Prevalence of atrial fibrillation in obstructive sleep apnea

Objective

Recent data suggest that obstructive sleep apnea (OSA) is significantly associated with atrial fibrillation (AF). In the present study, we aimed to investigate the prevalence of AF in a large cohort of OSA patients and to compare the characteristics of patients with vs. without AF.

Methods

We retrospectively analyzed electrocardiographic data from 587 patients who had been admitted to our sleep laboratory for suspected sleep apnea. In all patients, anthropometric parameters, medical history with special reference to cardiovascular and metabolic co-morbidities and polysomnographic data were evaluated. Patients without sleep apnea and those with other types of sleep-disordered breathing were excluded from further analysis.

Results

A total of 427 patients (i.e., 72.7%) were found to suffer from OSA. Of these patients, 38 (i.e., 8.9%) were identified as having AF; the other 389 patients were in sinus rhythm. OSA patients with AF were significantly older than those without AF, whereas BMI and gender distribution were similar. Compared to patients in sinus rhythm, the AF group had a higher percentage of patients with hypertension, coronary artery disease, and diabetes mellitus. The severity of OSA did not significantly differ between patients with vs. without AF.

Conclusions

The prevalence of AF in OSA is considerably higher than in the general population. Our data suggest that the risk of AF is particularly increased in elderly OSA patients suffering from concomitant cardiovascular and metabolic disease.     

Association between habitual naps and sleep apnea

STUDY OBJECTIVES: Taking an afternoon nap (siesta) is a common habit. A number of studies have shown an increased cardiovascular mortality in habitual nappers. Afternoon nappers have anthropometric characteristics similar to those of patients with sleep apnea. Nappers appear to suffer from more sleep apnea, which could contribute to cardiovascular disorders. Our aim was therefore to determine the association between sleep apnea and napping, as well as to analyze the relationship of sleep apnea and napping with hypertension. DESIGN: Case-control study. SETTING: Residents in the town of Caceres (Spain) with a population of 100,000 inhabitants. PARTICIPANTS: Four hundred five individuals were initially selected (186 nappers and 219 nonnappers). INTERVENTIONS: Telephone interviews were conducted to contact habitual nappers and nonnappers. Out of the total population selected, 90 nappers and 88 nonnappers completed the study protocol (personal interview and polysomnography). MEASUREMENTS AND RESULTS: The nappers had a higher frequency of sleep apnea at the 3 cutoff points studied (apnea and hypopnea index > or = 5, > or = 10, > or = 15). The adjusted odds ratio was between 2.8 (confidence interval, 1.3-5.8) and 5.5 (confidence interval, 2.3-13). Napping was associated with hypertension in the univariate analysis (odds ratio: 2.1; confidence interval, 1.1-4), but this association disappeared once sleep apnea was included as a covariate in the multivariate modeling (odds ratio dropped to 1.1). CONCLUSIONS: Our findings suggest that napping could be regarded as a marker of sleep apnea, which could account for the cardiovascular diseases observed in nappers. Given that napping is common and that sleep apnea is treatable, more attention should be focused on this population.     

Idiopathic central sleep apnea during REM sleep

Idiopathic central sleep apnea during rapid eye movement (REM) sleep is an extremely rare condition and only two cases have been reported so far. We present the case of a male patient who presented with chronic insomnia. Blood gas analysis during wakefulness suggested the presence of hypocapnia. Polysomnographic examination revealed central sleep apnea occurring predominantly during REM sleep. The patient responded well to continuous positive airway pressure (CPAP) at a pressure of 6 cmH₂O as well as to acetazolamide therapy.     

Association between polysomnographic sleep measures and health-related quality of life in obstructive sleep apnea

Many facets of health-related quality of life are diminished in obstructive sleep apnea (OSA) as they are in other chronic medical conditions. We speculated that impairment in health-related quality of life (HRQoL) might result from the fatigue and daytime somnolence associated with the sleep disorder, as an indirect result from the fragmentation of night-time sleep in OSA. Our hypothesis was that sleep fragmentation measures would correlate with poorer HRQoL measured by medical outcomes study (MOS) subscales. Thirty-nine patients with polysomnographically-confirmed OSA participated in this study. Pearson's correlations were performed with the following sleep architecture variables: wake after sleep onset, the total number of brief arousals, the number of respiratory-related arousals, the rate of respiratory events per hour, and total sleep time. To our surprise, although the total number of arousals was associated with health distress (r=-0.481, P < 0.005), it did not correlate with any other subscales indicating poorer physical and mental health. The relatively insensitive measure of total sleep time (TST) correlated in the expected direction with most subscales. However, after controlling for age and gender, respiratory disturbance indices (RDI) and/or number of arousals emerged as significantly associated with mobility, cognitive functioning, social functioning, energy and fatigue, and health distress. Our findings suggest that polysomnographic indicators of sleep quality and sleep continuity may be an important influence determining many aspects of HRQoL in OSA patients.     

Association between central sleep apnea and left ventricular structure: the Multi‐Ethnic Study of Atherosclerosis

We assessed whether the presence of central sleep apnea is associated with adverse left ventricular structural changes. We analysed 1412 participants from the Multi‐Ethnic Study of Atherosclerosis who underwent both overnight polysomnography and cardiac magnetic resonance imaging. Subjects had been recruited 10 years earlier when free of cardiovascular disease. Our main exposure is the presence of central sleep apnea as defined by central apnea–hypopnea index = 5 or the presence of Cheyne–Stokes breathing. Outcome variables were left ventricular mass/height, left ventricular ejection fraction, and left ventricular mass/volume ratio. Multivariate linear regression models adjusted for age, gender, race, waist circumference, tobacco use, hypertension, and the obstructive apnea–hypopnea index were fit for the outcomes. Of the 1412 participants, 27 (2%) individuals had central sleep apnea. After adjusting for covariates, the presence of central sleep apnea was significantly associated with elevated left ventricular mass/volume ratio (β = 0.11 ± 0.04 g mL⁻¹, P = 0.0071), an adverse cardiac finding signifying concentric remodelling.     

Treatment of central sleep apnea in heart failure

Recent studies show that central sleep apnea occur in about 40% of patients with heart failure and systolic dysfunction. The pathophysiological consequences of central sleep apnea may contribute to morbidity and mortality of heart failure. Three treatment modalities, oxygen, continuous positive airway pressure and theophylline have been shown to decrease periodic breathing modestly with considerable improvement in arterial oxyhemoglobin desaturation, and variable effects on sleep characteristics. However, long-term effects of central sleep apnea and its treatment on the natural history of heart failure remain to be determined.     

Association between left atrial enlargement and obstructive sleep apnea in a general population of 71‐year‐old men

Left atrial enlargement has been shown to be associated with obstructive sleep apnea in patients with coronary artery disease and in sleep clinic cohorts. However, data from the general population are limited. The aim of this study was to investigate whether there is an association between obstructive sleep apnea and left atrial enlargement in a random sample from a general population of 71‐year‐old men. As part of the longitudinal population study The Study of Men Born in 1943, we analysed cross‐sectional data for 411 men, all 71 years old, who had participated in an overnight home sleep study and a standardized echocardiographic examination. Of the 411 men, 29.4% had moderate to severe obstructive sleep apnea [apnea–hypopnea index score of ≥15 (n = 121)]. These participants showed a significantly higher frequency of systolic heart failure, hypertension, overweight, had greater waist circumference as well as higher left atrial areas compared with men with no or mild obstructive sleep apnea (23.7 ± 5.5 cm² versus 21.6 ± 4.5 cm², P < 0.001). In a linear regression analysis, obstructive sleep apnea was significantly associated with left atrial enlargement after adjusting for overweight, atrial fibrillation, heart failure with reduced ejection fraction, hypertension and mitral regurgitation. Compared with individuals without obstructive sleep apnea, the mean left atrial area was 1.7 ± 1.5 cm² larger in men with severe obstructive sleep apnea (P < 0.05) and 1.3 ± 1.1 cm² larger among men with moderate obstructive sleep apnea (P < 0.05). In this cross‐sectional study of 71‐year‐old men from the general population, left atrial area was independently associated with prevalence and severity of obstructive sleep apnea.     

Association between obstructive sleep apnea severity and endothelial dysfunction in an increased background of cardiovascular burden

The objective of this study is to examine whether increasing obstructive sleep apnea (OSA) severity is associated with worsening endothelial function. The design is a cross‐sectional examination of the baseline assessment of a multi‐centre randomized controlled clinical trial examining the effects of oxygen, continuous positive airway pressure (CPAP) therapy or lifestyle modifications on cardiovascular biomarkers. Participants were recruited from cardiology clinics at four sites. Participants with an apnea–hypopnea index (AHI) of 15–50 and known cardio/cerebrovascular disease (CVD) or CVD risk factors were included. OSA severity indices [oxygen desaturation index (ODI), AHI and percentage of sleep time below 90% oxygen saturation (total sleep time <90)] and a measure of endothelium‐mediated vasodilatation [Framingham reactive hyperaemia index (F‐RHI) derived from peripheral arterial tonometry (PAT)] were assessed. The sample included 267 individuals with a mean AHI of 25.0 ± 8.5 SD and mean F‐RHI 0.44 ± 0.38. In adjusted models, the slope of the relationship between ODI and F‐RHI differed above and below an ODI of 24.6 (P = 0.04), such that above an ODI of 24.6 there was a marginally significant decline in the geometric mean of the PAT ratio by 3% [95% confidence interval (CI): 0%, 5%; P = 0.05], while below this point, there was a marginally significant incline in the geometric mean of the PAT ratio by 13% (95% CI: 0%, 27%; P = 0.05) per 5‐unit increase in ODI. A similar pattern was observed between AHI and F‐RHI. No relation was noted with total sleep time <90 and F‐RHI. There was evidence of a graded decline in endothelial function in association with higher levels of intermittent hypoxaemia.     

Association between obstructive sleep apnea severity and glucose control in patients with untreated versus treated diabetes

The purpose of this study was to determine whether the association between obstructive sleep apnea severity and glucose control differs between patients with newly diagnosed and untreated type 2 diabetes, and patients with known and treated type 2 diabetes. This multicentre cross‐sectional study included 762 patients investigated by sleep recording for suspected obstructive sleep apnea, 497 of whom were previously diagnosed and treated for type 2 diabetes (treated diabetic patients), while 265 had no medical history of diabetes but had fasting blood glucose ≥126 mg dL^?1 and/or glycated haemoglobin (HbA_1c) ≥6.5% consistent with newly diagnosed type 2 diabetes (untreated diabetic patients). Multivariate regression analyses were performed to evaluate the independent association between HbA_1c and obstructive sleep apnea severity in treated and untreated patients with diabetes. In untreated diabetic patients, HbA_1c was positively associated with apnea–hypopnea index (P = 0.0007) and 3% oxygen desaturation index (P = 0.0016) after adjustment for age, gender, body mass index, alcohol habits, metabolic dyslipidaemia, hypertension, statin use and study site. The adjusted mean value of HbA_1c increased from 6.68% in the lowest quartile of the apnea–hypopnea index (<17) to 7.20% in the highest quartile of the apnea–hypopnea index (>61; P = 0.033 for linear trend). In treated patients with diabetes, HbA_1c was associated with non‐sleep variables, including age, metabolic dyslipidaemia and insulin use, but not with obstructive sleep apnea severity. Obstructive sleep apnea may adversely affect glucose control in patients with newly diagnosed and untreated type 2 diabetes, but may have a limited impact in patients with overt type 2 diabetes receiving anti‐diabetic medications.     

Association of psychiatric disorders and sleep apnea in a large cohort

STUDY OBJECTIVES: We conducted the present study to determine whether psychiatric disorders are commonly associated with sleep apnea in Veterans Health Administration beneficiaries. METHOD: The Veterans Health Administration maintains several centralized databases containing healthcare data for more than 4 million veterans. We reviewed data from 1998 to 2001 and identified patient records having International Classification of Diseases-Ninth Edition-Clinical Modification codes indicating sleep apnea and various psychiatric conditions. Subsequently, we compared age, sex, ethnicity, and prevalence of comorbid psychiatric conditions for Veterans Health Administration beneficiaries with and without sleep apnea. RESULTS: Out of 4,060,504 unique cases, 118,105 were identified as having sleep apnea (estimated prevalence of 2.91%). Mean age at the time of diagnosis was 57.6 years. Psychiatric comorbid diagnoses in the sleep apnea group included depression (21.8%), anxiety (16.7%), posttraumatic stress disorder (11.9%), psychosis (5.1), and bipolar disorders (3.3%). Compared with patients not diagnosed with sleep apnea, a significantly greater prevalence (P < .0001) was found for mood disorders, anxiety, posttraumatic stress disorder, psychosis, and dementia in patients with sleep apnea. CONCLUSIONS: Sleep apnea is associated with a higher prevalence of psychiatric comorbid conditions in Veterans Health Administration beneficiaries. This association suggests that patients with psychiatric disorders and coincident symptoms suggesting sleep-disordered breathing should be evaluated for sleep apnea.     

Association between proteomics and obstructive sleep apnea phenotypes in a community‐based cohort of women

Proteomic‐based technologies offer new opportunities to identify proteins that might reflect the cardiometabolic stress caused by different aspects of sleep‐disordered breathing. We aimed to investigate whether severe obstructive sleep apnea and severe obstructive sleep apnea during rapid eye movement sleep are associated with changed levels of inflammatory and cardiac disease‐related proteins in a population‐based cohort of women. In the community‐based “Sleep and Health in Women” (SHE) cohort study, 400 women underwent polysomnography, anthropometric measurements and blood sampling. Two proteomic assays (Olink Proseek^® Inflammation panel and Olink Proseek^® Cardiovascular II panel), each measuring 92 proteins, were analysed in a subsample of 253 women. p‐Values were adjusted for multiple testing, with false discovery rate set at 10%. In unadjusted models, 57 proteins were associated with apnea?hypopnea index, 56 proteins with oxygen desaturation index and 64 proteins with rapid eye movement?apnea?hypopnea index. After adjustment for age, body mass index and plate, there were no significant associations between apnea?hypopnea index or oxygen desaturation index and any of the proteins. Severe obstructive sleep apnea during rapid eye movement sleep (rapid eye movement?apnea?hypopnea index ≥ 30) was associated with decreased levels of two anti‐inflammatory proteins; Sirt2 (q‐value .016) and LAP‐TGF‐β₁ (q‐value .016). There was also a negative association between rapid eye movement?apnea?hypopnea index of ≥ 30 and Axin1 (q‐value .095), a protein thought to facilitate TGF‐β‐signalling. We conclude that severe obstructive sleep apnea during rapid eye movement sleep is associated with low levels of Sirt2, LAP‐TGF‐β₁ and Axin1, anti‐inflammatory proteins involved in metabolic regulation and in the atherosclerotic process. For obstructive sleep apnea based on a whole night, the associations with cardiac and inflammatory proteins are weaker, and explained to a large extent by age and body mass index.     

Relationship between smoking and sleep apnea in clinic population

STUDY OBJECTIVE: To examine the relationship between smoking and sleep apnea. DESIGN: Cross-sectional case study SETTING: University hospital sleep clinic PATIENTS: We studied 3,509 patients. INTERVENTIONS: None MEASUREMENTS AND RESULTS: Smoking history (past, present, never-smoker, pack-years of smoking) and nocturnal polysomnography was obtained in all patients. Data analysis was performed as follows: Patients were divided into groups based on apnea seventy (to compare smoking), and on smoking seventy (to compare apnea hypopnea index - AHI). The relationship between smoking and apnea was examined using univariate, multivariate, and logistic regression analysis. We found that patients with AHI greater than 50 were heavier smokers than nonapneic controls (14+/-17 vs. 10+/-17 pack-years, respectively). Conversely, heavy smokers had higher AHI than non-smokers (26.3+/-28.3 vs. 19.7+/-23.9, respectively). There was no significant relationship between AHI and smoking in multiple regression analysis. Although logistic regression revealed that heavy smokers (>30 pack-yrs) had almost twice the risk of having AHI greater than 50 compared to nonsmokers, the odds ratio fell below one after adjusting for age, BMI, and gender. CONCLUSIONS: In our patient population, smoking is not an independent risk factor for sleep apnea after adjusting for other confounding variables.     

Relationship between obstructive sleep apnea and diurnal leptin rhythms

STUDY OBJECTIVES: Several studies have reported an association between obstructive sleep apnea and leptin, a hormone that influences satiety and body weight. We evaluated the relationship of leptin levels and the overnight change in levels with sleep apnea. DESIGN: Cross-sectional analysis of data from a prospective cohort study. SETTING: Case Western Reserve University General Clinical Research Center. PATIENTS OR PARTICIPANTS: A total of 138 individuals participating in the Cleveland Family Study--59% women, 45% African-American, with mean apnea-hypopnea index (AHI) of 6.9 (range 0-106)--were studied. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Serum leptin was measured at 10:00 pm to 11:00 pm and at 7:00 am to 8:00 am. Leptin levels in both the morning and evening were positively correlated with apnea-hypopnea index (AHI) in age-, sex-, and race-adjusted analyses (P < .0001) but not after additional adjustment for body mass index. The evening/morning leptin ratio, however, was associated with AHI independent of age, sex, race, body mass index, and waist-hip ratio (P = .03). Conversely, AHI was an independent predictor of the leptin ratio (P = .001) and more predictive than arousal index, oxygenation indices, time asleep, or sleep-stage distribution. An AHI > 15 was associated with a 23% increase in leptin ratio. CONCLUSIONS: These findings suggest that sleep apnea may suppress secretion of leptin in the morning. Alternatively, the relative elevation in evening leptin may influence apnea pathogenesis.     

Inflammation,a link between obesity and atrial fibrillation

Inflammation Research - Despite the long belief that the role of the adipose tissue was restricted to that of a passive store of triglycerides and a rich source of fatty acids, accumulating data...