New research from the Mayo Clinic suggests that obstructive sleep apnea (OSA), particularly the low nighttime oxygen saturation of the blood caused by OSA, may be a risk factor for sudden cardiac death (SCD).

Mayo Clinic researchers studied the sleep characteristics of nearly 11,000 adults in overnight sleep studies, finding OSA as one of the two traits that contribute to the highest risk of SCD. (The second trait was an age of 60 years or older.)

“Nighttime low oxygen saturation in the blood is an important complication of obstructive sleep apnea,” says principal investigator Virend Somers, MD, PhD. “Our data showed that an average nighttime oxygen saturation of the blood of 93% and lowest nighttime saturation of 78% strongly predicted SCD, independent of other well-established risk factors, such as high cholesterol. These finding implicate OSA, a relatively common condition, as a novel risk factor for SCD.”

This is the first large study to rigorously test the hypothesis that OSA might be implicated in SCD because of evidence that low oxygen alters the blood vessels in a way that promotes heart disease. If further studies validate the findings, OSA could land on the list of established risk factors for SCD, which currently includes smoking, obesity, high cholesterol, and high blood pressure.