 36.9 ± 8.6 kg/m²) with OSAH with mean AHI 27.7 ± 26.4 events/h at 25.0 ± 4.9 weeks’ gestation. We found no significant relationships between AHI or other OSA severity measures and mean 24-h BP values, although BP was generally well-controlled. Most women were SBP non-dippers (78.4%). AHI showed a significant inverse correlation with % SBP dipping following adjustment for age, BMI, parity, gestational age, and BP medications (β = −0.11, p = 0.02). Significant inverse correlations were also observed between AHI and DBP (β = −0.16, p = 0.01) and MAP (β = −0.13, p = 0.02) % dipping. Oxygen desaturation index and sleep time below SaO₂ 90% were also inversely correlated with % dipping. Moreover, a significant positive correlation was observed between carotid-femoral pulse wave velocity (cfPWV) and REM AHI (β = 0.02, p = 0.04) in unadjusted but not adjusted analysis.

Conclusion: Blood pressure non-dipping was observed in a majority of women with HDP and OSAH. There were significant inverse relationships between OSAH severity measures and nocturnal % dipping. Increased arterial stiffness was associated with increasing severity of OSAH during REM sleep in unadjusted although not adjusted analysis. These findings suggest that OSAH may represent a therapeutic target to improve BP profile and vascular risk in HDP.

Arterial Stiffness Assessment Using the Arteriograph in Patients with Moderate-Severe OSA and Metabolic Syndrome-A Pilot Study

BACKGROUND

Both obstructive sleep apnea (OSA) and metabolic syndrome (MS) promote arterial stiffening. As a basis for this study, we presumed that arterial stiffness could be assessed using the Arteriograph (TensioMed, Budapest, Hungary) to detect early modifications induced by continuous positive airway therapy (CPAP) in reversing this detrimental vascular remodeling. Arterial stiffness is increasingly acknowledged as a major cardiovascular risk factor and a marker of subclinical hypertension-mediated organ damage. The aim of this pilot study was to evaluate the arterial stiffness changes in patients with moderate-severe OSA and MS after short-term CPAP use.

METHODS

We performed a prospective study that included patients with moderate-severe OSA and MS who had not undergone previous CPAP therapy. All subjects underwent clinical examination and arterial stiffness assessment using the oscillometric technique with Arteriograph (TensioMed, Budapest, Hungary) detection before and after 8-week CPAP therapy.

RESULTS

39 patients with moderate-severe OSA were included. Eight weeks of CPAP therapy significantly improved central systolic blood pressure (Δ = -11.4 mmHg, p = 0.009), aortic pulse wave velocity (aoPWV: Δ = -0.66 m/s, p = 0.03), and aortic augmentation index (aoAix: Δ = -8.25%, p = 0.01) only in patients who used the device for a minimum of 4 h/night (n = 20).

CONCLUSIONS

Arterial stiffness was improved only among CPAP adherent patients and could be detected using the Arteriograph (TensioMed, Budapest, Hungary), which involves a noninvasive procedure that is easy to implement for the clinical evaluation of arterial stiffness.

Sleep moderates the association between arterial stiffness and 24-hour blood pressure variability

BACKGROUND

Arterial stiffness and increased blood pressure variability (BPV) are important subclinical cardiovascular diseases (CVDs). Evidence is accumulating that poor sleep is associated with subclinical CVDs. The purpose of our study was to investigate how sleep was related to arterial stiffness and BPV. We also explored whether sleep moderated the association between arterial stiffness and BPV.

METHODS

We conducted a cross-sectional study including 78 healthy adults aged between 35 and 64 years. Variables of interest were: 1) objective seep characteristics, assessed with a wrist actigraphy for two consecutive nights; 2) arterial stiffness, measured by carotid-femoral pulse wave velocity (cfPWV); and 3) BPV, measured using an ambulatory blood pressure monitor over 24 h and estimated by average real variability.

RESULTS

Lower sleep efficiency was an independent predictor of higher cfPWV and higher systolic BPV, while longer wake after sleep onset (WASO) was an independent predictor of higher cfPWV only. In addition, cfPWV showed a positive relationship with systolic BPV, and this relationship was moderated by sleep efficiency and WASO, respectively. The relationship between cfPWV and systolic BPV became stronger among individuals who had a level of sleep efficiency lower than 84% and who had WASO higher than 67 min, respectively.

CONCLUSION

Our study showed that poor sleep not only directly linked with arterial stiffness and BPV but also moderated the relationship between these two subclinical CVDs. These findings suggest that improving sleep quality could be a target intervention to promote cardiovascular health in clinical practice.

Auto-adaptive positive airway pressure improves lung function and arterial stiffness parameters in patients with severe obstructive sleep apnea syndrome over a 1 year follow-up

OBJECTIVE

Auto-adaptive positive airway pressure (APAP) is an emerging therapeutic modality for obstructive sleep apnea (OSA) patients. However, their associated physiological effects have not been well-defined. Therefore, we aimed to investigate the impact of a 1 year APAP treatment on lung function and arterial stiffness parameters.

APPROACH

This study enrolled male patients with newly diagnosed severe OSA who have undergone APAP treatment. A total of 35 patients completed a 1 year follow up. Blood pressure, arterial stiffness (PWV, cAIx, pAIx, cSBP), and lung function readings (FEV₁, FVC, FEV₁/FVC, PEF) were obtained basally and after 1, 3, 6, and 12 months of treatment.

MAIN RESULTS

A gradual increase in FEV₁ has been observed over the follow-up (2.92 ± 0.88 versus 3.07 ± 0.92 versus 3.18 ± 0.93 versus 3.28 ± 0.93 versus 3.41 ± 0.97 L), while PWV showed a gradual decrease over the follow-up (9.72 ± 1.64 versus 9.32 ± 1.73 versus 8.89 ± 1.65 versus 8.53 ± 1.61 versus 8.46 ± 1.60 m s^-1), as measured by absolute values. Linear mixed effects model analysis revealed a statistically significantly higher FEV₁ values (coefficient of 0.11, 0.20, and 0.33 for 3rd month, 6th month, and 12th month, respectively, P < 0.001) and lower PWV values (coefficient of -0.69, -0.63, and -0.34 for 3rd month, 6th month, and 12th month, respectively, P < 0.001), after the initiation of APAP treatment.

SIGNIFICANCE

We conclude that APAP treatment improves main lung function and arterial stiffness parameters in male patients with severe OSA over a 1 year follow-up.

Impact of CPAP on arterial stiffness in patients with obstructive sleep apnea: a meta-analysis of randomized trials

PURPOSE

This study aimed to perform a systematic review and meta-analysis of randomized trials investigating the effect of continuous positive airway pressure (CPAP) on non-invasive markers of arterial stiffness in patients with OSA.

METHODS

The purpose of the study was to evaluate the effect of CPAP on markers of arterial stiffness (pulse wave velocity (PWV) and augmentation index (Aix)) in patients with OSA. The study adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We systematically reviewed MEDLINE, EMBASE, CENTRAL/CCTR, SciELO, and LILACS databases for randomized trials (RT) evaluating the changes in markers of arterial stiffness (pulse wave velocity (PWV) and augmentation index (Aix) comparing CPAP vs. controls in patients with OSA. Reviewer Manager version 5.3 (R Foundation for Statistical Computing, Vienna, Austria) was used to perform meta-analysis. Risk of bias analysis was performed using the Cochrane tool.

RESULTS

Of the 464 studies initially retrieved, 9 relevant studies with 685 participants were included in the analysis. The studies presented moderate risk of bias. CPAP did not significantly reduce Aix (mean difference, - 1.96 (95% confidence interval (CI) - 5.25 to 1.33), p = 0.24), whereas it significantly changed PWV (mean difference, - 0.44 (95% confidence interval (CI) - 0.76 to - 0.12), p = 0.00).

CONCLUSION

CPAP treatment was effective in improving arterial stiffness by reducing PWV in patients with OSA. Additional randomized trials, however, should be performed to confirm these findings.

Long-term variations of arterial stiffness in patients with obesity and obstructive sleep apnea treated with continuous positive airway pressure

BACKGROUND

Obstructive sleep apnea (OSA) is associated with cardiovascular co-morbidities and mortality. Arterial stiffness is an independent predictor of cardiovascular risk and mortality, and is influenced by the presence of OSA and related comorbidities. There is a paucity of data regarding long-term evolution of arterial stiffness in CPAP-treated OSA patients. We aimed to prospectively study long term PWV variations and determinants of PWV deterioration.

METHODS

In a prospective obese OSA cohort, at time of diagnosis and after several years of follow-up we collected arterial stiffness measured by carotid-femoral pulse wave velocity (PWV), clinical and metabolic parameters, and CPAP adherence. Univariate and multivariate analyses were performed in order to determine contributing factors.

RESULTS

Seventy two OSA patients (men: 52.8%, median age: 55.8 years and median BMI of 38.5 kg/m2) with a prevalence of hypertension: 58.3%, type 2 diabetes: 20.8%, hypercholesterolemia: 33.3%, current or past smoking: 59.7%, were evaluated after a median follow-up of 7.4 [5.8; 8.3] years. Over the period of follow-up, the median increase in PWV was 1.34 [0.10; 2.37] m/s. In multivariate analysis, the increase in PWV was associated with older age (10 extra years was associated with a 5.24 [1.35; 9.12] % increase in PWV) and hypertension (a significant increase in PWV of 8.24 [1.02; 15.57] %). No impact of CPAP adherence on PWV evolution was found.

CONCLUSION

PWV progression in CPAP-treated OSA patients is mainly related to pre-existing cardio-metabolic comorbidities and not influenced by CPAP adherence. In this high cardiovascular risk population, it is crucial to associated weight management and exercise with CPAP treatment.

Effect of Obstructive Sleep Apnea on Cardiovascular Function in Obese Youth

The increasing prevalence of overweight or obese children and adolescents is a significant global health concern. Although the effect of obesity on cardiovascular function has been investigated, little is known on the impact of associated obstructive sleep apnea (OSA) in obese youth. The aim of the present study was to investigate the influence of OSA on cardiovascular functional parameters in obese youth. This is a prospective single-center observational cross-sectional study. Forty-four obese patients and 44 age- and gender-matched control subjects were included. All patients underwent polysomnography and cardiovascular assessment including functional echocardiography and carotid-femoral pulse wave velocity (PWV). Obese patients had higher left ventricular (LV) mass/height^2.7, preserved LV systolic parameters, differences in LV diastolic parameters, and increased PWV and systolic blood pressure at rest compared with control group. In obese youth, 14 of 44 (32%) had OSA. There was no correlation between obesity and the apnea-hypopnea index (AHI). LV mass/height^2.7 significantly correlated with body mass index z-score (r = 0.648, p <0.001) whereas PWV correlated with AHI (r = 0.352, p = 0.038). In obese patients, body mass index z-score was an independent predictor for LV mass/height^2.7 (r = 0.61, p <0.001) and AHI was an independent predictor for higher PWV (r = 0.352, p = 0.038). In conclusion, both obesity and OSA influence cardiovascular performance in obese youth. Although obesity is associated with increased LV mass and reduced LV diastolic function, OSA is associated with changes in arterial stiffness.

Neurotrophic factor BDNF is upregulated in soft palate muscles of snorers and sleep apnea patients

Objectives

Neuromuscular injuries are suggested to contribute to upper airway collapse and swallowing dysfunction in patients with sleep apnea. Neurotrophins, a family of proteins involved in survival, development, and function of neurons, are reported to be upregulated in limb muscle fibers in response to overload and nerve damage. We aimed to investigate the expression of two important neurotrophins, brain‐derived neurotrophic factor (BDNF) and nerve growth factor (NGF), in muscle fibers of uvula from snorers and sleep apnea patients and to compare these findings with pharyngeal function.

Methods

Uvula muscle biopsies from 22 patients and 10 controls were analyzed for BDNF, NGF, and cytoskeletal protein desmin using immunohistochemistry. Pharyngeal swallowing function was assessed using videoradiography.

Results

BDNF, but not NGF, was significantly upregulated in a subpopulation of muscle fibers in snoring and sleep apnea patients. Two major immunoreaction patterns for BDNF were observed; a fine grainy point like BDNF staining was displayed in muscle fibers of both patients and controls (41 ± 23 vs. 25 ± 17%, respectively, P = .06), while an abnormal upregulated intense‐dotted or disorganized reaction was mainly observed in patients (8 ± 8 vs. 2 ± 2%, P = .02). The latter fibers, which often displayed an abnormal immunoreaction for desmin, were more frequent in patients with than without swallowing dysfunction (10 ± 8 vs. 3 ± 3%, P = .05).

Conclusion

BDNF is upregulated in the upper airway muscles of snorers and sleep apnea patients, and especially in patients with swallowing dysfunction. Upregulation of BDNF is suggested to be a response to denervation, reinnervation, and repair of injured muscle fibers. Our findings propose that damaged upper airway muscles might heal following treatment for snoring and sleep apnea.

Level of Evidence

NA

Actigraphy-based sleep characteristics and aortic stiffness: the Multi-Ethnic Study of Atherosclerosis

The study aimed to examine the association between objective estimates of sleep duration and quality and aortic stiffness while accounting for the potential confounding effect of sleep-disordered breathing. Participants were part of the Multi-Ethnic Study of Atherosclerosis Sleep study. Sleep duration and quality were assessed by 7-day wrist actigraphy, sleep-disordered breathing by home polysomnography, and aortic stiffness by magnetic resonance imaging-based aortic pulse wave velocity (aPWV), ascending and descending aorta distensibility. Aortic stiffness of participants with "normal" sleep duration (6-8 hours) were compared with those of "short" (<6 hours) and "long" sleep duration (>8 hours) adjusting for common cardiovascular risk factors and apnea-hypopnea index. The sample consisted of 908 participants (mean age 68.4 ± 9.1 years, 55.3% female). There was a significant linear trend of increased aPWV across short (n = 252), normal (n = 552), and long sleep durations (n = 104) (P for trend = .008). Multivariable analysis showed that people with short sleep duration had 0.94 m/s lower aPWV (95% CI: -1.54, -0.35), compared with those with normal sleep duration. In this ethnically diverse community cohort, habitual short sleep duration as estimated by actigraphy was associated with lower aortic stiffness.

Contribution of obstructive sleep apnoea to arterial stiffness: a meta-analysis using individual patient data

BACKGROUND

Arterial stiffness, measured by pulse wave velocity (PWV), is a strong independent predictor of late cardiovascular events and mortality. It is recognised that obstructive sleep apnoea (OSA) is associated with cardiovascular comorbidities and mortality. Although previous meta-analyses concluded that PWV is elevated in OSA, we feel that an individual patient data analysis from nine relatively homogeneous studies could help answer: to what extent does OSA drive arterial stiffness?

METHODS

Individual data from well-characterised patients referred for suspicion of OSA, included in nine studies in which carotid-femoral PWV was measured using a Complior device, were merged for an individual patient data meta-analysis.

RESULTS

893 subjects were included (age: 56±11 (mean±SD), 72% men, 84% with confirmed OSA). Body Mass Index varied from 15 to 81 kg/m² (30±7 kg/m²). PWV ranged from 5.3 to 20.5 m/s (10.4±2.3 m/s). In univariate analysis, log(PWV) was strongly related to age, gender, systolic blood pressure, presence of type 2 diabetes (all p<0.01) as well as to dyslipidaemia (p=0.03) and an Epworth Sleepiness Scale score ≥9 (p=0.04), whereas it was not related to obesity (p=0.54), a severe Apnoea-Hypopnoea Index (p=0.14), mean nocturnal saturation (p=0.33) or sleep time with oxygen saturation below 90% (p=0.47). In multivariable analysis, PWV was independently associated with age, systolic blood pressure and diabetes (all p<0.01), whereas severe OSA was not significantly associated with PWV.

CONCLUSION

Our individual patient meta-analysis showed that elevated arterial stiffness in patients with OSA is driven by conventional cardiovascular risk factors rather than apnoea parameters.

Arterial stiffness alteration and obstructive sleep apnea in an elderly cohort free of cardiovascular event history: the PROOF cohort study

INTRODUCTION

Several studies suggest in middle-aged subjects a relationship between arterial stiffness, a cardiovascular risk marker, and moderate to severe obstructive sleep apnea (OSA). No extensive data are present in older subjects. This study explores this association in a sample of healthy older subjects suffering OSA.

METHODS

A total of 101 volunteers aged 75.3 ± 0.7 years were examined at the hospital sleep center. Each subject was assessed for medical history, body mass index and 24-h blood pressure measures, biological blood samples, and home polygraphy in 2002-2003 (P2) as well as in 2009-2010 (P4). Arterial stiffness was also assessed using carotid-femoral and carotid-radial pulse wave velocity (cfPWV and crPWV) during P4 examination.

RESULTS

The total group consisted of 59 women and 42 men with a mean apnea-hypopnea index (AHI) of 17.8 ± 12.1 and a mean oxygen desaturation index (ODI) of 9.8 ± 8.9. No-OSA (AHI < 15) represented 50% of the sample, and severe cases (AHI > 30) 17%. No significant differences had been founded between men and women for blood pressure, cfPWV, and crPWV. Considering the severity of the AHI, no significant differences between groups were present for PWV and blood pressure values. No difference for PWV was present for subjects with and without hypertension. No correlation was found between PWV value and AHI and ODI values at P2 or between P2 and P4 visits. cfPWV was higher in patients demonstrating incident hypertension during the follow-up.

CONCLUSIONS

In this sample of older subjects, PWV is not affected by AHI and ODI but was associated with incident hypertension. These results may suggest potential protective and adaptive mechanisms in older sleep apnea patients.

CLINICAL TRIAL REGISTRATIONS

NCT 00759304 and NCT 00766584 .

Sleep-Disordered Breathing and Prevalent Albuminuria in Hispanics/Latinos

Introduction

Although sleep-disordered breathing has been found to be associated with higher urine albumin excretion, this association has not been evaluated in Hispanic/Latino populations, which experience a high burden of end-stage renal disease compared with non-Hispanics. We evaluated the association of sleep-disordered breathing with prevalent albuminuria among US Hispanics/Latinos.

Methods

This was a cross-sectional study of baseline data from participants in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), a population-based study that enrolled 16,415 adults in 4 US communities. Sleep-disordered breathing was assessed using a home sleep apnea monitor for overnight recording and was defined using 3 thresholds of the apnea−hypopnea index (AHI; 3% desaturation): ≥5, ≥15, and ≥30. Albuminuria was defined as a urine albumin-to-creatinine ratio of ≥30 mg/g.

Results

There were 12,572 participants with complete data available for analysis. The age- and sex-adjusted prevalence of albuminuria was 9.1%. Mean age was 41 years, and 48% were men. Age- and sex-adjusted prevalence of sleep-disordered breathing was higher among individuals with albuminuria compared with those without albuminuria (36% vs. 25% had AHI ≥5, 18% vs. 9% had AHI ≥15, and 9% vs. 4% had AHI ≥30). In multivariable logistic regression analyses, AHIs ≥5, ≥15, and ≥30 were associated with greater odds of albuminuria compared with those with AHIs <5, <15, and <30 (odds ratio [OR] 1.42, 95% confidence interval [CI]: 1.14−1.76; OR: 1.71, 95% CI: 1.33−2.20; and OR 1.93, 95% CI 1.34−2.79), respectively. This association varied by Hispanic/Latino background group.

Conclusion

In US Hispanic/Latinos, sleep-disordered breathing was independently associated with higher odds of prevalent albuminuria.

Obstructive sleep apnoea is associated with progression of arterial stiffness independent of obesity in participants without hypertension: A KoGES Prospective Cohort Study

Accumulating evidence shows that obstructive sleep apnoea (OSA) is associated with an increased risk of cardiovascular disease. However, there are no published prospective studies on the relationship between OSA and the progression of arterial stiffness. We hypothesised that OSA would increase the risk of arterial stiffness progression, independent of obesity. In the present large cohort study, 1921 participants were randomly selected and underwent polysomnography. The brachial ankle pulse wave velocity (baPWV) was measured at baseline and during the follow-period using a standard protocol. Elevated baPWV was defined as a value greater than the cut-off of highest tertile level in the complete study cohort. The percentage of elevated baPWV and the ΔbaPWV significantly increased with OSA severity. After adjusting for potential confounding factors, participants with moderate-to-severe OSA without hypertension had a significantly higher risk of elevated ΔbaPWV than those without OSA. More importantly, using multivariate mixed-effect models, we found that the ΔbaPWV over 6 years significantly differed according to OSA severity. Therefore, moderate-to-severe OSA in participants without hypertension was a predictor of future burden of arterial stiffness progression, independent of obesity, suggesting that it may contribute to the increased risk of cardiovascular disease.

Sleep disturbances in women with polycystic ovary syndrome: prevalence, pathophysiology, impact and management strategies

Polycystic ovary syndrome (PCOS) is a complex endocrine disorder affecting the reproductive, metabolic and psychological health of women. Clinic-based studies indicate that sleep disturbances and disorders including obstructive sleep apnea and excessive daytime sleepiness occur more frequently among women with PCOS compared to comparison groups without the syndrome. Evidence from the few available population-based studies is supportive. Women with PCOS tend to be overweight/obese, but this only partly accounts for their sleep problems as associations are generally upheld after adjustment for body mass index; sleep problems also occur in women with PCOS of normal weight. There are several, possibly bidirectional, pathways through which PCOS is associated with sleep disturbances. The pathophysiology of PCOS involves hyperandrogenemia, a form of insulin resistance unique to affected women, and possible changes in cortisol and melatonin secretion, arguably reflecting altered hypothalamic-pituitary-adrenal function. Psychological and behavioral pathways are also likely to play a role, as anxiety and depression, smoking, alcohol use and lack of physical activity are also common among women with PCOS, partly in response to the distressing symptoms they experience. The specific impact of sleep disturbances on the health of women with PCOS is not yet clear; however, both PCOS and sleep disturbances are associated with deterioration in cardiometabolic health in the longer term and increased risk of type 2 diabetes. Both immediate quality of life and longer-term health of women with PCOS are likely to benefit from diagnosis and management of sleep disorders as part of interdisciplinary health care.

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

PURPOSE OF REVIEW

The bidirectional relationships that have been demonstrated between heart failure (HF) and central sleep apnea (CSA) demand further exploration with respect to the implications that each condition has for the other. This review discusses the body of literature that has accumulated on these relationships and how CSA and its potential treatment may affect outcomes in patients with CSA.

RECENT FINDINGS

Obstructive sleep apnea (OSA) can exacerbate hypertension, type 2 diabetes, obesity, and atherosclerosis, which are known predicates of HF. Conversely, patients with HF more frequently exhibit OSA partly due to respiratory control system instability. These same mechanisms are responsible for the frequent association of HF with CSA with or without a Hunter-Cheyne-Stokes breathing (HCSB) pattern. Just as is the case with OSA, patients with HF complicated by CSA exhibit more severe cardiac dysfunction leading to increased mortality; the increase in severity of HF can in turn worsen the degree of sleep disordered breathing (SDB). Thus, a bidirectional relationship exists between HF and both phenotypes of SDB; moreover, an individual patient may exhibit a combination of these phenotypes. Both types of SDB remain significantly underdiagnosed in patients with HF and hence undertreated. Appropriate screening for, and treatment of, OSA is clearly a significant factor in the comprehensive management of HF, while the relevance of CSA remains controversial. Given the unexpected results of the Treatment of Sleep-Disordered Breathing with Predominant Central Sleep Apnea by Adaptive Servo Ventilation in Patients with Heart Failure trial, it is now of paramount importance that additional analysis of these data be expeditiously reported. It is also critical that ongoing and proposed prospective studies of this issue proceed without delay.

Nonmuscle Myosin Light Chain Kinase: A Key Player in Intermittent Hypoxia-Induced Vascular Alterations

Background

Obstructive sleep apnea is characterized by repetitive pharyngeal collapses during sleep, leading to intermittent hypoxia (IH), the main contributor of obstructive sleep apnea–related cardiovascular morbidity. In patients and rodents with obstructive sleep apnea exposed to IH, vascular inflammation and remodeling, endothelial dysfunction, and circulating inflammatory markers are linked with IH severity. The nonmuscle myosin light chain kinase (nmMLCK) isoform contributes to vascular inflammation and oxidative stress in different cardiovascular and inflammatory diseases. Thus, in the present study, we hypothesized that nmMLCK plays a key role in the IH‐induced vascular dysfunctions and inflammatory remodeling.

Methods and Results

Twelve‐week‐old nmMLCK^+/+ or nmMLCK^−/− mice were exposed to 14‐day IH or normoxia. IH was associated with functional alterations characterized by an elevation of arterial blood pressure and stiffness and perturbations of NO signaling. IH caused endothelial barrier dysfunction (ie, reduced transendothelial resistance in vitro) and induced vascular oxidative stress associated with an inflammatory remodeling, characterized by an increased intima‐media thickness and an increased expression and activity of inflammatory markers, such as interferon‐γ and nuclear factor‐κB, in the vascular wall. Interestingly, nmMLCK deletion prevented all IH‐induced functional and structural alterations, including the restoration of NO signaling, correction of endothelial barrier integrity, and reduction of both oxidative stress and associated inflammatory response.

Conclusions

nmMLCK is a key mechanism in IH‐induced vascular oxidative stress and inflammation and both functional and structural remodeling.

Cardiorespiratory interaction with continuous positive airway pressure

The treatment of choice for obstructive sleep apnoea (OSA) is continuous positive airway pressure therapy (CPAP). Since its introduction in clinical practice, CPAP has been used in various clinical conditions with variable and heterogeneous outcomes. In addition to the well-known effects on the upper airway CPAP impacts on intrathoracic pressures, haemodynamics and blood pressure (BP) control. However, short- and long-term effects of CPAP therapy depend on multiple variables which include symptoms, underlying condition, pressure used, treatment acceptance, compliance and usage. CPAP can alter long-term cardiovascular risk in patients with cardiorespiratory conditions. Furthermore, the effect of CPAP on the awake patient differs from the effect on the patients while asleep, and this might contribute to discomfort and removal of the use interface. The purpose of this review is to highlight the physiological impact of CPAP on the cardiorespiratory system, including short-term benefits and long-term outcomes.

Sleep disorder, an independent risk associated with arterial stiffness in menopause

As women age and go through menopause, they suffer a higher incidence of sleep disorder, cardiovascular morbidity and mortality. In addition, evidences suggested that sleep disorder was an important pathological indicator for coronary heart disease. However, the relationship between different menopausal status, sleep disorder and cardiovascular diseases was unclear. Thus, we aim to assess the association between sleep disorder with arterial stiffness in females of 40–60 years free of cardiovascular diseases through self-administered Pittsburgh Sleep Quality Index (PSQI) and brachial-ankle pulse wave velocity (baPWV). Logistic regression revealed that sleep disorder (PSQI score ≥ 8) was an independent indicator for higher risk of elevated arterial stiffness (baPWV ≥ 1465.5 cm/s, upper tertile) beyond other established cardiovascular confounders in peri-postmenopause (OR 2.83, 95% confidence interval (CI) 2.00–4.00, p < 0.001), but not in premenopause (OR 1.67, 95% CI 0.71–3.90, p = 0.223). Collectively, it clearly indicates that sleep disorder in menopausal women is of prominent value to predict arterial stiffness.

[Acute aortic syndromes and sleep apnea]

Obstructive sleep apnea (OSA) is a common disease, often present in "cardiovascular or metabolic patients". OSA favours the occurrence of arterial lesions, all the more if severe. There is a strong relationship between OSA and acute aortic syndromes (AAS). This relationship is in part explained by aortic dilatation linked to OSA. The presence of repeated episodes of sudden variation of transmural pressure applied on aortic wall seems to play a major role in this dilatation. All OSA patients should have a search of aortic dilatation by ultrasound (at a thoracic and abdominal level). Also, screening of OSA should be systematically performed in patients with aortic disease. The effect of continuous positive airway pressure in apneic patients with AAS has not been studied.

Use of CPAP to reduce arterial stiffness in moderate-to-severe obstructive sleep apnoea, without excessive daytime sleepiness (STIFFSLEEP): an observational cohort study protocol

INTRODUCTION

Sleepiness is a cardinal symptom in obstructive sleep apnoea (OSA) but most patients have unspecific symptoms. Arterial stiffness, evaluated by pulse wave velocity (PWV), is related to atherosclerosis and cardiovascular (CV) risk. Arterial stiffness was reported to be higher in patients with OSA, improving after treatment with continuous positive airway pressure (CPAP). This study aims to assess whether the same effect occurs in patients with OSA and without sleepiness.

METHODS AND ANALYSIS

This observational study assesses the CV effect of CPAP therapy on a cohort of patients with moderate-to-severe OSA; the effect on the subcohorts of sleepy and non-sleepy patients will be compared. A systematic and consecutive sample of patients advised CPAP therapy will be recruited from a single outpatient sleep clinic (Centro Hospitalar de Lisboa Central-CHLC, Portugal). Eligible patients are male, younger than 65 years, with confirmed moderate-to-severe OSA and apnoea-hypopnea index (AHI) above 15/hour. Other sleep disorders, diabetes or any CV disease other than hypertension are exclusion criteria. Clinical evaluation at baseline includes Epworth Sleepiness Scale (ESS), and sleepiness is defined as ESS above 10. OSA will be confirmed by polygraphic study (cardiorespiratory, level 3). Participants are advised to undertake an assessment of carotid-femoral PWV (cf-PWV) and 24 hours evaluation of ambulatory blood pressure monitoring (ABPM), at baseline and after 4 months of CPAP therapy. Compliance and effectiveness of CPAP will be assessed. The main outcome is the variation of cf-PWV over time.

ETHICS AND DISSEMINATION

This protocol was approved by the Ethics Committees of CHLC (reference number 84/2012) and NOVA Medical School (number36/2014/CEFCM), Lisbon. Informed, written consent will be obtained. Its results will be presented at conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT02273089; Pre-results.

Simple obstructive sleep apnea patients without hypertension or diabetes accelerate kidney dysfunction: a population follow-up cohort study from Taiwan

Backgrounds

Obstructive sleep apnea (OSA) is common in patients on hemodialysis, but its correlation with chronic kidney disease (CKD) is not clear. We aimed to clarify the relationship between OSA without hypertension or diabetes and incidence of CKD in Taiwan.

Methods

This population-based cohort study consisted of patients with newly diagnosed OSA between 2000 and 2009. The comparison cohort was matched for age, sex, diabetes mellitus, and hypertension. All subjects previously diagnosed with acute or chronic kidney disease were excluded. The primary end point was newly diagnosed CKD.

Results

We identified 6866 subjects with OSA during the 10-year study period. The median duration until development of CKD in the OSA cohort was 3.2 years, 2.5 months earlier than that in the non-OSA cohort. After exclusion of hypertension and diabetes, 4319 OSA patients was identified and the hazard ratio (HR) of CKD with OSA was 1.37 (95 % confidence interval [CI], 1.05–1.77; p = 0.019). In the subgroup analysis, an increased incidence of CKD in OSA was observed in women (HR, 1.41; 95 % CI, 1.12–1.78; p = 0.0036).

Conclusions

This longitudinal population-based cohort study provides evidence that patients with OSA even without diabetes or hypertension are at higher risk of developing CKD over the next 3 years and nearly 2.5 months earlier than the non-OSA cohort, particularly women.

Impact of Obstructive Sleep Apnea Syndrome on Endothelial Function, Arterial Stiffening, and Serum Inflammatory Markers: An Updated Meta-analysis and Metaregression of 18 Studies

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) has been indicated to contribute to the development of cardiovascular disease; however, the underlying mechanism remains unclear. This study aimed to test the hypothesis that OSAS may be associated with cardiovascular disease by elevating serum levels of inflammatory markers and causing arterial stiffening and endothelial dysfunction.

METHODS AND RESULTS

Related scientific reports published from January 1, 2006, to June 30, 2015, were searched in the following electronic literature databases: PubMed, Excerpta Medica Database, ISI Web of Science, Directory of Open Access Journals, and the Cochrane Library. The association of OSAS with serum levels of inflammatory markers, endothelial dysfunction, and arterial stiffening were investigated. Overall, 18 eligible articles containing 736 patients with OSAS and 424 healthy persons were included in this meta-analysis. Flow-mediated dilation in patients with moderate-severe OSAS was significantly lower than that in controls (standardized mean difference -1.02, 95% CI -1.31 to -0.73, P<0.0001). Carotid-femoral pulse wave velocity (standardized mean difference 0.45, 95% CI 0.21-0.69, P<0.0001), augmentation index (standardized mean difference 0.57, 95% CI 0.25-0.90, P<0.0001), and serum levels of high-sensitivity C-reactive protein and C-reactive protein (standardized mean difference 0.58, 95% CI 0.42-0.73, P<0.0001) were significantly higher in patients with OSAS than in controls.

CONCLUSION

OSAS, particularly moderate-severe OSAS, appeared to reduce endothelial function, increase arterial stiffness, and cause chronic inflammation, leading to the development of cardiovascular disease.

The association of sleep-disordered breathing with high cerebral pulsatility might not be related to diffuse small vessel disease. A pilot study

Background

In a population-based sampling study conducted in community-dwelling older adults living in rural Ecuador, we aimed to assess the relation among sleep-disordered breathing, cerebral pulsatility index, and diffuse small vessel disease.

Methods

Of 25 participants, 9 (36 %) had moderate-to-severe sleep-disordered breathing, characterized by an apnea/hypopnea index ≥15 per hour, and 10 (40 %) had moderate-to-severe white matter hyperintensities, graded according to the modified Fazekas scale. Mean (SD) pulsatility index in the middle cerebral artery was 1.18 (0.19) and positively correlated with the apnea/hypopnea index (R = .445, P = .03, [Pearson’s correlation coefficient]). The middle cerebral artery pulsatility index was increased in persons with moderate-to-severe sleep-disordered breathing compared with persons who had none-to-mild sleep-disordered breathing (mean [SD] 1.11 [0.12] vs. 1.3 [0.23], P = .01). No significant differences were found in the prevalence of moderate-to-severe white matter hyperintensities across groups of sleep-disordered breathing (P = .40) or in the mean apnea/hypopnea index across groups of persons with none-to-mild or moderate-to-severe white matter hyperintensities (P = .16).

Conclusions

This pilot study shows that moderate-to-severe sleep-disordered breathing correlates with cerebral pulsatility, but such association might be independent of diffuse small vessel disease.

Effect of CPAP on arterial stiffness in severely obese patients with obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea (OSA) may independently increase cardiovascular risk in obesity. Although there is evidence that arterial stiffness is altered in OSA, knowledge of these effects with continuous positive airway pressure (CPAP) in severe obesity (body mass index (BMI) ≥ 35 kg/m(2)) is limited. This study aimed to explore how arterial stiffness, as measured by the augmentation index (Aix), changed in severely obese patients with OSA who were treated with CPAP and in patients without OSA.

METHODS

Forty-two patients with severe obesity-22 with OSA, 20 without OSA-were recruited at baseline and followed-up after a median of 13.5 months. Pulse wave analysis (PWA) was performed using applanation tonometry at the radial artery to measure augmentation index (Aix), augmentation pressure (AP) and subendocardial viability ratio (SEVR). Cardiovascular parameters and body composition were also measured.

RESULTS

There were significant improvements in Aix, AP (both P < 0.001) and SEVR (P = 0.021) in OSA patients on CPAP compared with subjects without OSA. Epworth scores (P < 0.001), systolic (P < 0.001) and mean arterial pressures (P = 0.002) improved with CPAP. Regression showed that CPAP was significantly associated with change in arterial stiffness from baseline. However, patients with OSA on CPAP continued to have increased arterial stiffness (Aix) (P < 0.001), AP (P = 0.028) and reduced SEVR (P = 0.002) relative to non-OSA patients.

CONCLUSION

Although sleepiness and blood pressure improve with CPAP in severe obesity, CPAP alone is not sufficient to modify PWA measures to levels comparable with non-OSA patients. This supports a need for a multifaceted approach when managing cardiovascular risk in patients with severe obesity and obstructive sleep apnoea receiving CPAP therapy.