Daytime cardiac repolarization in patients with obstructive sleep apnea

Abstract

Purpose Obstructive sleep apnea (OSA) has been implicated in complications of cardiovascular disease, including arrhythmias and sudden cardiac death (SCD). Prolonged QT interval is associated with arrhythmias and SCD in patients with cardiovascular disease and apparently healthy humans. Apneic episodes during sleep in OSA patients are associated with QT prolongation due to increased vagal activity, but it is not understood whether chronic QT prolongation persists during normoxic daytime wakefulness. Methods To determine whether daytime QT intervals in OSA patients are prolonged compared to control subjects, we recruited 97 (76 male, 21 female) newly diagnosed patients with OSA [apnea-hypopnea index (AHI) ≥5 events/h] and 168 (100 male, 68 female) healthy volunteers (AHI <5 events/h) and measured daytime resting QT and RR intervals from the electrocardiograms to determine QT prolongation corrected for heart rate (QTc). Results All subjects with OSA were older and heavier, with increased heart rate and significantly increased AHI, arousal index, and reduced oxygen saturation (SpO2) during sleep, and spent less time in sleep with >90% SpO2 compared to respective controls. QTc in patients with OSA (410±3.3 for male and 433±5.6 for female) was significantly increased compared to respective control groups (399±2.9 for male and 417±2.9 for female), after adjustment for age and body mass index. Conclusions Our data show that OSA in either men or women is associated with a significant increase in resting daytime QTc. The propensity for ventricular arrhythmias in patients with OSA may be a result of abnormalities in resting cardiac repolarization.

Effect of Sleep-Disordered Breathing on Appropriate Implantable Cardioverter-Defibrillator Therapy in Patients With Heart Failure

“…29 Several electrocardiography-based studies have showed that patients with SDB exhibit abnormal ventricular repolarization, including prolongation of the QTc interval, prolongation of the interval between the peak and end of the T wave (Tp-e), the Tp-e/QT ratio, and the Tp-e/QTc ratio, which have all been implicated as risk factors for ventricular arrhythmogenesis. 30, 31 …”

Sleep-disordered breathing and daytime cardiac conduction abnormalities on 12-lead electrocardiogram in community-dwelling older men

“…However, we did not find any association of SDB with daytime QTc in this study. In contrast, a recent case-control study [38] in younger subjects (30–50 years old) reported longer daytime QTc in patients with SDB compared to those without. However, no associations were reported between OSA severity defined by AHI and daytime QTc.…”

Clues to the Pathophysiology of Sudden Cardiac Death in Obstructive Sleep Apnea

“…As mentioned above, studies examining the day-to-night correlation of myocardial instability markers, cardiac arrhythmias, provide contradictory information [25,27,42,51,54]. This is undoubtedly of clinical interest but does not allow us to draw strong conclusions about the circadian influence on SCD.…”

“…Studies which have examined the efficacy of CPAP in patients with cardiac arrhythmia and OSA, evaluated markers such as QT elongation, Tp-e intervals, atrial fibrillation progression, ventricular arrhythmia rate, atrioventricular block grade, and sinus arrest [25,26,[58][59][60]. However, these findings are not sufficient to recommend the obligatory implementation of CPAP treatment in order to prevent SCD.…”

“…The repolarization disorders that manifest the QT interval elongation were presented by Latshang et al [24], who established reliable relationships between hypoxia and the magnitude of the corrected QT interval. Interestingly, during the day, in the absence of episodes of hypoxia, OSA patients had an increased SCD risk against the background of a prolonged QT interval, which, according to Shamsuzzaman et al [25], may reflect the voltage of the compensatory capabilities of buffer electrolyte systems. Kilicaslan et al [26], on the other hand, did not observe a significant QT prolongation, but revealed an increase in Tp-e interval, Tp-e/ QT ratio, and Tp-e/QTc ratio among OSA patients.…”