Acute Effects of Obstructive Sleep Apnea on QT interval




Davis, Tyler
Elias, Christopher
Burk, John
Smith, Michael


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Over 20 million people in the United States suffer from Obstructive Sleep Apnea (OSA). Compared to the general population, OSA patients are 2.6 times more likely to experience sudden cardiac death (SCD), and it is suspected that this is due, in part, to QT prolongation leading to fatal dysrhythmias. We recently showed that 20 min of simulated OSA in healthy young individuals caused significant increases in QTc, however, it is not known what effect actual OSA events have on QT interval and what factors influence these responses. Thus, the purpose of this study was to evaluate whether obstructive apneic events in OSA patients leads to QT prolongation compared to baseline. Methods: We determined QTc intervals (determined by Bazett’s formula) from the electrocardiograms of 14 patients undergoing polysomnography for diagnosis of OSA and titration of treatment with positive airway pressure. IRB approval was obtained for our protocol (UNTHSC #2018-019). Patients that were selected had an apnea hypopnea index >20/Hr and had no prior myocardial infarction or heart failure. Each patient’s ECG during their sleep study was analyzed to assess QT interval throughout the night. Baseline QT intervals were compared to QT intervals during obstructive apneas before midnight (Early) and apneas after midnight (Late), thus, representing those in which there were few prior apneas (Early) versus those with numerous prior apneas (Late). The QTc intervals were compared between baseline awake and baseline asleep, and between baseline and Late apneas. Statistical comparisons were made with paired t tests. Results: Baseline QTc intervals were not different between awake and sleep (p > 0.60); however, during apneas (whether Early or Late), the QTc intervals were significantly prolonged (p = 0.008). Conclusions: In conclusion, OSA is often associated with acute QTc prolongation with the magnitude ranging from 5-42 msec in this patient cohort. Further analyses will be performed to determine factors that affect the magnitude of QT prolongation accompanying apneas during the night. In addition, future studies will focus on QTc changes in OSA patients with prior heart disease, as these are the patients at greatest risk for developing serious arrhythmias during the night.