Background: Obstructive sleep apnea (OSA) is considered an independent risk factor for cardiovascular disease and reported as the most common secondary cause of high blood pressure (BP) maintenance.
Objective: To determine the prevalence of OSA and verify its association with endothelial function behavior and anthropometric parameters in patients with resistant hypertension (RHGroup) and BP controlled by medication (CHGroup).
Methods: Cross-sectional study involving 40 hypertensive patients (20 in RHG and 20 in CHG), aged between 18 and 75 years. Endothelial function and OSA were assessed by peripheral arterial tonometry. BP was measured by oscillometric method on automatic device. Endothelial function was assessed by peripheral arterial tonometry (PAT) by EndoPAT2000 and the OSA diagnosis also through PAT, using the portable device WatchPAT200. Anthropometric evaluation was performed through measurements of waist (WaC), hip and neck circumference (NC), BMI, waist to height ratio (WHtR), and body composition assessed by BIA.
Results: The prevalence of OSA in RHG was 85% (17 of 20)[apnea-hypopnea index = 12.39±1.89], and 80% (16 of 20) in CHG (AHI=20.74±4.69) and it was more frequent in men (93.7% [15 of 16] vs 75% [16 of 24]; p=0.0455, OR=3.86; 95% IC 0.99 to 5.09). Both groups presented similar anthropometric parameters values. Endothelial function evaluated by reactive hyperemia index was similar in both groups (RHG: 1.88±0.44 vs CHG: 2.03±0.43; p=0.47). Although we found differences in oxygen desaturation> 4% (RHG: 28.75 ± 5.08 vs CHG: 64.15 ± 16.97, p = 0.05), total sleep time (RHG: 307.2 ± 71.3 vs CHG: 323.3 ± 83.8 min) and minimum saturation (RHG: 87.8±3.8 vs CHG: 83.3±10.6%) was not different. In general, OSA was correlated with weight (r = 0.5135, p = 0.0007), BMI (r = 0.4146, p = 0.0078), WaC (r = 0, 4458, p = 0.005), NC (r = 0.3863, p = 0.01) and WHtR (r = 0.3907, p = 0.01) and independently associated with impairment of endothelial function (p = 0.0297, OR = 0.17, 95% CI 0.04 to 0.72).
Conclusions: The findings of the present study show that the prevalence of OSA was similar in both groups and suggest that, in hypertensive subjects, OSA occurs more frequently in men, being associated with endothelial dysfunction and correlated positively with weight, BMI and WaC.