Polysomnographic phenotype as a risk factor for cardiovascular diseases in patients with obstructive sleep apnea syndrome: a retrospective cohort study

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is associated with the development of cardiovascular diseases caused by hypoxemia during sleeping. We classified OSAS phenotypes based on polysomnographic findings and aimed to evaluate that the unique phenotypes would be differentially associated with risk of cardiovascular disease. METHODS: This retrospective and observational study assessed adult patients who underwent polysomnography at the Wonju Severance Christian Hospital from November 2008 to February 2018. The OSAS phenotypes were classified as apnea-predominant, hypopnea-predominant, and respiratory effort-related arousal (RERA)-predominant based on the polysomnography results. The polysomnographic data were collected and analysed, and clinical features such as medical history and comorbidities were assessed by a review of the electronic medical records. RESULTS: A total of 860 adult patients were classified as apnea-predominant (n=220), hypopnea-predominant (n=119), or RERA-predominant (n=275). The hypopnea-predominant group had significantly higher rates of hyperlipidaemia (P<0.001), heart failure (15.5%, P<0.001), and coronary artery disease (20.9%, P=0.005) than the other groups. After classifying the patients according to severity of the hypopnea index, logistic regression analyses adjusted for age, sex, and smoking history revealed that the hypopnea index increased the risk for coronary artery disease and heart failure. CONCLUSIONS: The hypopnea-predominant group would be a specific phenotype that has a differential association with the risks for coronary artery disease and heart failure.