Association between Obstructive Sleep Apnea and SYNTAX Score

Sleep-disordered breathing and cardiovascular disease: who and why to test and how to intervene?

Sleep-disordered breathing (SDB) is common in individuals with established cardiovascular disease (CVD), particularly those with heart failure (HF). There are two main types of SDB, central sleep apnoea (CSA) and obstructive sleep apnoea (OSA) which frequently overlap as mixed SDB. Investigating for SDB could be considered in patients with excessive daytime sleepiness, male sex, high body mass index, low ejection fraction, atrial fibrillation (AF), in patients with no dipping blood pressure pattern, recurrent paroxysms of nocturnal dyspnoea or when an apnoea is witnessed. Excessive daytime sleepiness is less likely to be reported by patients with HF than by the general population. In patients with CVD and OSA, continuous positive airway pressure (CPAP) ventilation for over 4 hours daily reduced the risk of major adverse cardiovascular events, but there was no reduction in mortality. In patients with AF and OSA treated with AF ablation, CPAP use was associated with a reduced risk of recurrence of AF. In patients with HF and OSA, small studies have demonstrated that CPAP improves symptoms, brain natriuretic peptide levels and ejection fraction, but data on survival are lacking. Treatment remains unclear in patients with HF and CSA. The presence of CSA may be a defensive adaptive response to HF, and effectively treating CSA as demonstrated in a randomised clinical trial of adaptive servo-ventilation caused more harm than benefit when compared to optimal medical therapy. Thus, the focus of treating CSA should remain on improving the underlying HF by optimising medical therapy and, if indicated, cardiac resynchronisation therapy.

Sleep Spindle Characteristics and Relationship with Memory Ability in Patients with Obstructive Sleep Apnea-Hypopnea Syndrome

Obstructive sleep apnea syndrome (OSAS) causes intermittent hypoxia and sleep disruption in the brain, resulting in cognitive dysfunction, but its pathogenesis is unclear. The sleep spindle wave is a transient neural event involved in sleep memory consolidation and synaptic plasticity. This study aimed to investigate the characteristics of sleep spindle activity and its relationship with memory ability in patients with OSAS. A total of 119 patients, who were divided into the OSAS group (n = 59, AHI ≥ 15) and control group (n = 60, AHI < 15) according to the Apnea Hypopnea Index (AHI), were enrolled and underwent polysomnography. Power spectral density (PSD) and omega complexity were used to analyze the characteristics of single and different brain regions of sleep spindles. Memory-related cognitive functions were assessed in all subjects, including logical memory, digit ordering, pattern recognition, spatial recognition and spatial working memory. The spindle PSD of the OSAS group was significantly slower than the control group, regardless of the slow, fast, or total spindle. The complexity of the spindles in the prefrontal and central region decreased significantly, whereas it increased in the occipital region. Sleep spindle PSD was positively correlated with logical memory and working memory. Spindle complexity was positively correlated with immediate logical and visual memory in the prefrontal region and positively correlated with immediate/delayed logical and working memory in the central region. In contrast, spindle complexity in the occipital region negatively correlated with delayed logical memory. Spindle hyperconnectivity in the prefrontal and central regions underlies declines in logical, visual and working memory and weak connections in the occipital spindles underlie the decline in delayed logical memory.

Obstructive Sleep Apnea Increases the Risk of Perioperative Myocardial Infarction Following Off-Pump Coronary Artery Bypass Grafting

Background and Aims: The impact of obstructive sleep apnea (OSA) on perioperative myocardial infarction (PMI) following coronary artery bypass grafting (CABG) remains unclear. Off-pump CABG (OPCABG) has become a common practice for CABG in China. The present study investigated mainly the correlation between OSA and PMI following OPCABG.

Methods: In this prospective observational single-center study, consecutive eligible patients listed for elective OPCABG underwent cardiorespiratory polygraphy before surgery between January 2019 and June 2020. OSA was defined as an apnea-hypopnea index (AHI) ≥15 events/h. The primary end point was perioperative myocardial infarction (PMI) following OPCABG (type 5 MI).

Results: Patients with OSA accounted for 42.2% (62/147) of the cohort. Twenty-four patients (16.3%) met the protocol criteria for PMI: 17 (27.4%) in the OSA group and 7 (8.2%) in the non-OSA group (P = 0.002). Multivariate logistic regression analysis revealed that AHI (OR = 1.115, 95% CI 1.066 to 1.166, P < 0.001), high-sensitivity c-reactive protein (hs-CRP) (OR = 1.080, 95% CI 1.025 to 1.138, P = 0.004), and SYNTAX score (OR = 1.098, 95% CI 1.056 to 1.141, P < 0.001) were associated with PMI incidence. Furthermore, ROC analysis revealed that the AHI (AUC = 0.766, 95% CI 0.689 to 0.832, P < 0.001) and SYNTAX score (AUC = 0.789, 95% CI 0.715 to 0.852, P < 0.001) had predictive value for PMI. In addition, multiple linear regression analysis showed that the AHI was an independent influencing factor of hs-CRP (B = 0.176, 95% CI 0.090 to 0.263, P < 0.001) and the SYNTAX score (B = 0.553, 95% CI 0.397 to 0.709, P < 0.001).

Conclusions: OSA was independently associated with a higher incidence of PMI following OPCABG, and the formation of severe coronary atherosclerotic lesions aggravated by an enhanced inflammatory response might be the potential mechanism. The efficacy of CPAP treatment for improving prognosis after CABG remains to be further investigated.