Markers of Myocardial Ischemia in Patients With Coronary Artery Disease and Obstructive Sleep Apnea: Effect of Continuous Positive Airway Pressure Therapy

Impact of Snoring on the Cardiovascular System and its Treatment: Positive and Negative Effects of Continuous Positive Airway Pressure in Sleep Apnea

Obstructive sleep apnea (OSA) is a common condition, and if not treated can be a significant risk factor for multiple comorbidities like hypertension (HTN), coronary artery disease (CAD), and congestive heart failure (CHF). The underlying pathophysiology involves coagulation and inflammatory pathways, including an overactive sympathetic nervous system. This ultimately causes hemodynamic changes and subclinical myocardial injuries. We reviewed the published literature about the impact of continuous positive airway pressure (CPAP) when used as a mode of treatment to reduce the OSA effects on cardiomyocytes. We found that the results were mixed, including both ill and good effects. The cardiac markers like N-terminal pro-brain natriuretic peptide (NT-proBNP) and atrial natriuretic peptide (ANP) were reduced, implying the decrease in the incidence of heart failure with CPAP treatment in a few of the studies. They also proved a significant decrease in harmful cardiovascular (CV) outcomes, while others concluded that CPAP therapy might be stressful on the heart, causing an elevation in cardiac troponin T levels. However, the impact on inflammatory markers is still indeterminate and needs more research in future.

The Clinical Value of N-Terminal Pro B-Type Natriuretic Peptide in Evaluating Obstructive Sleep Apnea in Patients With Coronary Artery Disease

STUDY OBJECTIVES

Natriuretic peptides have been identified as biomarkers of increased myocardial wall stress in the context of obstructive sleep apnea (OSA) in the general population. However, the relationship between N-terminal pro B-type natriuretic peptide (NT-proBNP) and OSA remains unclear in patients with coronary artery disease (CAD). Hence, we aimed to investigate the clinical value of NT-proBNP in evaluating OSA in a large population of patients with CAD.

METHODS

Consecutive patients with CAD were prospectively enrolled between February 2015 and March 2018. Portable respiratory monitoring was applied to facilitate the diagnosis of sleep apnea. Patients were as assigned to the non-OSA (when the respiratory events index [REI] or 3% oxygen desaturation index [ODI] < 15 events/h) and OSA (when the REI or 3% ODI ≥ 15 events/h) groups. Multivariate analyses were used to explore the independent association between NT-proBNP levels and OSA.

RESULTS

A total of 1,292 consecutive patients were included with a mean NT-proBNP value of 826.57 μg/L. Patients with high levels of NT-proBNP experienced increasing severity of OSA in those with CAD (P = .0004). Univariate analysis demonstrated that NT-proBNP was a risk factor for OSA (odds ratio [OR] 1.10, 95% confidence interval [CI] 1.03-1.18, P = .005). In addition, multivariate analysis revealed that NT-proBNP was independently associated with the presence of OSA (OR 1.11, 95% CI 1.02-1.20, P = .012) even after adjusting for other cofounding factors.

CONCLUSIONS

Elevated levels of NT-proBNP were independently associated with a higher likelihood of OSA in patients with CAD. Periodically screening for NT-proBNP levels may provide early identification of OSA.

Continuous Positive Airway Pressure Therapy Improves Heterogeneity of R-R intervals in a Patient with Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea (OSA) is associated with the occurrence of various kinds of bradyarrhythmia and tachyarrhythmia. The activation of the autonomic nerve system is an important causative factor of the pathogenesis of the arrhythmia in OSA patients. Previous studies have shown that the R-R interval is an effective parameter for evaluating autonomic nerve activities. However, whether or not OSA can induce variations in the R-R interval and whether or not continuous positive airway pressure (CPAP) therapy can improve these variations in OSA patients are unclear. The present study explored whether or not CPAP therapy could improve the regularity of the R-R interval.

Untreated Obstructive Sleep Apnea Is Associated With Myocardial Injury Independent of Blood Pressure Control in Hypertension

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) and hypertension are independent risk factors of cardiovascular morbidities. This study aims to investigate the relationship between OSA, blood pressure (BP) control, and myocardial injury in patients with difficult-to-control hypertension.

METHODS

Patients with hypertension who required three or more medications were prospectively recruited at a tertiary referral center. In-laboratory polysomnography, followed by blood tests for fasting glucose, glycated hemoglobin, lipids, high-sensitivity troponin I (hsTnI), B-type natriuretic peptide (BNP), C-reactive protein, and advanced oxidation protein products were performed. After polysomnography, 24-hour ambulatory BP monitoring was arranged.

RESULTS

A total of 98 participants were analyzed, with mean age 51 ± 9 years and body mass index 30 ± 5 kg/m². Previously undiagnosed severe OSA (apneahypopnea index [AHI] ≥ 30 events/h) was present in 51 patients (52%). hsTnI was negatively correlated with nocturnal dip in systolic BP (r = -.205, P = .048). After controlling for confounders, including BP control, AHI and oxygen desaturation index (ODI) were positively correlated with hsTnI (r = .282, P = .009 and r = .279, P = .010, respectively) and C-reactive protein (r = .302, P = .005 and r = .285, P = .008, respectively), but not with BNP or advanced oxidation protein products. Age, ODI, and loss of nocturnal systolic BP dip were significant determinants of hsTnI level (β = .225, P = .022; β = .293, P = .003; and β = -.215, P = .029; R² = .151). Age, female sex, 24-hour mean diastolic BP, and metabolic syndrome, but not indices of apnea severity, were predictors of BNP level.

CONCLUSIONS

Unrecognized severe OSA was common in patients with difficult-to-control hypertension, and OSA severity was associated with myocardial injury, independent of BP control with medications.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov, Title: A Cross-sectional Study of the Occurrence and Effect of Obstructive Sleep Apnea in Subjects With Resistant Hypertension, Identifier: NCT00843583, URL: https://clinicaltrials.gov/ct2/show/NCT00843583.

High-sensitivity cardiac troponin T in obstructive sleep apnea patients without cardiovascular diseases: Efficacy of CPAP treatment

The aims of this article were to determine the levels of serum high-sensitivity cardiac troponin T (hs-cTnT) in obstructive sleep apnea (OSA) patients without cardiovascular disease (CVD) and to assess the efficacy of continuous positive airway pressure (CPAP). Snorers referred for polysomnography (PSG) for the investigation of OSA were eligible and hs-cTnT levels measured in our pilot study. Hs-cTnT was measured again after 3 months of CPAP treatment in participants with severe OSA. A total of 93 participants recruited after PSG. When compared with simple snoring group, severe OSA group had comparable higher hs-cTnT (7.5 ± 3.0 vs. 5.0 ± 2.1; p < 0.05). Hs-cTnT was positively correlated with apnea hypopnea index, and oxygen desaturation index (r = 0.283, 0.282; p = 0.006, 0.006, respectively). Hs-cTnT levels were not significantly altered in 28 individuals who received 3 months of CPAP treatment (8.4 ± 2.4 vs.7.6 ± 2.1; p = 0.064). Elevated hs-cTnT levels were observed in severe OSA patients without CVD, and CPAP treatment had no influence on this levels.

Sustained apnea induces endothelial activation

BACKGROUND

Apnea diving has gained worldwide popularity, even though the pathophysiological consequences of this challenging sport on the human body are poorly investigated and understood. This study aims to assess the influence of sustained apnea in healthy volunteers on circulating microparticles (MPs) and microRNAs (miRs), which are established biomarkers reflecting vascular function.

HYPOTHESIS

Short intermittent hypoxia due to voluntary breath-holding affects circulating levels of endothelial cell-derived MPs (EMPs) and endothelial cell-derived miRs.

METHODS

Under dry laboratory conditions, 10 trained apneic divers performed maximal breath-hold. Venous blood samples were taken, once before and at 4 defined points in time after apnea. Samples were analyzed for circulating EMPs and endothelial miRs.

RESULTS

Average apnea time was 329 seconds (±103), and SpO₂ at the end of apnea was 79% (±12). Apnea was associated with a time-dependent increase of circulating endothelial cell-derived EMPs and endothelial miRs. Levels of circulating EMPs in the bloodstream reached a peak 4 hours after the apnea period and returned to baseline levels after 24 hours. Circulating miR-126 levels were elevated at all time points after a single voluntary maximal apnea, whereas miR-26 levels were elevated significantly only after 30 minutes and 4 hours. Also miR-21 and miR-92 levels increased, but did not reach the level of significance.

CONCLUSIONS

Even a single maximal breath-hold induces acute endothelial activation and should be performed with great caution by subjects with preexisting vascular diseases. Voluntary apnea might be used as a model to simulate changes in endothelial function caused by hypoxia in humans.

Predictors of obstructive sleep apnoea in patients admitted for acute coronary syndrome

Identifying undiagnosed obstructive sleep apnoea (OSA) patients in cardiovascular clinics could improve their management. Aiming to build an OSA predictive model, a broad analysis of clinical variables was performed in a cohort of acute coronary syndrome (ACS) patients.

Sociodemographic, anthropometric, life-style and pharmacological variables were recorded. Clinical measures included blood pressure, electrocardiography, echocardiography, blood count, troponin levels and a metabolic panel. OSA was diagnosed using respiratory polygraphy. Logistic regression models and classification and regression trees were used to create predictive models.

A total of 978 patients were included (298 subjects with apnoea–hypopnoea index (AHI) <15 events·h−1and 680 with AHI ≥15 events·h−1). Age, BMI, Epworth sleepiness scale, peak troponin levels and use of calcium antagonists were the main determinants of AHI ≥15 events·h−1(C statistic 0.71; sensitivity 94%; specificity 24%). Age, BMI, blood triglycerides, peak troponin levels and Killip class ≥II were determinants of AHI ≥30 events·h−1(C statistic of 0.67; sensitivity 31%; specificity 86%).

Although a set of variables associated with OSA was identified, no model could successfully predict OSA in patients admitted for ACS. Given the high prevalence of OSA, the authors propose respiratory polygraphy as a to-be-explored strategy to identify OSA in ACS patients.

Sleep apnea in total joint arthroplasty patients and the role for cardiac biomarkers for risk stratification: an exploration of feasibility

Obstructive sleep apnea (OSA) is highly prevalent in patients undergoing total joint arthroplasty (TJA) and is a major risk factor for postoperative cardiovascular complications and death. Recognizing this, the American Society of Anesthesiologists urges clinicians to implement special considerations in the perioperative care of OSA patients. However, as the volume of patients presenting for TJA increases, resources to implement these recommendations are limited. This necessitates mechanisms to efficiently risk stratify patients having OSA who may be susceptible to post-TJA cardiovascular complications. We explore the role of perioperative measurement of cardiac troponins (cTns) and brain natriuretic peptides (BNPs) in helping determine which OSA patients are at increased risk for post-TJA cardiovascular-related morbidity.