Obstructive sleep apnea (OSA) is a novel risk factor for sudden cardiac death (SCD), according to a study published June 11 in the Journal of the American College of Cardiology (JACC).

The study looked at 10,701 adults referred for polysomnography and followed them for an average of 5.3 years for incidents of resuscitated or fatal SCD. Results showed that 142 patients experienced SCD, with the most common predictors being a patient aged 60 years (HR 5.53), having 20 apnea episodes an hour (HR 1.60) and having a lowest nocturnal oxygen saturation level of below 78 percent (HR 2.60, all p<0.0001). In addition, results showed that the severity of nocturnal hypoxemia strongly predicts SCD independently of other risk factors. Further, in the lowest nocturnal oxygen saturation, a drop to below 78 percent increases a patient's risk of SCD by 81 percent.

The study clarifies that sleep apnea patients' risk of SCD does not simply shift from daytime hours to nighttime hours, but that their overall risk of SCD is higher than people without sleep apnea. "People at risk for OSA ought to be screened with a sleep study, and potentially then being treated for sleep apnea might reduce the risk of dying suddenly," said Deepak Bhatt, MD, MPH, FACC, in a CardioSource Video News interview on the study's findings.

Moving forward, the authors suggest continued research into the mechanisms of SCD in individuals with OSA, as well as the development of clinical trials of OSA therapy in select populations at risk for SCD.

Meanwhile, Apoor Gami, MD, MSc, FACC, a cardiologist at Midwest Heart Specialists - Advocate Medical Group in Elmhust, Ill, and lead author of the study, notes that "the prevalence of obstructive sleep apnea in Western populations is high and will likely only continue to grow given the obesity epidemic and direct relationship between obesity and sleep apnea."

A separate study also published in JACC, supports this hypothesis. The study highlights current literature that "clearly points that OSA is an emerging risk factor for modulating the cardiometabolic consequences of obesity." According to the study authors, "there is a clear demand for additional research both at the basic science and clinical levels for understanding the mechanisms by which OSA and its components exacerbate metabolic dysfunction and vascular impairment in obesity and metabolic syndrome."

Keywords: Metabolic Syndrome, Risk Factors, Obesity, Death, Sudden, Cardiac, Sleep Apnea, Obstructive, United States