Heart rate turbulence (HRT) is regarded as a parameter of cardiac autonomic dysfunction. Several studies have suggested that patients with sleep disordered breathing (SDB) have an impaired HRT, which play a role in the relationship between SDB and risk of cardiovascular morbidity and mortality. However, the impact of SDB on HRT independent from obesity is still debatable. Data of eligible subjects who underwent sleep test and 24 h Holter electrocardiogram (ECG) recording from 2009-2012 were analyzed. HRT parameters, turbulence onset (TO), and turbulence slope (TS) in the 24 h recording, while awakening, and sleeping (TO-24 h, TO-awake, TO-sleep, TS-24 h, TS-awake, and TS-sleep, respectively) were compared across subjects with no-to-mild, moderate, and severe SDB. Univariable and multivariable regression analyses including TO or TS as a dependent variable were performed. Data from 41 subjects were evaluated. Compared with the no-to-mild and moderate SDB groups, in the severe SDB group, the TO-24 h and TO-awake were significantly greater, and the TS-24 h, TS-awake, and TS-sleep were significantly lower. In multivariable analyses, the apnea-hypopnea index (AHI) was correlated directly with TO-24 h (coefficient, 0.36; P = 0.03) and TO-awake (coefficient, 0.40; P = 0.01). SDB severity, as represented by AHI, is related to HRT impairments in non-obese subjects. SDB, independent from obesity, may affect cardiac autonomic dysfunction.
Keywords: Autonomic nerve system; Baroreflex sensitivity; Heart rate variability; Sleep apnea; Ventricular premature beat.