What Is the Relationship Between OSA, Cardiovascular Disease?

In assessing the relationship between obstructive sleep apnea (OSA) and cardiovascular disease (CVD), researchers of a review published in Cureus highlight that it remains unclear how OSA induces changes in those with the disease.¹

As researchers note, OSA is a common yet underdiagnosed condition known to cause brief episodes of partial or total upper airway obstruction during sleep, which leads to apnea or hypopnea. These intermittent and recurrent episodes of hypoxia could have extensive implications for those with CVD.

“Vascular endothelial cell (VEC) injury and other mechanisms seen in OSA lead to changes in the CV system,” explain researchers.

Examining 31 published articles from the PubMed database, researchers conducted a literature review to address existing gaps in knowledge about the relationship between OSA and its effect on CV changes. “Only those publications that explained the mechanism by which OSA itself poses a risk to CV health, rather than just the impact of obesity or metabolic syndrome on it, were selected.”

In the review of selected data for 21,763 subjects, researchers uncovered a myriad of CVDs associated with OSA, as well as the mechanism behind how OSA influences CV events.

Focusing on pathological changes reported in OSA, recurrent hypoxia was found to trigger systemic inflammation, causing an alteration in transmural, intrathoracic, and cardiac pressures. As referenced previously, VEC injury is then caused by this change in the human body, which causes damage to coronary arteries. This can then lead to coronary artery diseases or cardiac ischemia, noted the researchers.

As a potentially preventive discovery, they found several proteins that are released by repeated hypoxia due to OSA that then lead to VEC injury. This could assist in making diagnoses of comorbid OSA and CVD, as these proteins could serve as biomarkers for identifying even asymptomatic patients with OSA.

So, for those diagnosed with comorbid OSA and CVD, what therapies may enhance long-term health?

Exercise is often associated with significant effects on both OSA and CVD, particularly moderate to vigorous exercise. Authors of a study published yesterday in the Journal of Clinical Sleep Medicine sought to determine the effects of continuous positive airway pressure (CPAP) treatment on improving adherence to moderate to vigorous physical activity among those with comorbid OSA and CVD.²

In the study, titled the Sleep Apnea cardioVascular Endpoints (SAVE) trial, researchers recruited 2687 participants with confirmed CV disease history and OSA aged 45 to 75 years. The study cohort was randomly split into 2 groups, with the intervention group receiving CPAP plus usual care (n = 1346) and the control group receiving usual care alone (n = 1341).

Participants were followed for a mean of 3.7 years, with self-reported physical activity recorded at baseline, 6 months, 24 months, and 48 months via the Godin-Shepard Leisure Time Exercise Questionnaire (LTEQ).

“We also determined effects on any limitation of physical activity reported on the physical functioning subscale (PFS) of the 36-item short form questionnaire (SF-36) and proportions of participants reaching guideline recommended physical activity levels,” added researchers.

Comparing both groups, the intervention group that received CPAP reported significantly more physical activity (adjusted mean, 8.7; 95% CI, 7.5–9.9) than the control group (adjusted mean, 7.3; 95% CI, 6.1–8.5), attributed to approximately 20% higher moderate activity on the LTEQ during follow-up (P = .003).

Additionally, the intervention group reported more sufficient levels of physical activity to meet recommendations, with less limitation in physical activity (adjusted between-group difference in SF-36 PFS score, 1.66; 95% CI, 0.87–2.45; P < .001).

“CPAP has positive effects on improving physical activity levels, consistent with long-term health benefits,” concluded the study authors.

References

1. Rana D, Torrilus C, Ahmad W, et al. Obstructive sleep apnea and cardiovascular morbidities: a review article. Cureus. Published online September 13, 2020. doi:10.7759/cureus.10424

2. Stevens D, Loffler KA, Human MP, et al. CPAP increases physical activity in obstructive sleep apnea with cardiovascular disease. J Clin Sleep Med. Published online September 21, 2020. doi:10.5664/jcsm.8792