Pathophysiological Mechanisms to Review Association of Atrial Fibrillation in Heart Failure With Obstructive Sleep Apnea

Is obstructive sleep apnea a circadian rhythm disorder?

Obstructive sleep apnea is the most common sleep-related breathing disorder worldwide and remains underdiagnosed. Its multiple associated comorbidities contribute to a decreased quality of life and work performance as well as an increased risk of death. Standard treatment seems to have limited effects on cardiovascular and metabolic aspects of the disease, emphasising the need for early diagnosis and additional therapeutic approaches. Recent evidence suggests that the dysregulation of circadian rhythms, processes with endogenous rhythmicity that are adjusted to the environment through various cues, is involved in the pathogenesis of comorbidities. In patients with obstructive sleep apnea, altered circadian gene expression patterns have been demonstrated. Obstructive respiratory events may promote circadian dysregulation through the effects of sleep disturbance and intermittent hypoxia, with subsequent inflammation and disruption of neural and hormonal homeostasis. In this review, current knowledge on obstructive sleep apnea, circadian rhythm regulation, and circadian rhythm sleep disorders is summarised. Studies that connect obstructive sleep apnea to circadian rhythm abnormalities are critically evaluated. Furthermore, pathogenetic mechanisms that may underlie this association, most notably hypoxia signalling, are presented. A bidirectional relationship between obstructive sleep apnea and circadian rhythm dysregulation is proposed. Approaching obstructive sleep apnea as a circadian rhythm disorder may prove beneficial for the development of new, personalised diagnostic, therapeutic and prognostic tools. However, further studies are needed before the clinical approach to obstructive sleep apnea includes targeting the circadian system.

Relationship between sleep apnea and hospital readmission in rural and urban populations

OBJECTIVES

The aims of this study were to evaluate geographic differences in obstructive sleep apnea (OSA) prevalence, to determine if readmissions were more likely among rural patients with OSA than others, and to model predictors, including diagnosed OSA, of 30, 60, and 90-day acute-care readmissions.

DESIGN

This cohort study employed a secondary analysis of data extracted from the electronic health record shared by all hospitals in a north Texas healthcare system.

SAMPLE

The sample consisted of records associated with 472,503 adult patients admitted to any of the study system's acute-care facilities from 2016 through 2019.

MEASUREMENTS

Measurements consisted of case-level health information, including admissions, demographic variables, payors, diagnoses, screens, and physician orders.

RESULTS

OSA was significantly related to hospital readmission when considered in isolation but did not significantly predict readmission when modeled with plausible covariates. Screening rates for OSA did not vary by geography. Differences in rural/urban-suburban OSA prevalence were not statistically significant.

CONCLUSIONS

Findings contrast with previous suggestions that OSA plays an independent role in hospital readmissions or that rural resident may be disadvantaged regarding services that support the OSA diagnosis. Prevalence and screening rates were almost identical in urban and rural populations.

Association between obstructive sleep apnea and cardiovascular diseases

Obstructive sleep apnea (OSA) is a common respiratory disorder characterized by partial obstruction of upper respiratory tract and repetitive cessation of breathing during sleep. The etiology behind OSA is associated with the occurrence of intermittent hypoxemia, recurrent arousals and intrathoracic pressure swings. These contributing factors may turn on various signaling mechanisms including elevated sympathetic tone, oxidative stress, inflammation, endothelial dysfunction, cardiovascular variability, abnormal coagulation and metabolic defect ( e.g., insulin resistance, leptin resistance and altered hepatic metabolism). Given its close tie with major cardiovascular risk factors, OSA is commonly linked to the pathogenesis of a wide array of cardiovascular diseases (CVDs) including hypertension, heart failure, arrhythmias, coronary artery disease, stroke, cerebrovascular disease and pulmonary hypertension (PH). The current standard treatment for OSA using adequate nasal continuous positive airway pressure (CPAP) confers a significant reduction in cardiovascular morbidity. Nonetheless, despite the availability of effective therapy, patients with CVDs are still deemed highly vulnerable to OSA and related adverse clinical outcomes. A better understanding of the etiology of OSA along with early diagnosis should be essential for this undertreated disorder in the clinical setting.

Management of Obstructive Sleep Apnea in Patients With Heart Failure

Sleep apnea is traditionally classified as obstructive sleep apnea (OSA), which occurs when the upper airway collapses due to the relaxation of oropharyngeal musculature, and central sleep apnea occurs when the brainstem cannot stimulate breathing. Most sleep apnea in patients with heart failure (HF) results from coexisting OSA and central sleep apnea (CSA), or complex sleep apnea syndrome. OSA and CSA are common in HF and can be involved in its progression by exposure to the heart to intermittent hypoxia, increased preload and afterload, activating sympathetic, and decreased vascular endothelial function. A majority of treatments have been investigated in patients with CSA and HF; however, less or short-term randomized trials demonstrated whether treating OSA in patients with HF could improve morbidity and mortality. OSA could directly influence the patient's recovery. This review will focus on past and present studies on the various therapies for OSA in patients with HF and summarize CSA treatment options for reasons of reference and completeness. More specifically, the treatment covered include surgical and non-surgical treatments and reported the positive and negative consequences for these treatment options, highlighting possible implications for clinical practice and future research directions.

Detection of Common Arrhythmias by the Watch-PAT: Expression of Electrical Arrhythmias by Pulse Recording

BACKGROUND

The WatchPAT (WP) device was shown to be accurate for the diagnosis of sleep apnea and is widely used worldwide as an ambulatory diagnostic tool. While it records peripheral arterial tone (PAT) and not electrocardiogram (ECG), the ability of it to detect arrhythmias is unknown and was not studied previously. Common arrhythmias such as atrial fibrillation (AF) or premature beats may be uniquely presented while recording PAT/pulse wave.

PURPOSE

To examine the potential detection of common arrhythmias by analyzing the PAT amplitude and pulse rate/volume changes.

PATIENTS AND METHODS

Patients with suspected sleep disordered breathing (SDB) were recruited with preference for patients with previously diagnosed AF or congestive heart failure (CHF). They underwent simultaneous WP and PSG studies in 11 sleep centers. A novel algorithm was developed to detect arrhythmias while measuring PAT and was tested on these patients. Manual scoring of ECG channel (recorded as part of the PSG) was blinded to the automatically analyzed WP data.

RESULTS

A total of 84 patients aged 57±16 (54 males) participated in this study. Their BMI was 30±5.7Kg/m2. Of them, 41 had heart failure (49%) and 17 (20%) had AF. The sensitivity and specificity of the WP to detect AF segments (of at least 60 seconds) were 0.77 and 0.99, respectively. The correlation between the WP derived detection of premature beats (events/min) to that of the PSG one was 0.98 (p<0.001).

CONCLUSION

The novel automatic algorithm of the WP can reasonably detect AF and premature beats. We suggest that when the algorithm raises a flag for arrhythmia, the patients should shortly undergo ECG and/or Holter ECG study.