title: QT Interval Variability Index and QT Interval Duration in Different Sleep Stages: Analysis of Polysomnographic Recordings in Nonapneic Male Patients.
abstract: 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.
authors.affiliation: Technomedicum, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia ; Tallinn Health Care College, Kännu 67, 13418 Tallinn, Estonia.
authors.forename: Moonika
authors.initials: M
authors.lastname: Viigimae
authors.affiliation: Technomedicum, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia.
authors.forename: Deniss
authors.initials: D
authors.lastname: Karai
authors.affiliation: Mae Pindmaa Sleep Clinic, Narva mnt 112, 10127 Tallinn, Estonia.
authors.forename: Peeter
authors.initials: P
authors.lastname: Pirn
authors.affiliation: Technomedicum, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia.
authors.forename: Kristjan
authors.initials: K
authors.lastname: Pilt
authors.affiliation: Technomedicum, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia.
authors.forename: Kalju
authors.initials: K
authors.lastname: Meigas
authors.affiliation: Technomedicum, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia.
authors.forename: Jyri
authors.initials: J
authors.lastname: Kaik
mesh_terms: D000328:Adult; D002318:Cardiovascular Diseases / Q000150:complications / Q000503:physiopathology*; D004562:Electrocardiography; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology; D012895:Sleep, REM / Q000502:physiology*