CHICAGO — In a sleep-clinic study, CAD was associated with the presence and severity of obstructive sleep apnea and with shorter sleep duration, according to a study presented at the National Lipid Association Scientific Sessions.
The study included 928 patients observed at sleep clinics, with a median follow-up of 9 months. The population was 86.6% male and 61% black. Half of the patients had dyslipidemia and 43% were being treated for dyslipidemia at the time of the study.
The researchers evaluated the incidence of comorbidities and obstructive sleep apnea and the presence of cardiometabolic risk factors, as well as use of continuous positive airway pressure (CPAP) therapy and adherence to treatment.
Overall, 80.1% of patients had obstructive sleep apnea, and 77.8% were using CPAP therapy. During follow-up, patients using CPAP therapy had a median usage of 32% of nights, for a median duration of 4.7 hours.
More than 10% of patients also had CAD. Severe obstructive sleep apnea, as indicated by apnea hypopnea index, was more common in the patients with CAD (mean apnea hypopnea index, 22.3 vs. 15.8 among those without CAD; P = .0012). Adjustment for weight or BMI did not significantly influence this finding. Stratification according to apnea severity indicated that CAD was present in 7.4% of patients with mild sleep apnea, 13.9% of those with moderate sleep apnea and 16.8% of those with severe apnea (P = .01).
The researchers also observed an association between CAD and total sleep time. A shorter time was reported among patients with CAD compared with those without CAD (287 minutes vs. 315 minutes; P = .009). Stepwise multivariate analysis indicated that a model incorporating age, dyslipidemia or hypertension and central apnea index was predictive of CAD, with an area under the curve of 0.86 (P < .0001). The researchers noted that the central apnea index was a better differentiating factor than either the obstructive apnea index or the apnea hypopnea index.
“The central apnea index is a very important predictor of CAD,” Tina Constantin, MD, of the endocrinology division at Emory University School of Medicine, told Cardiology Today. “[Clinicians should] take a closer look at central apnea index — it doesn’t even have to be very high. Our population didn’t have a very high central apnea index; however, it correlated with CAD.”
Constantin said future studies will assess metabolic endpoints and focus on patients with diabetes. “Early analysis is now showing that in the diabetes group, patients with a higher number of hours at night on CPAP actually had a [nonsignificant] tendency toward improvement in HbA1c and weight, so our goal is to take a closer look at other metabolic endpoints such as changes in lipid profile, HbA1c and weight in different subgroups,” she said. – by Adam Taliercio
Constantin T, et al. Abstract #119. Presented at: National Lipid Association Scientific Sessions; June 11-14, 2015; Chicago.
Disclosure: Constantin reports no relevant financial disclosures.