0868 Cardiac Remodeling: Apnea-Hypopnea Index as a Predictor for Changes in Left Atrial Volume

Introduction Left atrial (LA) size and volume are of interest in sleep-disordered breathing (SDB) as they are associated with cardiac arrhythmias. However, whether the apnea-hypopnea index (AHI) predicts LA longitudinal changes over time remains unknown. Methods This retrospective cohort study includes adults (≥18 years) without congestive heart failure (CHF) who were referred for a diagnostic in-laboratory polysomnogram (PSG) between January 2019 and March 2020; a baseline echocardiogram within one year of the PSG; and a follow-up echocardiogram more than one year after the initial studies. Clinical, PSG and echocardiographic variables, including LA volume and LA size, were abstracted from the medical record. SDB was classified as absent, mild, moderate, or severe (AHI ≤4.9/h, 5.0-14.9/h, 15.0-29.9/h, and ≥30/h, respectively). Regression models were used to assess the baseline cross-sectional relationships between AHI and LA measures, and the association of baseline AHI with LA changes over time. Results We identified 103 patients (58.8% male, median age 66 years (interquartile range, IQR 52-71)) with and without SDB (AHI median 19.9, IQR 7.3 – 35.6). The median time between baseline and follow-up echocardiograms was 3.2 years (IQR 2.3-4.1). AHI was associated with larger LA volume (β=0.64, p=0.0002) and LA size (β=0.08, p=0.04) at baseline. AHI also predicted changes in LA volume over time (β=0.57, p=0.02), but not changes in LA size. A dose-dependent relationship between SDB severity and changes in LA volume was noted: Individuals without OSA demonstrated a slight decrease in LA volume over time (median -7, IQR -36 - -5) whereas those with severe SDB demonstrated an increase in LV volume (median 13, IQR -9 – +18). Individuals with mild/moderate SDB fell between those groups. Conclusion Many patients with SDB are at risk for cardiac arrhythmias. Our results indicate that SDB severity at baseline predicts changes in LA volume over time. These findings may help identify patients at risk for LA enlargement and associated arrhythmias, and suggest a potential opportunity for early intervention to decrease cardiovascular risk. Support (if any)