The differences between daytime and nighttime heart rate variability may usefully predict the apnea-hypopnea index in patients with obstructive sleep apnea

초록

Study Objectives: The association between daytime/nighttime heart rate variability (HRV) and the apnea-hypopnea index (AHI) remains unclear. We sought a relationship between AHI and the daytime-to-nighttime HRV ratio as measured by 24-hour Holter monitoring in patients with obstructive sleep apnea. Methods: We prospectively enrolled 66 patients who visited our sleep clinic complaining of habitual snoring or sleep apnea. All underwent 24-hour Holter monitoring (to measure HRV) combined with full-night polysomnography. Sixty-two met our enrollment criteria. We evaluated the associations between HRV frequency domains and the polysomnography indices. We also considered medical histories and anthropometric data. Results: The nighttime very-low-frequency (VLF), low-frequency (LF), and high-frequency HRVs were significantly higher than the daytime values. On correlation analysis, the day/night VLF (r =.550, P <.001), LF (r =.556, P <.001), and high-frequency (r =.303, P =.017) HRVs were significantly related to the AHI. Of the day/night HRV ratios, the VLF (P for trend =.003) and LF (P for trend =.013) ratios decreased significantly by obstructive sleep apnea severity. Multivariable analysis showed that the day/night VLF (beta = 16.387, P <.001) and day/night LF (beta = 25.248, P <.001) were independently (and significantly) associated with the AHI. Conclusions: Twenty-four-hour Holter monitoring may usefully predict AHI. The day/night VLF and day/night LF ratios tended to decrease by obstructive sleep apnea severity and were independently associated with the AHI.

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