0479 The Association of Positional Obstructive Sleep Apnea with Blood Pressure

Abstract Introduction Obstructive sleep apnea (OSA) is associated with hypertension and adverse cardiovascular (CV) outcomes. Sleep position plays a critical role in the pathophysiology of OSA. Generally, positional OSA (POSA) refers to OSA that mostly occurs in the supine position, the most vulnerable position for upper airway obstruction. It is unclear whether POSA has CV risk implications. The purpose of this study was to compare blood pressure (BP) and BP variability (BPV), two well-established CV risks between the patients with POSA and non-POSA. Methods We included patients who had at least three separate BP measurements taken during office visits within one year prior to clinically indicated polysomnography at a single center. Systolic BP (SBP), diastolic BP (DBP), SBP coefficient of variation (SBP-CV) and DBP coefficient of variation (DBP-CV) were measured. POSA was defined by patients with an apnea-hypopnea index (AHI) ≥5 events/hour as well as supine AHI at least twice as high as non-supine AHI. ePOSA consisted of the previously mentioned criteria with the additional requirement that non-supine AHI normalize to < 5 events/hour. Independent two sample t-tests were performed for comparison. Results We included 1,750 patients with OSA (age 54 years and 59.5% female). Patients with POSA or ePOSA had a lower BMI than those with non-POSA or non-ePOSA. Those with POSA or ePOSA were more likely to have mild OSA (AHI 5-15 events/hour) compared to patients with non-POSA or non-ePOSA (52.7% vs. 48.2%; 71.8% vs 44%). Patients with POSA or ePOSA had a significantly lower SBP-CV compared to non-POSA and non-ePOSA (9.7 [ 4] vs 10.2 [4.2], p=0.014; 9.5 [SD 4.2] vs. 10.1 [SD 4.1], p=0.005). There were no significant differences in mean SBP, mean DBP, or mean DBP-CV in the comparison of POSA vs non-POSA. However, patients with ePOSA had a lower mean SBP (128.8 vs 131.2 mmHg, p=0.003) and mean DBP (73.6 vs 75 mmHg, p=0.004) than those with non-ePOSA. Conclusion POSA is associated with lower BP risk profile. This may have implications for this subgroup of OSA patients and their risk for hypertension and cardiovascular outcomes. Future studies should consider the positional component in studying CV risks of OSA. Support (if any)