The pure effects of obstructive sleep apnea syndrome on cardiac autonomic functions: heart rate turbulence analysis

A. Erdem, O.T. Dogan, O.C. Yontar, K. Epozturk, M.F. Ozlu, S. Ozturk, S.S. Ayhan, F.H. Erdem, M. Yazici, I. Akkurt, F. Talay

Department of Cardiology, Faculty of Medicine, Abant Izzet Baysal University, Bolu, Turkey. cardiology14@gmail.com

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• Cardiology

OBJECTIVES: To demonstrate the pure effect of obstructive sleep apnea syndrome (OSAS) on cardiac autonomic function (CAF) using heart rate turbulence (HRT) parameters.

PATIENTS AND METHODS: A total of 64 patients with OSAS and 30 age- and gender-matched healthy subjects were enrolled. All subjects had normal coronary arteries and were free from diabetes mellitus (DM) and hypertension (HT). The HRT parameters (TO, turbulence onset; TS, turbulence slope) were obtained from 24-h ambulatory electrocardiogram (ECG) recordings. HRT parameters were compared between groups, and the relationship between HRT and the apnea-hypopnea index (AHI) was examined.

RESULTS: No between-group differences were found in age or gender. Mean TO was significantly higher in the OSAS group than in healthy controls (0.89 ± 0.5, -0.08 ± 0.26; p < 0.001; respectively). The mean TS did not differ between the two groups (2.81 ± 3.06 versus 3.14 ± 2.33; p = 0.212). The AHI was positively correlated with TO (r = 0.845, p < 0.001). The multiple logistic regression analysis revealed that after adjustment for other variables, TO was a significant and independent predictor of AHI, OR 2.394 (95% CI: 1.596-3.591).

CONCLUSIONS: HRT (TO in particular) is correlated with AHI. Thus, impaired HRT may be an important factor underlying the occurrence of arrhythmia and sudden cardiac death in patients with OSAS.

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