0553 Changes in QTc and QT Variability in Patients with OSA with and Without Heart Failure with PAP Based on Sleep Stage

Abstract Introduction Obstructive sleep apnea (OSA) is characterized by episodes of partial or complete collapse of the upper airway. OSA has been associated with increases in QTc interval and QT variability—risk factors for ventricular arrhythmias and death. This study explores how QTc and QT Variability change with positive airway pressure therapy (PAP) in patients without heart failure (HF), HF with preserved ejection fraction (HFpEF), and HF with reduced ejection fraction (HFrEF) based on sleep stage. Methods Consecutive patients with OSA undergoing diagnostic and PAP titration polysomnography (PSG) were included for analysis. Electrocardiogram (ECG) analysis during PSG was performed using Comprehensive Analysis of Repolarization Signal (COMPAS) software for the longest apnea/hypopnea events in NREM and REM for the diagnostic period as well as on the highest CPAP or BPAP pressure delivered for the titration PSG. Both Bazett’s (QTbc=QT/RR1/2) and Fridericia’s (QTfc=QT/RR1/3) corrections were used to calculate corrected QT. QT variability measures included the standard deviation of QT intervals (SDQT), normalized QT interval variance (QTVN), short-term interval beat-to-beat QT variability (STVQT) and QT Variability Index (QTVi). Sleep stages were characterized as Non-Rapid eye movement (NREM) vs. REM. Results Ninety two patient diagnostic and 92 titration PSG were reviewed (54% male, age 54 ± 15 years, BMI 38.5 ± 8.9, AHI 51.8/hr ± 39.0, minimum spO2 74.9% ± 14.4). Only eight percent of the patients had HF. There were no significant differences in QTfc and QTbc in NREM and REM. In the no HF cohort, QTVi decreased significantly in REM (n=31) during titration (0.78 ±1.79) when compared to baseline (1.64 ± 1.65), p=0.0026. In the no HF cohort, no significant changes were noted in QT variability during NREM (n=66) in the titration PSG when compared to the diagnostic PSG. No other findings in QT variability were statistically significant including the HFrEF and HfpEF cohorts however those sample sizes were very small. Conclusion PAP in patients with no HF may result in decreased QT variability and the effects may be varied based on sleep stage. Our findings need to be verified in larger cohorts. Support (if any) American Academy of Sleep Medicine Foundation, National Institutes of Health , The University of Arizona