0580 Obstructive Sleep Apnea and Daytime QT Interval by 12-Lead ECG

Introduction The association between obstructive sleep apnea (OSA) and sudden cardiac death (SCD) has been described. A prolonged QT interval is a recognized marker of abnormal ventricular repolarization linked to increased risk of SCD. We hypothesized that patients with OSA would have more marked abnormalities in daytime QT interval. Methods We identified consecutive patients who underwent clinically indicated diagnostic polysomnography with a 12-lead ECG at a single academic sleep center. Heart rate-corrected QT intervals (QTc) were compared by OSA severity class (normal/mild: apnea hypopnea index (AHI) 30) adjusting for age, sex, body mass index, hypertension, and heart failure (HF). Further evaluation was performed by dichotomizing patients into severe (AHI >30/hr) and non-severe (450msec / >470msec for men/women, respectively). Results A total of 249 patients (50.2% female, mean age 57.2 [12.5]) were included. This cohort had a high burden of cardiovascular disease (73% with hypertension, 20% with HF). Abnormal QTc was present in 34% of males and 31% of females. QTc increased across OSA groups (normal/mild: 435.6 msec; moderate: 431.36; severe: 444.4, p= 0.03). Patients with severe OSA had longer QTc compared with normal/mild OSA (mean difference 10.0msec [0.5,19.0], p=0.04). When stratified dichotomously, patients with severe OSA had longer QTc compared to non-severe (444.4 msec vs. 433.48 msec, p=0.004). Severe OSA was also associated with abnormal QTc (OR 2.68 [1.34,5.48], p=0.006). There was significant interaction by HF status as the difference in QTc by OSA status (non-severe vs. severe) was more prominent in patients with HF (456.1 msec [435.3-476.8] vs. 480.5 [458.9-502.1], p=0.028). Conclusion In a single sleep center cohort at elevated cardiovascular risk, patients with severe OSA had a prolonged daytime QTc compared to those with normal to mild OSA. Further, the prevalence of clinically significant abnormal QTc was higher in the severe (vs. non-severe) OSA group . The presence of severe OSA may represent a novel risk of SCD particularly in patients with HF. Support (If Any) None