Influence of gender on the QT interval variability and duration in different wake-sleep stages in non-sleep apneic individuals: Analysis of polysomnographic recordings.

Introduction: The aim of the study was to determine the influence of gender and sleep stages, especially rapid eye movement sleep (REM), on QT interval variability and duration in normal subjects.

Methods: Polysomnographic recordings of 24 male and 24 female patients without obstructive sleep apnea were analyzed. In each patient, the QT interval variability index (QTVI) and the corrected QT interval (QTc) values were calculated as means of 2 awake, 4 non-rapid eye movement sleep (NREM) and 3 REM episodes, 300s each. For the QTc calculation, five different correction formulas were used.

Results: Gender-related differences in the QT interval variability and duration were detected between all sleep stages (P<0.05). In males, mean values of QTVI while awake, in NREM and REM sleep were -1.1±0.2, -1.1±0.3, -1.3±0.2. In females, mean values of QTVI were -0.9±0.4, -0.9±0.4, and -1.1±0.3, respectively. No difference between sleep stages was detected in the mean values of QTVI and QTc in both groups (P>0.05).

Conclusion: The results of our study demonstrate no significant overall impact of sleep stages on ventricular repolarization variability and duration during physiological sleep in both genders. We found gender differences in the mean values of QTVI and QTc during different sleep stages, which confirm that gender is a modulating factor of ventricular repolarization.