Day-night variation of acute myocardial infarction in obstructive sleep apnea

Chronic intermittent hypoxia promotes myocardial ischemia-related ventricular arrhythmias and sudden cardiac death

We investigated the effects of intermittent hypoxia (IH), such as that encountered in severe obstructive sleep apnea (OSA) patients, on the development and severity of myocardial ischemia-related ventricular arrhythmias. Rats were exposed to 14 days of IH (30 s at 5%O₂ and 30 s at 21%O₂, 8 h·day⁻¹) or normoxia (N, similar air-air cycles) and submitted to a 30-min coronary ligature. Arterial blood pressure (BP) and ECG were recorded for power spectral analysis, ECG interval measurement and arrhythmia quantification. Left ventricular monophasic action potential duration (APD) and expression of L-type calcium (LTCC) and transient receptor potential (TRPC) channels were assessed in adjacent epicardial and endocardial sites. Chronic IH enhanced the incidence of ischemic arrhythmias, in particular ventricular fibrillation (66.7% vs. 33.3% in N rats, p < 0.05). IH also increased BP and plasma norepinephine levels along with increased low-frequency (LF), decreased high-frequency (HF) and increased LF/HF ratio of heart rate and BP variability. IH prolonged QTc and Tpeak-to-Tend intervals, increased the ventricular APD gradient and upregulated endocardial but not epicardial LTCC, TRPC1 and TRPC6 (p < 0.05). Chronic IH, is a major risk factor for sudden cardiac death upon myocardial ischemia through sympathoactivation and alterations in ventricular repolarization, transmural APD gradient and endocardial calcium channel expression.

Blood-pressure variability in patients with obstructive sleep apnea: current perspectives

Obstructive sleep apnea (OSA) is often associated with hypertension and other cardiovascular diseases. Blood pressure (BP) variability is part of the assessment of cardiovascular risk. In OSA, BP variability has been studied mainly as very short-term (beat-by-beat) and short-term (24-hour BP profile) variability. BP measured on consecutive heartbeats has been demonstrated to be highly variable, due to repeated peaks during sleep, so that an accurate assessment of nocturnal BP levels in OSA may require peculiar methodologies. In 24-hour recordings, BP frequently features a "nondipping" profile, ie, <10% fall from day to night, which may increase cardiovascular risk and occurrence of major cardiovascular events in the nocturnal hours. Also, BP tends to show a large "morning BP surge", a still controversial negative prognostic sign. Increased very short-term BP variability, high morning BP, and nondipping BP profile appear related to the severity of OSA. Treatment of OSA slightly reduces mean 24-hour BP levels and nocturnal beat-by-beat BP variability by abolishing nocturnal BP peaks. In some patients OSA treatment turns a nondipping into a dipping BP profile. Treatment of arterial hypertension in OSA usually requires both antihypertensive pharmacological therapy and treatment of apnea. Addressing BP variability could help improve the management of OSA and reduce cardiovascular risk. Possibly, drug administration at an appropriate time would ensure a dipping-BP profile.

Diurnal changes and levels of fibrin generation are not altered by continuous positive airway pressure (CPAP) in obstructive sleep apnoea (OSA)

Obstructive sleep apnoea (OSA) is associated with increased cardiovascular disease (CVD) risk. In the general population, CVD events peak at 9:00–10:00 AM, associated with diurnal changes in thrombotic potential. However in OSA, these CVD events occur frequently at night. Measuring thrombotic potential across the sleep-wake cycle may provide insight into the temporal association of OSA with CVD. This study aimed to determine diurnal changes in fibrin generation in OSA and whether treatment of OSA with continuous positive airway pressure (CPAP) alters fibrin generation across the sleep-wake cycle. In a randomised placebo-controlled crossover trial, patients with OSA were assigned to two months each of therapeutic CPAP and placebo. After each treatment period, fibrin generation was determined by overall haemostatic potential assay at seven time points over 24 hours (h). Twenty-eight patients (25 men, 3 women) with severe OSA (Apnoea Hypopnoea Index = 37.9 ± 23.9/h, Oxygen Desaturation Index 31.3 ± 22.4/h) completed the study. All parameters, except lag time to fibrin generation, showed significant diurnal changes, both on CPAP and placebo. Compared to 9:00 AM, fibrin generation parameters were significantly lower at midnight and 3:00 AM for overall coagulation potential (OCP), overall haemostasis potential (OHP), maximum optical density, and maximum slope (all p≤0.001). CPAP produced no change in fibrin generation parameters compared to placebo. In severe OSA patients, fibrin generation peaked at 6:00 AM and 9:00 AM rather than during the sleep period (midnight and 3:00 AM). These findings suggest a prothrombotic shift in the morning similar to individuals without OSA. There was no difference between CPAP and placebo on fibrin generation.

Review of and Updates on Hypertension in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a prevalent sleep disorder as is hypertension (HTN) in the 21st century with the rising incidence of obesity. Numerous studies have shown a strong association of OSA with cardiovascular morbidity and mortality. There is overwhelming evidence supporting the relationship between OSA and hypertension (HTN). The pathophysiology of HTN in OSA is complex and dependent on various factors such as sympathetic tone, renin-angiotensin-aldosterone system, endothelial dysfunction, and altered baroreceptor reflexes. The treatment of OSA is multifactorial ranging from CPAP to oral appliances to lifestyle modifications to antihypertensive drugs. OSA and HTN both need prompt diagnosis and treatment to help address the growing cardiovascular morbidity and mortality due to these two entities.

Obstructive sleep apnoea in diabetes: Does it matter?

Obstructive sleep apnoea (OSA) is very common in patients with Type 2 diabetes (T2D), which is not surprising considering that obesity is a common risk factor for both conditions. In general population studies, OSA has been shown to be associated with several comorbidities including increased risk of road traffic accidents, T2D, hypertension and lack of nocturnal dipping of blood pressure, hyperlipidaemia, increased inflammation, increased risk of cardiovascular disease and mortality, increased risk of atrial fibrillation, worse quality of life, and erectile dysfunction. However, the impact of OSA on diabetes-related vascular and metabolic outcomes remains unclear. Furthermore, the impact of continuous positive airway pressure (CPAP) treatment in patients with T2D is also unclear. This unclarity regarding the impact of OSA and CPAP in patients with T2D has possibly contributed to the lack of screening for OSA in patients with T2D in the UK despite the high prevalence of OSA in patients with T2D. In this commentary, I provide an overview about OSA with a particular focus on its role and impact in patients with T2D.

Association of obstructive sleep apnea with arterial stiffness and nondipping blood pressure in patients with hypertension

Whether sex influences the association of obstructive sleep apnea (OSA) with markers of cardiovascular risk in patients with hypertension is unknown. In this study, 95 hypertensive participants underwent carotid-femoral pulse wave velocity, 24-hour ambulatory blood pressure monitoring, echocardiogram, and polysomnography after a 30-day standardized treatment with hydrochlorothiazide plus enalapril or losartan. OSA was present in 52 patients. Compared with non-OSA patients, pulse wave velocity values were higher in the OSA group (men: 11.1±2.2 vs 12.7±2.4 m/s, P=.04; women: 11.8±2.4 vs 13.2±2.2 m/s, P=.03). The proportion of diastolic dysfunction was significant in men and women with OSA. Compared with non-OSA patients, nondipping systolic blood pressure in OSA was higher in men (14.3% vs 46.4%) and in women (41.4% vs 65.2%). OSA was independently associated with pulse wave velocity (β=1.050; P=.025) and nondipping systolic blood pressure (odds ratio, 3.03; 95% confidence interval, 1.08-8.55; P=.035) in the regression analysis. In conclusion, OSA is independently associated with arterial stiffness and nondipping blood pressure in patients with hypertension regardless of sex.

The relationship between apnoea hypopnoea index and Gensini score in patients with acute myocardial infarction undergoing emergency primary percutaneous coronary intervention

BACKGROUND

Sleep apnoea hypopnoea syndrome (SAHS) is characterised by repetitive nocturnal hypoxemia and has a high prevalence among patients with acute myocardial infarction (AMI). But there are few studies on patients with AMI undergoing emergency primary percutaneous coronary intervention (pPCI). In this study, we want to find the prevalence of SAHS among patients with AMI undergoing emergency pPCI and determine whether SAHS would worsen the condition among these people, and especially affect the damage degree of the coronary artery.

METHODS

Over four months, 95 patients admitted for the first time for AMI were observed. All of them had emergency primary PCIs. A total of 86 patients accepted the sleep study and were divided into four groups according to the apnoea hypopnoea index (AHI): SAHS was diagnosed when AHI ≥5/h and was defined as mild for AHI ≥5/h and <15/h, moderate for AHI ≥15/h and <30/h, and severe for AHI ≥30/h. On the contrary, the patients whose AHI <5/h were Non-SAHS. And the characteristics of the patients among these four groups were compared. According to the time of chest pain onset, the number of the patients between SAHS and non-SAHS, and patients' AHI during three intervals of one day were measured and compared; Makers including the sensitivity of serum troponin T (hs-TnT), creatine kinase isoenzyme MB (CK-MB), left ventricular ejection fraction (LVEF), pro-brain-type natriuretic peptide (pro-BNP), Gensini score and collateral vessels between the SAHS and non-SAHS were compared. And the relationships between the AHI of these patients and the markers were analysed.

RESULTS

Of the 86 patients studied, 65 had SAHS, representing a SAHS prevalence of 75.58% among patients with AMI undergoing emergency pPCI. There were significant differences in average ages, smoking and arrhythmia (P<0.05) between these four groups. There was no significant difference between AMI patients with or without SAHS regarding the day-night pattern. But there showed significant differences between SAHS and non-SAHS in Gensini score (P<0.05) and pro-BNP (P<0.05). Also, there were positive correlations between AHI and Gensini score (r=0.490, P<0.05) and pro-BNP (r=0.338, P<0.05).

CONCLUSIONS

Among patients with AMI undergoing emergency pPCI, there is a high prevalence of SAHS. There are also positive correlations between AHI and Gensini score, and pro-BNP. Therefore, guided by the results, should we conduct a routine screening to those patients normally and could we relieve the damage to the coronary artery by curing the SAHS?

Disrupted day-night pattern of cardiovascular death in obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) patients who suffer sudden cardiac death die predominantly during the night. We aimed to investigate whether all cardiovascular-related deaths display the same night-time peak as sudden cardiac death.

METHODS

Data from a large cohort of adults who underwent full-night polysomnography between 1985 and 2015 in a university-affiliated sleep clinic were analyzed. Time and cause of death of these patients and of persons from the general population were identified in death certificates from the State Health Secretariat. The day-night pattern of cardiovascular death was compared among groups of non-OSA, OSA (apnea-hypopnea index, AHI ≥5), CPAP users, and persons from the general population.

RESULTS

Among 619 certificates, 160 cardiovascular-related deaths were identified. The time of death of the 142 persons with OSA was uniformly distributed over 24 h, with neither an identifiable peak nor a circadian pattern (Rayleigh test; P = 0.8); the same flat distribution was seen in those with purported CPAP use (n = 49). Non-OSA individuals presented a morning peak and a night nadir of deaths, clearer when analyzed in eight-hour intervals. The same pattern was observed in 92 836 certificates from the State general population, with cardiovascular deaths showing the expected morning peak, night nadir, and a significant circadian pattern (Rayleigh test; P < 0.001).

CONCLUSIONS

In OSA patients, the distribution of cardiovascular-related deaths throughout the 24-h period is virtually flat, in contrast with the described nighttime peak of sudden cardiac death. OSA-related phenomena during nighttime might be blunting the mechanisms, arrhythmic or not, behind the morning peak of cardiovascular-related deaths.

Sleep Apnea: Types, Mechanisms, and Clinical Cardiovascular Consequences

Sleep apnea is highly prevalent in patients with cardiovascular disease. These disordered breathing events are associated with a profile of perturbations that include intermittent hypoxia, oxidative stress, sympathetic activation, and endothelial dysfunction, all of which are critical mediators of cardiovascular disease. Evidence supports a causal association of sleep apnea with the incidence and morbidity of hypertension, coronary heart disease, arrhythmia, heart failure, and stroke. Several discoveries in the pathogenesis, along with developments in the treatment of sleep apnea, have accumulated in recent years. In this review, we discuss the mechanisms of sleep apnea, the evidence that addresses the links between sleep apnea and cardiovascular disease, and research that has addressed the effect of sleep apnea treatment on cardiovascular disease and clinical endpoints. Finally, we review the recent development in sleep apnea treatment options, with special consideration of treating patients with heart disease. Future directions for selective areas are suggested.

Sleep duration and quality in heart failure patients

PURPOSE

Sleep-disordered breathing (SDB) is highly prevalent in patients with heart failure and reduced left ventricular ejection fraction (HF-REF). SDB is classified as predominant obstructive (OSA) or central (CSA) and may alter sleep duration, sleep quality, and quality of life. This study describes sleep quality and duration in well-characterized cohorts of these patients.

METHODS

Two hundred fifty consecutive patients with HF-REF (NYHA class ≥II, ejection fraction ≤45%) underwent cardiac and pulmonary examination, plus full attended in-hospital overnight polysomnography (PSG). PSG recordings were performed according to current recommendations and underwent independent, blinded analysis at a core laboratory.

RESULTS

Patients with HF-REF and CSA were older and had more impaired cardiac function compared to those with OSA. With respect to sleep parameters, patients with CSA spent more time in bed than those with OSA (468 ± 52 vs 454 ± 46 min, p = 0.021) while sleep efficiency was lower (67 ± 14 vs 72 ± 13% of total sleep time (TST), p = 0.008). In addition, CSA patients spent more time awake after sleep onset (101 ± 61 vs 71 ± 46 min, p = 0.001) and had more stage N1 (light) sleep (33 ± 19 vs 28 ± 16% of TST, p = 0.017). Overall, the proportion of sleep spent in N3 (slow-wave/deep) sleep in HF-REF patients with SDB was low (4.1 ± 6.3% of TST) compared with healthy adults.

CONCLUSIONS

HF-REF patients with CSA compared to OSA have worse sleep efficiency and quality. This could result in less restorative sleep, changes in sympathovagal balance, and impaired resetting of important reflexes, which might contribute to worse cardiovascular outcomes in HF-REF patients with SDB.

Obesity, Cardiovascular Disease and Sleep Disorders: Insights into the Rising Epidemic

Cardiovascular disease (CVD) is the main cause of death among adult men and women in the USA and impacts millions around the globe. Traditional risk factors for CVD include obesity, diabetes, hypertension and dyslipidemia. The modern-day epidemic of obesity not only increased the rate of CVD but also ushered in an additional CVD risk factor to be added to the list; that is obstructive sleep apnea (OSA). In this review, we discuss the growing epidemic of obesity and OSA, highlighting the common pathogenic hypotheses linking these risk factors to CVD. We will also highlight the therapeutic rationale of OSA as a way to reduce CVD risk.

Prevalence of sleep-disordered breathing in acute coronary syndrome: a systemic review and meta-analysis

PURPOSE

This study aimed to review the literature on the prevalence of sleep-disordered breathing (SDB) in patients with acute coronary syndrome (ACS).

METHODS

Relevant studies were searched on PubMed, EMBASE, and Cochrane Library through December 2014. Data were extracted using standardized forms. Pooled prevalence of all SDB (apnea-hypopnea index (AHI) > 5), moderate-to-severe SDB (AHI > 15), and severe SDB (AHI > 30) in ACS patients was calculated using DerSimonian-Laird random-effects model. Sensitivity analysis was performed based on races and diagnostic methods of SDB.

RESULTS

A total of 32 studies were included in the present meta-analysis, examining 3360 patients. The meta-analysis indicated that pooled prevalence of all SDB (AHI > 5), moderate-to-severe SDB (AHI > 15), and severe SDB (AHI > 30) in ACS patients were 69 % (95 % confidence interval (CI) = 61, 77 %), 43 % (95 % CI = 36, 49 %), and 25 % (95 % CI = 17, 33 %), respectively. Sensitivity analysis indicated that the pooled prevalence of SDB in Western population was similar to that in Asian population. However, diagnostic methods of SDB seemed to have various impacts on the prevalence of all SDB (AHI > 5), moderate-to-severe SDB (AHI > 15), and severe SDB (AHI > 30).

CONCLUSIONS

High prevalence of all SDB, moderate-to-severe SDB, and severe SDB was found in ACS patients. It is clinically important to screen for SDB in patients with ACS.

Sleep Disorders: Is the Trigemino-Cardiac Reflex a Missing Link?

Trigeminal innervated areas in face, nasolacrimal, and nasal mucosa can produce a wide array of cardiorespiratory manifestations that include apnea, bradypnea, bradycardia, hypotension, and arrhythmias. This reflex is a well-known entity called "trigemino-cardiac reflex" (TCR). The role of TCR is investigated in various pathophysiological conditions especially in neurosurgical, but also skull base surgery procedures. Additionally, its significance in various sleep-related disorders has also been highlighted recently. Though, the role of diving reflex, a subtype of TCR, has been extensively investigated in sudden infant death syndrome. The data related to other sleep disorders including obstructive sleep apnea, bruxism is very limited and thus, this mini review aims to investigate the possible role and correlation of TCR in causing such sleep abnormalities.

Novel Triggered Nocturnal Blood Pressure Monitoring for Sleep Apnea Syndrome: Distribution and Reproducibility of Hypoxia-Triggered Nocturnal Blood Pressure Measurements

Obstructive sleep apnea (OSA) causes blood pressure (BP) surges during sleep, which may lead to increased sleep-onset cardiovascular events. The authors recently developed a triggered nocturnal BP monitoring system that initiates BP measurements when oxygen desaturation falls below a variable threshold. The distribution and reproducibility of hypoxia-triggered nocturnal BP parameters compared with those of fixed-interval nocturnal BP parameters for two consecutive nights in 147 OSA patients (mean age 59.4 years, 86.4% men) were evaluated. The mean and distribution (standard deviation [SD]) of the hypoxia-peak systolic BP (SBP) were significantly greater than that of the mean nocturnal SBP (mean±SD: 148.8±20.5 vs 123.4±14.2 mm Hg, P<.001). The repeatability coefficient (expressed as %MV) of hypoxia-peak SBP between night 1 and night 2 was comparable to that of mean nocturnal SBP (43% vs 32%). In conclusion, hypoxia-peak nocturnal BP was much higher than mean nocturnal BP, and it was as reproducible as mean nocturnal BP.

Cardiopulmonary Interactions in Children with Heart Failure

Cardiopulmonary interactions are present but inconsequential in humans with normal cardiac and respiratory function; however, in the presence of significant impairment in either system, the importance of the interplay between cardiovascular and pulmonary systems cannot be overstated. This review will discuss the physiologic underpinnings and consequences of these interactions in patients with heart failure.

Cardiopulmonary Interactions

OBJECTIVES

The objectives of this review are to discuss the mechanisms by which respiration impacts cardiovascular function and vice versa, with an emphasis on the impact of these interactions in pediatric cardiac critical care.

DATA SOURCE

A search of MEDLINE was conducted using PubMed.

CONCLUSIONS

In the presence of underlying cardiac and respiratory disease, the interplay between these two systems is significant and plays a pivotal role in the pathophysiology of acute and chronic phases of a wide spectrum of diseases. An understanding of these relationships is essential to optimizing the care of critically ill patients.

Nocturnal Hypoxemia Due to Obstructive Sleep Apnea Is an Independent Predictor of Poor Prognosis After Myocardial Infarction

Background

Obstructive sleep apnea (OSA) is an important risk factor for the development of cardiovascular diseases including myocardial infarction (MI). The aim of this study was to investigate the effects of OSA on prognosis after MI, and to determine which specific measures of OSA severity best predicted outcomes.

Methods and Results

We performed a prospective study, in which 112 patients without a prior diagnosis of sleep apnea underwent comprehensive polysomnography within a median of 7 days after MI. Patients were followed up at 6‐monthly intervals (±2 weeks) for a total of 48 months. Patients classified with central apnea (n=6) or those using continuous positive airway pressure (n=8) after polysomnography were excluded from analyses. The primary end point was major adverse cardiac events, including death from any cause, recurrent MI, unstable angina, heart failure, stroke, and significant arrhythmic events. Forty of 98 patients (41%) had OSA (apnea‐hypopnea index ≥15 events/h). OSA patients had higher major adverse cardiac event rates when compared to those without OSA (47.5% versus 24.1%; χ²=5.41, P=0.020). In a multivariate model that adjusted for clinically relevant variables including age, left ventricular ejection fraction, diabetes mellitus, oxygen desaturation index, and arousal index, significant hypoxemia, as defined by nocturnal nadir oxygen saturation ≤85%, was an independent risk factor for major adverse cardiac events (hazard ratio=6.05, P=0.004) in follow‐up 15 months after baseline.

Conclusions

Nocturnal hypoxemia in OSA is an important predictor of poor prognosis for patients after MI. These findings suggest that routine use of low‐cost nocturnal oximetry may be an economical and practical approach to stratify risk in post‐MI patients.

Clinical neurocardiology defining the value of neuroscience-based cardiovascular therapeutics

The autonomic nervous system regulates all aspects of normal cardiac function, and is recognized to play a critical role in the pathophysiology of many cardiovascular diseases. As such, the value of neuroscience-based cardiovascular therapeutics is increasingly evident. This White Paper reviews the current state of understanding of human cardiac neuroanatomy, neurophysiology, pathophysiology in specific disease conditions, autonomic testing, risk stratification, and neuromodulatory strategies to mitigate the progression of cardiovascular diseases.

Altered clot microstructure detected in obstructive sleep apnoea hypopnoea syndrome

Abnormal clot microstructure plays a pivotal role in the pathophysiology of thromboembolic diseases. Assessing the viscoelastic properties of clot microstructure using novel parameters, Time to Gel Point (T_GP), Fractal Dimension (d_f) and clot elasticity (G׳_GP) could explain the increased cardiovascular and thromboembolic events in patients with Obstructive Sleep Apnoea Hypopnea Syndrome (OSAHS). We wanted to compare T_GP, d_f, and G׳_GP and their diurnal variation in OSAHS and symptomatic comparators. thirty six patients attending a sleep disturbed breathing clinic with symptoms of OSAHS were recruited. T_GP, d_f and G׳_GP were measured alongside standard coagulation screening, thrombin generation assays, and platelet aggregometry at 16:00 h and immediately after an in-patient sleep study at 07:30 h. OSAHS group had significantly lower afternoon d_f than comparators (1.705±0.033 vs. 1.731±0.031, p<0.05). d_f showed diurnal variation and only in the OSAHS group, being significantly lower in the afternoon than morning (p<0.05). Diurnal changes in d_f correlated with 4% DR, even after controlling for BMI (r=0.37, p=0.02). The lower d_f in the afternoon in OSAHS suggests a partial compensatory change that may make up for other pro-clotting abnormalities/hypertension during the night. The change to the thrombotic tendency in the afternoon is biggest in severe OSAHS. d_f Shows promise as a new microstructural indicator for abnormal haemostasis in OSAHS.

Sleep Disruption is Associated with Increased Ventricular Ectopy and Cardiac Arrest in Hospitalized Adults

STUDY OBJECTIVES

To determine whether sleep disruption increases ventricular ectopy and the risk of cardiac arrest in hospitalized patients.

METHODS

Hospital emergency codes (HEC) trigger multiple hospital-wide overhead announcements. In 2014 an electronic "code white" program was instituted to protect staff from violent patients. This resulted in an increase in nocturnal HEC. Telemetry data was examined between September 14 and October 2, 2014. The frequency of nocturnal announcements was correlated with changes in frequency of premature ventricular complexes per hour (PVC/h). Cardiac arrest data were examined over a 3-y period. All HEC were assumed to have triggered announcements. The relationship between nocturnal HEC and the incidence of subsequent cardiac arrest was examined.

RESULTS

2,603 hours of telemetry were analyzed in 87 patients. During nights with two or fewer announcements, PVC/h decreased 33% and remained 30% lower the next day. On nights with four or more announcements, PVC/h increased 23% (P < 0.001) and further increased 85% the next day (P = 0.001). In 2014, following the introduction of the code white program, the frequency of all HEC increased from 1.1/day to 6.2/day (P < 0.05). The frequency of cardiac arrest/24 h rose from 0.46/day in 2012-2013 to 0.62/day in 2014 (P = 0.001). During daytime hours (06:00-22:00), from 2012 through 2014, the frequency of cardiac arrest following zero, one or at least two nocturnal HEC were 0.331 ± 0.03, 0.396 ± 0.04 and 0.471 ± 0.09 respectively (R(2) = 0.99, P = 0.03).

CONCLUSIONS

Sleep disruption is associated with increased ventricular ectopy and increased frequency of cardiac arrest.

Evening versus morning dosing of antihypertensive drugs in hypertensive patients with sleep apnoea: a cross-over study

OBJECTIVE

Beneficial effects of continuous positive airway pressure (CPAP) on both blood pressure (BP) levels and variability have been documented in patients with obstructive sleep apnoea (OSA). We investigated the relevant impact of different dosing times of antihypertensive drugs beyond CPAP application.

METHODS

In this prospective, cross-over trial, we included 41 patients with newly diagnosed hypertension and never treated OSA (apnoea-hypopnea index ≥15/h), without increased daytime somnolence (Epworth Score ≤10 points). Patients first received treatment with valsartan or with a fixed combination of amlodipine and valsartan in a single morning dose for 8 weeks. In the following 8-week period, patients received the same therapeutic regimen in a single evening dose. Office and ambulatory BP were measured at baseline and after each treatment period.

RESULTS

Compared with morning administration, evening dosing induced a greater decrease in office SBP (by 3.7 ± 6.5 mmHg, P = 0.001). The decrease in 24-h SBP/DBP was significant and similar after morning and evening dosing (-16.4 ± 11/11.0 ± 7.5 and -18.4 ± 11/12.1 ± 7.5 mmHg, respectively, P < 0.001 for both). Evening compared with morning dosing further reduced night-time SBP/DBP by 4.4 ± 8.6/2.9 ± 5.6 mmHg (P = 0.007 and P = 0.006, respectively). Night-time dippers increased from 24% at baseline to 34% with morning dosing and to 61% with evening dosing. There was no significant interaction between concurrent CPAP application and drugs dosing time on BP changes.

CONCLUSION

Evening dosing of antihypertensive drugs improves night-time BP and dipping status in nonsleepy patients with OSA, irrespective of CPAP application.

Prediction of obstructive sleep apnea using visual photographic analysis

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) has been historically underdiagnosed and may be associated with grave perioperative complications. The ASA and American Academy of Sleep Medicine recommend OSA screening prior to surgery; however, only a minority of patients are screened. The objective of this study was to determine the proficiency of anesthesiologists, otolaryngologists, and internists at predicting the presence of OSA by visual photographic analysis without the use of a computer program to assist, and determine if prediction accuracy varies by provider type.

DESIGN

Prospective case series

SETTING

Tertiary care hospital-based academic center

PATIENTS

Fifty-six consecutive patients presenting to the sleep laboratory undergoing polysomnography had frontal and lateral photographs of the face and torso taken.

INTERVENTIONS

Not applicable.

MEASUREMENTS

Polysomnography outcomes and physician ratings. An obstructive apnea hypopnea index (oAHI) ≥15 was considered "positive." Twenty anesthesiologists, 10 otolaryngologists, and 11 internists viewed patient photographs and scored them as OSA "positive" or "negative" before and after being informed of patient comorbidities.

MAIN RESULTS

Nineteen patients had an oAHI <15, 18 were ≥15 but <30, and 19 were ≥30. The mean oAHI was 28.7 ± 26.7 events/h (range, 0-125.7), and the mean body mass index was 34.1 ± 9.7 kg/m(2) (range, 17.4-63.7). Overall, providers predicted the correct answer with 61.8% accuracy without knowledge of comorbidities and 62.6% with knowledge (P < .0001). There was no difference between provider groups (P = .307). Prediction accuracy was unrelated to patient age (P = .067), gender (P = .306), or race (P = .087), but was related to body mass index (P = .0002).

CONCLUSION

The ability to predict OSA based on visual inspection of frontal and lateral photographs is marginally superior to chance and did not differ by provider type. Knowledge of comorbidities did not improve prediction accuracy.

A clinical approach to obstructive sleep apnea as a risk factor for cardiovascular disease

Obstructive sleep apnea (OSA) is associated with cardiovascular risk factors, cardiovascular diseases, and increased mortality. Epidemiological studies have established these associations, and there are now numerous experimental and clinical studies which have provided information on the possible underlying mechanisms. Mechanistic proof-of-concept studies with surrogate endpoints have been performed to demonstrate that treatment of OSA by continuous positive airway pressure (CPAP) has the potential to reverse or at least to attenuate not only OSA but also the adverse cardiovascular effects associated with OSA. However, no randomized studies have been performed to demonstrate that treatment of OSA by CPAP improves clinical outcomes in patients with cardiovascular risk factors and/or established cardiovascular disease and concomitant OSA. In the present review, we summarize the current knowledge on the role of OSA as a potential cardiovascular risk factor, the impact of OSA on cardiac function, the role of OSA as a modifier of the course of cardiovascular diseases such as coronary artery disease, atrial fibrillation, and heart failure, and the insights from studies evaluating the impact of CPAP therapy on the cardiovascular features associated with OSA.

Impact of Obstructive Sleep Apnea on the Levels of Placental Growth Factor (PlGF) and Their Value for Predicting Short-Term Adverse Outcomes in Patients with Acute Coronary Syndrome

BACKGROUND

Placental growth factor (PlGF) induces angiogenesis and promotes tissue repair, and plasma PlGF levels change markedly during acute myocardial infarction (AMI). Currently, the impact of obstructive sleep apnea (OSA) in patients with AMI is a subject of debate. Our objective was to evaluate the relationships between PlGF levels and both the severity of acute coronary syndrome (ACS) and short-term outcomes after ACS in patients with and without OSA.

METHODS

A total of 538 consecutive patients (312 OSA patients and 226 controls) admitted for ACS were included in this study. All patients underwent polygraphy in the first 72 hours after hospital admission. The severity of disease and short-term prognoses were evaluated during the hospitalization period. Plasma PlGF levels were measured using an electrochemiluminescence immunoassay.

RESULTS

Patients with OSA were significantly older and more frequently hypertensive and had higher BMIs than those without OSA. After adjusting for age, smoking status, BMI and hypertension, PlGF levels were significantly elevated in patients with OSA compared with patients without OSA (19.9 pg/mL, interquartile range: 16.6-24.5 pg/mL; 18.5 pg/mL, interquartile range: 14.7-22.7 pg/mL; p<0.001), and a higher apnea-hypopnea index (AHI) was associated with higher PlGF concentrations (p<0.003). Patients with higher levels of PlGF had also an increased odds ratio for the presence of 3 or more diseased vessels and for a Killip score>1, even after adjustment.

CONCLUSIONS

The results of this study show that in patients with ACS, elevated plasma levels of PlGF are associated with the presence of OSA and with adverse outcomes during short-term follow-up.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01335087.

[Acute pain in myocardial infarction: analysis of concept]

OBJECTIVE

To analyze the concept "sharp pain" in the context of acute myocardial infarction.

METHODS

Conceptual analysis method proposed by Walker and Avant. This makes it possible to clarify the concept of attributes. We conducted an integrative review to assist the search of studies published in 2006 and 2012, using the descriptors 'Acute Pain' and 'myocardial infarction', through consultation to Cumulative Index to Nursing and Allied Health Literature (CINAHL), Scopus and Public/Publish Medline (PubMed) data.

RESULTS

A sample of 29 studies was selected in which the background identified was: reduction of myocardial perfusion and/or death of myocardial tissue; attributes: quality, location, time, duration and irradiation; and consequent: report of pain, dyspnea, high heart rate, nausea, vomiting, high blood pressure, high respiratory rate, sleep disturbance, diaphoresis, fatigue, paleness, weakness, anxiety and fear.

CONCLUSION

The findings have clarified the attributes of the concept sharp pain in myocardial infarction.

Arrhythmogenic Substrates in Sleep-Disordered Breathing with Arterial Hypertension

BACKGROUND

Sleep-disordered breathing (SDB) is highly associated with arterial hypertension (HT). Sympathetic hypertonia increases the risk of sudden cardiac death in patients with sleep apnea. This study aims to noninvasively investigate the electrophysiological features in SDB patients with and without arterial HT.

METHODS

Fifty-three patients with SDB were classified into two groups: SDB group and SDB + HT group. Twenty subjects with arterial HT were enrolled as controls (HT group). To assess arrhythmogenic vulnerability, high-resolution 24-hour ambulatory electrocardiograms were obtained for analyzing continuous late potential (LP), T-wave amplitude variability (TAV), and heart rate variability (HRV).

RESULTS

A higher incidence of positive LP was observed in the SDB + HT (85%) group than that observed in the SDB (50%) and HT (20%) groups (P < 0.01). TAV was highest in the SDB + HT group (78 μV) compared with the SDB (61 μV) and HT groups (42 μV; P < 0.01). Positive LP and TAV values were observed at night in the SDB + HT and SDB groups. The low-frequency/high-frequency of the HRV analysis was highest in the SDB + HT (4.7) group compared with that in the SDB (2.9) and HT (2.9) groups (P = 0.01).

CONCLUSION

Nocturnal LP, TAV, and HRV examinations were useful to investigate arrhythmogenesis. SDB patients with arterial HT showed a high prevalence of depolarization and repolarization abnormalities and relative sympathetic hyperactivity. This suggests that an electrophysiological instability is more prevalent in SDB patients with arterial HT.

Statistical analysis plan for the Sleep Apnea cardioVascular Endpoints study: An international randomised controlled trial to determine whether continuous positive airways pressure treatment for obstructive sleep apnea in patients with CV disease prevents secondary cardiovascular events

RATIONALE

Obstructive sleep apnea (OSA) is associated with increased risk of cardiovascular disease. Continuous positive airway pressure (CPAP) delivered via a nasal mask during sleep immediately alleviates obstructive apneas and improves sleep quality and daytime somnolence. However, there is uncertainty as to whether such treatment can modify CV risk and disease.

AIMS

The Sleep Apnea Cardiovascular Endpoints (SAVE) study aims to determine whether CPAP on top of best medical care compared to best medical care alone can reduce the risk of serious CV events in patients with co-morbid OSA and established CV disease.

DESIGN

SAVE is an investigator initiated and conducted, international, multicenter, open, blinded endpoint, randomized controlled trial. Participants were randomised to either CPAP or usual care between 2008 and 2013 and will be followed up for an average of approximately 4 years.

STUDY OUTCOME

The primary endpoint is a composite of CV death, myocardial infarction (MI, including silent MI), stroke, hospitalisation for heart failure, hospitalisation for an acute ischemic cardiac event (unstable angina) or cerebral event (transient ischemic event [TIA]).

DISCUSSION

The pre-specified statistical analysis plan (SAP) for the main analyses is presented. This SAP was finalised before patient follow-up was completed and before any unblinding of the data. The SAP outlines details of the primary, secondary and tertiary outcomes, together with planned subgroup and exploratory analyses.

Effect of beta-blocker therapy on heart rate response in patients with hypertension and newly diagnosed untreated obstructive sleep apnea syndrome

BACKGROUND

Beta1-receptor antagonists (BBs) are commonly administered in the treatment of cardiovascular disease (CVD). The reported benefits of BB use in CVD patients with concomitant obstructive sleep apnea (OSA) may be limited by their impact on apnea-induced bradycardias. Therefore the aim of the study was to test the influence of BBs on periapneic heart rate (HR) fluctuations in hypertensive patients with newly-detected and untreated OSA.

METHODS

We studied 88 hypertensive patients (56 on BBs and 32 BB naive) with newly-diagnosed moderate-to-severe OSA who were free of major pulmonary comorbidities and did not require antiarrhythmic therapy. ECGs recorded during sleep were investigated for heart rate (HR) responses to apneas allowing to compare extreme HR accelerations and decelerations between the groups.

RESULTS

Average sleep-time HR was comparable in BB-naive (BB-) and BB-treated (BB+) patients. Direct comparisons showed that HR decelerations were also similar in the two subgroups (53.8±9.6 vs. 54.4±7.8 bpm; P=0.78, for BB- and BB+, respectively) however, BBs blunted the OSA-induced HR accelerations (82.3±12.2 vs. 74.3±10.0; P=0.003). After adjusting for baseline HR and magnitude of desaturations, HR decelerations were more evident in BB-naive group whereas tachycardic responses remained blunted in the BB+ group. The incidence of ectopies and conduction abnormalities were comparable across two groups.

CONCLUSIONS

Beta-blockers do not potentiate apnea-induced HR decelerations, attenuate apnea-induced increases in heart rate and do not influence incidence of ectopies and conduction abnormalities in patients with hypertension and moderate-to-severe, untreated OSA.

Obstructive Sleep Apnoea and Vascular Disease in Patients with Type 2 Diabetes

Obstructive sleep apnoea (OSA) is common and is associated with many vascular risk factors, such as hypertension, insulin resistance, albuminuria, dyslipidaemia, increased inflammation and endothelial dysfunction. Epidemiological studies have shown that OSA is associated with increased cardiovascular disease (CVD) and that continuous positive airway pressure (CPAP) might reduce CVD events in patients with OSA. In addition, OSA has also been shown to be associated with albuminuria, chronic kidney disease, a wide range of ocular diseases and peripheral neuropathy. Considering that CVD and microvascular complications are major contributors to the morbidity, mortality and the economic burden of diabetes and that OSA is common in patients with type 2 diabetes (T2D), it is important to understand the role of OSA in the development and/or progression of vascular disease in patients with T2D and to explore the impact of CPAP on diabetes-related vascular outcomes. The purpose of this article is to review the evidence for the relationship and impact of OSA on vascular disease and vascular risk factors particularly in patients with T2D.

Sleep, death, and the heart

Obstructive and central sleep apnea have been associated with increased risk of adverse cardiovascular events and mortality. Sympathetic dysregulation occurring as a result of the respiratory disturbance is thought to play a role in this increased risk. Sleep apnea increases the risk of arrhythmias, myocardial ischemia/infarction, stroke, and heart failure, all of which may increase mortality risk. A higher incidence of nocturnal arrhythmias, cardiac ischemia, and sudden death has been noted in subjects with sleep-disordered breathing (SDB). In this review, the association between SDB and each of these conditions is discussed, as well as the potential mechanisms underlying these risks and the effects of treatment of SDB. Particular emphasis is placed on the relationship between SDB and nocturnal atrial and ventricular arrhythmias, myocardial ischemia/infarction and sudden death.

Effects of opioid, hypnotic and sedating medications on sleep-disordered breathing in adults with obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea (OSA) is a common sleep disorder characterised by partial or complete upper airway occlusion during sleep, leading to intermittent cessation (apnoea) or reduction (hypopnoea) of airflow and dips in arterial oxygen saturation during sleep. Many patients with recognised and unrecognised OSA receive hypnotics, sedatives and opiates/opioids to treat conditions including pain, anxiety and difficulty sleeping. Concerns have been expressed that administration of these drugs to people with co-existing OSA may worsen OSA.

OBJECTIVES

To investigate whether administration of sedative and hypnotic drugs exacerbates the severity of OSA (as measured by the apnoea-hypopnoea index (AHI) or the 4% oxygen desaturation index (ODI)) in people with known OSA.

SEARCH METHODS

We searched the Cochrane Airways Group Specialised Register (CAGR) of trials. The search was current as of March 2015.

SELECTION CRITERIA

Randomised, placebo-controlled trials including adult participants with confirmed OSA, where participants were randomly assigned to use opiates or opioids, sedatives, hypnotics or placebo. We included participants already using continuous positive airway pressure (CPAP) or a mandibular advancement device.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as recommended by The Cochrane Collaboration.

MAIN RESULTS

Fourteen studies examining the effects of 10 drugs and including a total of 293 participants contributed to this review. Trials were small, with only two trials, which used sodium oxybate, recruiting more than 40 participants, and all but three trials were of only one to three nights in duration. Most participants had mild to moderate OSA with a mean AHI of 11 to 25 events/h, and only two trials recruited patients with severe OSA. Two trials investigating the effects of ramelteon, a treatment option for insomnia, recruited adults over 60 years of age with OSA and concomitant insomnia.The drugs studied in this review included remifentanil (infusion) 0.75 mcg/kg/h, eszopiclone 3 mg, zolpidem 10 and 20 mg, brotizolam 0.25 mg, flurazepam 30 mg, nitrazepam 10 mg to 15 mg, temazepam 10 mg, triazolam 0.25 mg, ramelteon 8 mg and 16 mg and sodium oxybate 4.5 g and 9 g. We were unable to pool most of the data, with the exception of data for eszopiclone and ramelteon.None of the drugs in this review produced a significant increase in AHI or ODI. Two trials have shown a beneficial effect on OSA. One study showed that a single administration of eszopiclone 3 mg significantly decreased AHI compared with placebo (24 ± 4 vs 31 ± 5; P value < 0.05), and a second study of sodium oxybate 4.5 g showed a significant decrease in AHI compared with placebo (mean difference (MD) -7.41, 95% confidence interval (CI) -14.17 to -0.65; N = 48).Only four trials reported outcome data on ODI. No significant increase, in comparison with placebo, was shown with eszopiclone (21 (22 to 37) vs 28.0 (15 to 36); P value = NS), zolpidem (0.81 ± 0.29 vs 1.46 ± 0.53; P value = NS), flurazepam (18.6 ± 19 vs 19.6 ± 15.9; P value = NS) and temazepam (6.53 ± 9.4 vs 6.56 ± 8.3; P value = 0.98).A significant decrease in minimum nocturnal peripheral capillary oxygen saturation (SpO2) was observed with zolpidem 20 mg (76.8 vs 85.2; P value = 0.002), flurazepam 30 mg (81.7 vs 85.2; P value = 0.002), remifentanil infusion (MD -7.00, 95% CI -11.95 to -2.05) and triazolam 0.25 mg in both rapid eye movement (REM) and non-REM (NREM) sleep (MD -14.00, 95% CI -21.84 to -6.16; MD -10.20, 95% CI -16.08 to -4.32, respectively.One study investigated the effect of an opiate (remifentanil) on patients with moderate OSA. Remifentanil infusion did not significantly change AHI (MD 10.00, 95% CI -9.83 to 29.83); however it did significantly decrease the number of obstructive apnoeas (MD -9.00, 95% CI -17.40 to -0.60) and significantly increased the number of central apnoeas (MD 16.00, 95% CI -2.21 to 34.21). Similarly, although without significant effect on obstructive apnoeas, central apnoeas were increased in the sodium oxybate 9 g treatment group (MD 7.3 (18); P value = 0.005) in a cross-over trial.Drugs studied in this review were generally well tolerated, apart from adverse events reported in 19 study participants prescribed remifentanil (n = 1), eszopiclone (n = 6), sodium oxybate (n = 9) or ramelteon (n = 3).

AUTHORS' CONCLUSIONS

The findings of this review show that currently no evidence suggests that the pharmacological compounds assessed have a deleterious effect on the severity of OSA as measured by change in AHI or ODI. Significant clinical and statistical decreases in minimum overnight SpO2 were observed with remifentanil, zolpidem 20 mg and triazolam 0.25 mg. Eszopiclone 3 mg and sodium oxybate 4.5 g showed a beneficial effect on the severity of OSA with a reduction in AHI and may merit further assessment as a potential therapeutic option for a subgroup of patients with OSA. Only one trial assessed the effect of an opioid (remifentanil); some studies included CPAP treatment, whilst in a significant number of participants, previous treatment with CPAP was not stated and thus a residual treatment effect of CPAP could not be excluded. Most studies were small and of short duration, with indiscernible methodological quality.Caution is therefore required when such agents are prescribed for patients with OSA, especially outside the severity of the OSA cohorts and the corresponding dose of compounds given in the particular studies. Larger, longer trials involving patients across a broader spectrum of OSA severity are needed to clarify these results.

Use of continuous positive airway pressure after rhinoplasty, septoplasty, and sinus surgery: A survey of current practice patterns

OBJECTIVE

To explore current practice patterns in the use of continuous positive airway pressure (CPAP) following nasal or sinus surgery.

STUDY DESIGN

Cross-sectional survey.

METHODS

An electronic 24-question survey was created to evaluate surgeon practice patterns for restarting CPAP after nasal surgery. We also explored factors contributing to their decisions (1-5 Likert scale) and complications believed to be directly related to restarting CPAP. Factors with a median rating score greater than 3 out of 5 were deemed "important." Subgroup analyses were performed to assess the impact of practice setting and clinical experience.

RESULTS

A total of 407 physicians completed the survey (27.4% response rate for those that opened the e-mail). The majority of surgeons temporarily stop CPAP after nasal surgery, generally for 1 to 2 weeks, although the range of time is wide. There are also many surgeons who do not stop CPAP after any of these procedures and who reported that complications were fairly minimal. Severity of obstructive sleep apnea (OSA) was deemed important for all procedures. There were additional patient and surgery-specific factors considered important for each individual surgery. Subgroup analysis revealed significant differences in physician practice setting and clinical experience.

CONCLUSION

Regarding the use of CPAP after nasal surgery, considerable variation existed in the practice patterns of physicians. Severity of OSA was universally considered important, but the remaining factors were less consistent. A comparative study investigating the outcomes of various protocols is necessary.

LEVEL OF EVIDENCE

N/A.

Obstructive sleep apnea and acute coronary syndromes: etiology, risk, and management

Obstructive sleep apnea (OSA) is characterized by upper airway collapse and airflow reduction despite respiratory effort, resulting in intermittent hypoxia and arousals, leading to a cascade of hemodynamic, autonomic, inflammatory, and metabolic effects, responsible for its adverse cardiovascular effect. OSA is an independent risk factor for cardiovascular disease, and its prevalence in patients presenting with acute coronary syndromes is up to 69%. Furthermore, OSA has been associated with increased risk of adverse events after an acute coronary syndrome. Continuous positive airway pressure is considered the mainstay of treatment of OSA and has been shown to reduce the risk of cardiovascular events. However, the proper time to start treatment in the acute setting is unknown. A prospective randomized clinical trial is currently underway to answer this question.

Inflammatory response mechanisms exacerbating hypoxemia in coexistent pulmonary fibrosis and sleep apnea

Mediators of inflammation, oxidative stress, and chemoattractants drive the hypoxemic mechanisms that accompany pulmonary fibrosis. Patients with idiopathic pulmonary fibrosis commonly have obstructive sleep apnea, which potentiates the hypoxic stimuli for oxidative stress, culminating in systemic inflammation and generalized vascular endothelial damage. Comorbidities like pulmonary hypertension, obesity, gastroesophageal reflux disease, and hypoxic pulmonary vasoconstriction contribute to chronic hypoxemia leading to the release of proinflammatory cytokines that may propagate clinical deterioration and alter the pulmonary fibrotic pathway. Tissue inhibitor of metalloproteinase (TIMP-1), interleukin- (IL-) 1α, cytokine-induced neutrophil chemoattractant (CINC-1, CINC-2α/β), lipopolysaccharide induced CXC chemokine (LIX), monokine induced by gamma interferon (MIG-1), macrophage inflammatory protein- (MIP-) 1α, MIP-3α, and nuclear factor- (NF-) κB appear to mediate disease progression. Adipocytes may induce hypoxia inducible factor (HIF) 1α production; GERD is associated with increased levels of lactate dehydrogenase (LDH), alkaline phosphatase (ALP), and tumor necrosis factor alpha (TNF-α); pulmonary artery myocytes often exhibit increased cytosolic free Ca2+. Protein kinase C (PKC) mediated upregulation of TNF-α and IL-1β also occurs in the pulmonary arteries. Increased understanding of the inflammatory mechanisms driving hypoxemia in pulmonary fibrosis and obstructive sleep apnea may potentiate the identification of appropriate therapeutic targets for developing effective therapies.

Influence of the Cardiomyocyte Circadian Clock on Cardiac Physiology and Pathophysiology

Cardiac function and dysfunction exhibit striking time-of-day-dependent oscillations. Disturbances in both daily rhythms and sleep are associated with increased risk of heart disease, adverse cardiovascular events, and worsening outcomes. For example, the importance of maintaining normal daily rhythms is highlighted by epidemiologic observations that night shift workers present with increased incidence of cardiovascular disease. Rhythmicity in cardiac processes is mediated by a complex interaction between extracardiac (e.g., behaviors and associated neural and humoral fluctuations) and intracardiac influences. Over the course of the day, the intrinsic properties of the myocardium vary at the levels of gene and protein expression, metabolism, responsiveness to extracellular stimuli/stresses, and ion homeostasis, all of which affect contractility (e.g., heart rate and force generation). Over the past decade, the circadian clock within the cardiomyocyte has emerged as an essential mechanism responsible for modulating the intrinsic properties of the heart. Moreover, the critical role of this mechanism is underscored by reports that disruption, through genetic manipulation, results in development of cardiac disease and premature mortality in mice. These findings, in combination with reports that numerous cardiovascular risk factors (e.g., diet, diabetes, aging) distinctly affect the clock in the heart, have led to the hypothesis that aberrant regulation of this mechanism contributes to the etiology of cardiac dysfunction and disease. Here, we provide a comprehensive review on current knowledge regarding known roles of the heart clock and discuss the potential for using these insights for the future development of innovative strategies for the treatment of cardiovascular disease.

Intermittent hypoxemia and OSA: implications for comorbidities

OSA is a common chronic disorder that is associated with significant morbidity and mortality including cardiovascular, metabolic, and neurocognitive disease and increased cancer-related deaths. OSA is characterized by recurrent episodes of apneas and hypopneas associated with repetitive episodes of intermittent hypoxemia, intrathoracic pressure changes, and arousals. Intermittent hypoxemia (IH) is now being recognized as a potential major factor contributing to the pathogenesis of OSA-related comorbidities. OSA-related high-frequency IH is characterized by cycles of hypoxemia with reoxygenation that is distinctly different than sustained low-frequency hypoxia and contributes to ischemia-reperfusion injury. Data from both animal and human studies support mechanistic links between IH and its adverse impact at the tissue level. IH promotes oxidative stress by increased production of reactive oxygen species and angiogenesis, increased sympathetic activation with BP elevation, and systemic and vascular inflammation with endothelial dysfunction that contributes to diverse multiorgan chronic morbidity and mortality affecting cardiovascular disease, metabolic dysfunction, cognitive decline, and progression of cancer. Data from observational studies in large population groups also support the role for hypoxia in the pathogenesis of OSA comorbidity. Treatment with CPAP to reverse OSA-related symptoms and comorbidities has been shown to provide variable benefit in some but not all patient groups. Early treatment with CPAP makes intuitive sense to promote maximal functional recovery and minimize residual injury. More studies are needed to determine the interacting effects of IH and obesity, differential effects of both short-term and long-term hypoxemia, and the effect of CPAP treatment.

OSACS score-a new simple tool for identifying high risk for Obstructive Sleep Apnea Syndrome based on clinical parameters

OBJECTIVE

Obstructive sleep apnea syndrome (OSAS) is a cardiovascular risk factor associated with clinical complications like hypertension, ischaemic heart disease or thrombosis. The aim of this study was to develop a new scoring system, based on objective clinical and echocardiographic parameters.

METHODS

One hundred fifty-eight consecutive acute coronary syndrome (ACS) patients underwent standard clinical, laboratory and echocardiography assessment after ACS, and their risk of OSAS was assessed using Berlin Questionnaire and Epworth Sleepiness Scale. Creation of OSACS (Obstructive Sleep Apnea in Acute Coronary Syndrome patients) score was attempted, with risk factors evaluated in multiple logistic regression model.

RESULTS

In 34.2% patients, who were at high risk of OSAS left ventricular diastolic diameter, left atrial diameter, and intrventricular septal thickness were elevated. In multiple logistic regression analysis: history of hypertension (Odds Ratio 4.42; 95% CI 0.96-20.5, p=0.06), body mass index (OR 6.82; 95% CI 2.33-20; p<0.001), diastolic blood pressure (OR 6.4; 95% CI 1.58-25.9; p=0.01), left ventricular diastolic diameter (OR 3.5; 95% CI 1.05-11.6; p=0.04), left ventricular mass index (OR 0.26; 95% CI 0.07-0.94; p=0.04), interventricular septal thickness (OR 4.44; 95% CI 1.15-17.1; p=0.03) were independent risk factors for high risk of OSAS. All independent risk factor were implemented into risk prediction model called OSACS. The area under the ROC curve for the OSACS score was 0.87.

CONCLUSION

OSAS is highly prevalent in ACS patients. The new OSACS score has a high predictive value in assessment of risk of OSAS in these patients, and it can be used as an objective tool, and an alternative for the Berlin Questionnaire.