Abstract 12935: Hypocaloric Diet and Exercise Training Improves the Chemoreflex Sensitivity in Patients With Metabolic Syndrome and Obstructive Sleep Apnea
Introduction. Metabolic syndrome (MetSyn) and obstructive sleep apnea (OSA) cause sympathetic hyperactivation and chemoreflex hypersensitivity.
Hypothesis. We tested the hypotheses that: 1) Hypocaloric diet associated with exercise training (D+ET) would improve chemoreflex sensitivity in patients with MetSyn, and 2) The effects of D+ET on autonomic control would be more pronounced in MetSyn+OSA than in patients without OSA (MetSyn-OSA).
Methods. Twenty seven never treated MetSyn (ATP-III) were allocated into: 1) MetSyn+OSA (n=15, 53±2 yrs); and 2) MetSyn-OSA (n=12, 43±2 yrs). OSA was characterized by an apnea-hypopnea index (AHI) >15 events/hour (polysomnography). We evaluated muscle sympathetic nerve activity (MSNA, microneurography) and blood pressure (BP, oscillatory method) and peripheral chemoreflex sensitivity by inhalation of 10%O2 and 90%N2 with CO2 titrated, and central chemoreflex by 7%CO2 and 93%O2 for 3 min. The diet was set at -500 kcal and exercise by 3 times/week over 4 months.
Results. D+ET similarly reduced body weight (6.2±0.7 and 7.0±0.8 kg, P=0.47), abdominal circumference (5.6±1.2 and 5.4±1.0 cm, P=0.91), systolic (11±3 vs. 13±3 mmHg, P=0.62) and diastolic BP (8±2 vs. 8±1 mmHg, P=0.95), and similarly increased peak oxygen consumption (21±7 and 20±7%, P=0.90) in both groups. D+ET significantly reduced AHI (36±6 vs. 18±4 events/hour, P=0.01) and minimal O2 saturation (81±2 vs. 84±2%, P=0.001) in MetSyn+OSA. D+ET reduced MSNA levels during hypoxia in MetSyn+OSA (41±2 vs. 33±2 bursts/min, P=0.02) and MetSyn-OSA (36±3 vs. 28±2 bursts/min, P=0.05). D+ET reduced MSNA levels during hypercapnia in MetSyn+OSA (39±2 vs. 30±1 bursts/min, P= 0.0005), but not in MetSyn-OSA.
Conclusions. Non-pharmacological therapy based on D+ET improves peripheral chemoreflex control of MSNA in MetSyn. This autonomic change is more pronounced in MetSyn+OSA, in whom D+ET improves both peripheral and central chemoreflex controls. In addition, D+ET improves sleep disorder in MetSyn+OSA. Altogether, these findings suggest that D+ET reduce cardiovascular risk in patients with MetSyn mainly in those with OSA.
- © 2011 by American Heart Association, Inc.