Clinically Different Phenotypes of Obstructive Sleep Apnea according to 24 Hours Heart Rate Tachogram Pattern

Background and Objective Heart rate vatiability (HRV) parameters are altered during sleep in patients with obstructive sleep apnea (OSA). Nondipping of nocturnal heart rate during sleep is characteristic, but not all patients with OSA show this. The aim of this study was to identify differences in OSA patients with or without nocturnal heart rate dipping. Methods We retrospectively reviewed patients (n = 40) who were confirmed to have OSA [4% Oxygen desaturation index (ODI4) > 5/hr) by a simplified sleep study and underwent a 24 hours Holter electrocardiogram. The OSA patients were compared with control subjects (n = 72), who had been found to have no significant medical diseases. Results Most HRV parameters were lowered in OSA patients [standard deviation of all normal R-R intervals (SDNN): 99.23 vs. 149.06 ms: p < 0.0001]. The OSA patients were divided to two subgroups according to their 24 hours HR tachogram patterns. A HR nondipper subgroup (n = 18) showed a marked decrease in SDNN when compared with a HR dipper subgroup (n = 22)(SDNN 71.72 vs. 121.72 ms: p < 0.0001). SDNN was not associated with a severity index of OSA (ODI4)(r = −0.15, p = 0.3619). Conclusions In the OSA patients, most HRV parameters (SDNN, standard deviation of the average normal R-R intervals for each 5-min period (SDANN), percentage of adjacent cycles that are > 50 ms apart (pNN50%), root mean square successive differences in milliseconds were lower than in the control subjects. The OSA patients can be divided to two subgroups according to a 24 hours HR tachogram patterns (HR dipper and nondipper). In HR nondipper OSA subgroup, HRV parameters (SDNN, SDANN), Mean SaO2 and basal heart rate during sleep were markedly lowered, but were not associated with an OSA severity (ODI4).

Abstract licence: CC BY-NC-ND

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