Obstructive sleep apnea and coronary artery disease: from pathophysiology to clinical implications. Pulm Med. 2013;2013:768064. [PMID: 23691310 PMCID: PMC3649685 DOI: 10.1155/2013/768064]

Association of nocturnal oxygen saturation with coronary artery calcification: cross-sectional evidence from the population-based SESSA study among Japanese men

OBJECTIVE

We investigated the associations of nocturnal oxygen saturation (SpO2) with prevalence of coronary artery calcification (CAC) and its level of burden, and whether the associations differ by obesity and mediate through diabetes mellitus (DM), dyslipidaemia and hypertension.

DESIGN

Observational study.

SETTING

Kusatsu, Shiga.

PARTICIPANTS

We analysed data from 510 Japanese men (aged 46-76 years) with no history of myocardial infarction.

PRIMARY AND SECONDARY OUTCOMES

Mean SpO2, minimum SpO2 and oxygen desaturation index (ODI) were measured using overnight pulse oximetry (primary exposures), while CAC was assessed using CT. Prevalence of CAC (>0) and its burden (CAC 0, >0-100, >100-400 and>400) were evaluated as outcomes. Body mass index≥25.0 kg/m2 defined as obesity.

RESULTS

Mean±SD age was 66.7±7.2 years. The prevalence of CAC was 64.7% (CAC scores>0-100, 31.4%; >100-400, 20.0% and>400, 13.3%). In multivariable binary logistic regression, the OR and 95% CI for the prevalence of CAC were 1.25 (1.02 to 1.53) per 1-SD decrement in mean SpO2 and 1.25 (1.01 to 1.55) per 1-SD increment in ODI. The associations lost their significance while further adjusted for DM and dyslipidaemia. Similar trends were observed for the level of CAC burden in multivariable ordinal logistic regression. Obesity did not show significant interaction with SpO2 on CAC. In mediation analysis, the OR (95% CI) for natural indirect effect; percentage mediated through dyslipidaemia in association of 1-SD decrement in mean SpO2 with prevalence of CAC were 1.06 (1.01 to 1.10); 25.4%. These estimates for mediation through DM and dyslipidaemia for 1-SD increment in ODI in the associations were 1.07 (1.01 to 1.12); 29.6% and 1.04 (1.00 to 1.08); 17.5%, respectively.

CONCLUSIONS

Lower mean SpO2 and higher ODI are associated with CAC among Japanese men, independent of age, lifestyle factors and obesity. The associations became non-significant after adjusting for diabetes and dyslipidaemia, but were mediated through these factors.

Snoring Survivors: the impact of obstructive sleep apnoea and continuous positive airway pressure use on in-hospital mortality, length of stay and costs among patients hospitalised with acute cardiovascular disease - A retrospective analysis of 2016-2019 National Inpatient Sample Data

BACKGROUND

The routine administration of supplemental oxygen to non-hypoxic patients with acute myocardial infarction (AMI) has been abandoned for lack of mortality benefit. However, the benefits of continuous positive airway pressure (CPAP) use in patients hospitalised with acute cardiovascular disease and concomitant obstructive sleep apnoea (OSA) remain to be elucidated.

METHODS

In this retrospective case-control analysis, using 10th International Classification of Diseases, Clinical Modification (ICD-10) codes, we searched the 2016-2019 Nationwide Inpatient Sample for patients diagnosed with unstable angina (UA), AMI, acute decompensated heart failure (ADHF) and atrial fibrillation with rapid ventricular response (AFRVR), who also carried a diagnosis of OSA. We identified in-hospital CPAP use with ICD-10-Procedure Coding System codes. In-hospital death, length of stay (LOS) and hospital charges were compared between patients with and without OSA, and between OSA patients with and without CPAP use.

RESULTS

Our sample included 2 959 991 patients, of which 1.5% were diagnosed with UA, 30.3% with AMI, 37.5% with ADHF and 45.8% with AFRVR. OSA was present in 12.3%. Patients with OSA were more likely to be younger, male, smokers, obese and have chronic obstructive pulmonary disease, renal failure and heart failure (p<0.001 for all). Patients with OSA had significantly lower in-hospital mortality (aOR 0.71, 95% CI (0.7 to 0.73)). Among patients with OSA, CPAP use significantly increased the odds of in-hospital death (aOR 1.51, 95% CI (1.44 to 1.60)), LOS (adjusted mean difference of 1.49 days, 95% CI (1.43 to 1.55)) and hospital charges (adjusted mean difference of US$1168, 95% CI (273 to 2062)).

CONCLUSION

Our study showed that patients with recognised OSA hospitalised for AMI, ADHF and AFRVR had significantly lower mortality regardless of CPAP use, while CPAP treatment among these patients was associated with significantly higher in-hospital mortality and resource utilisation. The routine use of CPAP during acute cardiovascular encounters could neutralise the impact of chronic intermittent ischaemic preconditioning.

Obstructive sleep apnea modulates clinical outcomes post-acute myocardial infarction: A large longitudinal veterans' dataset report

BACKGROUND

While the longer-term Obstructive Sleep apnea (OSA)-related intermittent hypoxia (IH) leads to various comorbidities, it has become increasingly evident that OSA confers protective advantages during and after acute myocardial infarction (AMI). We hypothesized in patients who were admitted with acute MI, the presence of OSA is associated with lower in-hospital mortality compared to those without a prior diagnosis of OSA.

METHODS

In this nationwide retrospective study utilizing Veterans Health Administration records, we included patients hospitalized for MI with a history of sleep disorders from 1999 to 2020. We divided patients into two cohorts: those with OSA and those without OSA. The primary outcome was in-hospital mortality during AMI hospitalization. We analyzed the data using logistic regression and calculated the odds ratio of in-hospital mortality.

RESULTS

Out of more than four million veterans with any sleep diagnosis, 76,359 patients were hospitalized with a diagnosis of AMI. We observed 30,116 with OSA (age, 64 ± 10 years; BMI, 33 ± 7 kg/m2) and 43,480 without OSA (age, 68 ± 12 years; BMI, 29 ± 6 kg/m2). The aOR of in-patient mortality (n = 333 (1.1%)) was lower in those with OSA (aOR, 0.43; 95% CI, 0.38 to 0.49) compared to without-OSA (n = 1,102, 2.5%). However, the OSA cohort had a higher proportion of the prolonged length of stay (28.1%).

CONCLUSIONS

Presence of OSA is associated with lower in-hospital mortality among patients admitted for AMI, after adjusting for various demographic and co-morbidity factors. This study highlights the complex relationship between OSA and cardiovascular health and highlights the need for further research in this area.

Cardiovascular Disease in Patients with Chronic Obstructive Pulmonary Disease, Obstructive Sleep Apnoea Syndrome and Overlap Syndrome

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnoea syndrome (OSAS) are among the most prevalent chronic respiratory disorders. Accumulating data suggest that there is a significant burden of cardiovascular disease (CVD) in patients with COPD and OSAS, affecting negatively patients' quality of life and survival. Overlap syndrome (OS), i.e. the co-existence of both COPD and OSAS in the same patient, has an additional impact on the cardiovascular system multiplying the risk of morbidity and mortality. The underlying mechanisms for the development of CVD in patients with either OSAS or COPD and OS are not entirely elucidated. Several mechanisms, in addition to smoking and obesity, may be implicated, including systemic inflammation, increased sympathetic activity, oxidative stress and endothelial dysfunction. Early diagnosis and proper management of these patients might reduce cardiovascular risk and improve patients' survival. In this review, we summarize the current knowledge regarding epidemiological aspects, pathophysiological mechanisms and present point-to-point specific associations between COPD, OSAS, OS and components of CVD, namely, pulmonary hypertension, coronary artery disease, peripheral arterial disease and stroke.

Undiagnosed sleep apnoea in cardiac rehabilitation: Age-dependent effect on diastolic function in coronary artery disease patients with preserved ejection fraction

BACKGROUND

Focusing on detection of sleep apnoea early in the cardiac rehabilitation process may improve the recovery process and reduce recurrence of cardiovascular events. Patients who continue to be undiagnosed may experience a significantly worse outcome during their cardiac rehabilitation and recovery. Diastolic dysfunction has both diagnostic and prognostic importance in the management of coronary artery disease. We hypothesise that undiagnosed/untreated sleep apnoea in middle-aged coronary artery disease patients with preserved left ventricular ejection fraction changes the pattern of diastolic filling close to that in elderly patients without sleep apnoea.

METHODS AND RESULTS

This cross-sectional study included the 450 coronary artery disease patients with undiagnosed sleep apnoea who had left ventricular ejection fraction ⩾50% and were referred consecutively to the Clinic of Cardiovascular Rehabilitation within two weeks after treatment for acute coronary syndrome. Polysomnographic and echocardiographic measurements were analysed. Mild to severe sleep apnoea was defined as the apnoea-hypopnea index ⩾5. Age was dichotomised into under the age of 60 years and age 60 years or over. Up to 35% of coronary artery disease patients were likely to have undiagnosed sleep apnoea. There was a statistically significant interaction between the effect of sleep apnoea and age group on diastolic function defined as the ratio peak flow velocity in early diastole/peak flow velocity in atrial contraction ratio (p=0.036). This ratio was significantly (p=0.029) lower in the mild-severe sleep apnoea group (0.97, 95% confidence interval 0.88-1.06) than in the non-sleep apnoea group (1.09, 95% confidence interval 1.03-1.15) among middle aged (<60 years) coronary artery disease patients. Therefore, filling patterns in the middle aged (<60 years) patients with sleep apnoea resemble those observed in the elderly (⩾60 years) patients without sleep apnoea. The effect of sleep apnoea on left ventricular filling pattern in elderly was not observed.

CONCLUSIONS

Age modifies the effect of sleep apnoea on cardiovascular outcomes. The findings that undiagnosed sleep apnoea impairs diastolic function in a middle-aged coronary artery disease patient underscore the importance of early diagnosis and treatment of sleep apnoea. It is recommended to train and educate cardiac rehabilitation staff on the importance of sleep disorders in this population.

Prevalence and Patterns of Obstructive Sleep Apnea in Asian Indians With Congestive Heart Failure

Background Sleep-disordered breathing (SDB) has a potential association with the pathogenesis of congestive heart failure (CHF). We assessed the prevalence and patterns of obstructive sleep apnea (OSA) in patients presenting with CHF. Method This was a prospective, observational, all-comers study of consecutive 77 confirmed cases of CHF. All these patients were clinically assessed and evaluated for OSA with sleep study after routine blood testing, electrocardiogram (ECG), chest X-ray, and echocardiography. Results Of 77 patients with CHF 38 (49.4%) had apnea-hypopnea index (AHI) <5 while 39 (50.6%) had AHI >5. Of these 39, 37 (94.8%) patients showed the clinical features of OSA. The majority (64.9%) of them were males. The majority of OSA (64.9%) had coronary artery disease (CAD) (p<0.05) as the etiology of CHF, followed by dilated cardiomyopathy (32.4%) and valvular heart disease (2.7%). The prevalence of OSA was higher amongst New York Heart Association (NYHA) class 2 (51.4%) as compared to NYHA class 3 (37.8%) and NYHA class 4 (10.8%). There were 12 (32.8%) patients, each having OSA with a heart rate between 71 and 80 bpm and 81 and 90 bpm. Twenty-two (59.5%) had systolic blood pressure (BP) more than 120 mmHg and 20 (54.1%) had diastolic BP more than 80 mmHg. The majority (64.9%) patients had the lowest O2 saturation between 80% and 90%. A significantly large number of patients (62.2%) had ejection fraction 21%-30% (p<0.05). The majority (62.16%) of patients with OSA had AHI between 5 and 15. With 5-15 AHI, 20 (87%) patients with OSA had a snoring, tiredness, observed apnea, high BP, BMI, age, neck circumference, and male gender (STOP-Bang) score between 3 and 7 with AHI 5-15 (p<0.05). Conclusions In our cohort, the prevalence of OSA in CHF was 50.6%. Predictors of OSA in CHF were left ventricular ejection fraction (LVEF) 20%-30% and NYHA class 2. The majority had AHI between 5 and 15. Sleep apnea screening should be routinely implemented in the evaluation and follow-up of heart failure patients.

Relation of Age to Survival in Patients with Obstructive Sleep Apnea who Develop an Acute Coronary Event (from the National Inpatient Sample)

This study was undertaken to investigate whether obstructive sleep apnea (OSA) produces a survival advantage in acute coronary syndrome (ACS), and to evaluate the mechanism of any benefit, including the impact of age and other risk factors. The National Inpatient Sample was queried for all patients who were admitted for ACS during the years 2013 to 2014. The primary outcomes were all-cause in-hospital mortality and cardiogenic shock (CS). Multivariable logistic regression was used for analysis. A total of 1,080,340 patients with ACS were included, 63,255 patients had OSA. The majority of patients were males (60.3%) and of Caucasian race (75%). The mean age was 67 years (SEM: 0.1). Despite a higher burden of risk factors and older age, OSA patients had a lower risk for mortality and cardiogenic shock adjusted OR 0.68 (95%CI 0.61-0.75), p <0.001 and 0.81 (95%CI: 0.74 to 0.89), p <0.001 respectively. Age was an important effect modifier. Survival advantage and lower risk for CS arises at the age above 55 and become more apparent with increasing age. In conclusion, despite a higher CV risk profile, and older age, OSA produces a survival benefit in ACS. Age is a significant modifier of risk in OSA patients with ACS. Ischemic preconditioning might explain these results.

Syndrome 'Z': A Predictor of Angiographic Severity of Coronary Artery Disease in Patients of Acute Coronary Syndrome

BACKGROUND

Owing to the growing evidence that the pathophysiology of obstructive sleep apnoea (OSA) and metabolic syndrome (MS) overlap considerably and both adversely impact cardiovascular health, we hypothesised that the presence of OSA with MS additively and adversely affect the severity of coronary artery disease (CAD). Exploration and understanding of this may have direct implications for the development of targeted, preventive strategies for CAD. Thus, this prospective study was aimed to determine the prevalence of 'Syndrome Z' in patients of MS who present with an acute coronary event and to correlate it with the angiographic severity of CAD in these patients.

METHODS

The present study was a single centre, cross sectional study conducted in a university teaching hospital. In a span of 6 months, 922 patients with acute coronary syndromes (ACS) were screened for the study. Among these, 861 patients had no evidence of MS. The remaining 61 patients who were diagnosed to have MS were then subjected to an overnight sleep study. Only 58 had good sleep data so were included for further analysis. Angiographic parameters in terms of number of vessels involved and culprit lesions were noted and correlated with presence and absence of OSA and also with its severity based on the Apnoea/Hypopnoea Index (AHI).

RESULTS

The prevalence of OSA positivity in patients with MS who presented with ACS was 34.5% (n=20). Most of the patients in the OSA negative group (78.9%, n=30) had disease limited to only one vessel while in the OSA positive group only a minority (15%, n=3) of patients had their disease limited to a single vessel (p=0.001). The number of lesions in the culprit vessel was also significantly less in the OSA negative group compared to the OSA positive group. While in the OSA negative group 68.4% (n=26) patients had a solitary lesion, followed by two and three lesions in 15.8% (n=6) of the patients each, multiple lesions were more common in OSA positive patients, involving 80% of cases (45.0%, n=9 with two lesions; 35.0%, n=7 with three lesions; only 20%, n=4 had a solitary lesion).

CONCLUSIONS

Prevalence of 'Syndrome Z' is high in patients having MS presenting with ACS and it correlates with the angiographic severity of CAD.

Screening for obstructive sleep apnea among patients undergoing coronary catheterization in Jordan

Aims: This study aimed to utilize a validated sleep questionnaire as a screening tool for symptoms and risk of obstructive sleep apnea in patients undergoing coronary catheterization in Jordan.

Materials and methods: A cross-sectional design was used to screen adult patients undergoing coronary catheterization for obstructive sleep apnea (OSA). The Berlin sleep questionnaire was used to record nocturnal and daytime symptoms of OSA and to stratify patients into “low-risk” or “high-risk” for OSA. Coronary artery disease was defined as ≥50% intraluminal stenosis in at least one coronary vessel.

Results: A total of 398 patients were studied, mean age was 58.7 years (SD=10.70), ranging from 21–92 years, and 68.6% were males. Based on the Berlin sleep questionnaire’s definition, 176 patients (44.2%) were at high-risk for obstructive sleep apnea. Snoring was reported by 61%; loud in 42.1%, and frequent in 62%. Daytime sleepiness was reported by 36%, and 18.9% had fallen asleep while driving. Witnessed apnea during sleep was less reported (7.8%). Prevalence of symptoms and risk of OSA were not different between patients with and without coronary artery disease, P>0.05. In addition, logistic regression indicated that there was no significant association between risk of OSA and coronary artery disease, adjusted (odds ratio=0.93, 95% Confidence Interval=0.60–1.44, P=0.752).

Conclusions: Symptoms and risk of obstructive sleep apnea were common among adult Jordanians undergoing coronary catheterization. There was no association between risk of obstructive sleep apnea and coronary artery disease. Larger studies are needed to assess the role of screening for obstructive sleep apnea in this patient population.

Lax eyelid syndrome (LES), obstructive sleep apnea (OSA), and ocular surface inflammation

PURPOSE

Lax eyelid syndrome (LES) is defined as the association of distensible "floppy" eyelids and chronic papillary conjunctivitis. LES is also found in patients with obstructive sleep apnea (OSA) who have systemic elevation of inflammatory markers, including matrix metalloproteinases (MMP). Locally elevated MMP levels have also been demonstrated co-localized with elastin loss in eyelids of patients with LES, accounting for their "floppiness." The purpose of this study was to investigate tear film MMP levels and determine their association with eyelid laxity and OSA. We also evaluated 3 previous grading systems to determine the severity of lid laxity and introduced a new "laxometer" device.

METHODS

Thirty-seven subjects underwent bilateral eyelid laxity assessments prior to polysomnography testing. OSA severity was graded using the apnea hypopnea index (AHI). The degree of eyelid laxity was determined using three published methods and a newly proposed "laxometer" method. Commercially available InflammaDry^® kits were used to determine the presence of MMP-9 in the tear film.

RESULTS

There was a significant elevation in tear MMP-9 levels in patients with LES compared to controls (p < .05). Of the 37 total patients enrolled in this study, 2 patients (5.4%) did not have sleep study results. Thirty-two of the remaining 35 patients (91.4%) were determined to have OSA (AHI > 5). In this sample, there was no meaningful association between OSA and MMP-9 (p = .12). Although there were positive associations between OSA severity, laxometer measurements, and previously established grading methods, none achieved statistical significance (all p > .05).

CONCLUSIONS

There was an elevation of MMP-9 in tears of patients with LES. Elevated tear MMP-9 was also not associated with OSA. Although there is some evidence to support the association of eyelid laxity and OSA, the most accurate and reliable method for grading eyelid laxity remains unclear.

Sleep Architecture in Patients With Primary Snoring and Obstructive Sleep Apnea

Introduction:

This study aimed to investigate sleep architecture in patients with primary snoring and obstructive sleep apnea.

Methods:

In this study, we analyzed polysomnographic data of 391 clients who referred to Sleep Disorders Research Center (SDRS). These people were classified into three groups based on their Apnea-Hypopnea Index (AHI) and snoring; control, Primary Snoring (PS), and Obstructive Sleep Apnea (OSA) group. Sleep architecture variables were then assessed in all groups.

Results:

The results of this study indicated a decrease in deep sleep or Slow Waves Sleep (SWS) and increase in light sleep or stage 1 of non-REM sleep (N1) in OSA patients compared with the control and PS groups. After controlling the effects of confounding factors, i.e. age and Body Mass Index (BMI) (which was performed through multiple regression analysis) significant differences were observed among the three groups with regard to N1. However, with regard to SWS, after controlling confounding variables (age and BMI), no significant difference was found among the groups.

Conclusion:

The results indicated that OSA, regardless of age and BMI, may increase light (N1) sleep possibly via a decline in blood oxygen saturation (SpO₂ ). Such increase in N1 may be responsible for brain arousal. In addition, by controlling confounding factors (age and BMI), OSA did not affect SWS in OSA patients. However, further research is necessary to determine sleep architecture in more detail in the patients with OSA.

Obstructive Sleep Apnea in a rural population in South India: Feasibility of health care workers to administer level III sleep study

Objectives:

To estimate the occurrence of obstructive sleep apnea (OSA) and its risk factors in a rural Indian population using screening questionnaire and Level III sleep study. To determine the feasibility to train community health workers to administer Level III sleep study in the high-risk population.

Materials and Methods:

The study was conducted from seven villages with adult population of 2247, in Mugalur, near Bengaluru, from January to April 2014. Berlin questionnaire was used to screen 321 participants chosen by stratified random sampling. A total of 26 out of 321 patients underwent Level III sleep study at home, administered by the health workers, who were trained in three sessions to hook up the machine. Data were verified by a certified sleep physician.

Results:

The mean age was 39.43 ± 15.6 years with the M:F ratio of 0.98:1. Prevalence of risk of OSA by Berlin questionnaire was 8.72% (95% confidence interval [CI] 5.63, 11.81) in the total population, 7.4% in males and 11.7% in females. Older age (odds ratio [OR] 3.97; CI 1.63, 9.6), hypertension (OR 11; CI 4.3, 28.2), obesity (OR 2.35; CI 1, 5.5), and higher Mallampati score (OR 3.78; CI 1.7, 8.4) were significantly associated with high risk of OSA (P = 0.0001–0.04). Twenty-six patients underwent Level III sleep study and OSA was diagnosed in 12 patients. The mean apnea–hypopnea index (AHI) of this group was 9.7/h. The prevalence of OSA by AHI criteria was 3.74%.

Conclusions:

OSA is underdiagnosed in rural populations, although risk factors are present. Training community health workers to administer Level III sleep study is a feasible and cost-effective strategy.

Long-term use of continuous positive airway pressure therapy in coronary artery disease patients with nonsleepy obstructive sleep apnea

BACKGROUND

Excessive daytime sleepiness is a frequent symptom of obstructive sleep apnea (OSA) and has been proposed as a motivator for adherence to continuous positive airway pressure (CPAP) therapy. However, excessive daytime sleepiness is absent in many patients with coronary artery disease (CAD) and concomitant OSA. We evaluated long-term use of CPAP and predictors of CPAP use in nonsleepy and sleepy OSA patients from a CAD cohort.

HYPOTHESIS

Long-term CPAP use is lower in CAD patients with nonsleepy OSA vs sleepy OSA.

METHODS

Nonsleepy (Epworth Sleepiness Scale [ESS] score < 10) OSA patients randomized to CPAP (n = 122) and sleepy (ESS ≥10) OSA patients offered CPAP (n = 155) in the RICCADSA trial in Sweden were included in this substudy. The median follow-up was 4.8 years for the main trial, with a predefined minimum follow-up of 2 years.

RESULTS

The probability of remaining on CPAP at 2 years was 60% in nonsleepy patients and 77% in sleepy patients. Multivariate analyses indicated that age and hours of CPAP use per night at 1 month were independently associated with long-term CPAP use in nonsleepy patients. In the sleepy phenotype, body mass index, acute myocardial infarction at baseline, and hours of CPAP use per night at 1 month were predictors of long-term CPAP use.

CONCLUSIONS

Long-term use of CPAP is likely to be challenging for CAD patients with nonsleepy OSA. Early CPAP use is an important predictor of continued long-term use of CPAP, so optimizing patients' initial experience with CPAP could promote adherence.

Prevalence of Sleep-Disordered Breathing and Patient Characteristics in a Coronary Artery Disease Cohort Undergoing Cardiovascular Rehabilitation

PURPOSE

Coronary artery disease (CAD) is a leading cause of death and identification of risk factors for CAD is crucial. One such potential risk factor is sleep-disordered breathing (SDB). This prospective cohort study investigated the prevalence of SDB and determined risk factors for the presence of SDB in a large CAD cohort undergoing cardiac rehabilitation.

METHODS

A total of 1425 patients with confirmed CAD starting rehabilitation were screened for SDB using cardiorespiratory polygraphy (n = 921) or polygraphy plus pulse oximetry (n = 484).

RESULTS

A total of 1408 patients were included; 69.5% were male, 78% had acute coronary syndrome, and 22% had stable CAD. The prevalence of SDB (apnea-hypopnea index [AHI] ≥5/h) was 83%. Moderate to severe SDB (AHI ≥15/h) was present in 53%. Up to 70% of coronary artery bypass graft (CABG) recipients had an AHI ≥15/h versus 33% of those who had not undergone CABG. SDB severity did not vary significantly in patients with stable CAD or on the basis of left ventricular ejection fraction. SDB was more severe and the frequency of oxygen desaturation was higher in men than in women. Multivariate logistic regression identified age, sex, body mass index, and CABG as independent risk factors for severe SDB.

CONCLUSION

SDB is a highly prevalent comorbidity in patients with CAD, particularly those who have undergone CABG. These results strengthen existing associations and emphasize the importance of diagnosing and monitoring SDB in patients with CAD entering a cardiac rehabilitation program. Early diagnosis and intervention has the potential to have a beneficial effect on CAD prognosis.

The association of sleep disordered breathing with left ventricular remodeling in CAD patients: a cross-sectional study

Background

There is still insufficient knowledge on the potential effect of mild to moderate sleep-disordered breathing (SDB) that is widely prevalent, often asymptomatic, and largely undiagnosed in patients with stable coronary artery disease (CAD). SDB affects 34% of men and 17% of women aged between 30 and 70. The objective of this study was to evaluate the association between SDB and left ventricular (LV) hypertrophy as well as structural remodeling in stable CAD patients.

Methods

The study was based on a cross-sectional design. Echocardiography and polysomnography was performed in 772 patients with CAD and with untreated sleep apnea. All study participants underwent testing by Epworth Sleepiness Scale questionnaire. Their mean age, NYHA and left ventricular ejection fraction were, respectively: 57 ± 9 years, 2.1 ± 0.5 and 51 ± 8%, and 76% were men. Sleep apnea (SA) was defined as an apnea-hypopnea-index (AHI) ≥5 events/h, and, non-SA, as an AHI <5.

Results

Sleep apnea was present in 39% of patients, and a large fraction of those patients had no complaints on excessive daytime sleepiness. The patients with SA were older, with higher body mass and higher prevalence of hypertension. LV hypertrophy (LVH), defined by allometrically corrected (LV mass/height^2.7) gender-independent criteria, was more common among the patients with SA than those without (86% vs. 74%, p < 0.001). The frequency of LVH by wall thickness criteria (interventricular septal thickness or posterior wall thickness ≥ 12 mm: 49% vs. 33%, p < 0.001) and concentric LVH (61% vs. 47%, p = 0.001) was higher in CAD patients with SA. The patients with SA had significantly higher values of both interventricular septal thickness and posterior wall thickness. Multiple logistic regression analysis showed that even mild sleep apnea was an independent predictor for LVH by wall thickness criteria and concentric LVH (OR = 1.5; 95% CI 1.04–2.2 and OR = 1.9; 1.3–2.9 respectively).

Conclusions

We concluded that unrecognized sleep apnea was highly prevalent among patients with stable CAD, and the majority of those patients did not report daytime sleepiness. Mild to moderate sleep apnea was associated with increased LV wall thickness, LV mass, and with higher prevalence of concentric LV hypertrophy independently of coexisting obesity, hypertension, diabetes mellitus or advancing age.

Pathway for the Management of Sleep Apnea in the Cardiac Patient

Sleep-disordered breathing is a highly prevalent medical condition, which if undiagnosed leads to increased morbidity and mortality, particularly related to increased incidence of cardiovascular events. It is therefore imperative that we identify patient population at high risk for sleep apnea and refer them to the appropriate therapy as early as possible. Up-to-date there is no management guideline specifically geared towards cardiac patients. Thus, we propose a (SAP) Sleep Apnea Pathway to correctly identify and triage these patients to the appropriate therapy.

High risk for obstructive sleep apnea in patients with acute myocardial infarction

OBJECTIVES

to stratify the risk for obstructive sleep apnea in patients with acute myocardial infarction, treated at a public, tertiary, teaching hospital of the state of São Paulo, Brazil, and to identify related sociodemographic and clinical factors.

METHOD

cross-sectional analytical study with 113 patients (mean age 59.57 years, 70.8% male). A specific questionnaire was used for the sociodemographic and clinical characterization and the Berlin Questionnaire for the stratification of the risk of obstructive sleep apnea syndrome.

RESULTS

the prevalence of high risk was 60.2% and the outcome of clinical worsening during hospitalization was more frequent among these patients. The factors related to high risk were body mass index over 30 kg/m2, arterial hypertension and waist circumference indicative of cardiovascular risk, while older age (60 years and over) constituted a protective factor.

CONCLUSION

considering the high prevalence of obstructive sleep apnea and its relation to clinical worsening, it is suggested that nurses should monitor, in their clinical practice, people at high risk for this syndrome, guiding control measures of modifiable factors and aiming to prevent the associated complications, including worsening of cardiovascular diseases.

Prevalence and predictors of sleep apnea in patients with stable coronary artery disease: a cross-sectional study

BACKGROUND

Sleep apnea (SA) is increasingly recognized as being important in the prognosis of patients with coronary artery disease (CAD); however, symptoms of SA are not easily identified, and as many as 80% of sufferers remain undiagnosed.

AIM

This cross-sectional study investigated the prevalence and predictors of SA that may help to increase the awareness and diagnosis of SA in stable CAD patients.

MATERIALS AND METHODS

Polysomnography was performed in 772 medically stable CAD patients with untreated SA recruited from the Clinic of Cardiovascular Rehabilitation. Patients were predominantly male (76%), median age was 58 years (32-81). All subjects completed the Epworth sleepiness scale (ESS). The frequency of all apneas and hypopneas associated with 3% oxygen desaturation is referred to as the apnea-hypopnea index (AHI). Mild-to-severe SA was defined as AHI ≥5/h, moderate-to-severe SA as AHI ≥15/h.

RESULTS

AHI was within a range of values that was considered normal or only mildly elevated. The median AHI was 3.4 (interquartile range [IQR 1-9]), and 39% of patients had unrecognized mild-to-severe SA (moderate-to-severe in 14%), which was not higher than other known risk indicators for CAD such as hypertension and obesity (83% and 47%, respectively). These patients did not show sleepiness and the risk-related cut-off score for excessive daily sleepiness was lower than the official for ESS.

CONCLUSION

Hypertension, age, male gender, obesity, ESS ≥6, and left ventricular ejection fraction ≤45% were the best predictors of mild-to-severe SA. While, male gender, age 50-70 years and, mainly, the presence of obesity but not hypertension were clinical predictors for moderate-to-severe SA. In addition, association between mild-to-severe SA and obesity was not evident in women. SA is prevalent comorbidity in the stable CAD patients, especially in its asymptomatic mild form. We suggest that SA should be considered in the secondary prevention protocols for CAD.

Hindi translation of Berlin questionnaire and its validation as a screening instrument for obstructive sleep apnea

Background:

Obstructive sleep apnea (OSA) is a fairly common problem with adverse health consequences. However, any screening questionnaire is not available in Hindi to screen sleep apnea.

Materials and Methods:

Subjects undergoing video-synchronized in laboratory attended polysomnography were requested to participate in this study. They were screened with the help of Hindi version of Berlin questionnaire (BQ). Outcome of the BQ was tested against the gold standard polysomnography. Descriptive statistics, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of Hindi version were calculated.

Results:

38 patients with polysomnography diagnosed OSA and 12 controls were included in this study. Average body mass index (BMI) in the OSA group was 33.12 + 6.66 kg/m² whereas in the control group BMI was 25.01 + 4.20 kg/m². Average age in the OSA group was 48.9 + 10.2 years whereas the control group was older (56.9 + 12.1 years). Hindi version had sensitivity of 89% and specificity of 58%. PPV of the instrument was 0.87 whereas NPV was 0.63.

Conclusion:

Hindi version of BQ is a valid tool for screening the OSA irrespective of the literacy status of the subjects.

Serum Levels of Vascular Endothelial Growth Factor and Insulin-like Growth Factor Binding Protein-3 in Obstructive Sleep Apnea Patients: Effect of Continuous Positive Airway Pressure Treatment

Background and Aim:

Hypoxia, a major feature of obstructive sleep apnea (OSA), modifies Vascular Endothelial Growth Factor (VEGF) and Insulin-like Growth Factor Binding Protein-3 (IGFBP-3) levels, which contribute to atherogenesis and occurrence of cardiovascular (CV) events. We assessed and compared serum levels of VEGF and IGFBP-3 in newly diagnosed OSA patients and controls, to explore associations with anthropometric and sleep parameters and to study the effect of continuous positive airway pressure (CPAP) treatment on these levels.

Materials and Methods:

Serum levels of VEGF and IGFBP-3 were measured in 65 OSA patients and 31 age- and body mass index- matched controls. In OSA patients, measurements were repeated after 6 months of CPAP therapy. All participants were non-smokers, without any comorbidities or systemic medication use.

Results:

At baseline, serum VEGF levels in OSA patients were higher compared with controls (p<0.001), while IGFBP-3 levels were lower (1.41±0.56 vs. 1.61±0.38 μg/ml, p=0.039). VEGF levels correlated with apnea-hypopnea index (r=0.336, p=0.001) and oxygen desaturation index (r=0.282, p=0.007). After 6 months on CPAP treatment, VEGF levels decreased in OSA patients (p<0.001), while IGFBP-3 levels increased (p<0.001).

Conclusion:

In newly diagnosed OSA patients, serum levels of VEGF are elevated, while IGFBP-3 levels are low. After 6 months of CPAP treatment these levels change. These results may reflect an increased CV risk in untreated OSA patients, which is ameliorated after CPAP therapy.

Inflammation induced by increased frequency of intermittent hypoxia is attenuated by tempol administration

The levels of serum inflammatory cytokines and the activation of nuclear factor kappa B (NF-κB) and hypoxia inducible factor-1α (HIF-1α) in heart tissues in response to different frequencies of intermittent hypoxia (IH) and the antioxidant tempol were evaluated. Wistar rats (64 males, 200-220 g) were randomly divided into 6 experimental groups and 2 control groups. Four groups were exposed to IH 10, 20, 30, or 40 times/h. The other 2 experimental groups were challenged with IH (30 times/h) plus tempol, either beginning on day 0 (IH30T0) or on day 29 (IH30T29). After 6 weeks of challenge, serum levels of tumor necrosis factor (TNF)-α, intracellular adhesion molecule (ICAM)-1, and interleukin-10 were measured, and western blot analysis was used to detect NF-κB p65 and HIF-1α in myocardial tissues. Serum levels of TNF-α and ICAM-1 and myocardial expression of NF-κB p65 and HIF-1α were all significantly higher in IH rats than in controls (P<0.001). Increased IH frequency resulted in more significant changes. Administration of tempol in IH rats significantly reduced levels of TNF-α, ICAM-1, NF-κB and HIF-1α compared with the non-tempol-treated group (F=16.936, P<0.001). IH induced an inflammatory response in a frequency-dependent manner. Additionally, HIF-1α and NF-κB were increased following IH administration. Importantly, tempol treatment attenuated this effect.

Established vascular effects of continuous positive airway pressure therapy in patients with obstructive sleep apnoea-an update

The aim of this review was to summarize the current data from randomised controlled trials (RCTs) on vascular effects of continuous positive airway pressure (CPAP) therapy in patients with obstructive sleep apnoea (OSA). There is good evidence from RCTs that CPAP lowers blood pressure (BP) to a clinically significant amount. The effect seems to be dependent on the hours of nightly CPAP usage. Data from RCTs have also proven a beneficial effect of CPAP on measures of vascular function such as endothelial function and arterial stiffness. However, there is still a lack of evidence from RCTs proving that CPAP reduces vascular events and mortality.

Markers of Myocardial Ischemia in Patients with Obstructive Sleep Apnea and Coronary Artery Disease

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia during sleep. We tested the hypothesis that nocturnal myocardial ischemia is detectable by ST segment depression and elevation of high sensitive troponin T (hsTrop T) and B-type natriuretic peptide (NT-proBNP) in patients with OSA and coexisting coronary artery disease (CAD). Twenty-one patients with OSA and CAD and 20 patients with OSA alone underwent in-hospital polysomnography. Blood samples for hsTrop T and NT-proBNP measurements were drawn before and after sleep. ST segment depression was measured at the time of maximum oxygen desaturation during sleep. The apnea-hypopnea-index (AHI), oxygen saturation nadir, and time in bed with oxygen saturation of ≤80% were similar in both groups. Levels of hsTrop T and NT-proBNP did not differ significantly before and after sleep but NT-proBNP levels were significantly higher in patients suffering from OSA and CAD compared to patients with OSA alone. No significant ST depression was found at the time of oxygen saturation nadir in either group. Despite the fact that patients with untreated OSA and coexisting CAD experienced severe nocturnal hypoxemia, we were unable to detect myocardial ischemia or myocyte necrosis based on significant ST segment depression or elevation of hsTrop T and NT-proBNP, respectively.

Update on the use of portable monitoring system for the diagnosis of sleep apnea in specific population

The prevalence and severity of obstructive sleep apnea (OSA) is higher in specific population: children, elderly, obese and patients with pulmonary and cardiovascular diseases, compared to the general population. OSA is associated with greater morbidity and mortality in these patients. Although full-night polysomnography is still the gold standard diagnostic sleep study for OSA, it is a time consuming, expensive and technically demanding exam. Over the last few years, there is growing evidence on the use of portable monitors (PM) as an alternative for the diagnosis of OSA. These devices were developed specially for sleep evaluation at home, at a familiar environment, with easy self-application of monitoring, unattended. The use of PM is stablished for populations with high pre-test probability of OSA. However, there is a lack of studies on the use of PM in age extremes and patients with comorbidities. The purpose of this review is to present the studies that evaluated the use of PM in specific population, as well as to describe the advantages, limitations and applications of these devices in this particular group of patients. Although the total loss rate of recordings is variable in different studies, the agreement with full-night polysomnography justifies the use of PM in this population.

Impact of obstructive sleep apnea on cardiovascular outcomes in patients treated with percutaneous coronary intervention: rationale and design of the sleep and stent study

Elucidating the effects of obstructive sleep apnea (OSA) on cardiovascular outcomes is crucial in risk assessments and therapeutic recommendations for affected individuals. The Sleep and Stent Study is a multicenter observational study investigating the relationships between OSA and cardiovascular outcomes in patients treated with percutaneous coronary intervention (PCI). Eight centers in 5 countries (Singapore, China and Hong Kong, India, Myanmar, and Brazil) are participating in the study, and the recruitment target is 1600 patients. Adult patients age 18 to 80 years who have undergone successful PCI are eligible. Recruited patients will undergo an overnight sleep study using a level-3 portable diagnostic device before hospital discharge. The sleep tracings will be analyzed by a certified sleep technologist and audited by a sleep physician, both of whom will be blinded to other study data. The patients will be divided into 2 groups based on apnea-hypopnea index (AHI): OSA (AHI ≥15) and non-OSA (AHI <15) groups. The primary study endpoint of cardiovascular death, myocardial infarction, stroke, and unplanned revascularization will be compared between the OSA and non-OSA groups at a median follow-up of 2 years. Secondary endpoints include all-cause mortality, target-vessel revascularization, stent thrombosis, and hospitalization for heart failure. As of December 31, 2013, a total of 1358 patients have been recruited. Based on the complete preliminary results of the first 785 recruited patients, the prevalence of OSA was 48.3%. We expect the follow-up for primary endpoint to be completed in late 2015; study results will be presented in 2016.

Correlation between Obstructive Sleep Apnea Syndrome and Cardiac Disease Severity

Background. Obstructive sleep apnea (OSA) syndrome is one of the most common respiratory disorders in humans. There is emerging evidence linking OSA to vascular disease, particularly hypertension. The underlying pathophysiological mechanisms that link OSA to cardiovascular diseases such as hypertension, congestive heart failure, and atrial fibrillation are not entirely understood. The aim of this study was to investigate the association of obstructive sleep apnea hypopnea syndrome (OSAHS) with coronary atherosclerotic disease (CAD). Methods. A questionnaire survey based on Berlin questionnaire and Epworth Sleepiness Scale (ESS) was conducted among 406 patients to assess demographic data and the symptoms, such as excessive daytime sleepiness and snoring. Epworth Sleepiness Scale and Berlin questionnaire were completed by all of the patients. Venous blood samples were obtained for biochemical tests. Characteristics of coronary arteries were collected from angiographies' reports. All patients were divided into two groups based on results from Berlin questionnaire: low risk patients for OSA and high risk patients for OSA. Data were analyzed by SPSS software version 13. Results. Mean age of patients was 61.8 ± 10.5. 212 (52.2%) patients were categorized as high risk group for apnea. Also, excessive daytime sleepiness was reported in 186 patients (45.8%). The severity of coronary artery involvement, daytime sleepiness, and electrocardiogram abnormalities was significantly higher in high risk patients for OSA compared with low risk patients. High risk patients had higher level of FBS and LDL and lower level of HDL cholesterol (P < 0.05). Conclusion. Our study found a strong correlation between the number of stenotic vessels and OSA. Based on our findings, OSA can be a predisposing factor for cardiac diseases.

The association of sleep disordered breathing with heart failure and other cardiovascular conditions

An abundance of evidence exists in support of primary and secondary prevention for tackling the scourge of cardiovascular disease. Despite our wealth of knowledge, certain deficiencies still remain. One such example is the association between sleep disordered breathing (SDB) and cardiovascular disease. A clear body of evidence exists to link these two disease entities (independent of other factors such as obesity and smoking), yet our awareness of this association and its clinical implication does not match that of other established cardiovascular risk factors. Here, we outline the available evidence linking SDB and cardiovascular disease as well as discussing the potential consequences and management in the cardiovascular disease population.