Key result
REM sleep did not significantly alter mean QT interval duration or variability compared to NREM sleep in male patients without obstructive sleep apnea.
Why the study?
Does REM sleep affect QT interval duration and variability compared to NREM sleep and awake states in nonapneic male patients?
Observational (n=30)
Does REM sleep affect QT interval duration and variability compared to NREM sleep and awake states in nonapneic male patients?
Physiological sympathetic surges during REM sleep do not induce repolarization variability in patients without structural heart disease, suggesting that elevated QTVI seen in OSA patients is pathological rather than a normal physiological response.
Supports QT variability in OSA as pathological; leaves open effects in structural heart disease or women.
The aim of the study was to determine whether different sleep stages, especially REM sleep, affect QT interval duration and variability in male patients without obstructive sleep apnea (OSA). Polysomnographic recordings of 30 patients were analyzed. Beat-to-beat QT interval variability was calculated using QTV index (QTVI) formula. For QTc interval calculation, in addition to Bazett's formula, linear and parabolic heart rate correction formulas with two separate α values were used. QTVI and QTc values were calculated as means of 2 awake, 3 NREM, and 3 REM sleep episodes; the duration of each episode was 300 sec. Mean QTVI values were not statistically different between sleep stages. Therefore, elevated QTVI values found in patients with OSA cannot be interpreted as physiological sympathetic impact during REM sleep and should be considered as a risk factor for potentially life-threatening ventricular arrhythmias. The absence of difference of the mean QTc interval values between NREM and REM stages seems to confirm our conclusion that sympathetic surges during REM stage do not induce repolarization variability. In patients without notable structural and electrical remodeling of myocardium, physiological elevation in sympathetic activity during REM sleep remains subthreshold concerning clinically significant increase of myocardial electrical instability.
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Viigimäe et al. (2015) conducted an observational in Without obstructive sleep apnea (n=30). REM sleep vs. NREM sleep and awake stages was evaluated on QT interval duration (QTc) and variability (QTVI). REM sleep did not significantly alter mean QT interval duration or variability compared to NREM sleep in male patients without obstructive sleep apnea.
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