Comparative analysis of cardiac autonomic dysfunction between apnea-predominant and hypopnea-predominant obstructive sleep apnea: a study matched for age, sex, and apnea-hypopnea index Short running title: cardiovascular risk of apnea vs. hypopnea in OSA

초록

Purpose Comparative knowledge of cardiac autonomic dysfunction between apnea and hypopnea events is limited. This study aimed to investigate the differences in cardiac autonomic dysfunction between apnea-predominant and hypopneapredominant in patients with obstructive sleep apnea (OSA). Methods This was a single-center retrospective study conducted at Kangwon National University Hospital. Patients were selected based on standard polysomnographic diagnostic criteria for OSA. Patients were categorized into apnea-or hypopnea-predominant groups according to the proportion of apneas within apnea-hypopnea index (AHI) and matched for age, sex, and AHI. Heart rate variability (HRV) metrics were calculated from nocturnal electrocardiogram. SPSS version 20.0 was used for statistical analyses. Results Polysomnographic parameters (AHI, oxygen desaturation index, arousal, and oxygen saturation) of 473 patients correlated with HF, LF/HF, and low frequency normalized unit (LFnu). In the matched cohort, no differences were found between the two groups in basic characteristics, except the hypopnea-predominant group had a higher body mass index (28.9 +/- 4.6 vs. 27.1 +/- 3.6, respectively, p = 0.003, Cohen's d = 0.44). Frequency domain analyses showed comparable results: TP (p = 0.450), VLF (p = 0.862), LF (p = 0.514), and HF (p = 0.251). Additionally, for apnea-predominant and hypopneapredominant groups, LF/HF (3.1 +/- 1.9 vs. 3.1 +/- 2.1, respectively; p = 0.968, Cohen's d = 0.00) and LFnu (70.7 +/- 11.8 vs. 69.3 +/- 13.7, respectively; p = 0.480, Cohen's d = 0.11) were comparable. Conclusion No significant differences were found in HRV between the apnea-predominant and hypopnea-predominant groups after matching for age, sex, and AHI. Therefore, the cardiac autonomic dysfunctions associated with apnea and hypopnea events should be considered equivalent in patients with OSA.

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