Reevaluating Obstructive Sleep Apnea as a Risk Factor for Cerebrovascular Disease

Circulating markers of oxidative stress and risk of incident cardiovascular events in obstructive sleep apnea

The identification of which patients with obstructive sleep apnea (OSA) are more likely to develop cardiovascular disease (CVD) remains a challenge. OSA causes oxidative stress (OS) which may contribute to CVD pathogenesis. Therefore, OS markers could be useful in risk-stratifying cardiovascular (CV) risk in OSA patients. The purpose of this pilot study was to assess whether three OS marker levels could be associated with incident CVD in suspected OSA patients. Morning plasma levels of 8-isoprostane, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and superoxide dismutase (SOD) were measured in patients with suspected OSA referred for a polysomnogram (PSG). A composite outcome of CV events was defined by linkage with provincial administrative health databases. Cox proportional hazards models were used to assess the relationship between the levels of OS markers and events. 352 patients were included (mean age of 51.4 years, 68% male, median apnea hypopnea index of 16/h). Thirty-one first CV events occurred over an 8-year follow-up. In univariate or fully adjusted models, none of the OS markers were significantly associated with incident CV events (hazard ratio in adjusted models of: 1.25 (95% CI 0.56-2.80, p = 0.59), 1.15 (0.52-2.57, p = 0.73), 0.77 (0.37-1.61, p = 0.48), for 8-OHdG, 8-isoprostane and SOD; however, confidence intervals were wide. In this small preliminary study, oxidative stress markers were not significantly associated with risk of CV events. However, moderate associations between these markers and risk of CV events are possible and should be the focus of future larger studies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41105-022-00399-0.

Cerebral hemodynamic changes at basilar artery in patients with obstructive sleep apnea syndrome. A case-control study

INTRODUCTION

Obstructive sleep apnea syndrome (OSAS) is characterized in polysomnography by recurrent airflow obstruction during sleep. The underlying pathogenic mechanisms of neuropsychological and cerebrovascular events in patients with OSAS have not been clarified unequivocally.

MATERIAL AND METHODS

Case-control study to evaluate the cerebral vasomotor reactivity assessed by breath-holding maneuver at basilar artery in patients with OSAS compared to control subjects.

RESULTS

The study included 76 patients with OSAS and 76 controls. Vascular risk factors (arterial hypertension, diabetes mellitus, hypercholesterolemia, smoking), age, gender, coronary, and peripheral arterial diseases were similar in both groups. Patients with OSAS had breath-holding test values (31.9 ± 13.35%) lower than controls (39.06 ± 13.16%), (P = 0.001). Patients with OSAS had higher systolic and diastolic blood pressure both basal and apnea and also a higher basal heart rate.

CONCLUSIONS

Altered cerebral hemodynamics together with increased blood pressure values in patients with OSAS may play a role in the association between this disease and the development of cerebrovascular events. This implies that this disease should be identified through guide symptoms such as snoring, sleep apnea, and daytime sleepiness in all patients who consult for these symptoms to reduce the number of cerebrovascular events.