Subclinical Changes in Cardiac Functional Parameters as Determined by Cardiovascular Magnetic Resonance (CMR) Imaging in Sleep Apnea and Snoring: Findings from UK Biobank

Obstructive sleep apnea and right ventricular function: A meta-analysis of speckle tracking echocardiographic studies

The authors investigated the association between obstructive sleep apnea (OSA) and right ventricular (RV) systolic dysfunction trough a meta‐analysis of echocardiographic studies providing data on RV mechanics as assessed by longitudinal strain (LS). A systematic search was conducted using PubMed, OVID‐MEDLINE, and Cochrane library databases to search English‐language review papers published from inception to March 31, 2022. Only studies reporting data on RV free‐wall or global LS in patients with OSA of different severity and non‐OSA controls were reviewed. Data of interest were pooled to obtain standard means difference (SMD) with 95% confidence interval (CI). The meta‐analysis included 628 participants (436 with OSA and 192 controls) from eight studies. Compared to controls, RV free wall LS was significantly reduced in the pooled OSA group (SMD 1.02 ± .33, CI:.17/1.24, P < .002); this was also the case for RV global LS (SMD: .72 ± .11, CI: .50/.93, P < .0001). Notably, compared to patients with mild‐OSA those with moderate and severe OSA exhibited significantly lower RV free‐wall LS and global LS values; this was not the case for tricuspid annular plane excursion. In conclusions, both RV free‐wall and global LS are impaired in patients with OSA; deterioration of these indices, unlike TAPSE, was already evident in the early stages and was related to the severity of the syndrome. Thus, RV myocardial strain should be considered to be included in echocardiographic evaluation of OSA patients in order to detect subclinical cardiac damage in these patients regardless of its degree of severity.

Silencing MR-1 Protects against Myocardial Injury Induced by Chronic Intermittent Hypoxia by Targeting Nrf2 through Antioxidant Stress and Anti-Inflammation Pathways

BACKGROUND

Patients with obstructive sleep apnea hypopnea syndrome (OSAHS) often have cardiac insufficiency mainly due to hypoxia/reperfusion injury caused by chronic intermittent hypoxia (CIH). Inflammation and oxidative stress are involved in the cardiovascular events of OSAHS patients. Studies have found that myofibrillation regulator-1 (MR-1) participates in the pathological process of OSAHS-induced myocardial injury, but the specific mechanism is still unclear.

METHODS

We used a CIH-induced rat model to simulate the process of OSAHS disease. Indices of myocardial injury, inflammation, and oxidative stress were detected using quantitative PCR and enzyme-linked immunosorbent assay (ELISA). After administration of adenoassociated viral vector (AAV) encoding silencing RNA against MR-1, we examined expression of the classic antioxidant stress pathway protein NF-E2-related factor 2 (Nrf2) using western blotting.

RESULTS

We found that levels of serum inflammatory factors tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-8 were increased, and we further observed disturbance of the oxidative stress system, in which the content of reactive oxygen species (ROS), superoxide dismutase (SOD), reduced glutathione (GSH), and malondialdehyde (MDA) was enhanced in CIH-induced rats. Subsequently, we detected that expression of Nrf2 and heme oxygenase-1 (HO-1) was slightly increased, while the expression of Kelch-like ECH-associated protein 1 (Keap-1) was significantly increased in the CIH model. Interestingly, after administration of silencing MR-1 AAV, the elevated levels of inflammatory factors were reduced, and the disordered oxidative stress system was corrected. Additionally, the expression of Nrf2 and HO-1 was distinctly increased, but the high expression of Keap-1 was decreased.

CONCLUSIONS

Our research results demonstrate that silencing MR-1 rescued the myocardium the injury from inflammatory and oxidative stress in CIH-induced rats by administration of the Nrf2 signaling pathway.