BENEFICIAL EFFECTS OF WEIGHT LOSS ON CENTRAL PRESSURE, ARTERIAL STIFFNESS AND SYMPATHETIC TONE IN OBESE SUBJECTS WITH OBSTRUCTIVE SLEEP APNEA

Abstract

Objective: Obstructive sleep apnea (OSA) is known to be an independent cardiovascular risk factor. The presence of OSA and obesity may have synergistic effects on the progression of cardiovascular disease. To evaluate the effect of weight loss on vascular disease in obese patients with different OSA severity levels. Design and method: Individuals of both sexes, age between 40 and 70 years and body mass index (BMI) > = 30 and < 40 kg/m2 were submitted to nutritional intervention for 8 weeks with restriction of 800 kcal/day. Pulse wave velocity (PWV) and central hemodynamic parameters were evaluated by oscillometry (Mobil-O-Graph) and sympathetic tone by heart rate variability (HRV). The sleep study was performed using a portable home device (WatchPAT). Results: Patients (n = 70) were divided into two groups based on the apnea-hypopnea index (AHI): mild-absent (MA) group (AHI< 15 events/h, n = 25) with mean age 50 ± 6 years, BMI = 34.5 ± 2.8 kg/m2 and moderate-severe (MS) group (AHI> = 15 events/h, n = 45) with mean age 54 ± 8 years, BMI = 33.8 ± 2.6 kg/m2. After the intervention, weight loss was similar in both groups (-3.20 vs -3.32 kg). Both groups showed a significant reduction in anthropometric parameters. The MS group showed a significant reduction in peripheral systolic blood pressure (BP) (127 ± 15 vs 122 ± 15 mmHg, p = 0.007) and the MA group demonstrated a significant reduction in diastolic BP (78 ± 6 vs 75 ± 6 mmHg, p = 0.046). Central systolic pressure (116 ± 13 vs 107 ± 11 mmHg, p = 0.007), PWV (6.9 ± 0.6 vs 6.7 ± 0.6 m/s, p = 0.002) and vascular age (48 ± 6 vs 46 ± 6 years, p = 0.020) were significantly reduced only in the MA group. This group also demonstrated a significant increase in the RR interval (838 ± 225 vs 948 ± 130 ms, p = 0.032) with a reduction in heart rate (69 ± 5 vs 64 ± 8 bpm, p = 0.015). Conclusions: A small weight loss in a short period of time was able to promote more beneficial effects in obese individuals with non-severe sleep apnea including favorable outcomes on central hemodynamic parameters, arterial stiffness and autonomic activity.