A pilot study of heart rate variability and apneic-hypopneic events in non-obese women with polycystic ovary syndrome during sleep

Background: Patients with polycystic ovary syndrome (PCOS) have a higher apnea-hypopnea index (AHI) than did controls. The relationship between heart rate variability (HRV) changes and apneic-hypopneic events in non-obese women with PCOS during sleep is yet to be determined. Methods: All participants (14 untreated women with PCOS and 11 age- and BMI-controlled healthy women, with mean body mass indexes of 21.51 ± 0.63 and 21.27 ± 0.66 Kg/cm ², respectively) underwent whole-night standard polysomnographic (PSG) monitoring and assessment of serum hormone and homeostasis model assessment of insulin resistance (HOMA-IR). Short-term HRV (in different sleep stages) and long-term HRV (6-hour sleep) were obtained by a power spectral analys is. Results: The AHI and arousal index during the non-rapid eye movement stage (AHI _NREM and ARI _NREM) were both higher in non-obese women with PCOS than those in the control group (0.032 ± 0.028 vs. 0.698 ± 0.243 p = 0.004; 11.45 ± 0.864 vs. 8.636 ± 0.847 p = 0.045). Triangular interpolation of the NN interval histogram (TINN) of long-term HRV in the PCOS group was also lower (303.9 ± 19.23 vs. 355.9 ±1 0.97, p = 0.0484) TINN in all subjects was negatively correlated to the AHI, after adjusting for age, body fat percentage, and serum androgens. TINN had a negative relation with highly sensitive C-reactive protein (hsCRP), while AHI _REM was positively related to hsCRP. Conclusions: Non-obese patients with PCOS showed poorer long-term TINN during sleep compared to the controls. The TINN was related to AHI and hsCRP. PCOS patients suffered from worsened cardiac nerve autonomous function that could lead to long-term cardiovascular risk during sleep even when they are not obese.