Sleep-Disordered Breathing Destabilizes Ventricular Repolarization

RATIONALE Sleep-disordered breathing (SDB) increases the risk of cardiac arrhythmias, sudden death, and all-cause mortality. OBJECTIVES To characterize the associations between SDB, intermittent hypoxemia, and the QT variability index (QTVI), a measure of ventricular repolarization lability associated with a higher risk for cardiac arrhythmias, sudden death, and cardiovascular mortality. METHODS Polysomnograms from three cohorts were used: a matched sample of 122 participants with and without severe SDB, a matched sample of 52 participants with and without incident SDB, and a cohort of 19 healthy adults exposed to intermittent hypoxia and ambient air on two separate days. Electrocardiographic measures were calculated from one-lead electrocardiograms. MEASUREMENTS AND MAIN RESULTS Compared to those without SDB, participants with severe SDB had larger QTVI (-1.19 vs. -1.43, P =0.027), heart rate (68.34 vs. 64.92 beats/minute; P =0.028), and hypoxemia burden during sleep as assessed by the total sleep time with oxygen saturation less than 90% (TST 90 ; 11.39% vs. 1.32%, P