Rationale and design of the SERVE-HF study: treatment of sleep-disordered breathing with predominant central sleep apnoea with adaptive servo-ventilation in patients with chronic heart failure

Circulating miR-133a-3p defines a low-risk subphenotype in patients with heart failure and central sleep apnea: a decision tree machine learning approach

BACKGROUND

Patients with heart failure with reduced ejection fraction (HFrEF) and central sleep apnea (CSA) are at a very high risk of fatal outcomes.

OBJECTIVE

To test whether the circulating miRNome provides additional information for risk stratification on top of clinical predictors in patients with HFrEF and CSA.

METHODS

The study included patients with HFrEF and CSA from the SERVE-HF trial. A three-step protocol was applied: microRNA (miRNA) screening (n = 20), technical validation (n = 60), and biological validation (n = 587). The primary outcome was either death from any cause, lifesaving cardiovascular intervention, or unplanned hospitalization for worsening of heart failure, whatever occurred first. MiRNA quantification was performed in plasma samples using miRNA sequencing and RT-qPCR.

RESULTS

Circulating miR-133a-3p levels were inversely associated with the primary study outcome. Nonetheless, miR-133a-3p did not improve a previously established clinical prognostic model in terms of discrimination or reclassification. A customized regression tree model constructed using the Classification and Regression Tree (CART) algorithm identified eight patient subphenotypes with specific risk patterns based on clinical and molecular characteristics. MiR-133a-3p entered the regression tree defining the group at the lowest risk; patients with log(NT-proBNP) ≤ 6 pg/mL (miR-133a-3p levels above 1.5 arbitrary units). The overall predictive capacity of suffering the event was highly stable over the follow-up (from 0.735 to 0.767).

CONCLUSIONS

The combination of clinical information, circulating miRNAs, and decision tree learning allows the identification of specific risk subphenotypes in patients with HFrEF and CSA.

Effect of adaptive servo-ventilation for central sleep apnoea in systolic heart failure on muscle sympathetic nerve activity: a SERVE-HF randomised ancillary study

BACKGROUND

Adaptive servo-ventilation (ASV) effectively suppresses central sleep apnoea (CSA) but has been associated with increased all-cause and cardiovascular mortality in chronic heart failure patients with reduced ventricular ejection fraction (HFrEF). All-cause and, especially, cardiovascular mortality in chronic heart failure is highly correlated with sympathetic tone. This analysis of SERVE-HF data investigated the effect of ASV on sympathetic tone in patients with HFrEF and CSA.

METHODS

HFrEF patients in the SERVE-HF trial (left ventricular ejection fraction (LVEF) ≤45%, apnoea-hypopnoea index (AHI) ≥15 events·h^-1 with predominant CSA) were randomly assigned to receive guideline-based heart failure treatment alone (controls) or plus ASV. For this analysis, the primary outcome was change in muscle sympathetic nerve activity (MSNA) at 3-month follow-up. The effects of baseline MSNA and change in MSNA over time on mortality in the main study were also assessed.

RESULTS

40 patients with HFrEF were included in this analysis (age 71.3±11.7 years, LVEF 34.2±7.7%, 57.5% in New York Heart Association (NYHA) Functional Class II, 42.5% in NYHA Functional Class III, AHI 35.2±11 events·h^-1). Sympathetic tone evolution during follow-up did not differ between groups (controls: 47.6±8.3 bursts·min^-1 at baseline to 44.6±11.2 bursts·min^-1; ASV group: 43.0±9.0 bursts·min^-1 at baseline to 42.74±9.45 bursts·min^-1). The reduction in sympathetic tone was associated with significantly increased cardiovascular mortality in the ASV group, whereas in the control group reduced sympathetic tone appeared to be protective.

CONCLUSIONS

Suppression of CSA with ASV did not seem to have a significant effect on chronic heart failure-related sympathetic activation. Simultaneous suppression of CSA and reduction in MSNA was associated with increased cardiovascular mortality.

Effect of adaptive servo ventilation on central sleep apnea and sleep structure in systolic heart failure patients: polysomnography data from the SERVE-HF major sub study

This SERVE-HF (Treatment of Predominant Central Sleep Apnea by Adaptive Servo Ventilation in Patients With Heart Failure) sub study analysis evaluated polysomnography (PSG) data in patients with heart failure with reduced ejection fraction (HFrEF) and predominant central sleep apnea (CSA) randomised to guideline-based medical therapy, with or without adaptive servo ventilation (ASV). Patients underwent full overnight PSG at baseline and at 12 months. All PSG recordings were analysed by a core laboratory. Only data for patients with baseline and 3- or 12-month values were included. The sub study included 312 patients; the number with available PSG data differed for each variable (94-103 in the control group, 77-99 in the ASV group). After 12 months, baseline-adjusted respiratory measures were significantly better in the ASV group versus control. Although some between-group differences in sleep measures were seen at 12 months (e.g., better sleep efficiency in the ASV group), these were unlikely to be clinically significant. The number of periodic leg movements during sleep (PLMS) increased in the ASV group (p = 0.039). At 12 months, the respiratory arousal index was significantly lower in the ASV versus control group (p < 0.001), whilst the PLMS-related arousal index was significantly higher in the ASV group (p = 0.04 versus control). ASV attenuated the respiratory variables characterising sleep apnea in patients with HFrEF and predominant CSA in SERVE-HF. Sleep quality improvements during ASV therapy were small and unlikely to be clinically significant. The increase in PLMS and PLMS-related arousals during ASV warrants further investigation, particularly relating to their potential association with increased cardiovascular risk.

Treatment of Cheyne-Stokes respiration with adaptive servoventilation-analysis of patients with regard to therapy restriction

Purpose

The SERVE-HF study revealed no benefit of adaptive servoventilation (ASV) versus guideline-based medical treatment in patients with symptomatic heart failure, an ejection fraction (EF) ≤45% and a predominance of central events (apnoea-hypopnea Index [AHI] > 15/h). Because both all-cause and cardiovascular mortality were higher in the ASV group, an EF ≤ 45% in combination with AHI 15/h, central apnoea-hyponoea index [CAHI/AHI] > 50% and central apnoea index [CAI] > 10/h were subsequently listed as contraindications for ASV. The intention of our study was to analyse the clinical relevance of this limitation.

Methods

Data were analysed retrospectively for patients treated with ASV who received follow-up echocardiography to identify contraindications for ASV.

Results

Echocardiography was conducted in 23 patients. The echocardiogram was normal in 10 cases, a left ventricular hypertrophy with normal EF was found in 8 patients, there was an EF 45-50% in 2 cases and a valvular aortic stenosis (grade II) with normal EF was found in 1 case. EF <45% was present in just 2 cases, and only 1 of these patients also had more than 50% central events in the diagnostic night.

Conclusion

The population typically treated with ASV is entirely different from the study population in SERVE-HF, as nearly half of the patients treated with ASV showed a normal echocardiogram. Thus, the modified indication for ASV has little impact on the majority of treated patients. The current pathomechanistic hypothesis of central apnoea must be reviewed.

Adaptive servo-ventilation therapy does not favourably alter sympatho-vagal balance in sleeping patients with systolic heart failure and central apnoeas: Preliminary data

BACKGROUND

In contrast to continuous positive airway pressure (CPAP), the use of adaptive servo-ventilation (ASV) for treatment of central sleep apnoea (CSA) was associated with increased mortality in patients with chronic systolic heart failure (CHF). In order to characterize the interplay between sleep-disordered breathing, CHF and sympathovagal balance (SVB) this study investigated the effect of nocturnal CPAP and ASV on SVB in CSA patients with or without CHF.

METHODS

Thirty-seven patients with ongoing positive airway pressure therapy (CPAP or ASV) for CSA (17 patients with systolic CHF - left ventricular ejection fraction <50% - and 20 patients with CSA but no CHF) underwent evaluation of SVB (spectral analysis of heart rate -HRV- and diastolic blood pressure variability) during full nocturnal polysomnography. The night was randomly split into equal parts including no treatment (NT), automatic CPAP and ASV. Data analysis was restricted to stable N2 sleep.

RESULTS

In patients with CSA and systolic CHF, neither automatic CPAP nor ASV showed favourable effects on parameters reflecting SVB during N2 sleep (all p > 0.05). In contrast, in subjects with CSA without CHF automatic CPAP, but not ASV, favourably altered SVB by decreasing the low frequency and increasing the high frequency component of HRV (both p = 0.03).

CONCLUSIONS

Effects of various modes of positive airway pressure therapy of CSA on SVB during sleep depend on the mode of pressure support and underlying cardiac function. Automatic CPAP but not ASV favourably influences SVB in subjects without CHF, whereas both interventions leave SVB unchanged in patients with CHF.

ERS International Congress, Madrid, 2019: highlights from the Sleep and Clinical Physiology Assembly

The 2019 European Respiratory Society (ERS) International Congress took place in Madrid, Spain, and served as a platform to find out the latest advances in respiratory diseases research. The research aims are to understand the physiology and consequences of those diseases, as well as the improvement in their diagnoses, treatments and patient care. In particular, the scientific sessions arranged by ERS Assembly 4 provided novel insights into sleep-disordered breathing and new knowledge in respiratory physiology. This article, divided by session, will summarise the most relevant studies presented at the ERS International Congress. Each section has been written by Early Career Members specialising in the different fields of this interdisciplinary assembly.

Biomarkers in patients with heart failure and central sleep apnoea: findings from the SERVE-HF trial

Aims

The Treatment of Sleep‐Disordered Breathing with Predominant Central Sleep Apnoea by Adaptive Servo Ventilation in Patients with Heart Failure trial investigated the effects of adaptive servo‐ventilation (ASV) (vs. control) on outcomes of 1325 patients with heart failure and reduced ejection fraction (HFrEF) and central sleep apnoea (CSA). The primary outcome (a composite of all‐cause death or unplanned HF hospitalization) did not differ between the two groups. However, all‐cause and cardiovascular (CV) mortality were higher in the ASV group. Circulating biomarkers may help in better ascertain patients' risk, and this is the first study applying a large set of circulating biomarkers in patients with both HFrEF and CSA.

Methods and results

Circulating protein‐biomarkers (n = 276) ontologically involved in CV pathways, were studied in 749 (57% of the trial population) patients (biomarker substudy), to investigate their association with the study outcomes (primary outcome, CV death and all‐cause death). The mean age was 69 ± 10 years, and > 90% were male. The groups (ASV vs. control and biomarker substudy vs. no biomarker) were well balanced. The “best” clinical prognostic model included male sex, systolic blood pressure < 120 mmHg, diabetes, loop diuretic, cardiac device, 6‐min walking test distance, and N‐terminal pro BNP as the strongest prognosticators. On top of the “best” clinical prognostic model, the biomarkers that significantly improved both the discrimination (c‐index) and the net reclassification index (NRI) of the model were soluble suppression of tumorigenicity 2 for the primary outcome; neurogenic locus notch homolog protein 3 (Notch‐3) for CV‐death and all‐cause death; and growth differentiation factor 15 (GDF‐15) for all‐cause death only.

Conclusions

We studied 276 circulating biomarkers in patients with HFrEF and central sleep apnoea; of these biomarkers, three added significant prognostic information on top of the best clinical model: soluble suppression of tumorigenicity 2 (primary outcome), Notch‐3 (CV and all‐cause death), and GDF‐15 (all‐cause death).

Positive airway pressure therapy for the treatment of central sleep apnoea associated with heart failure

BACKGROUND

Ischaemic heart disease including heart failure is the most common cause of death in the world, and the incidence of the condition is rapidly increasing. Heart failure is characterised by symptoms such as fatigue and breathlessness during light activity, as well as disordered breathing during sleep. In particular, sleep disordered breathing (SDB), including central sleep apnoea (CSA) and obstructive sleep apnoea (OSA), is highly prevalent in people with chronic heart failure. A previous meta-analysis demonstrated that positive airway pressure (PAP) therapy dramatically increased the survival rate of people with heart failure who had CSA, and thus could contribute to improving the prognosis of these individuals. However, recent trials found that adaptive servo-ventilation (ASV) including PAP therapy had a higher risk of all-cause mortality and cardiovascular mortality. A meta-analysis that included recent trials was therefore needed.

OBJECTIVES

To assess the effects of positive airway pressure therapy for people with heart failure who experience central sleep apnoea.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE, Embase, and Web of Science Core Collection on 7 February 2019 with no limitations on date, language, or publication status. We also searched two clinical trials registers in July 2019 and checked the reference lists of primary studies.

SELECTION CRITERIA

We excluded cross-over trials and included individually randomised controlled trials, reported as full-texts, those published as abstract only, and unpublished data.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted outcome data from the included studies. We double-checked that data had been entered correctly by comparing the data presented in the systematic review with study reports. We analysed dichotomous data as risk ratios (RRs) with 95% confidence intervals (CIs) and continuous data as mean difference (MD) or standardised mean difference (SMD) with 95% CIs. Furthermore, we performed subgroup analysis in the ASV group or continuous PAP group separately. We used GRADEpro GDT software to assess the quality of evidence as it relates to those studies that contribute data to the meta-analyses for the prespecified outcomes.

MAIN RESULTS

We included 16 randomised controlled trials involving a total of 2125 participants. The trials evaluated PAP therapy consisting of ASV or continuous PAP therapy for 1 to 31 months. Many trials included participants with heart failure with reduced ejection fraction. Only one trial included participants with heart failure with preserved ejection fraction. We are uncertain about the effects of PAP therapy on all-cause mortality (RR 0.81, 95% CI 0.54 to 1.21; participants = 1804; studies = 6; I² = 47%; very low-quality evidence). We found moderate-quality evidence of no difference between PAP therapy and usual care on cardiac-related mortality (RR 0.97, 95% CI 0.77 to 1.24; participants = 1775; studies = 5; I² = 11%). We found low-quality evidence of no difference between PAP therapy and usual care on all-cause rehospitalisation (RR 0.95, 95% CI 0.70 to 1.30; participants = 1533; studies = 5; I² = 40%) and cardiac-related rehospitalisation (RR 0.97, 95% CI 0.70 to 1.35; participants = 1533; studies = 5; I² = 40%). In contrast, PAP therapy showed some indication of an improvement in quality of life scores assessed by all measurements (SMD -0.32, 95% CI -0.67 to 0.04; participants = 1617; studies = 6; I² = 76%; low-quality evidence) and by the Minnesota Living with Heart Failure Questionnaire (MD -0.51, 95% CI -0.78 to -0.24; participants = 1458; studies = 4; I² = 0%; low-quality evidence) compared with usual care. Death due to pneumonia (N = 1, 3% of PAP group); cardiac arrest (N = 18, 3% of PAP group); heart transplantation (N = 8, 1% of PAP group); cardiac worsening (N = 3, 9% of PAP group); deep vein thrombosis/pulmonary embolism (N = 1, 3% of PAP group); and foot ulcer (N = 1, 3% of PAP group) occurred in the PAP therapy group, whereas cardiac arrest (N = 16, 2% of usual care group); heart transplantation (N = 12, 2% of usual care group); cardiac worsening (N = 5, 14% of usual care group); and duodenal ulcer (N = 1, 3% of usual care group) occurred in the usual care group across three trials.

AUTHORS' CONCLUSIONS

The effect of PAP therapy on all-cause mortality was uncertain. In addition, although we found evidence that PAP therapy did not reduce the risk of cardiac-related mortality and rehospitalisation, there was some indication of an improvement in quality of life for heart failure patients with CSA. Furthermore, the evidence was insufficient to determine whether adverse events were more common with PAP than with usual care. These findings were limited by low- or very low-quality evidence. PAP therapy may be worth considering for individuals with heart failure to improve quality of life.

Bioprofiles and mechanistic pathways associated with Cheyne-Stokes respiration: insights from the SERVE-HF trial

INTRODUCTION

The SERVE-HF trial included patients with heart failure and reduced ejection fraction (HFrEF) with sleep-disordered breathing, randomly assigned to treatment with Adaptive-Servo Ventilation (ASV) or control. The primary outcome was the first event of death from any cause, lifesaving cardiovascular intervention, or unplanned hospitalization for worsening heart failure. A subgroup analysis of the SERVE-HF trial suggested that patients with Cheyne-Stokes respiration (CSR) < 20% (low CSR) experienced a beneficial effect from ASV, whereas in patients with CSR ≥ 20% ASV might have been harmful. Identifying the proteomic signatures and the underlying mechanistic pathways expressed in patients with CSR could help generating hypothesis for future research.

METHODS

Using a large set of circulating protein-biomarkers (n = 276, available in 749 patients; 57% of the SERVE-HF population) we sought to investigate the proteins associated with CSR and to study the underlying mechanisms that these circulating proteins might represent.

RESULTS

The mean age was 69 ± 10 years and > 90% were male. Patients with CSR < 20% (n = 139) had less apnoea-hypopnea index (AHI) events per hour and less oxygen desaturation. Patients with CSR < 20% might have experienced a beneficial effect of ASV treatment (primary outcome HR [95% CI] = 0.55 [0.34-0.88]; p = 0.012), whereas those with CSR ≥ 20% might have experienced a detrimental effect of ASV treatment (primary outcome HR [95% CI] = 1.39 [1.09-1.76]; p = 0.008); p for interaction = 0.001. Of the 276 studied biomarkers, 8 were associated with CSR (after adjustment and with a FDR1%-corrected p value). For example, higher PAR-1 and ITGB2 levels were associated with higher odds of having CSR < 20%, whereas higher LOX-1 levels were associated with higher odds of CSR ≥ 20%. Signalling, metabolic, haemostatic and immunologic pathways underlie the expression of these biomarkers.

CONCLUSION

We identified proteomic signatures that may represent underlying mechanistic pathways associated with patterns of CSR in HFrEF. These hypothesis-generating findings require further investigation towards better understanding of CSR in HFrEF.

SUMMARY OF THE FINDINGS

PAR-1 proteinase-activated receptor 1, ADM adrenomedullin, HSP-27 heat shock protein-27, ITGB2 integrin beta 2, GLO1 glyoxalase 1, ENRAGE/S100A12 S100 calcium-binding protein A12, LOX-1 lectin-like LDL receptor 1, ADAM-TS13 disintegrin and metalloproteinase with a thrombospondin type 1 motif, member13 also known as von Willebrand factor-cleaving protease.

Detecting central sleep apnea in adult patients using WatchPAT-a multicenter validation study

Study objectives

To assess the accuracy of WatchPAT (WP—Itamar-Medical, Caesarea, Israel) enhanced with a novel systolic upstroke analysis coupled with respiratory movement analysis derived from a dedicated snoring and body position (SBP) sensor, to enable automated algorithmic differentiation between central sleep apnea (CSA) and obstructive sleep apnea (OSA) compared with simultaneous in-lab sleep studies with polysomnography (PSG).

Methods

Eighty-four patients with suspected sleep-disordered breathing (SDB) underwent simultaneous WP and PSG studies in 11 sleep centers. PSG scoring was blinded to the automatically analyzed WP data.

Results

Overall WP apnea-hypopnea index (AHI; mean ± SD) was 25.2 ± 21.3 (range 0.2–101) versus PSG AHI 24.4 ± 21.2 (range 0–110) (p = 0.514), and correlation was 0.87 (p < 0.001). Using a threshold of AHI ≥ 15, the sensitivity and specificity of WP versus PSG for diagnosing sleep apnea were 85% and 70% respectively and agreement was 79% (kappa = 0.867). WP central AHI (AHIc) was 4.2 ± 7.7 (range 0–38) versus PSG AHIc 5.9 ± 11.8 (range 0–63) (p = 0.034), while correlation was 0.90 (p < 0.001). Using a threshold of AHI ≥ 15, the sensitivity and specificity of WP versus PSG for diagnosing CSA were 67% and 100% respectively with agreement of 95% (kappa = 0.774), and receiver operator characteristic (ROC) area under the curve of 0.866, (p < 0.01). Using a threshold of AHI ≥ 10 showed comparable overall sleep apnea and CSA diagnostic accuracies.

Conclusions

These findings show that WP can accurately detect overall AHI and effectively differentiate between CSA and OSA.

Sleep-disordered breathing in patients with cardiovascular diseases cannot be detected by ESS, STOP-BANG, and Berlin questionnaires

Sleep-disordered breathing (SDB) is highly prevalent in patients with cardiovascular diseases (CVD) and associated with poor outcome. At least 50% of heart failure (HF) patients present with SDB, equally divided in obstructive sleep apnea (OSA) and central sleep apnea (CSA). CVD patients with SDB do not always present with typical SDB symptoms. Therefore, we asked whether established questionnaires allow for the reliable detection of SDB. In this prospective cohort study, 89 CVD patients (54 male, 59 ± 15 years, BMI 30 ± 6 kg/m²) in stable clinical state underwent an ambulatory polygraphy. SDB was defined as an apnea-hypopnea index (AHI) ≥ 15/h. We evaluated the Epworth Sleepiness Scale (ESS), STOP-BANG and Berlin questionnaires as well as anthropometric data and comorbidities regarding their ability to predict SDB. The ESS showed no correlation with SDB. The sensitivity of the Berlin Questionnaire to detect SDB was 73%, specificity was 42%. The STOP-BANG questionnaire showed a sensitivity of 97% while specificity was 13%. Coronary heart disease and/or history of myocardial infarction, hyperuricemia and age significantly contributed to a logistic regression model predicting presence of SDB. However, our regression model explains only 36% of the variance regarding the presence or absence of SDB. The approach to find variables, which would allow an early and reliable differentiation between patients with CVD and coexistence or absence of SDB, failed. Thus, as CVD patients show a high SDB prevalence and poor outcome, only a systematic screening based on measures of respiration-related parameters (i.e., respiratory flow, blood oxygen saturation, etc.) allows for a reliable SDB assessment.

Adaptive servo-ventilation to treat central sleep apnea in heart failure with reduced ejection fraction: the Bad Oeynhausen prospective ASV registry

BACKGROUND

Central sleep apnea (CSA) is highly prevalent in heart failure patients with reduced left ventricular ejection fraction (HF-REF). The Bad Oeynhausen Adaptive Servo-ventilation (ASV) registry (NCT01657188) was designed to investigate whether treatment of CSA with ASV improved survival in HF-REF patients; the effects of ASV on symptoms and cardiopulmonary performance were also investigated.

METHODS AND RESULTS

From January 2004 to October 2013, the registry prospectively enrolled HF-REF patients [NYHA class ≥ II, left ventricular ejection fraction (LVEF) ≤ 45%] with moderate to severe predominant CSA [apnea-hypopnea index (AHI) ≥ 15/h]. ASV-treated patients were followed up at 3, 6, 12 and 24 months, including natriuretic peptide concentrations, blood gas analyses, echocardiography, 6-min walk distance (6MWD), and cardiopulmonary exercise (CPX) testing. 550 patients were included [age 67.7 ± 10 years, 90% male, 52% in NYHA class ≥ III, LVEF 29.9 ± 8%, AHI 35.4 ± 13.6/h, and time with nocturnal oxygen saturation < 90% (T < 90%) 58 ± 73 min]; ASV was prescribed to 224 patients. Over a median follow-up of 6.6 years, 109 (48.7%) ASV-treated patients and 191 (58.6%) controls died (adjusted Cox modelling hazard ratio of 0.95, 95% confidence interval 0.68-1.24; p = 0.740); older age, lower LVEF, impaired renal function, low sodium concentration, and nocturnal hypoxemia were significant predictors of mortality. Patient reported NYHA functional class improved in the ASV group, but LVEF, CPX, 6MWD, natriuretic peptides and blood gases remained unchanged.

CONCLUSIONS

Long-term ASV treatment of predominant CSA in HF-REF patients included in our registry had no statistically significant effect on survival. ASV improved HF symptoms, but had no significant effects on exercise capacity, LVEF, natriuretic peptide concentrations or blood gases during follow-up as compared to control patients.

Dissociation of Objective and Subjective Daytime Sleepiness and Biomarkers of Systemic Inflammation in Sleep-Disordered Breathing and Systolic Heart Failure

STUDY OBJECTIVES

Subjective versus objective sleepiness in heart failure (HF) remains understudied; therefore, we sought to examine the association of these measures and interrelationships with biochemical markers.

METHODS

Participants with stable systolic HF recruited from a clinic-based program underwent attended polysomnography, Multiple Sleep Latency Testing, questionnaire data collection including Epworth Sleepiness Scale (ESS), and morning phlebotomy for biochemical markers. Linear regression was used to assess the association of mean sleep latency (MSL) and ESS (and other reported outcomes) with adjustment of age or body mass index or left ventricular ejection fraction (LVEF) (beta coefficients, 95% confidence interval) and also with biochemical markers (beta coefficients, 95% confidence interval).

RESULTS

The final analytic sample comprised 26 participants: 52 ± 14 years with apnea-hypopnea index (AHI): 34 ± 27, LVEF: 34 ± 12%, MSL: 7 ± 5 minutes and ESS: 7 (5, 10). There was no significant association of MSL and ESS (-0.36, -0.81 to 0.09, P = .11), AHI, or other questionnaire-based outcomes in adjusted analyses. Although statistically significant associations of ESS and biomarkers were not observed, there were associations of MSL and cortisol (μg/dL) [-0.05: -0.08, -0.01, P = .012] and interleukin-6 (pg/mL) [-0.11: -0.18, -0.04, P = .006], which persisted in adjusted models.

CONCLUSIONS

In systolic HF, although overall objective sleepiness was observed, this was not associated with subjective sleepiness (ie, a discordance was identified). Differential upregulation of systemic inflammation in objective sleepiness was observed, findings not observed with subjective sleepiness. These findings suggest that underlying mechanistic pathways of inflammation may provide the explanation for dissonance of objective and subjective sleepiness symptoms in HF, thus potentially informing targeted diagnostic and therapeutic approaches.

COMMENTARY

A commentary on this article appears in this issue on page 1369.

Microstructural cerebral lesions are associated with the severity of central sleep apnea with Cheyne-Stokes-respiration in heart failure and are modified by PAP-therapy

This study investigated the association of microstructural cerebral lesions with central sleep apnea with Cheyne-Stokes-respiration (CSA-CSR) in heart failure (HF) patients and the effect of positive airway pressure therapy (PAP) of CSA-CSR on these lesions. PAP-therapy was initiated in patients with HF with midrange and with reduced ejection fraction (NYHA≥II; left ventricular ejection fraction <50%) and proven CSA-CSR. Cerebral magnetic resonance imaging (MRI) scans at 3T including diffusion tensor imaging were obtained before and after 4 months of PAP-therapy. Cerebral MRI scans revealed microstructural lesions in all 11 patients with HF with midrange or reduced ejection fraction and CSA-CSR (64±8years, 82% male, left ventricular ejection fraction 37±11%) that were focussed on the brainstem and frontal cerebral regions. This microstructural damage correlated with the severity of CSA-CSR and 4 months of PAP-therapy lead to voxel clusters of altered fiber integrity in these lesions. Microstructural cerebral lesions might contribute to the pathophysiology of CSA-CSR in HF. In these patients PAP-therapy induces neuronal plasticity.

Respiratory polygraphy monitoring of intensive care patients receiving non-invasive ventilation

Introduction

Patients that started on Non-Invasive Ventilation (NIV) need to define several parameters selected on the basis of diurnal arterial blood gas and underlying disease. We hypothesize that respiratory polygraphy (RP) could be useful to monitor NIV. This retrospective work describes RP findings and their impact on the setting of continuous flow ventilators from patients on NIV of Intensive Care Unit (ICU).

Material and Methods

Patient's data on NIV from at the ICU of Hospital Británico were included in this study. RP recordings were performed in all of them. Respiratory events, such as ventilatory pattern changes, impact on oximetry or tidal volume, were observed to modify the ventilatory mode after RP.

Results

The RP findings have contributes to change the ventilatory mode for one third of the patients. The mean values of expiratory positive airway pressure (EPAP) and inspiratory positive airway pressure (IPAP) were not significantly different across all the population before or after RP: 8.7±0.3 vs. 8.6±0.4; p<0.88 and 18.6±0.6 vs. 17.7±0.7; p<0.26 respectively, however, half the patients presented > 2 cmH₂O pressure value changes after RP.

Conclusions

RP recordings could contribute to broad range of data useful to make decisions about changes in programming and allowed to identify adverse events related to positive pressure.

Adaptive servo ventilation for central sleep apnoea in heart failure: SERVE-HF on-treatment analysis

This on-treatment analysis was conducted to facilitate understanding of mechanisms underlying the increased risk of all-cause and cardiovascular mortality in heart failure patients with reduced ejection fraction and predominant central sleep apnoea randomised to adaptive servo ventilation versus the control group in the SERVE-HF trial.Time-dependent on-treatment analyses were conducted (unadjusted and adjusted for predictive covariates). A comprehensive, time-dependent model was developed to correct for asymmetric selection effects (to minimise bias).The comprehensive model showed increased cardiovascular death hazard ratios during adaptive servo ventilation usage periods, slightly lower than those in the SERVE-HF intention-to-treat analysis. Self-selection bias was evident. Patients randomised to adaptive servo ventilation who crossed over to the control group were at higher risk of cardiovascular death than controls, while control patients with crossover to adaptive servo ventilation showed a trend towards lower risk of cardiovascular death than patients randomised to adaptive servo ventilation. Cardiovascular risk did not increase as nightly adaptive servo ventilation usage increased.On-treatment analysis showed similar results to the SERVE-HF intention-to-treat analysis, with an increased risk of cardiovascular death in heart failure with reduced ejection fraction patients with predominant central sleep apnoea treated with adaptive servo ventilation. Bias is inevitable and needs to be taken into account in any kind of on-treatment analysis in positive airway pressure studies.

Validation of a non-contact screening device for the combination of sleep-disordered breathing and periodic limb movements in sleep

PURPOSE

Recent studies found that the non-contact screening device SleepMinder (ResMed Sensor Technologies, Dublin, Ireland) detects sleep-disordered breathing (SDB) with high diagnostic accuracy in cohorts suspected of this disorder. However, it was reported that in patients with periodic limb movement in sleep (PLMS), this non-contact device overestimates the apnea-hypopnea index (AHI). We aimed to overcome this limitation by introducing the novel sleep disorder index (SDI) which is sum of the AHI and the period limb movement index (PLMI).

METHODS

Between January 2011 and December 2013, we studied a mixed cohort of 57 patients (31 OSA, 19 PLMS). The easy-to-use non-contact device emits a very weak electromagnetic radiation and detects body movement by measuring the Doppler effect. We interpreted the device-generated movement index as the SDI and validated the diagnostic accuracy against simultaneous application of the gold-standard polysomnography (PSG).

RESULTS

We found that the SDI of the non-contact device correlated well with the sum of AHI and PLMI derived from PSG (r = 0.79, p = 0.01). For PSG-derived SDI cutoff ≥ 15/h, we obtained a sensitivity of 92.2% and a specificity of 95.8%. Positive likelihood ratio was 23.3 and negative likelihood ratio 0.03.

CONCLUSIONS

The studied non-contact screening device detects accurately the combination of the sleep disorders SDB and/or PLM. However, further testing is required in order to specify the nature of the underlying sleep disorder. At the current stage of algorithm development, the clinical strength is that the studied non-contact device can be used as a rule-out screening device for SDB and PLM.

Recognition and treatment of sleep-disordered breathing: an important component of chronic disease management

Sleep-disordered breathing (SDB) is a highly prevalent condition, and is associated with many debilitating chronic diseases. The role of untreated obstructive sleep apnea (OSA) in arterial hypertension has been recognized in international guidelines. Treatment with continuous positive airway pressure (CPAP) is associated with clinically-relevant reductions in blood pressure. In heart failure (HF), SDB is associated with worse prognosis and increased mortality. Major HF guidelines recommend that patients should be treated for sleep apnea to improve their HF status. Severe OSA increases the risk of arrhythmias, including atrial fibrillation, influences risk management in stroke, and is highly prevalent in patients with type 2 diabetes. Effective treatment with CPAP improves the success of antiarrhythmic interventions, improves outcomes in stroke and reduces hyperglycemia in diabetes. Patients with coronary artery disease also have a high prevalence of SDB, which is independently associated with worse outcomes. The role of CPAP for secondary cardiovascular prevention remains to be determined. Data from large, well-conducted clinical trials have shown that noninvasive ventilation, targeted to markedly reduce hypercapnia, significantly improves survival and reduces readmission in stable hypercapnic chronic obstructive pulmonary disease. The association of SDB with chronic diseases contributes to the high healthcare costs incurred by SDB patients. SDB also has an important negative impact on quality of life, which is reversed by CPAP treatment. The high prevalence of SDB, and its association with diseases that cause significant morbidity and mortality, suggest that the diagnosis and management of SDB is an important therapeutic goal. First, adherent CPAP treatment significantly improves the quality of life of all patients with SDB; second, it eliminates the negative impact of untreated SDB on any associated chronic diseases; and third, it significantly reduces the increased costs of all hospital and medical services directly associated with untreated SDB. In short, the recognition and treatment of SDB is vital for the continued health and wellbeing of individual patients with SDB.

Advanced positive airway pressure modes: adaptive servo ventilation and volume assured pressure support

INTRODUCTION

Volume assured pressure support (VAPS) and adaptive servo ventilation (ASV) are non-invasive positive airway pressure (PAP) modes with sophisticated negative feedback control systems (servomechanism), having the capability to self-adjust in real time its respiratory controlled variables to patient's respiratory fluctuations. However, the widespread use of VAPS and ASV is limited by scant clinical experience, high costs, and the incomplete understanding of propriety algorithmic differences in devices' response to patient's respiratory changes. Hence, we will review and highlight similarities and differences in technical aspects, control algorithms, and settings of each mode, focusing on the literature search published in this area.

AREAS COVERED

One hundred twenty relevant articles were identified by Scopus, PubMed, and Embase databases from January 2010 to 2016, using a combination of MeSH terms and keywords. Articles were further supplemented by pearling. Recommendations were based on the literature review and the authors' expertise in this area. Expert commentary: ASV and VAPS differ in their respiratory targets and response to a respiratory fluctuation. The VAPS mode targets a more consistent minute ventilation, being recommended in the treatment of sleep related hypoventilation disorders, while ASV mode attempts to provide a more steady breathing airflow pattern, treating successfully most central sleep apnea syndromes.

Clinical Use of Loop Gain Measures to Determine Continuous Positive Airway Pressure Efficacy in Patients with Complex Sleep Apnea. A Pilot Study

RATIONALE

Measures of unstable ventilatory control (loop gain) can be obtained directly from the periodic breathing duty ratio on polysomnography in patients with Cheyne-Stokes respiration/central sleep apnea and can predict the efficacy of continuous positive airway pressure (CPAP) therapy.

OBJECTIVES

In this pilot study, we aimed to determine if this measure could also be applied to patients with complex sleep apnea (predominant obstructive sleep apnea, with worsening or emergent central apneas on CPAP). We hypothesized that loop gain was higher in patients whose central events persisted 1 month later despite CPAP treatment versus those whose events resolved over time.

METHODS

We calculated the duty ratio of the periodic central apneas remaining on the CPAP titration (or second half of the split night) while patients were on optimal CPAP with the airway open (obstructive apnea index < 1/h). Loop gain was calculated by the formula: LG = 2π/[(2πDR - sin(2πDR)]. Patients were followed on CPAP for 1 month. Post-treatment apnea-hypopnea index and compliance data were recorded from smart cards.

MEASUREMENTS AND MAIN RESULTS

Thirty-two patients with complex sleep apnea were identified, and 17 patients had full data sets. Eight patients continued to have a total of more than five events per hour (11.8 ± 0.5/h) (nonresponders). The remaining nine patients had an apnea-hypopnea index less than 5/h (2.2 ± 0.4/h) (responders). Loop gain was higher in the nonresponders versus responders (2.0 ± 0.1 vs. 1.7 ± 0.2, P = 0.026). Loop gain and the residual apnea-hypopnea index 1 month after CPAP were associated (r = 0.48, P = 0.02). CPAP compliance was similar between groups.

CONCLUSIONS

In this pilot study, loop gain was higher for patients with complex sleep apnea in whom central apneas persisted after 1 month of CPAP therapy (nonresponders). Loop gain measurement may enable an a priori determination of those who need alternative modes of positive airway pressure.

Development and validation of a novel non-contact monitor of nocturnal respiration for identifying sleep-disordered breathing in patients with heart failure

Aims

At least 50% of patients with heart failure (HF) may have sleep‐disordered breathing (SDB). Overnight in‐hospital polysomnography (PSG) is considered the gold standard for diagnosis, but a lack of access to such testing contributes to under‐diagnosis of SDB. Therefore, there is a need for simple and reliable validated methods to aid diagnosis in patients with HF. The aim of this study was to investigate the accuracy of a non‐contact type IV screening device, SleepMinder^TM (SM), compared with in‐hospital PSG for detecting SDB in patients with HF.

Methods and results

The study included 75 adult patients with systolic HF and suspected SDB who underwent simultaneous PSG and SM recordings. An algorithm was developed from the SM signals, using digital signal processing and pattern recognition techniques to calculate the SM apnoea‐hypopnoea index (AHI). This was then compared with expert‐scored PSG_AHI. The SM algorithm had 70% sensitivity and 89% specificity for identifying patients with clinically significant SDB (AHI ≥ 15/h). At this threshold, it had a positive likelihood ratio of 6.3 and a negative likelihood ratio of 0.16. The overall accuracy of the SM_AHI algorithm was 85.8% as shown by the area under a receiver operator characteristic curve. The mean AHI with SM was 3.8/h (95% confidence interval 0.5–7.1) lower than that with PSG.

Conclusions

The accuracy of the non‐contact type IV screening device SM is good for clinically significant SDB in patients with systolic HF and could be considered as a simple first step in the diagnostic pathway.

Sleep-disordered breathing and cardiovascular disease

Sleep-disordered breathing (SDB) is a common comorbidity in a number of cardiovascular diseases, and mounting clinical evidence demonstrates that it has important implications in the long-term outcomes of patients with cardiovascular disease (CVD). While recognition among clinicians of the role of SDB in CVD is increasing, it too often remains neglected in the routine care of patients with CVD, and therefore remains widely undiagnosed and untreated. In this article, we provide an overview of SDB and its relationship to CVD, with the goal of helping cardiovascular clinicians better recognize and treat this important comorbidity in their patients. We will describe the two major types of SDB and discuss the pathophysiologic, diagnostic, and therapeutic considerations of SDB in patients with CVD.