Researchers have found that people with obstructive sleep apnea have an increased cardiovascular risk due to reduced blood oxygen levels, largely explained by interrupted breathing. Obstructive sleep apnea has long been associated with increased risk of cardiovascular issues, including heart attack, stroke, and death, but the findings from this study, partially supported by the National Institutes of Health and published in the American Journal of Respiratory and Critical Care Medicine, show the mechanism mostly responsible for the link.
Researchers reviewed data from more than 4,500 middle-aged and older adults who participated in the Osteoporotic Fractures in Men Study (MrOS) and the Multi-Ethnic Study of Atherosclerosis (MESA), and sought to identify features of obstructive sleep apnea that could explain why some people were more likely than others to develop cardiovascular disease or related death.
Through MrOS, 2,627 men, with an average age of 76, were followed for about nine to 12 years. MESA included data from 1,973 men and women, with an average age of 67, who were followed for about seven years. During this time, participants completed medical check-ins and sleep assessments and shared information about their health. Approximately 110 participants in MESA and 382 in MrOS experienced a primary cardiovascular event.
For every measure of observed reduction in blood oxygen levels, or hypoxic burden, a person in MESA had a 45% increased associated risk for having a primary cardiovascular event. In MrOS, the observed increased risk was 13%. Airway obstruction, measured by a full or partial closing of the airways, accounted for 38% of observed risks in MESA and for 12% in MrOS. Similar findings for predicting premature death based on hypoxic and ventilatory burden were also observed. Sudden awakenings weren’t associated with cardiovascular outcomes in MESA, but were linked with cardiovascular-related deaths in MrOS. Additionally, the researchers found that a high hypoxic burden was mostly due to severe obstruction of the airway and not other factors, such as abdominal obesity or reduced lung function.
